added migrated 2.x add-ons

Signed-off-by: Kai Kreuzer <kai@openhab.org>

bundles/org.openhab.binding.mqtt.homeassistant/.classpath

@@ -0,0 +1,38 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="src" output="target/classes" path="src/main/java">
+		<attributes>
+			<attribute name="optional" value="true"/>
+			<attribute name="maven.pomderived" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry excluding="**" kind="src" output="target/classes" path="src/main/resources">
+		<attributes>
+			<attribute name="maven.pomderived" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="src" output="target/test-classes" path="src/test/java">
+		<attributes>
+			<attribute name="optional" value="true"/>
+			<attribute name="maven.pomderived" value="true"/>
+			<attribute name="test" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-11">
+		<attributes>
+			<attribute name="maven.pomderived" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER">
+		<attributes>
+			<attribute name="maven.pomderived" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry excluding="**" kind="src" output="target/test-classes" path="src/test/resources">
+		<attributes>
+			<attribute name="maven.pomderived" value="true"/>
+			<attribute name="test" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="output" path="target/classes"/>
+</classpath>

bundles/org.openhab.binding.mqtt.homeassistant/.project

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>org.openhab.binding.mqtt.homeassistant</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+		<buildCommand>
+			<name>org.eclipse.m2e.core.maven2Builder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+		<nature>org.eclipse.m2e.core.maven2Nature</nature>
+	</natures>
+</projectDescription>

bundles/org.openhab.binding.mqtt.homeassistant/NOTICE

@@ -0,0 +1,44 @@
+This content is produced and maintained by the Eclipse SmartHome project.
+
+* Project home: https://openhab.org/
+
+== Declared Project Licenses
+
+This program and the accompanying materials are made available under the terms
+of the Eclipse Public License 2.0 which is available at
+https://www.eclipse.org/legal/epl-2.0/.
+
+The MQTT Homie convention is made available under the MIT license, attached at the end of this file.
+
+== Source Code
+
+https://github.com/eclipse/smarthome
+
+== Copyright Holders
+
+See the NOTICE file distributed with the source code at
+https://github.com/eclipse/smarthome/blob/master/NOTICE
+for detailed information regarding copyright ownership.
+
+== MIT license ==
+MIT License
+
+Copyright (c) 2017 Marvin Roger
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

bundles/org.openhab.binding.mqtt.homeassistant/README.md

@@ -0,0 +1,18 @@
+# HomeAssistant MQTT Components Binding
+
+HomeAssistant MQTT Components are recognized as well. The base topic needs to be **homeassistant**. 
+The mapping is structured like this:
+
+
+| HA MQTT               | Framework     | Example MQTT topic                 |
+|-----------------------|---------------|------------------------------------|
+| Object                | Thing         | homeassistant/../../object         |
+| Component+Node        | Channel Group | homeassistant/component/node/object|
+| -> Component Features | Channel       | state/topic/defined/in/comp/config |
+
+## Limitations
+
+* The HomeAssistant Fan Components only support ON/OFF.
+* The HomeAssistant Cover Components only support OPEN/CLOSE/STOP.
+* The HomeAssistant Light Component only supports RGB color changes.
+* The HomeAssistant Climate Components is not yet supported.

bundles/org.openhab.binding.mqtt.homeassistant/pom.xml

@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+  <modelVersion>4.0.0</modelVersion>
+
+  <parent>
+    <groupId>org.openhab.addons.bundles</groupId>
+    <artifactId>org.openhab.addons.reactor.bundles</artifactId>
+    <version>3.0.0-SNAPSHOT</version>
+  </parent>
+
+  <artifactId>org.openhab.binding.mqtt.homeassistant</artifactId>
+
+  <name>openHAB Add-ons :: Bundles :: MQTT HomeAssistant Convention</name>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.openhab.addons.bundles</groupId>
+      <artifactId>org.openhab.binding.mqtt</artifactId>
+      <version>${project.version}</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.openhab.addons.bundles</groupId>
+      <artifactId>org.openhab.binding.mqtt.generic</artifactId>
+      <version>${project.version}</version>
+      <scope>provided</scope>
+    </dependency>
+  </dependencies>
+</project>

bundles/org.openhab.binding.mqtt.homeassistant/src/main/feature/feature.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<features name="org.openhab.binding.mqtt.homeassistant-${project.version}" xmlns="http://karaf.apache.org/xmlns/features/v1.4.0">
+	<repository>mvn:org.openhab.core.features.karaf/org.openhab.core.features.karaf.openhab-core/${ohc.version}/xml/features</repository>
+
+	<feature name="openhab-binding-mqtt-homeassistant" description="MQTT Binding Homeassistant" version="${project.version}">
+		<feature>openhab-runtime-base</feature>
+		<feature>openhab-transport-mqtt</feature>
+		<bundle start-level="80">mvn:org.openhab.addons.bundles/org.openhab.binding.mqtt/${project.version}</bundle>
+		<bundle start-level="81">mvn:org.openhab.addons.bundles/org.openhab.binding.mqtt.generic/${project.version}</bundle>
+		<bundle start-level="82">mvn:org.openhab.addons.bundles/org.openhab.binding.mqtt.homeassistant/${project.version}</bundle>
+	</feature>
+
+</features>

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/generic/internal/MqttBindingConstants.java

@@ -0,0 +1,33 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.generic.internal;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.openhab.core.thing.ThingTypeUID;
+
+/**
+ * The {@link MqttBindingConstants} class defines common constants, which are
+ * used across the whole binding.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class MqttBindingConstants {
+
+    public static final String BINDING_ID = "mqtt";
+
+    // List of all Thing Type UIDs
+    public static final ThingTypeUID HOMEASSISTANT_MQTT_THING = new ThingTypeUID(BINDING_ID, "homeassistant");
+
+    public static final String CONFIG_HA_CHANNEL = "mqtt:ha_channel";
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/generic/internal/MqttThingHandlerFactory.java

@@ -0,0 +1,96 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.generic.internal;
+
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.apache.commons.lang.StringUtils;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.MqttChannelTypeProvider;
+import org.openhab.binding.mqtt.generic.TransformationServiceProvider;
+import org.openhab.binding.mqtt.homeassistant.internal.handler.HomeAssistantThingHandler;
+import org.openhab.core.thing.Thing;
+import org.openhab.core.thing.ThingTypeUID;
+import org.openhab.core.thing.binding.BaseThingHandlerFactory;
+import org.openhab.core.thing.binding.ThingHandler;
+import org.openhab.core.thing.binding.ThingHandlerFactory;
+import org.openhab.core.transform.TransformationHelper;
+import org.openhab.core.transform.TransformationService;
+import org.osgi.service.component.ComponentContext;
+import org.osgi.service.component.annotations.Activate;
+import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Deactivate;
+import org.osgi.service.component.annotations.Reference;
+
+/**
+ * The {@link MqttThingHandlerFactory} is responsible for creating things and thing
+ * handlers.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@Component(service = ThingHandlerFactory.class)
+@NonNullByDefault
+public class MqttThingHandlerFactory extends BaseThingHandlerFactory implements TransformationServiceProvider {
+    private @NonNullByDefault({}) MqttChannelTypeProvider typeProvider;
+    private static final Set<ThingTypeUID> SUPPORTED_THING_TYPES_UIDS = Stream
+            .of(MqttBindingConstants.HOMEASSISTANT_MQTT_THING).collect(Collectors.toSet());
+
+    @Override
+    public boolean supportsThingType(ThingTypeUID thingTypeUID) {
+        return SUPPORTED_THING_TYPES_UIDS.contains(thingTypeUID) || isHomeassistantDynamicType(thingTypeUID);
+    }
+
+    private boolean isHomeassistantDynamicType(ThingTypeUID thingTypeUID) {
+        return StringUtils.equals(MqttBindingConstants.BINDING_ID, thingTypeUID.getBindingId())
+                && StringUtils.startsWith(thingTypeUID.getId(), MqttBindingConstants.HOMEASSISTANT_MQTT_THING.getId());
+    }
+
+    @Activate
+    @Override
+    protected void activate(ComponentContext componentContext) {
+        super.activate(componentContext);
+    }
+
+    @Deactivate
+    @Override
+    protected void deactivate(ComponentContext componentContext) {
+        super.deactivate(componentContext);
+    }
+
+    @Reference
+    protected void setChannelProvider(MqttChannelTypeProvider provider) {
+        this.typeProvider = provider;
+    }
+
+    protected void unsetChannelProvider(MqttChannelTypeProvider provider) {
+        this.typeProvider = null;
+    }
+
+    @Override
+    protected @Nullable ThingHandler createHandler(Thing thing) {
+        ThingTypeUID thingTypeUID = thing.getThingTypeUID();
+
+        if (supportsThingType(thingTypeUID)) {
+            return new HomeAssistantThingHandler(thing, typeProvider, this, 10000, 2000);
+        }
+        return null;
+    }
+
+    @Override
+    public @Nullable TransformationService getTransformationService(String type) {
+        return TransformationHelper.getTransformationService(bundleContext, type);
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/AbstractComponent.java

@@ -0,0 +1,220 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.stream.Collectors;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.ChannelStateUpdateListener;
+import org.openhab.binding.mqtt.generic.MqttChannelTypeProvider;
+import org.openhab.binding.mqtt.generic.utils.FutureCollector;
+import org.openhab.binding.mqtt.generic.values.Value;
+import org.openhab.binding.mqtt.homeassistant.generic.internal.MqttBindingConstants;
+import org.openhab.binding.mqtt.homeassistant.internal.CFactory.ComponentConfiguration;
+import org.openhab.core.io.transport.mqtt.MqttBrokerConnection;
+import org.openhab.core.thing.ChannelGroupUID;
+import org.openhab.core.thing.type.ChannelDefinition;
+import org.openhab.core.thing.type.ChannelGroupDefinition;
+import org.openhab.core.thing.type.ChannelGroupType;
+import org.openhab.core.thing.type.ChannelGroupTypeBuilder;
+import org.openhab.core.thing.type.ChannelGroupTypeUID;
+
+/**
+ * A HomeAssistant component is comparable to an ESH channel group.
+ * It has a name and consists of multiple channels.
+ *
+ * @author David Graeff - Initial contribution
+ * @param <C> Config class derived from {@link BaseChannelConfiguration}
+ */
+@NonNullByDefault
+public abstract class AbstractComponent<C extends BaseChannelConfiguration> {
+    // Component location fields
+    private final ComponentConfiguration componentConfiguration;
+    protected final ChannelGroupTypeUID channelGroupTypeUID;
+    protected final ChannelGroupUID channelGroupUID;
+    protected final HaID haID;
+
+    // Channels and configuration
+    protected final Map<String, CChannel> channels = new TreeMap<>();
+    // The hash code ({@link String#hashCode()}) of the configuration string
+    // Used to determine if a component has changed.
+    protected final int configHash;
+    protected final String channelConfigurationJson;
+    protected final C channelConfiguration;
+
+    protected boolean configSeen;
+
+    /**
+     * Provide a thingUID and HomeAssistant topic ID to determine the ESH channel group UID and type.
+     *
+     * @param thing A ThingUID
+     * @param haID A HomeAssistant topic ID
+     * @param configJson The configuration string
+     * @param gson A Gson instance
+     */
+    public AbstractComponent(CFactory.ComponentConfiguration componentConfiguration, Class<C> clazz) {
+        this.componentConfiguration = componentConfiguration;
+
+        this.channelConfigurationJson = componentConfiguration.getConfigJSON();
+        this.channelConfiguration = componentConfiguration.getConfig(clazz);
+        this.configHash = channelConfigurationJson.hashCode();
+
+        this.haID = componentConfiguration.getHaID();
+
+        String groupId = this.haID.getGroupId(channelConfiguration.unique_id);
+
+        this.channelGroupTypeUID = new ChannelGroupTypeUID(MqttBindingConstants.BINDING_ID, groupId);
+        this.channelGroupUID = new ChannelGroupUID(componentConfiguration.getThingUID(), groupId);
+
+        this.configSeen = false;
+
+        String availability_topic = this.channelConfiguration.availability_topic;
+        if (availability_topic != null) {
+            componentConfiguration.getTracker().addAvailabilityTopic(availability_topic,
+                    this.channelConfiguration.payload_available, this.channelConfiguration.payload_not_available);
+        }
+    }
+
+    protected CChannel.Builder buildChannel(String channelID, Value valueState, String label,
+            ChannelStateUpdateListener channelStateUpdateListener) {
+        return new CChannel.Builder(this, componentConfiguration, channelID, valueState, label,
+                channelStateUpdateListener);
+    }
+
+    public void setConfigSeen() {
+        this.configSeen = true;
+    }
+
+    /**
+     * Subscribes to all state channels of the component and adds all channels to the provided channel type provider.
+     *
+     * @param connection The connection
+     * @param channelStateUpdateListener A listener
+     * @return A future that completes as soon as all subscriptions have been performed. Completes exceptionally on
+     *         errors.
+     */
+    public CompletableFuture<@Nullable Void> start(MqttBrokerConnection connection, ScheduledExecutorService scheduler,
+            int timeout) {
+        return channels.values().parallelStream().map(v -> v.start(connection, scheduler, timeout))
+                .collect(FutureCollector.allOf());
+    }
+
+    /**
+     * Unsubscribes from all state channels of the component.
+     *
+     * @return A future that completes as soon as all subscriptions removals have been performed. Completes
+     *         exceptionally on errors.
+     */
+    public CompletableFuture<@Nullable Void> stop() {
+        return channels.values().parallelStream().map(CChannel::stop).collect(FutureCollector.allOf());
+    }
+
+    /**
+     * Add all channel types to the channel type provider.
+     *
+     * @param channelTypeProvider The channel type provider
+     */
+    public void addChannelTypes(MqttChannelTypeProvider channelTypeProvider) {
+        channelTypeProvider.setChannelGroupType(groupTypeUID(), type());
+        channels.values().forEach(v -> v.addChannelTypes(channelTypeProvider));
+    }
+
+    /**
+     * Removes all channels from the channel type provider.
+     * Call this if the corresponding Thing handler gets disposed.
+     *
+     * @param channelTypeProvider The channel type provider
+     */
+    public void removeChannelTypes(MqttChannelTypeProvider channelTypeProvider) {
+        channels.values().forEach(v -> v.removeChannelTypes(channelTypeProvider));
+        channelTypeProvider.removeChannelGroupType(groupTypeUID());
+    }
+
+    /**
+     * Each HomeAssistant component corresponds to an ESH Channel Group Type.
+     */
+    public ChannelGroupTypeUID groupTypeUID() {
+        return channelGroupTypeUID;
+    }
+
+    /**
+     * The unique id of this component within the ESH framework.
+     */
+    public ChannelGroupUID uid() {
+        return channelGroupUID;
+    }
+
+    /**
+     * Component (Channel Group) name.
+     */
+    public String name() {
+        return channelConfiguration.name;
+    }
+
+    /**
+     * Each component consists of multiple ESH Channels.
+     */
+    public Map<String, CChannel> channelTypes() {
+        return channels;
+    }
+
+    /**
+     * Return a components channel. A HomeAssistant MQTT component consists of multiple functions
+     * and those are mapped to one or more ESH channels. The channel IDs are constants within the
+     * derived Component, like the {@link ComponentSwitch#switchChannelID}.
+     *
+     * @param channelID The channel ID
+     * @return A components channel
+     */
+    public @Nullable CChannel channel(String channelID) {
+        return channels.get(channelID);
+    }
+
+    /**
+     * @return Returns the configuration hash value for easy comparison.
+     */
+    public int getConfigHash() {
+        return configHash;
+    }
+
+    /**
+     * Return the channel group type.
+     */
+    public ChannelGroupType type() {
+        final List<ChannelDefinition> channelDefinitions = channels.values().stream().map(CChannel::type)
+                .collect(Collectors.toList());
+        return ChannelGroupTypeBuilder.instance(channelGroupTypeUID, name()).withChannelDefinitions(channelDefinitions)
+                .build();
+    }
+
+    /**
+     * Resets all channel states to state UNDEF. Call this method after the connection
+     * to the MQTT broker got lost.
+     */
+    public void resetState() {
+        channels.values().forEach(CChannel::resetState);
+    }
+
+    /**
+     * Return the channel group definition for this component.
+     */
+    public ChannelGroupDefinition getGroupDefinition() {
+        return new ChannelGroupDefinition(channelGroupUID.getId(), groupTypeUID(), name(), null);
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/BaseChannelConfiguration.java

@@ -0,0 +1,161 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import java.util.List;
+import java.util.Map;
+
+import org.apache.commons.lang.StringUtils;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.core.thing.Thing;
+import org.openhab.core.util.UIDUtils;
+
+import com.google.gson.Gson;
+import com.google.gson.annotations.JsonAdapter;
+import com.google.gson.annotations.SerializedName;
+
+/**
+ * Base class for home assistant configurations.
+ *
+ * @author Jochen Klein - Initial contribution
+ */
+@NonNullByDefault
+public abstract class BaseChannelConfiguration {
+
+    /**
+     * This class is needed, to be able to parse only the common base attributes.
+     * Without this, {@link BaseChannelConfiguration} cannot be instantiated, as it is abstract.
+     * This is needed during the discovery.
+     */
+    private static class Config extends BaseChannelConfiguration {
+        public Config() {
+            super("private");
+        }
+    }
+
+    /**
+     * Parse the configJSON into a subclass of {@link BaseChannelConfiguration}
+     *
+     * @param configJSON
+     * @param gson
+     * @param clazz
+     * @return configuration object
+     */
+    public static <C extends BaseChannelConfiguration> C fromString(final String configJSON, final Gson gson,
+            final Class<C> clazz) {
+        return gson.fromJson(configJSON, clazz);
+    }
+
+    /**
+     * Parse the base properties of the configJSON into a {@link BaseChannelConfiguration}
+     *
+     * @param configJSON
+     * @param gson
+     * @return configuration object
+     */
+    public static BaseChannelConfiguration fromString(final String configJSON, final Gson gson) {
+        return fromString(configJSON, gson, Config.class);
+    }
+
+    public String name;
+
+    protected String icon = "";
+    protected int qos; // defaults to 0 according to HA specification
+    protected boolean retain; // defaults to false according to HA specification
+    protected @Nullable String value_template;
+    protected @Nullable String unique_id;
+
+    protected @Nullable String availability_topic;
+    protected String payload_available = "online";
+    protected String payload_not_available = "offline";
+
+    @SerializedName(value = "~")
+    protected String tilde = "";
+
+    protected BaseChannelConfiguration(String defaultName) {
+        this.name = defaultName;
+    }
+
+    public @Nullable String expand(@Nullable String value) {
+        return value == null ? null : value.replaceAll("~", tilde);
+    }
+
+    protected @Nullable Device device;
+
+    static class Device {
+        @JsonAdapter(ListOrStringDeserializer.class)
+        protected @Nullable List<String> identifiers;
+        protected @Nullable List<Connection> connections;
+        protected @Nullable String manufacturer;
+        protected @Nullable String model;
+        protected @Nullable String name;
+        protected @Nullable String sw_version;
+
+        @Nullable
+        public String getId() {
+            return StringUtils.join(identifiers, "_");
+        }
+    }
+
+    @JsonAdapter(ConnectionDeserializer.class)
+    static class Connection {
+        protected @Nullable String type;
+        protected @Nullable String identifier;
+    }
+
+    public String getThingName() {
+        @Nullable
+        String result = null;
+
+        if (this.device != null) {
+            result = this.device.name;
+        }
+        if (result == null) {
+            result = name;
+        }
+        return result;
+    }
+
+    public String getThingId(String defaultId) {
+        @Nullable
+        String result = null;
+        if (this.device != null) {
+            result = this.device.getId();
+        }
+        if (result == null) {
+            result = unique_id;
+        }
+        return UIDUtils.encode(result != null ? result : defaultId);
+    }
+
+    public Map<String, Object> appendToProperties(Map<String, Object> properties) {
+        final Device device_ = device;
+        if (device_ == null) {
+            return properties;
+        }
+        final String manufacturer = device_.manufacturer;
+        if (manufacturer != null) {
+            properties.put(Thing.PROPERTY_VENDOR, manufacturer);
+        }
+        final String model = device_.model;
+        if (model != null) {
+            properties.put(Thing.PROPERTY_MODEL_ID, model);
+        }
+        final String sw_version = device_.sw_version;
+        if (sw_version != null) {
+            properties.put(Thing.PROPERTY_FIRMWARE_VERSION, sw_version);
+        }
+        return properties;
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/CChannel.java

@@ -0,0 +1,243 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import java.net.URI;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ScheduledExecutorService;
+
+import org.apache.commons.lang.StringUtils;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.ChannelConfigBuilder;
+import org.openhab.binding.mqtt.generic.ChannelState;
+import org.openhab.binding.mqtt.generic.ChannelStateTransformation;
+import org.openhab.binding.mqtt.generic.ChannelStateUpdateListener;
+import org.openhab.binding.mqtt.generic.MqttChannelTypeProvider;
+import org.openhab.binding.mqtt.generic.TransformationServiceProvider;
+import org.openhab.binding.mqtt.generic.values.Value;
+import org.openhab.binding.mqtt.homeassistant.generic.internal.MqttBindingConstants;
+import org.openhab.binding.mqtt.homeassistant.internal.CFactory.ComponentConfiguration;
+import org.openhab.core.config.core.Configuration;
+import org.openhab.core.io.transport.mqtt.MqttBrokerConnection;
+import org.openhab.core.thing.Channel;
+import org.openhab.core.thing.ChannelUID;
+import org.openhab.core.thing.binding.builder.ChannelBuilder;
+import org.openhab.core.thing.type.ChannelDefinition;
+import org.openhab.core.thing.type.ChannelDefinitionBuilder;
+import org.openhab.core.thing.type.ChannelType;
+import org.openhab.core.thing.type.ChannelTypeBuilder;
+import org.openhab.core.thing.type.ChannelTypeUID;
+import org.openhab.core.types.StateDescription;
+
+/**
+ * An {@link AbstractComponent}s derived class consists of one or multiple channels.
+ * Each component channel consists of the determined ESH channel type, channel type UID and the
+ * ESH channel description itself as well as the the channels state.
+ *
+ * After the discovery process has completed and the tree of components and component channels
+ * have been built up, the channel types are registered to a custom channel type provider
+ * before adding the channel descriptions to the ESH Thing themselves.
+ * <br>
+ * <br>
+ * An object of this class creates the required {@link ChannelType} and {@link ChannelTypeUID} as well
+ * as keeps the {@link ChannelState} and {@link Channel} in one place.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class CChannel {
+    private static final String JINJA = "JINJA";
+
+    private final ChannelUID channelUID;
+    private final ChannelState channelState; // Channel state (value)
+    private final Channel channel; // ESH Channel
+    private final ChannelType type;
+    private final ChannelTypeUID channelTypeUID;
+    private final ChannelStateUpdateListener channelStateUpdateListener;
+
+    private CChannel(ChannelUID channelUID, ChannelState channelState, Channel channel, ChannelType type,
+            ChannelTypeUID channelTypeUID, ChannelStateUpdateListener channelStateUpdateListener) {
+        super();
+        this.channelUID = channelUID;
+        this.channelState = channelState;
+        this.channel = channel;
+        this.type = type;
+        this.channelTypeUID = channelTypeUID;
+        this.channelStateUpdateListener = channelStateUpdateListener;
+    }
+
+    public ChannelUID getChannelUID() {
+        return channelUID;
+    }
+
+    public Channel getChannel() {
+        return channel;
+    }
+
+    public ChannelState getState() {
+        return channelState;
+    }
+
+    public CompletableFuture<@Nullable Void> stop() {
+        return channelState.stop();
+    }
+
+    public CompletableFuture<@Nullable Void> start(MqttBrokerConnection connection, ScheduledExecutorService scheduler,
+            int timeout) {
+        // Make sure we set the callback again which might have been nulled during an stop
+        channelState.setChannelStateUpdateListener(this.channelStateUpdateListener);
+
+        return channelState.start(connection, scheduler, timeout);
+    }
+
+    public void addChannelTypes(MqttChannelTypeProvider channelTypeProvider) {
+        channelTypeProvider.setChannelType(channelTypeUID, type);
+    }
+
+    public void removeChannelTypes(MqttChannelTypeProvider channelTypeProvider) {
+        channelTypeProvider.removeChannelType(channelTypeUID);
+    }
+
+    public ChannelDefinition type() {
+        return new ChannelDefinitionBuilder(channelUID.getId(), channelTypeUID).build();
+    }
+
+    public void resetState() {
+        channelState.getCache().resetState();
+    }
+
+    public static class Builder {
+        private AbstractComponent<?> component;
+        private ComponentConfiguration componentConfiguration;
+        private String channelID;
+        private Value valueState;
+        private String label;
+        private @Nullable String state_topic;
+        private @Nullable String command_topic;
+        private boolean retain;
+        private boolean trigger;
+        private @Nullable Integer qos;
+        private ChannelStateUpdateListener channelStateUpdateListener;
+
+        private @Nullable String templateIn;
+
+        public Builder(AbstractComponent<?> component, ComponentConfiguration componentConfiguration, String channelID,
+                Value valueState, String label, ChannelStateUpdateListener channelStateUpdateListener) {
+            this.component = component;
+            this.componentConfiguration = componentConfiguration;
+            this.channelID = channelID;
+            this.valueState = valueState;
+            this.label = label;
+            this.channelStateUpdateListener = channelStateUpdateListener;
+        }
+
+        public Builder stateTopic(@Nullable String state_topic) {
+            this.state_topic = state_topic;
+            return this;
+        }
+
+        public Builder stateTopic(@Nullable String state_topic, @Nullable String... templates) {
+            this.state_topic = state_topic;
+            if (StringUtils.isNotBlank(state_topic)) {
+                for (String template : templates) {
+                    if (StringUtils.isNotBlank(template)) {
+                        this.templateIn = template;
+                        break;
+                    }
+                }
+            }
+            return this;
+        }
+
+        /**
+         * @deprecated use commandTopic(String, boolean, int)
+         * @param command_topic
+         * @param retain
+         * @return
+         */
+        @Deprecated
+        public Builder commandTopic(@Nullable String command_topic, boolean retain) {
+            this.command_topic = command_topic;
+            this.retain = retain;
+            return this;
+        }
+
+        public Builder commandTopic(@Nullable String command_topic, boolean retain, int qos) {
+            this.command_topic = command_topic;
+            this.retain = retain;
+            this.qos = qos;
+            return this;
+        }
+
+        public Builder trigger(boolean trigger) {
+            this.trigger = trigger;
+            return this;
+        }
+
+        public CChannel build() {
+            return build(true);
+        }
+
+        public CChannel build(boolean addToComponent) {
+            ChannelUID channelUID;
+            ChannelState channelState; // Channel state (value)
+            Channel channel; // ESH Channel
+            ChannelType type;
+            ChannelTypeUID channelTypeUID;
+
+            channelUID = new ChannelUID(component.channelGroupUID, channelID);
+            channelTypeUID = new ChannelTypeUID(MqttBindingConstants.BINDING_ID,
+                    channelUID.getGroupId() + "_" + channelID);
+            channelState = new ChannelState(
+                    ChannelConfigBuilder.create().withRetain(retain).withQos(qos).withStateTopic(state_topic)
+                            .withCommandTopic(command_topic).makeTrigger(trigger).build(),
+                    channelUID, valueState, channelStateUpdateListener);
+
+            if (StringUtils.isBlank(state_topic) || this.trigger) {
+                type = ChannelTypeBuilder.trigger(channelTypeUID, label)
+                        .withConfigDescriptionURI(URI.create(MqttBindingConstants.CONFIG_HA_CHANNEL)).build();
+            } else {
+                StateDescription description = valueState.createStateDescription(command_topic == null).build()
+                        .toStateDescription();
+                type = ChannelTypeBuilder.state(channelTypeUID, label, channelState.getItemType())
+                        .withConfigDescriptionURI(URI.create(MqttBindingConstants.CONFIG_HA_CHANNEL))
+                        .withStateDescription(description).build();
+            }
+
+            Configuration configuration = new Configuration();
+            configuration.put("config", component.channelConfigurationJson);
+            component.haID.toConfig(configuration);
+
+            channel = ChannelBuilder.create(channelUID, channelState.getItemType()).withType(channelTypeUID)
+                    .withKind(type.getKind()).withLabel(label).withConfiguration(configuration).build();
+
+            CChannel result = new CChannel(channelUID, channelState, channel, type, channelTypeUID,
+                    channelStateUpdateListener);
+
+            @Nullable
+            TransformationServiceProvider transformationProvider = componentConfiguration
+                    .getTransformationServiceProvider();
+
+            final String templateIn = this.templateIn;
+            if (templateIn != null && transformationProvider != null) {
+                channelState
+                        .addTransformation(new ChannelStateTransformation(JINJA, templateIn, transformationProvider));
+            }
+            if (addToComponent) {
+                component.channels.put(channelID, result);
+            }
+            return result;
+        }
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/CFactory.java

@@ -0,0 +1,140 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.AvailabilityTracker;
+import org.openhab.binding.mqtt.generic.ChannelStateUpdateListener;
+import org.openhab.binding.mqtt.generic.TransformationServiceProvider;
+import org.openhab.core.thing.ThingUID;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.gson.Gson;
+
+/**
+ * A factory to create HomeAssistant MQTT components. Those components are specified at:
+ * https://www.home-assistant.io/docs/mqtt/discovery/
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class CFactory {
+    private static final Logger logger = LoggerFactory.getLogger(CFactory.class);
+
+    /**
+     * Create a HA MQTT component. The configuration JSon string is required.
+     *
+     * @param thingUID The Thing UID that this component will belong to.
+     * @param haID The location of this component. The HomeAssistant ID contains the object-id, node-id and
+     *            component-id.
+     * @param configJSON Most components expect a "name", a "state_topic" and "command_topic" like with
+     *            "{name:'Name',state_topic:'homeassistant/switch/0/object/state',command_topic:'homeassistant/switch/0/object/set'".
+     * @param updateListener A channel state update listener
+     * @return A HA MQTT Component
+     */
+    public static @Nullable AbstractComponent<?> createComponent(ThingUID thingUID, HaID haID,
+            String channelConfigurationJSON, ChannelStateUpdateListener updateListener, AvailabilityTracker tracker,
+            Gson gson, TransformationServiceProvider transformationServiceProvider) {
+        ComponentConfiguration componentConfiguration = new ComponentConfiguration(thingUID, haID,
+                channelConfigurationJSON, gson, updateListener, tracker)
+                        .transformationProvider(transformationServiceProvider);
+        try {
+            switch (haID.component) {
+                case "alarm_control_panel":
+                    return new ComponentAlarmControlPanel(componentConfiguration);
+                case "binary_sensor":
+                    return new ComponentBinarySensor(componentConfiguration);
+                case "camera":
+                    return new ComponentCamera(componentConfiguration);
+                case "cover":
+                    return new ComponentCover(componentConfiguration);
+                case "fan":
+                    return new ComponentFan(componentConfiguration);
+                case "climate":
+                    return new ComponentClimate(componentConfiguration);
+                case "light":
+                    return new ComponentLight(componentConfiguration);
+                case "lock":
+                    return new ComponentLock(componentConfiguration);
+                case "sensor":
+                    return new ComponentSensor(componentConfiguration);
+                case "switch":
+                    return new ComponentSwitch(componentConfiguration);
+            }
+        } catch (UnsupportedOperationException e) {
+            logger.warn("Not supported", e);
+        }
+        return null;
+    }
+
+    protected static class ComponentConfiguration {
+        private final ThingUID thingUID;
+        private final HaID haID;
+        private final String configJSON;
+        private final ChannelStateUpdateListener updateListener;
+        private final AvailabilityTracker tracker;
+        private final Gson gson;
+        private @Nullable TransformationServiceProvider transformationServiceProvider;
+
+        protected ComponentConfiguration(ThingUID thingUID, HaID haID, String configJSON, Gson gson,
+                ChannelStateUpdateListener updateListener, AvailabilityTracker tracker) {
+            this.thingUID = thingUID;
+            this.haID = haID;
+            this.configJSON = configJSON;
+            this.gson = gson;
+            this.updateListener = updateListener;
+            this.tracker = tracker;
+        }
+
+        public ComponentConfiguration transformationProvider(
+                TransformationServiceProvider transformationServiceProvider) {
+            this.transformationServiceProvider = transformationServiceProvider;
+            return this;
+        }
+
+        public ThingUID getThingUID() {
+            return thingUID;
+        }
+
+        public HaID getHaID() {
+            return haID;
+        }
+
+        public String getConfigJSON() {
+            return configJSON;
+        }
+
+        public ChannelStateUpdateListener getUpdateListener() {
+            return updateListener;
+        }
+
+        @Nullable
+        public TransformationServiceProvider getTransformationServiceProvider() {
+            return transformationServiceProvider;
+        }
+
+        public Gson getGson() {
+            return gson;
+        }
+
+        public AvailabilityTracker getTracker() {
+            return tracker;
+        }
+
+        public <C extends BaseChannelConfiguration> C getConfig(Class<C> clazz) {
+            return BaseChannelConfiguration.fromString(configJSON, gson, clazz);
+        }
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ChannelConfigurationTypeAdapterFactory.java

@@ -0,0 +1,148 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import java.io.IOException;
+import java.lang.reflect.Field;
+
+import org.apache.commons.lang.StringUtils;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+
+import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+
+/**
+ * This a Gson type adapter factory.
+ *
+ * It will create a type adapter for every class derived from {@link BaseChannelConfiguration} and ensures,
+ * that abbreviated names are replaces with their long versions during the read.
+ *
+ * In elements, whose name end in'_topic' '~' replacement is performed.
+ *
+ * The adapters also handle {@link BaseChannelConfiguration.Device}
+ *
+ * @author Jochen Klein - Initial contribution
+ */
+@NonNullByDefault
+public class ChannelConfigurationTypeAdapterFactory implements TypeAdapterFactory {
+
+    @Override
+    @Nullable
+    public <T> TypeAdapter<T> create(@Nullable Gson gson, @Nullable TypeToken<T> type) {
+        if (gson == null || type == null) {
+            return null;
+        }
+        if (BaseChannelConfiguration.class.isAssignableFrom(type.getRawType())) {
+            return createHAConfig(gson, type);
+        }
+        if (BaseChannelConfiguration.Device.class.isAssignableFrom(type.getRawType())) {
+            return createHADevice(gson, type);
+        }
+        return null;
+    }
+
+    /**
+     * Handle {@link BaseChannelConfiguration}
+     *
+     * @param gson
+     * @param type
+     * @return
+     */
+    private <T> TypeAdapter<T> createHAConfig(Gson gson, TypeToken<T> type) {
+        /* The delegate is the 'default' adapter */
+        final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
+
+        return new TypeAdapter<T>() {
+            @Override
+            public T read(@Nullable JsonReader in) throws IOException {
+                if (in == null) {
+                    return null;
+                }
+                /* read the object using the default adapter, but translate the names in the reader */
+                T result = delegate.read(MappingJsonReader.getConfigMapper(in));
+                /* do the '~' expansion afterwards */
+                expandTidleInTopics(BaseChannelConfiguration.class.cast(result));
+                return result;
+            }
+
+            @Override
+            public void write(@Nullable JsonWriter out, T value) throws IOException {
+                delegate.write(out, value);
+            }
+        };
+    }
+
+    private <T> TypeAdapter<T> createHADevice(Gson gson, TypeToken<T> type) {
+        /* The delegate is the 'default' adapter */
+        final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);
+
+        return new TypeAdapter<T>() {
+            @Override
+            public T read(@Nullable JsonReader in) throws IOException {
+                if (in == null) {
+                    return null;
+                }
+                /* read the object using the default adapter, but translate the names in the reader */
+                T result = delegate.read(MappingJsonReader.getDeviceMapper(in));
+                return result;
+            }
+
+            @Override
+            public void write(@Nullable JsonWriter out, T value) throws IOException {
+                delegate.write(out, value);
+            }
+        };
+    }
+
+    private void expandTidleInTopics(BaseChannelConfiguration config) {
+        Class<?> type = config.getClass();
+
+        String tilde = config.tilde;
+
+        while (type != Object.class) {
+            Field[] fields = type.getDeclaredFields();
+
+            for (Field field : fields) {
+                if (String.class.isAssignableFrom(field.getType()) && field.getName().endsWith("_topic")) {
+                    field.setAccessible(true);
+
+                    try {
+                        final String oldValue = (String) field.get(config);
+
+                        String newValue = oldValue;
+                        if (StringUtils.isNotBlank(oldValue)) {
+                            if (oldValue.charAt(0) == '~') {
+                                newValue = tilde + oldValue.substring(1);
+                            } else if (oldValue.charAt(oldValue.length() - 1) == '~') {
+                                newValue = oldValue.substring(0, oldValue.length() - 1) + tilde;
+                            }
+                        }
+
+                        field.set(config, newValue);
+                    } catch (IllegalArgumentException e) {
+                        throw new RuntimeException(e);
+                    } catch (IllegalAccessException e) {
+                        throw new RuntimeException(e);
+                    }
+                }
+            }
+
+            type = type.getSuperclass();
+        }
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ComponentAlarmControlPanel.java

@@ -0,0 +1,87 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.values.TextValue;
+
+/**
+ * A MQTT alarm control panel, following the https://www.home-assistant.io/components/alarm_control_panel.mqtt/
+ * specification.
+ *
+ * The implemented provides three state-less switches (For disarming, arming@home, arming@away) and one alarm state
+ * text.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class ComponentAlarmControlPanel extends AbstractComponent<ComponentAlarmControlPanel.ChannelConfiguration> {
+    public static final String stateChannelID = "alarm"; // Randomly chosen channel "ID"
+    public static final String switchDisarmChannelID = "disarm"; // Randomly chosen channel "ID"
+    public static final String switchArmHomeChannelID = "armhome"; // Randomly chosen channel "ID"
+    public static final String switchArmAwayChannelID = "armaway"; // Randomly chosen channel "ID"
+
+    /**
+     * Configuration class for MQTT component
+     */
+    static class ChannelConfiguration extends BaseChannelConfiguration {
+        ChannelConfiguration() {
+            super("MQTT Alarm");
+        }
+
+        protected @Nullable String code;
+
+        protected String state_topic = "";
+        protected String state_disarmed = "disarmed";
+        protected String state_armed_home = "armed_home";
+        protected String state_armed_away = "armed_away";
+        protected String state_pending = "pending";
+        protected String state_triggered = "triggered";
+
+        protected @Nullable String command_topic;
+        protected String payload_disarm = "DISARM";
+        protected String payload_arm_home = "ARM_HOME";
+        protected String payload_arm_away = "ARM_AWAY";
+    }
+
+    public ComponentAlarmControlPanel(CFactory.ComponentConfiguration componentConfiguration) {
+        super(componentConfiguration, ChannelConfiguration.class);
+
+        final String[] state_enum = { channelConfiguration.state_disarmed, channelConfiguration.state_armed_home,
+                channelConfiguration.state_armed_away, channelConfiguration.state_pending,
+                channelConfiguration.state_triggered };
+        buildChannel(stateChannelID, new TextValue(state_enum), channelConfiguration.name,
+                componentConfiguration.getUpdateListener())
+                        .stateTopic(channelConfiguration.state_topic, channelConfiguration.value_template)//
+                        .build();
+
+        String command_topic = channelConfiguration.command_topic;
+        if (command_topic != null) {
+            buildChannel(switchDisarmChannelID, new TextValue(new String[] { channelConfiguration.payload_disarm }),
+                    channelConfiguration.name, componentConfiguration.getUpdateListener())//
+                            .commandTopic(command_topic, channelConfiguration.retain)//
+                            .build();
+
+            buildChannel(switchArmHomeChannelID, new TextValue(new String[] { channelConfiguration.payload_arm_home }),
+                    channelConfiguration.name, componentConfiguration.getUpdateListener())//
+                            .commandTopic(command_topic, channelConfiguration.retain)//
+                            .build();
+
+            buildChannel(switchArmAwayChannelID, new TextValue(new String[] { channelConfiguration.payload_arm_away }),
+                    channelConfiguration.name, componentConfiguration.getUpdateListener())//
+                            .commandTopic(command_topic, channelConfiguration.retain)//
+                            .build();
+        }
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ComponentBinarySensor.java

@@ -0,0 +1,57 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.values.OnOffValue;
+
+/**
+ * A MQTT BinarySensor, following the https://www.home-assistant.io/components/binary_sensor.mqtt/ specification.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class ComponentBinarySensor extends AbstractComponent<ComponentBinarySensor.ChannelConfiguration> {
+    public static final String sensorChannelID = "sensor"; // Randomly chosen channel "ID"
+
+    /**
+     * Configuration class for MQTT component
+     */
+    static class ChannelConfiguration extends BaseChannelConfiguration {
+        ChannelConfiguration() {
+            super("MQTT Binary Sensor");
+        }
+
+        protected @Nullable String device_class;
+        protected boolean force_update = false;
+        protected int expire_after = 0;
+
+        protected String state_topic = "";
+        protected String payload_on = "ON";
+        protected String payload_off = "OFF";
+    }
+
+    public ComponentBinarySensor(CFactory.ComponentConfiguration componentConfiguration) {
+        super(componentConfiguration, ChannelConfiguration.class);
+
+        if (channelConfiguration.force_update) {
+            throw new UnsupportedOperationException("Component:Sensor does not support forced updates");
+        }
+
+        buildChannel(sensorChannelID, new OnOffValue(channelConfiguration.payload_on, channelConfiguration.payload_off),
+                channelConfiguration.name, componentConfiguration.getUpdateListener())//
+                        .stateTopic(channelConfiguration.state_topic, channelConfiguration.value_template)//
+                        .build();
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ComponentCamera.java

@@ -0,0 +1,49 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.openhab.binding.mqtt.generic.values.ImageValue;
+
+/**
+ * A MQTT camera, following the https://www.home-assistant.io/components/camera.mqtt/ specification.
+ *
+ * At the moment this only notifies the user that this feature is not yet supported.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class ComponentCamera extends AbstractComponent<ComponentCamera.ChannelConfiguration> {
+    public static final String cameraChannelID = "camera"; // Randomly chosen channel "ID"
+
+    /**
+     * Configuration class for MQTT component
+     */
+    static class ChannelConfiguration extends BaseChannelConfiguration {
+        ChannelConfiguration() {
+            super("MQTT Camera");
+        }
+
+        protected String topic = "";
+    }
+
+    public ComponentCamera(CFactory.ComponentConfiguration componentConfiguration) {
+        super(componentConfiguration, ChannelConfiguration.class);
+
+        ImageValue value = new ImageValue();
+
+        buildChannel(cameraChannelID, value, channelConfiguration.name, componentConfiguration.getUpdateListener())//
+                .stateTopic(channelConfiguration.topic)//
+                .build();
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ComponentClimate.java

@@ -0,0 +1,40 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+
+/**
+ * A MQTT climate component, following the https://www.home-assistant.io/components/climate.mqtt/ specification.
+ *
+ * At the moment this only notifies the user that this feature is not yet supported.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class ComponentClimate extends AbstractComponent<ComponentClimate.ChannelConfiguration> {
+
+    /**
+     * Configuration class for MQTT component
+     */
+    static class ChannelConfiguration extends BaseChannelConfiguration {
+        ChannelConfiguration() {
+            super("MQTT HVAC");
+        }
+    }
+
+    public ComponentClimate(CFactory.ComponentConfiguration componentConfiguration) {
+        super(componentConfiguration, ChannelConfiguration.class);
+        throw new UnsupportedOperationException("Component:Climate not supported yet");
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ComponentCover.java

@@ -0,0 +1,56 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.values.RollershutterValue;
+
+/**
+ * A MQTT Cover component, following the https://www.home-assistant.io/components/cover.mqtt/ specification.
+ *
+ * Only Open/Close/Stop works so far.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class ComponentCover extends AbstractComponent<ComponentCover.ChannelConfiguration> {
+    public static final String switchChannelID = "cover"; // Randomly chosen channel "ID"
+
+    /**
+     * Configuration class for MQTT component
+     */
+    static class ChannelConfiguration extends BaseChannelConfiguration {
+        ChannelConfiguration() {
+            super("MQTT Cover");
+        }
+
+        protected @Nullable String state_topic;
+        protected @Nullable String command_topic;
+        protected String payload_open = "OPEN";
+        protected String payload_close = "CLOSE";
+        protected String payload_stop = "STOP";
+    }
+
+    public ComponentCover(CFactory.ComponentConfiguration componentConfiguration) {
+        super(componentConfiguration, ChannelConfiguration.class);
+
+        RollershutterValue value = new RollershutterValue(channelConfiguration.payload_open,
+                channelConfiguration.payload_close, channelConfiguration.payload_stop);
+
+        buildChannel(switchChannelID, value, channelConfiguration.name, componentConfiguration.getUpdateListener())//
+                .stateTopic(channelConfiguration.state_topic, channelConfiguration.value_template)//
+                .commandTopic(channelConfiguration.command_topic, channelConfiguration.retain)//
+                .build();
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ComponentFan.java

@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.values.OnOffValue;
+
+/**
+ * A MQTT Fan component, following the https://www.home-assistant.io/components/fan.mqtt/ specification.
+ *
+ * Only ON/OFF is supported so far.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class ComponentFan extends AbstractComponent<ComponentFan.ChannelConfiguration> {
+    public static final String switchChannelID = "fan"; // Randomly chosen channel "ID"
+
+    /**
+     * Configuration class for MQTT component
+     */
+    static class ChannelConfiguration extends BaseChannelConfiguration {
+        ChannelConfiguration() {
+            super("MQTT Fan");
+        }
+
+        protected @Nullable String state_topic;
+        protected String command_topic = "";
+        protected String payload_on = "ON";
+        protected String payload_off = "OFF";
+    }
+
+    public ComponentFan(CFactory.ComponentConfiguration componentConfiguration) {
+        super(componentConfiguration, ChannelConfiguration.class);
+
+        OnOffValue value = new OnOffValue(channelConfiguration.payload_on, channelConfiguration.payload_off);
+        buildChannel(switchChannelID, value, channelConfiguration.name, componentConfiguration.getUpdateListener())//
+                .stateTopic(channelConfiguration.state_topic, channelConfiguration.value_template)//
+                .commandTopic(channelConfiguration.command_topic, channelConfiguration.retain)//
+                .build();
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ComponentLight.java

@@ -0,0 +1,175 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.stream.Stream;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.ChannelStateUpdateListener;
+import org.openhab.binding.mqtt.generic.mapping.ColorMode;
+import org.openhab.binding.mqtt.generic.values.ColorValue;
+import org.openhab.core.io.transport.mqtt.MqttBrokerConnection;
+import org.openhab.core.thing.ChannelUID;
+import org.openhab.core.types.Command;
+import org.openhab.core.types.State;
+
+/**
+ * A MQTT light, following the https://www.home-assistant.io/components/light.mqtt/ specification.
+ *
+ * This class condenses the three state/command topics (for ON/OFF, Brightness, Color) to one
+ * color channel.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class ComponentLight extends AbstractComponent<ComponentLight.ChannelConfiguration>
+        implements ChannelStateUpdateListener {
+    public static final String switchChannelID = "light"; // Randomly chosen channel "ID"
+    public static final String brightnessChannelID = "brightness"; // Randomly chosen channel "ID"
+    public static final String colorChannelID = "color"; // Randomly chosen channel "ID"
+
+    /**
+     * Configuration class for MQTT component
+     */
+    static class ChannelConfiguration extends BaseChannelConfiguration {
+        ChannelConfiguration() {
+            super("MQTT Light");
+        }
+
+        protected int brightness_scale = 255;
+        protected boolean optimistic = false;
+        protected @Nullable List<String> effect_list;
+
+        // Defines when on the payload_on is sent. Using last (the default) will send any style (brightness, color, etc)
+        // topics first and then a payload_on to the command_topic. Using first will send the payload_on and then any
+        // style topics. Using brightness will only send brightness commands instead of the payload_on to turn the light
+        // on.
+        protected String on_command_type = "last";
+
+        protected @Nullable String state_topic;
+        protected @Nullable String command_topic;
+        protected @Nullable String state_value_template;
+
+        protected @Nullable String brightness_state_topic;
+        protected @Nullable String brightness_command_topic;
+        protected @Nullable String brightness_value_template;
+
+        protected @Nullable String color_temp_state_topic;
+        protected @Nullable String color_temp_command_topic;
+        protected @Nullable String color_temp_value_template;
+
+        protected @Nullable String effect_command_topic;
+        protected @Nullable String effect_state_topic;
+        protected @Nullable String effect_value_template;
+
+        protected @Nullable String rgb_command_topic;
+        protected @Nullable String rgb_state_topic;
+        protected @Nullable String rgb_value_template;
+        protected @Nullable String rgb_command_template;
+
+        protected @Nullable String white_value_command_topic;
+        protected @Nullable String white_value_state_topic;
+        protected @Nullable String white_value_template;
+
+        protected @Nullable String xy_command_topic;
+        protected @Nullable String xy_state_topic;
+        protected @Nullable String xy_value_template;
+
+        protected String payload_on = "ON";
+        protected String payload_off = "OFF";
+    }
+
+    protected CChannel colorChannel;
+    protected CChannel switchChannel;
+    protected CChannel brightnessChannel;
+    private final @Nullable ChannelStateUpdateListener channelStateUpdateListener;
+
+    public ComponentLight(CFactory.ComponentConfiguration builder) {
+        super(builder, ChannelConfiguration.class);
+        this.channelStateUpdateListener = builder.getUpdateListener();
+        ColorValue value = new ColorValue(ColorMode.RGB, channelConfiguration.payload_on,
+                channelConfiguration.payload_off, 100);
+
+        // Create three MQTT subscriptions and use this class object as update listener
+        switchChannel = buildChannel(switchChannelID, value, channelConfiguration.name, this)//
+                // Some lights use the value_template field for the template, most use state_value_template
+                .stateTopic(channelConfiguration.state_topic, channelConfiguration.state_value_template,
+                        channelConfiguration.value_template)//
+                .commandTopic(channelConfiguration.command_topic, channelConfiguration.retain)//
+                .build(false);
+
+        colorChannel = buildChannel(colorChannelID, value, channelConfiguration.name, this)//
+                .stateTopic(channelConfiguration.rgb_state_topic, channelConfiguration.rgb_value_template)//
+                .commandTopic(channelConfiguration.rgb_command_topic, channelConfiguration.retain)//
+                .build(false);
+
+        brightnessChannel = buildChannel(brightnessChannelID, value, channelConfiguration.name, this)//
+                .stateTopic(channelConfiguration.brightness_state_topic, channelConfiguration.brightness_value_template)//
+                .commandTopic(channelConfiguration.brightness_command_topic, channelConfiguration.retain)//
+                .build(false);
+
+        channels.put(colorChannelID, colorChannel);
+    }
+
+    @Override
+    public CompletableFuture<@Nullable Void> start(MqttBrokerConnection connection, ScheduledExecutorService scheduler,
+            int timeout) {
+        return Stream.of(switchChannel, brightnessChannel, colorChannel) //
+                .map(v -> v.start(connection, scheduler, timeout)) //
+                .reduce(CompletableFuture.completedFuture(null), (f, v) -> f.thenCompose(b -> v));
+    }
+
+    @Override
+    public CompletableFuture<@Nullable Void> stop() {
+        return Stream.of(switchChannel, brightnessChannel, colorChannel) //
+                .map(v -> v.stop()) //
+                .reduce(CompletableFuture.completedFuture(null), (f, v) -> f.thenCompose(b -> v));
+    }
+
+    /**
+     * Proxy method to condense all three MQTT subscriptions to one channel
+     */
+    @Override
+    public void updateChannelState(ChannelUID channelUID, State value) {
+        ChannelStateUpdateListener listener = channelStateUpdateListener;
+        if (listener != null) {
+            listener.updateChannelState(colorChannel.getChannelUID(), value);
+        }
+    }
+
+    /**
+     * Proxy method to condense all three MQTT subscriptions to one channel
+     */
+    @Override
+    public void postChannelCommand(ChannelUID channelUID, Command value) {
+        ChannelStateUpdateListener listener = channelStateUpdateListener;
+        if (listener != null) {
+            listener.postChannelCommand(colorChannel.getChannelUID(), value);
+        }
+    }
+
+    /**
+     * Proxy method to condense all three MQTT subscriptions to one channel
+     */
+    @Override
+    public void triggerChannel(ChannelUID channelUID, String eventPayload) {
+        ChannelStateUpdateListener listener = channelStateUpdateListener;
+        if (listener != null) {
+            listener.triggerChannel(colorChannel.getChannelUID(), eventPayload);
+        }
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ComponentLock.java

@@ -0,0 +1,60 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import org.apache.commons.lang.StringUtils;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.values.OnOffValue;
+
+/**
+ * A MQTT lock, following the https://www.home-assistant.io/components/lock.mqtt/ specification.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class ComponentLock extends AbstractComponent<ComponentLock.ChannelConfiguration> {
+    public static final String switchChannelID = "lock"; // Randomly chosen channel "ID"
+
+    /**
+     * Configuration class for MQTT component
+     */
+    static class ChannelConfiguration extends BaseChannelConfiguration {
+        ChannelConfiguration() {
+            super("MQTT Lock");
+        }
+
+        protected boolean optimistic = false;
+
+        protected String state_topic = "";
+        protected String payload_lock = "LOCK";
+        protected String payload_unlock = "UNLOCK";
+        protected @Nullable String command_topic;
+    }
+
+    public ComponentLock(CFactory.ComponentConfiguration componentConfiguration) {
+        super(componentConfiguration, ChannelConfiguration.class);
+
+        // We do not support all HomeAssistant quirks
+        if (channelConfiguration.optimistic && StringUtils.isNotBlank(channelConfiguration.state_topic)) {
+            throw new UnsupportedOperationException("Component:Lock does not support forced optimistic mode");
+        }
+
+        buildChannel(switchChannelID,
+                new OnOffValue(channelConfiguration.payload_lock, channelConfiguration.payload_unlock),
+                channelConfiguration.name, componentConfiguration.getUpdateListener())//
+                        .stateTopic(channelConfiguration.state_topic, channelConfiguration.value_template)//
+                        .commandTopic(channelConfiguration.command_topic, channelConfiguration.retain)//
+                        .build();
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ComponentSensor.java

@@ -0,0 +1,75 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import java.util.regex.Pattern;
+
+import org.apache.commons.lang.StringUtils;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.values.NumberValue;
+import org.openhab.binding.mqtt.generic.values.TextValue;
+import org.openhab.binding.mqtt.generic.values.Value;
+
+/**
+ * A MQTT sensor, following the https://www.home-assistant.io/components/sensor.mqtt/ specification.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class ComponentSensor extends AbstractComponent<ComponentSensor.ChannelConfiguration> {
+    public static final String sensorChannelID = "sensor"; // Randomly chosen channel "ID"
+    private static final Pattern triggerIcons = Pattern.compile("^mdi:(toggle|gesture).*$");
+
+    /**
+     * Configuration class for MQTT component
+     */
+    static class ChannelConfiguration extends BaseChannelConfiguration {
+        ChannelConfiguration() {
+            super("MQTT Sensor");
+        }
+
+        protected @Nullable String unit_of_measurement;
+        protected @Nullable String device_class;
+        protected boolean force_update = false;
+        protected int expire_after = 0;
+
+        protected String state_topic = "";
+    }
+
+    public ComponentSensor(CFactory.ComponentConfiguration componentConfiguration) {
+        super(componentConfiguration, ChannelConfiguration.class);
+
+        if (channelConfiguration.force_update) {
+            throw new UnsupportedOperationException("Component:Sensor does not support forced updates");
+        }
+
+        Value value;
+
+        String uom = channelConfiguration.unit_of_measurement;
+
+        if (uom != null && StringUtils.isNotBlank(uom)) {
+            value = new NumberValue(null, null, null, uom);
+        } else {
+            value = new TextValue();
+        }
+
+        String icon = channelConfiguration.icon;
+
+        boolean trigger = triggerIcons.matcher(icon).matches();
+
+        buildChannel(sensorChannelID, value, channelConfiguration.name, componentConfiguration.getUpdateListener())//
+                .stateTopic(channelConfiguration.state_topic, channelConfiguration.value_template)//
+                .trigger(trigger).build();
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ComponentSwitch.java

@@ -0,0 +1,74 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import org.apache.commons.lang.StringUtils;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.values.OnOffValue;
+
+/**
+ * A MQTT switch, following the https://www.home-assistant.io/components/switch.mqtt/ specification.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class ComponentSwitch extends AbstractComponent<ComponentSwitch.ChannelConfiguration> {
+    public static final String switchChannelID = "switch"; // Randomly chosen channel "ID"
+
+    /**
+     * Configuration class for MQTT component
+     */
+    static class ChannelConfiguration extends BaseChannelConfiguration {
+        ChannelConfiguration() {
+            super("MQTT Switch");
+        }
+
+        protected @Nullable Boolean optimistic;
+
+        protected @Nullable String command_topic;
+        protected String state_topic = "";
+
+        protected @Nullable String state_on;
+        protected @Nullable String state_off;
+        protected String payload_on = "ON";
+        protected String payload_off = "OFF";
+
+        protected @Nullable String json_attributes_topic;
+        protected @Nullable String json_attributes_template;
+    }
+
+    public ComponentSwitch(CFactory.ComponentConfiguration componentConfiguration) {
+        super(componentConfiguration, ChannelConfiguration.class);
+
+        boolean optimistic = channelConfiguration.optimistic != null ? channelConfiguration.optimistic
+                : StringUtils.isBlank(channelConfiguration.state_topic);
+
+        if (optimistic && StringUtils.isNotBlank(channelConfiguration.state_topic)) {
+            throw new UnsupportedOperationException("Component:Switch does not support forced optimistic mode");
+        }
+
+        String state_on = channelConfiguration.state_on != null ? channelConfiguration.state_on
+                : channelConfiguration.payload_on;
+        String state_off = channelConfiguration.state_off != null ? channelConfiguration.state_off
+                : channelConfiguration.payload_off;
+
+        OnOffValue value = new OnOffValue(state_on, state_off, channelConfiguration.payload_on,
+                channelConfiguration.payload_off);
+
+        buildChannel(switchChannelID, value, "state", componentConfiguration.getUpdateListener())//
+                .stateTopic(channelConfiguration.state_topic, channelConfiguration.value_template)//
+                .commandTopic(channelConfiguration.command_topic, channelConfiguration.retain, channelConfiguration.qos)//
+                .build();
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ConnectionDeserializer.java

@@ -0,0 +1,36 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import java.lang.reflect.Type;
+
+import com.google.gson.*;
+
+/**
+ * The {@link ConnectionDeserializer} will de-serialize a connection-list
+ *
+ * see: https://www.home-assistant.io/integrations/sensor.mqtt/#connections
+ *
+ * @author Jan N. Klug - Initial contribution
+ */
+public class ConnectionDeserializer implements JsonDeserializer<BaseChannelConfiguration.Connection> {
+    @Override
+    public BaseChannelConfiguration.Connection deserialize(JsonElement json, Type typeOfT,
+            JsonDeserializationContext context) throws JsonParseException {
+        JsonArray list = json.getAsJsonArray();
+        BaseChannelConfiguration.Connection conn = new BaseChannelConfiguration.Connection();
+        conn.type = list.get(0).getAsString();
+        conn.identifier = list.get(1).getAsString();
+        return conn;
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/DiscoverComponents.java

@@ -0,0 +1,186 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import java.lang.ref.WeakReference;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.AvailabilityTracker;
+import org.openhab.binding.mqtt.generic.ChannelStateUpdateListener;
+import org.openhab.binding.mqtt.generic.TransformationServiceProvider;
+import org.openhab.binding.mqtt.generic.utils.FutureCollector;
+import org.openhab.core.io.transport.mqtt.MqttBrokerConnection;
+import org.openhab.core.io.transport.mqtt.MqttMessageSubscriber;
+import org.openhab.core.thing.ThingUID;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.gson.Gson;
+
+/**
+ * Responsible for subscribing to the HomeAssistant MQTT components wildcard topic, either
+ * in a time limited discovery mode or as a background discovery.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class DiscoverComponents implements MqttMessageSubscriber {
+    private final Logger logger = LoggerFactory.getLogger(DiscoverComponents.class);
+    private final ThingUID thingUID;
+    private final ScheduledExecutorService scheduler;
+    private final ChannelStateUpdateListener updateListener;
+    private final AvailabilityTracker tracker;
+    private final TransformationServiceProvider transformationServiceProvider;
+
+    protected final CompletableFuture<@Nullable Void> discoverFinishedFuture = new CompletableFuture<>();
+    private final Gson gson;
+
+    private @Nullable ScheduledFuture<?> stopDiscoveryFuture;
+    private WeakReference<@Nullable MqttBrokerConnection> connectionRef = new WeakReference<>(null);
+    protected @NonNullByDefault({}) ComponentDiscovered discoveredListener;
+    private int discoverTime;
+    private Set<String> topics = new HashSet<>();
+
+    /**
+     * Implement this to get notified of new components
+     */
+    public static interface ComponentDiscovered {
+        void componentDiscovered(HaID homeAssistantTopicID, AbstractComponent<?> component);
+    }
+
+    /**
+     * Create a new discovery object.
+     *
+     * @param thingUID The Thing UID to perform the discovery for.
+     * @param scheduler A scheduler for timeouts
+     * @param channelStateUpdateListener Channel update listener. Usually the handler.
+     */
+    public DiscoverComponents(ThingUID thingUID, ScheduledExecutorService scheduler,
+            ChannelStateUpdateListener channelStateUpdateListener, AvailabilityTracker tracker, Gson gson,
+            TransformationServiceProvider transformationServiceProvider) {
+        this.thingUID = thingUID;
+        this.scheduler = scheduler;
+        this.updateListener = channelStateUpdateListener;
+        this.gson = gson;
+        this.tracker = tracker;
+        this.transformationServiceProvider = transformationServiceProvider;
+    }
+
+    @Override
+    public void processMessage(String topic, byte[] payload) {
+        if (!topic.endsWith("/config")) {
+            return;
+        }
+
+        HaID haID = new HaID(topic);
+        String config = new String(payload);
+
+        AbstractComponent<?> component = null;
+
+        if (config.length() > 0) {
+            component = CFactory.createComponent(thingUID, haID, config, updateListener, tracker, gson,
+                    transformationServiceProvider);
+        }
+        if (component != null) {
+            component.setConfigSeen();
+
+            logger.trace("Found HomeAssistant thing {} component {}", haID.objectID, haID.component);
+            if (discoveredListener != null) {
+                discoveredListener.componentDiscovered(haID, component);
+            }
+        } else {
+            logger.debug("Configuration of HomeAssistant thing {} invalid: {}", haID.objectID, config);
+        }
+    }
+
+    /**
+     * Start a components discovery.
+     *
+     * <p>
+     * We need to consider the case that the remote client is using node IDs
+     * and also the case that no node IDs are used.
+     * </p>
+     *
+     * @param connection A MQTT broker connection
+     * @param discoverTime The time in milliseconds for the discovery to run. Can be 0 to disable the
+     *            timeout.
+     *            You need to call {@link #stopDiscovery(MqttBrokerConnection)} at some
+     *            point in that case.
+     * @param topicDescription Contains the object-id (=device id) and potentially a node-id as well.
+     * @param componentsDiscoveredListener Listener for results
+     * @return A future that completes normally after the given time in milliseconds or exceptionally on any error.
+     *         Completes immediately if the timeout is disabled.
+     */
+    public CompletableFuture<@Nullable Void> startDiscovery(MqttBrokerConnection connection, int discoverTime,
+            Set<HaID> topicDescriptions, ComponentDiscovered componentsDiscoveredListener) {
+        this.topics = topicDescriptions.stream().map(id -> id.getTopic("config")).collect(Collectors.toSet());
+        this.discoverTime = discoverTime;
+        this.discoveredListener = componentsDiscoveredListener;
+        this.connectionRef = new WeakReference<>(connection);
+
+        // Subscribe to the wildcard topic and start receive MQTT retained topics
+        this.topics.parallelStream().map(t -> connection.subscribe(t, this)).collect(FutureCollector.allOf())
+                .thenRun(this::subscribeSuccess).exceptionally(this::subscribeFail);
+
+        return discoverFinishedFuture;
+    }
+
+    private void subscribeSuccess() {
+        final MqttBrokerConnection connection = connectionRef.get();
+        // Set up a scheduled future that will stop the discovery after the given time
+        if (connection != null && discoverTime > 0) {
+            this.stopDiscoveryFuture = scheduler.schedule(() -> {
+                this.stopDiscoveryFuture = null;
+                this.topics.parallelStream().forEach(t -> connection.unsubscribe(t, this));
+                this.discoveredListener = null;
+                discoverFinishedFuture.complete(null);
+            }, discoverTime, TimeUnit.MILLISECONDS);
+        } else {
+            // No timeout -> complete immediately
+            discoverFinishedFuture.complete(null);
+        }
+    }
+
+    private @Nullable Void subscribeFail(Throwable e) {
+        final ScheduledFuture<?> scheduledFuture = this.stopDiscoveryFuture;
+        if (scheduledFuture != null) { // Cancel timeout
+            scheduledFuture.cancel(false);
+            this.stopDiscoveryFuture = null;
+        }
+        this.discoveredListener = null;
+        final MqttBrokerConnection connection = connectionRef.get();
+        if (connection != null) {
+            this.topics.parallelStream().forEach(t -> connection.unsubscribe(t, this));
+            connectionRef.clear();
+        }
+        discoverFinishedFuture.completeExceptionally(e);
+        return null;
+    }
+
+    /**
+     * Stops an ongoing discovery or do nothing if no discovery is running.
+     *
+     * @param connection A MQTT broker connection
+     */
+    public void stopDiscovery() {
+        subscribeFail(new Throwable("Stopped"));
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/HaID.java

@@ -0,0 +1,264 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+import org.apache.commons.lang.StringUtils;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.core.config.core.Configuration;
+import org.openhab.core.util.UIDUtils;
+
+/**
+ * HomeAssistant MQTT components use a specific MQTT topic layout,
+ * starting with a base prefix (usually "homeassistant"),
+ * followed by the component id, an optional node id and the object id.
+ *
+ * This helper class can split up an MQTT topic into such parts.
+ * <p>
+ * Implementation note: This is an immutable class.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class HaID {
+    public final String baseTopic;
+    public final String component;
+    public final String nodeID;
+    public final String objectID;
+
+    private final String topic;
+
+    /**
+     * Creates a {@link HaID} object for a given HomeAssistant MQTT topic.
+     *
+     * @param mqttTopic A topic like "homeassistant/binary_sensor/garden/config" or
+     *            "homeassistant/binary_sensor/0/garden/config"
+     */
+    public HaID(String mqttTopic) {
+        String[] strings = mqttTopic.split("/");
+        if (strings.length < 4 || strings.length > 5) {
+            throw new IllegalArgumentException("MQTT topic not a HomeAssistant topic (wrong length)!");
+        }
+        if (!"config".equals(strings[strings.length - 1])) {
+            throw new IllegalArgumentException("MQTT topic not a HomeAssistant topic ('config' missing)!");
+        }
+
+        baseTopic = strings[0];
+        component = strings[1];
+
+        if (strings.length == 5) {
+            nodeID = strings[2];
+            objectID = strings[3];
+        } else {
+            nodeID = "";
+            objectID = strings[2];
+        }
+
+        this.topic = createTopic(this);
+    }
+
+    public HaID() {
+        this("", "", "", "");
+    }
+
+    /**
+     * Creates a {@link HaID} by providing all components separately.
+     *
+     * @param baseTopic The base topic. Usually "homeassistant".
+     * @param objectID The object ID
+     * @param nodeID The node ID (can be the empty string)
+     * @param component The component ID
+     */
+    private HaID(String baseTopic, String objectID, String nodeID, String component) {
+        this.baseTopic = baseTopic;
+        this.objectID = objectID;
+        this.nodeID = nodeID;
+        this.component = component;
+        this.topic = createTopic(this);
+    }
+
+    private static final String createTopic(HaID id) {
+        StringBuilder str = new StringBuilder();
+        str.append(id.baseTopic).append('/').append(id.component).append('/');
+        if (StringUtils.isNotBlank(id.nodeID)) {
+            str.append(id.nodeID).append('/');
+        }
+        str.append(id.objectID).append('/');
+        return str.toString();
+    }
+
+    /**
+     * Extract the HaID information from a channel configuration.
+     * <p>
+     * <code>objectid</code>, <code>nodeid</code>, and <code>component</code> values are fetched from the configuration.
+     *
+     * @param baseTopic
+     * @param config
+     * @return newly created HaID
+     */
+    public static HaID fromConfig(String baseTopic, Configuration config) {
+        String component = (String) config.get("component");
+        String nodeID = (String) config.getProperties().getOrDefault("nodeid", "");
+        String objectID = (String) config.get("objectid");
+        return new HaID(baseTopic, objectID, nodeID, component);
+    }
+
+    /**
+     * Add the HaID information to a channel configuration.
+     * <p>
+     * <code>objectid</code>, <code>nodeid</code>, and <code>component</code> values are added to the configuration.
+     *
+     * @param config
+     * @return the modified configuration
+     */
+    public Configuration toConfig(Configuration config) {
+        config.put("objectid", objectID);
+        config.put("nodeid", nodeID);
+        config.put("component", component);
+        return config;
+    }
+
+    /**
+     * Extract the HaID information from a thing configuration.
+     * <p>
+     * <code>basetpoic</code> and <code>objectid</code> are taken from the configuration.
+     * The <code>objectid</code> string may be in the form <code>nodeid/objectid</code>.
+     * <p>
+     * The <code>component</code> component in the resulting HaID will be set to <code>+</code>.
+     * This enables the HaID to be used as an mqtt subscription topic.
+     *
+     * @param config
+     * @return newly created HaID
+     */
+    public static Collection<HaID> fromConfig(HandlerConfiguration config) {
+        Collection<HaID> result = new ArrayList<>();
+
+        for (String topic : config.topics) {
+            String[] parts = topic.split("/");
+
+            switch (parts.length) {
+                case 2:
+                    result.add(new HaID(config.basetopic, parts[1], "", parts[0]));
+                    break;
+                case 3:
+                    result.add(new HaID(config.basetopic, parts[2], parts[1], parts[0]));
+                    break;
+                default:
+                    throw new IllegalArgumentException(
+                            "Bad configuration. topic must be <component>/<objectId> or <component>/<nodeId>/<objectId>!");
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Return the topic to put into the HandlerConfiguration for this component.
+     * <p>
+     * <code>objectid</code> in the thing configuration will be
+     * <code>nodeID/objectID<code> from the HaID, if <code>nodeID</code> is not empty.
+     * <p>
+     *
+     * @return the short topic.
+     */
+    public String toShortTopic() {
+        String objectID = this.objectID;
+        if (StringUtils.isNotBlank(nodeID)) {
+            objectID = nodeID + "/" + objectID;
+        }
+
+        return component + "/" + objectID;
+    }
+
+    /**
+     * The default group id is the unique_id of the component, given in the config-json.
+     * If the unique id is not set, then a fallback is constructed from the HaID information.
+     *
+     * @return group id
+     */
+    public String getGroupId(@Nullable final String uniqueId) {
+        String result = uniqueId;
+
+        // the null test is only here so the compile knows, result is not null afterwards
+        if (result == null || StringUtils.isBlank(result)) {
+            StringBuilder str = new StringBuilder();
+
+            if (StringUtils.isNotBlank(nodeID)) {
+                str.append(nodeID).append('_');
+            }
+            str.append(objectID).append('_').append(component);
+            result = str.toString();
+        }
+
+        return UIDUtils.encode(result);
+    }
+
+    /**
+     * Return a topic, which can be used for a mqtt subscription.
+     * Defined values for suffix are:
+     * <ul>
+     * <li>config</li>
+     * <li>state</li>
+     * </ul>
+     *
+     * @return fallback group id
+     */
+    public String getTopic(String suffix) {
+        return topic + suffix;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + baseTopic.hashCode();
+        result = prime * result + component.hashCode();
+        result = prime * result + nodeID.hashCode();
+        result = prime * result + objectID.hashCode();
+        return result;
+    }
+
+    @Override
+    public boolean equals(@Nullable Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        HaID other = (HaID) obj;
+        if (!baseTopic.equals(other.baseTopic)) {
+            return false;
+        }
+        if (!component.equals(other.component)) {
+            return false;
+        }
+        if (!nodeID.equals(other.nodeID)) {
+            return false;
+        }
+        if (!objectID.equals(other.objectID)) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public String toString() {
+        return topic;
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/HandlerConfiguration.java

@@ -0,0 +1,87 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.openhab.binding.mqtt.homeassistant.internal.handler.HomeAssistantThingHandler;
+
+/**
+ * The {@link HomeAssistantThingHandler} manages Things that are responsible for
+ * HomeAssistant MQTT components.
+ * This class contains the necessary configuration for such a Thing handler.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class HandlerConfiguration {
+    /**
+     * hint: cannot be final, or <code>getConfigAs</code> will not work.
+     * The MQTT prefix topic
+     */
+    public String basetopic;
+
+    /**
+     * hint: cannot be final, or <code>getConfigAs</code> will not work.
+     * List of configuration topics.
+     * <ul>
+     * <li>
+     * Each topic is gets the base topic prepended.
+     * </li>
+     * <li>
+     * each topic has:
+     * <ol>
+     * <li>
+     * <code>component</code> (e.g. "switch", "light", ...)
+     * </li>
+     * <li>
+     * <code>node_id</code> (optional)
+     * </li>
+     * <li>
+     * <code>object_id</code> This is only to allow for separate topics for each device
+     * </li>
+     * <li>
+     * "config"
+     * </li>
+     * </ol>
+     * </li>
+     * </ul>
+     *
+     */
+    public List<String> topics;
+
+    public HandlerConfiguration() {
+        this("homeassistant", Collections.emptyList());
+    }
+
+    public HandlerConfiguration(String basetopic, List<String> topics) {
+        super();
+        this.basetopic = basetopic;
+        this.topics = topics;
+    }
+
+    /**
+     * Add the <code>basetopic</code> and <code>objectid</code> to the properties.
+     *
+     * @param properties
+     * @return the modified properties
+     */
+    public <T extends Map<String, Object>> T appendToProperties(T properties) {
+        properties.put("basetopic", basetopic);
+        properties.put("topics", topics);
+        return properties;
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/ListOrStringDeserializer.java

@@ -0,0 +1,92 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+
+import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.Nullable;
+
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+
+/**
+ * JsonTypeAdapter which will read a single string or a string list
+ *
+ * see: https://www.home-assistant.io/components/binary_sensor.mqtt/ -> device / identifiers
+ *
+ * @author Jochen Klein - Initial contribution
+ */
+public class ListOrStringDeserializer extends TypeAdapter<List<String>> {
+
+    @Override
+    public void write(@Nullable JsonWriter out, @Nullable List<String> value) throws IOException {
+        Objects.requireNonNull(out);
+
+        if (value == null) {
+            out.nullValue();
+            return;
+        }
+
+        out.beginArray();
+        for (String str : value) {
+            out.jsonValue(str);
+        }
+        out.endArray();
+    }
+
+    @Override
+    public @Nullable List<String> read(@Nullable JsonReader in) throws IOException {
+        Objects.requireNonNull(in);
+
+        JsonToken peek = in.peek();
+
+        switch (peek) {
+            case NULL:
+                in.nextNull();
+                return null;
+            case STRING:
+                return Arrays.asList(in.nextString());
+            case BEGIN_ARRAY:
+                return readList(in);
+            default:
+                throw new IOException("unexpected token " + peek + ". Array of string or string expected");
+        }
+    }
+
+    private @NonNull List<String> readList(@NonNull JsonReader in) throws IOException {
+        in.beginArray();
+
+        List<String> result = new ArrayList<>();
+
+        JsonToken peek = in.peek();
+
+        while (peek != JsonToken.END_ARRAY) {
+            if (peek == JsonToken.STRING) {
+                result.add(in.nextString());
+            } else {
+                throw new IOException("unexpected token " + peek + ". Array of string or string expected");
+            }
+            peek = in.peek();
+        }
+        in.endArray();
+
+        return result;
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/MappingJsonReader.java

@@ -0,0 +1,257 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.openhab.binding.mqtt.generic.tools.JsonReaderDelegate;
+
+import com.google.gson.stream.JsonReader;
+
+/**
+ * JsonReader which will replace specific names.
+ *
+ * @author Jochen Klein - Initial contribution
+ */
+@NonNullByDefault
+public class MappingJsonReader extends JsonReaderDelegate {
+
+    private static final Map<String, String> ABBREVIATIONS = new HashMap<>();
+    private static final Map<String, String> DEVICE_ABBREVIATIONS = new HashMap<>();
+
+    static {
+        ABBREVIATIONS.put("act_t", "action_topic");
+        ABBREVIATIONS.put("act_tpl", "action_template");
+        ABBREVIATIONS.put("atype", "automation_type");
+        ABBREVIATIONS.put("aux_cmd_t", "aux_command_topic");
+        ABBREVIATIONS.put("aux_stat_tpl", "aux_state_template");
+        ABBREVIATIONS.put("aux_stat_t", "aux_state_topic");
+        ABBREVIATIONS.put("avty", "availability");
+        ABBREVIATIONS.put("avty_t", "availability_topic");
+        ABBREVIATIONS.put("away_mode_cmd_t", "away_mode_command_topic");
+        ABBREVIATIONS.put("away_mode_stat_tpl", "away_mode_state_template");
+        ABBREVIATIONS.put("away_mode_stat_t", "away_mode_state_topic");
+        ABBREVIATIONS.put("b_tpl", "blue_template");
+        ABBREVIATIONS.put("bri_cmd_t", "brightness_command_topic");
+        ABBREVIATIONS.put("bri_scl", "brightness_scale");
+        ABBREVIATIONS.put("bri_stat_t", "brightness_state_topic");
+        ABBREVIATIONS.put("bri_tpl", "brightness_template");
+        ABBREVIATIONS.put("bri_val_tpl", "brightness_value_template");
+        ABBREVIATIONS.put("clr_temp_cmd_tpl", "color_temp_command_template");
+        ABBREVIATIONS.put("bat_lev_t", "battery_level_topic");
+        ABBREVIATIONS.put("bat_lev_tpl", "battery_level_template");
+        ABBREVIATIONS.put("chrg_t", "charging_topic");
+        ABBREVIATIONS.put("chrg_tpl", "charging_template");
+        ABBREVIATIONS.put("clr_temp_cmd_t", "color_temp_command_topic");
+        ABBREVIATIONS.put("clr_temp_stat_t", "color_temp_state_topic");
+        ABBREVIATIONS.put("clr_temp_tpl", "color_temp_template");
+        ABBREVIATIONS.put("clr_temp_val_tpl", "color_temp_value_template");
+        ABBREVIATIONS.put("cln_t", "cleaning_topic");
+        ABBREVIATIONS.put("cln_tpl", "cleaning_template");
+        ABBREVIATIONS.put("cmd_off_tpl", "command_off_template");
+        ABBREVIATIONS.put("cmd_on_tpl", "command_on_template");
+        ABBREVIATIONS.put("cmd_t", "command_topic");
+        ABBREVIATIONS.put("cmd_tpl", "command_template");
+        ABBREVIATIONS.put("cod_arm_req", "code_arm_required");
+        ABBREVIATIONS.put("cod_dis_req", "code_disarm_required");
+        ABBREVIATIONS.put("curr_temp_t", "current_temperature_topic");
+        ABBREVIATIONS.put("curr_temp_tpl", "current_temperature_template");
+        ABBREVIATIONS.put("dev", "device");
+        ABBREVIATIONS.put("dev_cla", "device_class");
+        ABBREVIATIONS.put("dock_t", "docked_topic");
+        ABBREVIATIONS.put("dock_tpl", "docked_template");
+        ABBREVIATIONS.put("err_t", "error_topic");
+        ABBREVIATIONS.put("err_tpl", "error_template");
+        ABBREVIATIONS.put("fanspd_t", "fan_speed_topic");
+        ABBREVIATIONS.put("fanspd_tpl", "fan_speed_template");
+        ABBREVIATIONS.put("fanspd_lst", "fan_speed_list");
+        ABBREVIATIONS.put("flsh_tlng", "flash_time_long");
+        ABBREVIATIONS.put("flsh_tsht", "flash_time_short");
+        ABBREVIATIONS.put("fx_cmd_t", "effect_command_topic");
+        ABBREVIATIONS.put("fx_list", "effect_list");
+        ABBREVIATIONS.put("fx_stat_t", "effect_state_topic");
+        ABBREVIATIONS.put("fx_tpl", "effect_template");
+        ABBREVIATIONS.put("fx_val_tpl", "effect_value_template");
+        ABBREVIATIONS.put("exp_aft", "expire_after");
+        ABBREVIATIONS.put("fan_mode_cmd_t", "fan_mode_command_topic");
+        ABBREVIATIONS.put("fan_mode_stat_tpl", "fan_mode_state_template");
+        ABBREVIATIONS.put("fan_mode_stat_t", "fan_mode_state_topic");
+        ABBREVIATIONS.put("frc_upd", "force_update");
+        ABBREVIATIONS.put("g_tpl", "green_template");
+        ABBREVIATIONS.put("hold_cmd_t", "hold_command_topic");
+        ABBREVIATIONS.put("hold_stat_tpl", "hold_state_template");
+        ABBREVIATIONS.put("hold_stat_t", "hold_state_topic");
+        ABBREVIATIONS.put("hs_cmd_t", "hs_command_topic");
+        ABBREVIATIONS.put("hs_stat_t", "hs_state_topic");
+        ABBREVIATIONS.put("hs_val_tpl", "hs_value_template");
+        ABBREVIATIONS.put("ic", "icon");
+        ABBREVIATIONS.put("init", "initial");
+        ABBREVIATIONS.put("json_attr", "json_attributes");
+        ABBREVIATIONS.put("json_attr_t", "json_attributes_topic");
+        ABBREVIATIONS.put("json_attr_tpl", "json_attributes_template");
+        ABBREVIATIONS.put("max_mirs", "max_mireds");
+        ABBREVIATIONS.put("min_mirs", "min_mireds");
+        ABBREVIATIONS.put("max_temp", "max_temp");
+        ABBREVIATIONS.put("min_temp", "min_temp");
+        ABBREVIATIONS.put("mode_cmd_t", "mode_command_topic");
+        ABBREVIATIONS.put("mode_stat_tpl", "mode_state_template");
+        ABBREVIATIONS.put("mode_stat_t", "mode_state_topic");
+        ABBREVIATIONS.put("name", "name");
+        ABBREVIATIONS.put("off_dly", "off_delay");
+        ABBREVIATIONS.put("on_cmd_type", "on_command_type");
+        ABBREVIATIONS.put("opt", "optimistic");
+        ABBREVIATIONS.put("osc_cmd_t", "oscillation_command_topic");
+        ABBREVIATIONS.put("osc_stat_t", "oscillation_state_topic");
+        ABBREVIATIONS.put("osc_val_tpl", "oscillation_value_template");
+        ABBREVIATIONS.put("pl", "payload");
+        ABBREVIATIONS.put("pl_arm_away", "payload_arm_away");
+        ABBREVIATIONS.put("pl_arm_home", "payload_arm_home");
+        ABBREVIATIONS.put("pl_arm_custom_b", "payload_arm_custom_bypass");
+        ABBREVIATIONS.put("pl_arm_nite", "payload_arm_night");
+        ABBREVIATIONS.put("pl_avail", "payload_available");
+        ABBREVIATIONS.put("pl_cln_sp", "payload_clean_spot");
+        ABBREVIATIONS.put("pl_cls", "payload_close");
+        ABBREVIATIONS.put("pl_disarm", "payload_disarm");
+        ABBREVIATIONS.put("pl_hi_spd", "payload_high_speed");
+        ABBREVIATIONS.put("pl_home", "payload_home");
+        ABBREVIATIONS.put("pl_lock", "payload_lock");
+        ABBREVIATIONS.put("pl_loc", "payload_locate");
+        ABBREVIATIONS.put("pl_lo_spd", "payload_low_speed");
+        ABBREVIATIONS.put("pl_med_spd", "payload_medium_speed");
+        ABBREVIATIONS.put("pl_not_avail", "payload_not_available");
+        ABBREVIATIONS.put("pl_not_home", "payload_not_home");
+        ABBREVIATIONS.put("pl_off", "payload_off");
+        ABBREVIATIONS.put("pl_off_spd", "payload_off_speed");
+        ABBREVIATIONS.put("pl_on", "payload_on");
+        ABBREVIATIONS.put("pl_open", "payload_open");
+        ABBREVIATIONS.put("pl_osc_off", "payload_oscillation_off");
+        ABBREVIATIONS.put("pl_osc_on", "payload_oscillation_on");
+        ABBREVIATIONS.put("pl_paus", "payload_pause");
+        ABBREVIATIONS.put("pl_stop", "payload_stop");
+        ABBREVIATIONS.put("pl_strt", "payload_start");
+        ABBREVIATIONS.put("pl_stpa", "payload_start_pause");
+        ABBREVIATIONS.put("pl_ret", "payload_return_to_base");
+        ABBREVIATIONS.put("pl_toff", "payload_turn_off");
+        ABBREVIATIONS.put("pl_ton", "payload_turn_on");
+        ABBREVIATIONS.put("pl_unlk", "payload_unlock");
+        ABBREVIATIONS.put("pos_clsd", "position_closed");
+        ABBREVIATIONS.put("pos_open", "position_open");
+        ABBREVIATIONS.put("pow_cmd_t", "power_command_topic");
+        ABBREVIATIONS.put("pow_stat_t", "power_state_topic");
+        ABBREVIATIONS.put("pow_stat_tpl", "power_state_template");
+        ABBREVIATIONS.put("r_tpl", "red_template");
+        ABBREVIATIONS.put("ret", "retain");
+        ABBREVIATIONS.put("rgb_cmd_tpl", "rgb_command_template");
+        ABBREVIATIONS.put("rgb_cmd_t", "rgb_command_topic");
+        ABBREVIATIONS.put("rgb_stat_t", "rgb_state_topic");
+        ABBREVIATIONS.put("rgb_val_tpl", "rgb_value_template");
+        ABBREVIATIONS.put("send_cmd_t", "send_command_topic");
+        ABBREVIATIONS.put("send_if_off", "send_if_off");
+        ABBREVIATIONS.put("set_fan_spd_t", "set_fan_speed_topic");
+        ABBREVIATIONS.put("set_pos_tpl", "set_position_template");
+        ABBREVIATIONS.put("set_pos_t", "set_position_topic");
+        ABBREVIATIONS.put("pos_t", "position_topic");
+        ABBREVIATIONS.put("spd_cmd_t", "speed_command_topic");
+        ABBREVIATIONS.put("spd_stat_t", "speed_state_topic");
+        ABBREVIATIONS.put("spd_val_tpl", "speed_value_template");
+        ABBREVIATIONS.put("spds", "speeds");
+        ABBREVIATIONS.put("src_type", "source_type");
+        ABBREVIATIONS.put("stat_clsd", "state_closed");
+        ABBREVIATIONS.put("stat_closing", "state_closing");
+        ABBREVIATIONS.put("stat_off", "state_off");
+        ABBREVIATIONS.put("stat_on", "state_on");
+        ABBREVIATIONS.put("stat_open", "state_open");
+        ABBREVIATIONS.put("stat_opening", "state_opening");
+        ABBREVIATIONS.put("stat_locked", "state_locked");
+        ABBREVIATIONS.put("stat_unlocked", "state_unlocked");
+        ABBREVIATIONS.put("stat_t", "state_topic");
+        ABBREVIATIONS.put("stat_tpl", "state_template");
+        ABBREVIATIONS.put("stat_val_tpl", "state_value_template");
+        ABBREVIATIONS.put("stype", "subtype");
+        ABBREVIATIONS.put("sup_feat", "supported_features");
+        ABBREVIATIONS.put("swing_mode_cmd_t", "swing_mode_command_topic");
+        ABBREVIATIONS.put("swing_mode_stat_tpl", "swing_mode_state_template");
+        ABBREVIATIONS.put("swing_mode_stat_t", "swing_mode_state_topic");
+        ABBREVIATIONS.put("temp_cmd_t", "temperature_command_topic");
+        ABBREVIATIONS.put("temp_hi_cmd_t", "temperature_high_command_topic");
+        ABBREVIATIONS.put("temp_hi_stat_tpl", "temperature_high_state_template");
+        ABBREVIATIONS.put("temp_hi_stat_t", "temperature_high_state_topic");
+        ABBREVIATIONS.put("temp_lo_cmd_t", "temperature_low_command_topic");
+        ABBREVIATIONS.put("temp_lo_stat_tpl", "temperature_low_state_template");
+        ABBREVIATIONS.put("temp_lo_stat_t", "temp_lo_stat_t");
+        ABBREVIATIONS.put("temp_stat_tpl", "temperature_state_template");
+        ABBREVIATIONS.put("temp_stat_t", "temperature_state_topic");
+        ABBREVIATIONS.put("temp_unit", "temperature_unit");
+        ABBREVIATIONS.put("tilt_clsd_val", "tilt_closed_value");
+        ABBREVIATIONS.put("tilt_cmd_t", "tilt_command_topic");
+        ABBREVIATIONS.put("tilt_inv_stat", "tilt_invert_state");
+        ABBREVIATIONS.put("tilt_max", "tilt_max");
+        ABBREVIATIONS.put("tilt_min", "tilt_min");
+        ABBREVIATIONS.put("tilt_opnd_val", "tilt_opened_value");
+        ABBREVIATIONS.put("tilt_opt", "tilt_optimistic");
+        ABBREVIATIONS.put("tilt_status_t", "tilt_status_topic");
+        ABBREVIATIONS.put("tilt_status_tpl", "tilt_status_template");
+        ABBREVIATIONS.put("t", "topic");
+        ABBREVIATIONS.put("uniq_id", "unique_id");
+        ABBREVIATIONS.put("unit_of_meas", "unit_of_measurement");
+        ABBREVIATIONS.put("val_tpl", "value_template");
+        ABBREVIATIONS.put("whit_val_cmd_t", "white_value_command_topic");
+        ABBREVIATIONS.put("whit_val_scl", "white_value_scale");
+        ABBREVIATIONS.put("whit_val_stat_t", "white_value_state_topic");
+        ABBREVIATIONS.put("whit_val_tpl", "white_value_template");
+        ABBREVIATIONS.put("xy_cmd_t", "xy_command_topic");
+        ABBREVIATIONS.put("xy_stat_t", "xy_state_topic");
+        ABBREVIATIONS.put("xy_val_tpl", "xy_value_template");
+
+        DEVICE_ABBREVIATIONS.put("cns", "connections");
+        DEVICE_ABBREVIATIONS.put("ids", "identifiers");
+        DEVICE_ABBREVIATIONS.put("name", "name");
+        DEVICE_ABBREVIATIONS.put("mf", "manufacturer");
+        DEVICE_ABBREVIATIONS.put("mdl", "model");
+        DEVICE_ABBREVIATIONS.put("sw", "sw_version");
+    }
+
+    private final Map<String, String> mapping;
+
+    /**
+     *
+     * @param delegate
+     * @return return a JsonReader which replaces all config abbreviations
+     */
+    public static MappingJsonReader getConfigMapper(JsonReader delegate) {
+        return new MappingJsonReader(JsonReaderDelegate.getDelegate(delegate), ABBREVIATIONS);
+    }
+
+    /**
+     *
+     * @param delegate
+     * @return return a JsonReader which replaces all config.device abbreviations
+     */
+    public static MappingJsonReader getDeviceMapper(JsonReader delegate) {
+        return new MappingJsonReader(JsonReaderDelegate.getDelegate(delegate), DEVICE_ABBREVIATIONS);
+    }
+
+    private MappingJsonReader(JsonReader delegate, Map<String, String> mapping) {
+        super(delegate);
+        this.mapping = mapping;
+    }
+
+    @Override
+    public String nextName() throws IOException {
+        String name = super.nextName();
+        return mapping.getOrDefault(name, name);
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/discovery/HomeAssistantDiscovery.java

@@ -0,0 +1,221 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal.discovery;
+
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+
+import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.discovery.AbstractMQTTDiscovery;
+import org.openhab.binding.mqtt.discovery.MQTTTopicDiscoveryService;
+import org.openhab.binding.mqtt.generic.MqttChannelTypeProvider;
+import org.openhab.binding.mqtt.homeassistant.generic.internal.MqttBindingConstants;
+import org.openhab.binding.mqtt.homeassistant.internal.BaseChannelConfiguration;
+import org.openhab.binding.mqtt.homeassistant.internal.ChannelConfigurationTypeAdapterFactory;
+import org.openhab.binding.mqtt.homeassistant.internal.HaID;
+import org.openhab.binding.mqtt.homeassistant.internal.HandlerConfiguration;
+import org.openhab.core.config.discovery.DiscoveryResult;
+import org.openhab.core.config.discovery.DiscoveryResultBuilder;
+import org.openhab.core.config.discovery.DiscoveryService;
+import org.openhab.core.io.transport.mqtt.MqttBrokerConnection;
+import org.openhab.core.thing.ThingTypeUID;
+import org.openhab.core.thing.ThingUID;
+import org.openhab.core.thing.type.ThingType;
+import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Reference;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+
+/**
+ * The {@link HomeAssistantDiscovery} is responsible for discovering device nodes that follow the
+ * Home Assistant MQTT discovery convention (https://www.home-assistant.io/docs/mqtt/discovery/).
+ *
+ * @author David Graeff - Initial contribution
+ */
+@Component(immediate = true, service = DiscoveryService.class, configurationPid = "discovery.mqttha")
+@NonNullByDefault
+public class HomeAssistantDiscovery extends AbstractMQTTDiscovery {
+    @SuppressWarnings("unused")
+    private final Logger logger = LoggerFactory.getLogger(HomeAssistantDiscovery.class);
+    protected final Map<String, Set<HaID>> componentsPerThingID = new TreeMap<>();
+    protected final Map<String, ThingUID> thingIDPerTopic = new TreeMap<>();
+    protected final Map<String, DiscoveryResult> results = new ConcurrentHashMap<>();
+
+    private @Nullable ScheduledFuture<?> future;
+    private final Gson gson;
+
+    public static final Map<String, String> HA_COMP_TO_NAME = new TreeMap<>();
+    {
+        HA_COMP_TO_NAME.put("alarm_control_panel", "Alarm Control Panel");
+        HA_COMP_TO_NAME.put("binary_sensor", "Sensor");
+        HA_COMP_TO_NAME.put("camera", "Camera");
+        HA_COMP_TO_NAME.put("cover", "Blind");
+        HA_COMP_TO_NAME.put("fan", "Fan");
+        HA_COMP_TO_NAME.put("climate", "Climate Control");
+        HA_COMP_TO_NAME.put("light", "Light");
+        HA_COMP_TO_NAME.put("lock", "Lock");
+        HA_COMP_TO_NAME.put("sensor", "Sensor");
+        HA_COMP_TO_NAME.put("switch", "Switch");
+    }
+
+    static final String BASE_TOPIC = "homeassistant";
+
+    @NonNullByDefault({})
+    protected MqttChannelTypeProvider typeProvider;
+
+    @NonNullByDefault({})
+    protected MQTTTopicDiscoveryService mqttTopicDiscovery;
+
+    public HomeAssistantDiscovery() {
+        super(null, 3, true, BASE_TOPIC + "/#");
+        this.gson = new GsonBuilder().registerTypeAdapterFactory(new ChannelConfigurationTypeAdapterFactory()).create();
+    }
+
+    @Reference
+    public void setMQTTTopicDiscoveryService(MQTTTopicDiscoveryService service) {
+        mqttTopicDiscovery = service;
+    }
+
+    public void unsetMQTTTopicDiscoveryService(@Nullable MQTTTopicDiscoveryService service) {
+        mqttTopicDiscovery.unsubscribe(this);
+        this.mqttTopicDiscovery = null;
+    }
+
+    @Override
+    protected MQTTTopicDiscoveryService getDiscoveryService() {
+        return mqttTopicDiscovery;
+    }
+
+    @Reference
+    protected void setTypeProvider(MqttChannelTypeProvider provider) {
+        this.typeProvider = provider;
+    }
+
+    protected void unsetTypeProvider(MqttChannelTypeProvider provider) {
+        this.typeProvider = null;
+    }
+
+    @Override
+    public Set<@NonNull ThingTypeUID> getSupportedThingTypes() {
+        return typeProvider.getThingTypeUIDs();
+    }
+
+    @Override
+    public void receivedMessage(ThingUID connectionBridge, MqttBrokerConnection connection, String topic,
+            byte[] payload) {
+        resetTimeout();
+
+        // For HomeAssistant we need to subscribe to a wildcard topic, because topics can either be:
+        // homeassistant/<component>/<node_id>/<object_id>/config OR
+        // homeassistant/<component>/<object_id>/config.
+        // We check for the last part to filter all non-config topics out.
+        if (!topic.endsWith("/config")) {
+            return;
+        }
+
+        // Reset the found-component timer.
+        // We will collect components for the thing label description for another 2 seconds.
+        final ScheduledFuture<?> future = this.future;
+        if (future != null) {
+            future.cancel(false);
+        }
+        this.future = scheduler.schedule(this::publishResults, 2, TimeUnit.SECONDS);
+
+        BaseChannelConfiguration config = BaseChannelConfiguration
+                .fromString(new String(payload, StandardCharsets.UTF_8), gson);
+
+        // We will of course find multiple of the same unique Thing IDs, for each different component another one.
+        // Therefore the components are assembled into a list and given to the DiscoveryResult label for the user to
+        // easily recognize object capabilities.
+
+        HaID haID = new HaID(topic);
+        final String thingID = config.getThingId(haID.objectID);
+
+        final ThingTypeUID typeID = new ThingTypeUID(MqttBindingConstants.BINDING_ID,
+                MqttBindingConstants.HOMEASSISTANT_MQTT_THING.getId() + "_" + thingID);
+
+        final ThingUID thingUID = new ThingUID(typeID, connectionBridge, thingID);
+
+        thingIDPerTopic.put(topic, thingUID);
+
+        // We need to keep track of already found component topics for a specific thing
+        Set<HaID> components = componentsPerThingID.computeIfAbsent(thingID, key -> ConcurrentHashMap.newKeySet());
+        components.add(haID);
+
+        final String componentNames = components.stream().map(id -> id.component)
+                .map(c -> HA_COMP_TO_NAME.getOrDefault(c, c)).collect(Collectors.joining(", "));
+
+        final List<String> topics = components.stream().map(HaID::toShortTopic).collect(Collectors.toList());
+
+        Map<String, Object> properties = new HashMap<>();
+        HandlerConfiguration handlerConfig = new HandlerConfiguration(haID.baseTopic, topics);
+        properties = handlerConfig.appendToProperties(properties);
+        properties = config.appendToProperties(properties);
+
+        // Because we need the new properties map with the updated "components" list
+        results.put(thingUID.getAsString(),
+                DiscoveryResultBuilder.create(thingUID).withProperties(properties).withRepresentationProperty(thingID)
+                        .withBridge(connectionBridge).withLabel(config.getThingName() + " (" + componentNames + ")")
+                        .build());
+    }
+
+    protected void publishResults() {
+        Collection<DiscoveryResult> localResults;
+
+        localResults = new ArrayList<>(results.values());
+        results.clear();
+        componentsPerThingID.clear();
+        for (DiscoveryResult result : localResults) {
+            final ThingTypeUID typeID = result.getThingTypeUID();
+            ThingType type = typeProvider.derive(typeID, MqttBindingConstants.HOMEASSISTANT_MQTT_THING).build();
+            typeProvider.setThingTypeIfAbsent(typeID, type);
+
+            thingDiscovered(result);
+        }
+    }
+
+    @Override
+    public void topicVanished(ThingUID connectionBridge, MqttBrokerConnection connection, String topic) {
+        if (!topic.endsWith("/config")) {
+            return;
+        }
+        if (thingIDPerTopic.containsKey(topic)) {
+            ThingUID thingUID = thingIDPerTopic.remove(topic);
+            final String thingID = thingUID.getId();
+
+            HaID haID = new HaID(topic);
+
+            Set<HaID> components = componentsPerThingID.getOrDefault(thingID, Collections.emptySet());
+            components.remove(haID);
+            if (components.isEmpty()) {
+                thingRemoved(thingUID);
+            }
+        }
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/java/org/openhab/binding/mqtt/homeassistant/internal/handler/HomeAssistantThingHandler.java

@@ -0,0 +1,326 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal.handler;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.function.Consumer;
+import java.util.stream.Collectors;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+import org.openhab.binding.mqtt.generic.AbstractMQTTThingHandler;
+import org.openhab.binding.mqtt.generic.ChannelState;
+import org.openhab.binding.mqtt.generic.MqttChannelTypeProvider;
+import org.openhab.binding.mqtt.generic.TransformationServiceProvider;
+import org.openhab.binding.mqtt.generic.tools.DelayedBatchProcessing;
+import org.openhab.binding.mqtt.generic.utils.FutureCollector;
+import org.openhab.binding.mqtt.homeassistant.generic.internal.MqttBindingConstants;
+import org.openhab.binding.mqtt.homeassistant.internal.AbstractComponent;
+import org.openhab.binding.mqtt.homeassistant.internal.CChannel;
+import org.openhab.binding.mqtt.homeassistant.internal.CFactory;
+import org.openhab.binding.mqtt.homeassistant.internal.ChannelConfigurationTypeAdapterFactory;
+import org.openhab.binding.mqtt.homeassistant.internal.DiscoverComponents;
+import org.openhab.binding.mqtt.homeassistant.internal.DiscoverComponents.ComponentDiscovered;
+import org.openhab.binding.mqtt.homeassistant.internal.HaID;
+import org.openhab.binding.mqtt.homeassistant.internal.HandlerConfiguration;
+import org.openhab.core.io.transport.mqtt.MqttBrokerConnection;
+import org.openhab.core.thing.Channel;
+import org.openhab.core.thing.ChannelUID;
+import org.openhab.core.thing.Thing;
+import org.openhab.core.thing.ThingStatus;
+import org.openhab.core.thing.ThingStatusDetail;
+import org.openhab.core.thing.ThingTypeUID;
+import org.openhab.core.thing.ThingUID;
+import org.openhab.core.thing.type.ChannelDefinition;
+import org.openhab.core.thing.type.ChannelGroupDefinition;
+import org.openhab.core.thing.type.ChannelGroupType;
+import org.openhab.core.thing.type.ThingType;
+import org.openhab.core.thing.util.ThingHelper;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+
+/**
+ * Handles HomeAssistant MQTT object things. Such an HA Object can have multiple HA Components with different instances
+ * of those Components. This handler auto-discovers all available Components and Component Instances and
+ * adds any new appearing components over time.<br>
+ * <br>
+ *
+ * The specification does not cover the case of disappearing Components. This handler doesn't as well therefore.<br>
+ * <br>
+ *
+ * A Component Instance equals an ESH Channel Group and the Component parts equal ESH Channels.<br>
+ * <br>
+ *
+ * If a Components configuration changes, the known ChannelGroupType and ChannelTypes are replaced with the new ones.
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class HomeAssistantThingHandler extends AbstractMQTTThingHandler
+        implements ComponentDiscovered, Consumer<List<AbstractComponent<?>>> {
+    public static final String AVAILABILITY_CHANNEL = "availability";
+
+    private final Logger logger = LoggerFactory.getLogger(HomeAssistantThingHandler.class);
+
+    protected final MqttChannelTypeProvider channelTypeProvider;
+    public final int attributeReceiveTimeout;
+    protected final DelayedBatchProcessing<AbstractComponent<?>> delayedProcessing;
+    protected final DiscoverComponents discoverComponents;
+
+    private final Gson gson;
+    protected final Map<String, AbstractComponent<?>> haComponents = new HashMap<>();
+
+    protected HandlerConfiguration config = new HandlerConfiguration();
+    private Set<HaID> discoveryHomeAssistantIDs = new HashSet<>();
+
+    protected final TransformationServiceProvider transformationServiceProvider;
+
+    private boolean started;
+
+    /**
+     * Create a new thing handler for HomeAssistant MQTT components.
+     * A channel type provider and a topic value receive timeout must be provided.
+     *
+     * @param thing The thing of this handler
+     * @param channelTypeProvider A channel type provider
+     * @param subscribeTimeout Timeout for the entire tree parsing and subscription. In milliseconds.
+     * @param attributeReceiveTimeout The timeout per attribute field subscription. In milliseconds.
+     */
+    public HomeAssistantThingHandler(Thing thing, MqttChannelTypeProvider channelTypeProvider,
+            TransformationServiceProvider transformationServiceProvider, int subscribeTimeout,
+            int attributeReceiveTimeout) {
+        super(thing, subscribeTimeout);
+        this.gson = new GsonBuilder().registerTypeAdapterFactory(new ChannelConfigurationTypeAdapterFactory()).create();
+        this.channelTypeProvider = channelTypeProvider;
+        this.transformationServiceProvider = transformationServiceProvider;
+        this.attributeReceiveTimeout = attributeReceiveTimeout;
+        this.delayedProcessing = new DelayedBatchProcessing<>(attributeReceiveTimeout, this, scheduler);
+        this.discoverComponents = new DiscoverComponents(thing.getUID(), scheduler, this, this, gson,
+                this.transformationServiceProvider);
+    }
+
+    @SuppressWarnings({ "null", "unused" })
+    @Override
+    public void initialize() {
+        started = false;
+
+        config = getConfigAs(HandlerConfiguration.class);
+        if (config.topics == null || config.topics.isEmpty()) {
+            updateStatus(ThingStatus.OFFLINE, ThingStatusDetail.CONFIGURATION_ERROR, "Device topics unknown");
+            return;
+        }
+        discoveryHomeAssistantIDs.addAll(HaID.fromConfig(config));
+
+        for (Channel channel : thing.getChannels()) {
+            final String groupID = channel.getUID().getGroupId();
+            if (groupID == null) {
+                logger.warn("Channel {} has no groupd ID", channel.getLabel());
+                continue;
+            }
+            // Already restored component?
+            @Nullable
+            AbstractComponent<?> component = haComponents.get(groupID);
+            if (component != null) {
+                // the types may have been removed in dispose() so we need to add them again
+                component.addChannelTypes(channelTypeProvider);
+                continue;
+            }
+
+            HaID haID = HaID.fromConfig(config.basetopic, channel.getConfiguration());
+            discoveryHomeAssistantIDs.add(haID);
+            ThingUID thingUID = channel.getUID().getThingUID();
+            String channelConfigurationJSON = (String) channel.getConfiguration().get("config");
+            if (channelConfigurationJSON == null) {
+                logger.warn("Provided channel does not have a 'config' configuration key!");
+            } else {
+                component = CFactory.createComponent(thingUID, haID, channelConfigurationJSON, this, this, gson,
+                        transformationServiceProvider);
+            }
+
+            if (component != null) {
+                haComponents.put(component.uid().getId(), component);
+                component.addChannelTypes(channelTypeProvider);
+            } else {
+                logger.warn("Could not restore component {}", thing);
+            }
+        }
+        updateThingType();
+
+        super.initialize();
+    }
+
+    @Override
+    public void dispose() {
+        // super.dispose() calls stop()
+        super.dispose();
+        haComponents.values().forEach(c -> c.removeChannelTypes(channelTypeProvider));
+    }
+
+    @Override
+    public CompletableFuture<Void> unsubscribeAll() {
+        // already unsubscribed everything by calling stop()
+        return CompletableFuture.allOf();
+    }
+
+    /**
+     * Start a background discovery for the configured HA MQTT object-id.
+     */
+    @Override
+    protected CompletableFuture<@Nullable Void> start(MqttBrokerConnection connection) {
+        started = true;
+
+        connection.setQos(1);
+        updateStatus(ThingStatus.UNKNOWN);
+
+        // Start all known components and channels within the components and put the Thing offline
+        // if any subscribing failed ( == broker connection lost)
+        CompletableFuture<@Nullable Void> future = haComponents.values().parallelStream()
+                .map(e -> e.start(connection, scheduler, attributeReceiveTimeout))
+                .reduce(CompletableFuture.completedFuture(null), (a, v) -> a.thenCompose(b -> v)) // reduce to one
+                .exceptionally(e -> {
+                    updateStatus(ThingStatus.OFFLINE, ThingStatusDetail.CONFIGURATION_ERROR, e.getMessage());
+                    return null;
+                });
+
+        return future
+                .thenCompose(b -> discoverComponents.startDiscovery(connection, 0, discoveryHomeAssistantIDs, this));
+    }
+
+    @Override
+    protected void stop() {
+        if (started) {
+            discoverComponents.stopDiscovery();
+            delayedProcessing.join();
+            // haComponents does not need to be synchronised -> the discovery thread is disabled
+            haComponents.values().parallelStream().map(AbstractComponent::stop) //
+                    // we need to join all the stops, otherwise they might not be done when start is called
+                    .collect(FutureCollector.allOf()).join();
+
+            started = false;
+        }
+        super.stop();
+    }
+
+    @SuppressWarnings({ "null", "unused" })
+    @Override
+    public @Nullable ChannelState getChannelState(ChannelUID channelUID) {
+        String groupID = channelUID.getGroupId();
+        if (groupID == null) {
+            return null;
+        }
+        AbstractComponent<?> component;
+        synchronized (haComponents) { // sync whenever discoverComponents is started
+            component = haComponents.get(groupID);
+        }
+        if (component == null) {
+            return null;
+        }
+        CChannel componentChannel = component.channel(channelUID.getIdWithoutGroup());
+        if (componentChannel == null) {
+            return null;
+        }
+        return componentChannel.getState();
+    }
+
+    /**
+     * Callback of {@link DiscoverComponents}. Add to a delayed batch processor.
+     */
+    @Override
+    public void componentDiscovered(HaID homeAssistantTopicID, AbstractComponent<?> component) {
+        delayedProcessing.accept(component);
+    }
+
+    /**
+     * Callback of {@link DelayedBatchProcessing}.
+     * Add all newly discovered components to the Thing and start the components.
+     */
+    @SuppressWarnings("null")
+    @Override
+    public void accept(List<AbstractComponent<?>> discoveredComponentsList) {
+        MqttBrokerConnection connection = this.connection;
+        if (connection == null) {
+            return;
+        }
+
+        synchronized (haComponents) { // sync whenever discoverComponents is started
+            for (AbstractComponent<?> discovered : discoveredComponentsList) {
+                AbstractComponent<?> known = haComponents.get(discovered.uid().getId());
+                // Is component already known?
+                if (known != null) {
+                    if (discovered.getConfigHash() != known.getConfigHash()) {
+                        // Don't wait for the future to complete. We are also not interested in failures.
+                        // The component will be replaced in a moment.
+                        known.stop();
+                    } else {
+                        known.setConfigSeen();
+                        continue;
+                    }
+                }
+
+                // Add channel and group types to the types registry
+                discovered.addChannelTypes(channelTypeProvider);
+                // Add component to the component map
+                haComponents.put(discovered.uid().getId(), discovered);
+                // Start component / Subscribe to channel topics
+                discovered.start(connection, scheduler, 0).exceptionally(e -> {
+                    logger.warn("Failed to start component {}", discovered.uid(), e);
+                    return null;
+                });
+
+                Collection<Channel> channels = discovered.channelTypes().values().stream().map(CChannel::getChannel)
+                        .collect(Collectors.toList());
+                ThingHelper.addChannelsToThing(thing, channels);
+            }
+        }
+
+        updateThingType();
+    }
+
+    @Override
+    protected void updateThingStatus(boolean messageReceived, boolean availabilityTopicsSeen) {
+        if (!messageReceived || availabilityTopicsSeen) {
+            updateStatus(ThingStatus.ONLINE, ThingStatusDetail.NONE);
+        } else {
+            updateStatus(ThingStatus.OFFLINE, ThingStatusDetail.NONE);
+        }
+    }
+
+    private void updateThingType() {
+        // if this is a dynamic type, then we update the type
+        ThingTypeUID typeID = thing.getThingTypeUID();
+        if (!MqttBindingConstants.HOMEASSISTANT_MQTT_THING.equals(typeID)) {
+            List<ChannelGroupDefinition> groupDefs;
+            List<ChannelDefinition> channelDefs;
+            synchronized (haComponents) { // sync whenever discoverComponents is started
+                groupDefs = haComponents.values().stream().map(AbstractComponent::getGroupDefinition)
+                        .collect(Collectors.toList());
+                channelDefs = haComponents.values().stream().map(AbstractComponent::type)
+                        .map(ChannelGroupType::getChannelDefinitions).flatMap(List::stream)
+                        .collect(Collectors.toList());
+            }
+            ThingType thingType = channelTypeProvider.derive(typeID, MqttBindingConstants.HOMEASSISTANT_MQTT_THING)
+                    .withChannelDefinitions(channelDefs).withChannelGroupDefinitions(groupDefs).build();
+
+            channelTypeProvider.setThingType(typeID, thingType);
+        }
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/main/resources/OH-INF/config/homeassistant-channel-config.xml

@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<config-description:config-descriptions
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xmlns:config-description="https://openhab.org/schemas/config-description/v1.0.0"
+	xsi:schemaLocation="https://openhab.org/schemas/config-description/v1.0.0 https://openhab.org/schemas/config-description-1.0.0.xsd">
+
+	<config-description uri="mqtt:ha_channel">
+		<parameter name="component" type="text" readOnly="true" required="true">
+			<label>Component</label>
+			<description>HomeAssistant component type (e.g. binary_sensor, switch, light)</description>
+			<default></default>
+		</parameter>
+		<parameter name="nodeid" type="text" readOnly="true">
+			<label>Node ID</label>
+			<description>Optional node name of the component</description>
+			<default></default>
+		</parameter>
+		<parameter name="objectid" type="text" readOnly="true" required="true">
+			<label>Object ID</label>
+			<description>Object id of the component</description>
+			<default></default>
+		</parameter>
+		<parameter name="config" type="text" readOnly="true" required="true">
+			<label>Json Configuration</label>
+			<description>The json configuration string received by the component via MQTT.</description>
+			<default></default>
+		</parameter>
+	</config-description>
+</config-description:config-descriptions>

bundles/org.openhab.binding.mqtt.homeassistant/src/main/resources/OH-INF/thing/homeassistant-thing.xml

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<thing:thing-descriptions bindingId="mqtt"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xmlns:thing="https://openhab.org/schemas/thing-description/v1.0.0"
+	xsi:schemaLocation="https://openhab.org/schemas/thing-description/v1.0.0 https://openhab.org/schemas/thing-description-1.0.0.xsd">
+
+	<thing-type id="homeassistant">
+		<supported-bridge-type-refs>
+			<bridge-type-ref id="broker"/>
+			<bridge-type-ref id="systemBroker"/>
+		</supported-bridge-type-refs>
+		<label>HomeAssistant MQTT Component</label>
+		<description>You need a configured Broker first. This Thing represents a device, that follows the "HomeAssistant MQTT
+			Component" specification.</description>
+		<config-description>
+			<parameter name="topics" type="text" required="true" multiple="true">
+				<label>MQTT Config Topic</label>
+				<description>List of HomeAssistant configuration topics (e.g. /homeassistant/switch/4711/config)</description>
+			</parameter>
+
+			<parameter name="basetopic" type="text" required="true">
+				<label>MQTT Base Prefix</label>
+				<description>MQTT base prefix</description>
+				<default>homeassistant</default>
+			</parameter>
+		</config-description>
+	</thing-type>
+</thing:thing-descriptions>

bundles/org.openhab.binding.mqtt.homeassistant/src/test/java/org/openhab/binding/mqtt/homeassistant/internal/HAConfigurationTests.java

@@ -0,0 +1,144 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.hamcrest.collection.IsIterableContainingInOrder.contains;
+import static org.junit.Assert.assertThat;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+import java.util.List;
+
+import org.eclipse.jdt.annotation.NonNull;
+import org.junit.Test;
+import org.openhab.binding.mqtt.homeassistant.internal.BaseChannelConfiguration.Connection;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+
+/**
+ * @author Jochen Klein - Initial contribution
+ */
+public class HAConfigurationTests {
+
+    private Gson gson = new GsonBuilder().registerTypeAdapterFactory(new ChannelConfigurationTypeAdapterFactory())
+            .create();
+
+    private static String readTestJson(final String name) {
+        StringBuilder result = new StringBuilder();
+
+        try (BufferedReader in = new BufferedReader(
+                new InputStreamReader(HAConfigurationTests.class.getResourceAsStream(name), "UTF-8"))) {
+            String line;
+
+            while ((line = in.readLine()) != null) {
+                result.append(line).append('\n');
+            }
+            return result.toString();
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @Test
+    public void testAbbreviations() {
+        String json = readTestJson("configA.json");
+
+        BaseChannelConfiguration config = BaseChannelConfiguration.fromString(json, gson);
+
+        assertThat(config.name, is("A"));
+        assertThat(config.icon, is("2"));
+        assertThat(config.qos, is(1));
+        assertThat(config.retain, is(true));
+        assertThat(config.value_template, is("B"));
+        assertThat(config.unique_id, is("C"));
+        assertThat(config.availability_topic, is("D/E"));
+        assertThat(config.payload_available, is("F"));
+        assertThat(config.payload_not_available, is("G"));
+
+        assertThat(config.device, is(notNullValue()));
+
+        BaseChannelConfiguration.Device device = config.device;
+        if (device != null) {
+            assertThat(device.identifiers, contains("H"));
+            assertThat(device.connections, is(notNullValue()));
+            List<@NonNull Connection> connections = device.connections;
+            if (connections != null) {
+                assertThat(connections.get(0).type, is("I1"));
+                assertThat(connections.get(0).identifier, is("I2"));
+            }
+            assertThat(device.name, is("J"));
+            assertThat(device.model, is("K"));
+            assertThat(device.sw_version, is("L"));
+            assertThat(device.manufacturer, is("M"));
+        }
+    }
+
+    @Test
+    public void testTildeSubstritution() {
+        String json = readTestJson("configB.json");
+
+        ComponentSwitch.ChannelConfiguration config = BaseChannelConfiguration.fromString(json, gson,
+                ComponentSwitch.ChannelConfiguration.class);
+
+        assertThat(config.availability_topic, is("D/E"));
+        assertThat(config.state_topic, is("O/D/"));
+        assertThat(config.command_topic, is("P~Q"));
+        assertThat(config.device, is(notNullValue()));
+
+        BaseChannelConfiguration.Device device = config.device;
+        if (device != null) {
+            assertThat(device.identifiers, contains("H"));
+        }
+    }
+
+    @Test
+    public void testSampleFanConfig() {
+        String json = readTestJson("configFan.json");
+
+        ComponentFan.ChannelConfiguration config = BaseChannelConfiguration.fromString(json, gson,
+                ComponentFan.ChannelConfiguration.class);
+        assertThat(config.name, is("Bedroom Fan"));
+    }
+
+    @Test
+    public void testDeviceListConfig() {
+        String json = readTestJson("configDeviceList.json");
+
+        ComponentFan.ChannelConfiguration config = BaseChannelConfiguration.fromString(json, gson,
+                ComponentFan.ChannelConfiguration.class);
+        assertThat(config.device, is(notNullValue()));
+
+        BaseChannelConfiguration.Device device = config.device;
+        if (device != null) {
+            assertThat(device.identifiers, is(Arrays.asList("A", "B", "C")));
+        }
+    }
+
+    @Test
+    public void testDeviceSingleStringConfig() {
+        String json = readTestJson("configDeviceSingleString.json");
+
+        ComponentFan.ChannelConfiguration config = BaseChannelConfiguration.fromString(json, gson,
+                ComponentFan.ChannelConfiguration.class);
+        assertThat(config.device, is(notNullValue()));
+
+        BaseChannelConfiguration.Device device = config.device;
+        if (device != null) {
+            assertThat(device.identifiers, is(Arrays.asList("A")));
+        }
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/test/java/org/openhab/binding/mqtt/homeassistant/internal/HaIDTests.java

@@ -0,0 +1,75 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.core.IsCollectionContaining.hasItem;
+import static org.junit.Assert.assertThat;
+
+import java.util.Collection;
+import java.util.Collections;
+
+import org.junit.Test;
+import org.openhab.core.config.core.Configuration;
+
+/**
+ * @author Jochen Klein - Initial contribution
+ */
+public class HaIDTests {
+
+    @Test
+    public void testWithoutNode() {
+        HaID subject = new HaID("homeassistant/switch/name/config");
+
+        assertThat(subject.objectID, is("name"));
+
+        assertThat(subject.component, is("switch"));
+        assertThat(subject.getTopic("suffix"), is("homeassistant/switch/name/suffix"));
+
+        Configuration config = new Configuration();
+        subject.toConfig(config);
+
+        HaID restore = HaID.fromConfig("homeassistant", config);
+
+        assertThat(restore, is(subject));
+
+        HandlerConfiguration haConfig = new HandlerConfiguration(subject.baseTopic,
+                Collections.singletonList(subject.toShortTopic()));
+
+        Collection<HaID> restoreList = HaID.fromConfig(haConfig);
+        assertThat(restoreList, hasItem(new HaID("homeassistant/switch/name/config")));
+    }
+
+    @Test
+    public void testWithNode() {
+        HaID subject = new HaID("homeassistant/switch/node/name/config");
+
+        assertThat(subject.objectID, is("name"));
+
+        assertThat(subject.component, is("switch"));
+        assertThat(subject.getTopic("suffix"), is("homeassistant/switch/node/name/suffix"));
+
+        Configuration config = new Configuration();
+        subject.toConfig(config);
+
+        HaID restore = HaID.fromConfig("homeassistant", config);
+
+        assertThat(restore, is(subject));
+
+        HandlerConfiguration haConfig = new HandlerConfiguration(subject.baseTopic,
+                Collections.singletonList(subject.toShortTopic()));
+
+        Collection<HaID> restoreList = HaID.fromConfig(haConfig);
+        assertThat(restoreList, hasItem(new HaID("homeassistant/switch/node/name/config")));
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/test/java/org/openhab/binding/mqtt/homeassistant/internal/handler/ThingChannelConstants.java

@@ -0,0 +1,60 @@
+/**
+ * Copyright (c) 2010-2020 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.binding.mqtt.homeassistant.internal.handler;
+
+import static org.openhab.binding.mqtt.homeassistant.generic.internal.MqttBindingConstants.*;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.openhab.core.config.core.Configuration;
+import org.openhab.core.thing.Channel;
+import org.openhab.core.thing.ThingUID;
+import org.openhab.core.thing.type.ChannelTypeUID;
+
+/**
+ * Static test definitions, like thing, bridge and channel definitions
+ *
+ * @author David Graeff - Initial contribution
+ */
+@NonNullByDefault
+public class ThingChannelConstants {
+    // Common ThingUID and ChannelUIDs
+    public static final ThingUID testHomeAssistantThing = new ThingUID(HOMEASSISTANT_MQTT_THING, "device234");
+
+    public static final ChannelTypeUID unknownChannel = new ChannelTypeUID(BINDING_ID, "unknown");
+
+    public static final String jsonPathJSON = "{ \"device\": { \"status\": { \"temperature\": 23.2 }}}";
+    public static final String jsonPathPattern = "$.device.status.temperature";
+
+    public static final List<Channel> thingChannelList = new ArrayList<>();
+    public static final List<Channel> thingChannelListWithJson = new ArrayList<>();
+
+    static Configuration textConfiguration() {
+        Map<String, Object> data = new HashMap<>();
+        data.put("stateTopic", "test/state");
+        data.put("commandTopic", "test/command");
+        return new Configuration(data);
+    }
+
+    static Configuration textConfigurationWithJson() {
+        Map<String, Object> data = new HashMap<>();
+        data.put("stateTopic", "test/state");
+        data.put("commandTopic", "test/command");
+        data.put("transformationPattern", "JSONPATH:" + jsonPathPattern);
+        return new Configuration(data);
+    }
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/test/resources/org/openhab/binding/mqtt/homeassistant/internal/configA.json

@@ -0,0 +1,27 @@
+{
+	"name": "A",
+	"icon": "2",
+	"qos": 1,
+	"retain": true,
+	"val_tpl": "B",
+	"uniq_id": "C",
+	"avty_t": "~E",
+	"pl_avail": "F",
+	"pl_not_avail": "G",
+	"device": {
+		"ids": [
+			"H"
+		],
+		"cns": [
+			[
+				"I1",
+				"I2"
+			]
+		],
+		"name": "J",
+		"mdl": "K",
+		"sw": "L",
+		"mf": "M"
+	},
+	"~": "D/"
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/test/resources/org/openhab/binding/mqtt/homeassistant/internal/configB.json

@@ -0,0 +1,28 @@
+{
+	"name": "A",
+	"icon": "2",
+	"qos": 1,
+	"retain": true,
+	"val_tpl": "B",
+	"uniq_id": "C",
+	"avty_t": "~E",
+	"pl_avail": "F",
+	"pl_not_avail": "G",
+	"optimistic": true,
+	"state_topic": "O/~",
+	"command_topic": "P~Q",
+	"device": {
+		"ids": "H",
+		"cns": [
+			[
+				"I1",
+				"I2"
+			]
+		],
+		"name": "J",
+		"mdl": "K",
+		"sw": "L",
+		"mf": "M"
+	},
+	"~": "D/"
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/test/resources/org/openhab/binding/mqtt/homeassistant/internal/configDeviceList.json

@@ -0,0 +1,9 @@
+{
+	"device": {
+		"ids": [
+			"A",
+			"B",
+			"C"
+		]
+	}
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/test/resources/org/openhab/binding/mqtt/homeassistant/internal/configDeviceSingleString.json

@@ -0,0 +1,5 @@
+{
+	"device": {
+		"ids": "A"
+	}
+}

bundles/org.openhab.binding.mqtt.homeassistant/src/test/resources/org/openhab/binding/mqtt/homeassistant/internal/configFan.json

@@ -0,0 +1,22 @@
+{
+	"name": "Bedroom Fan",
+	"state_topic": "bedroom_fan/on/state",
+	"command_topic": "bedroom_fan/on/set",
+	"oscillation_state_topic": "bedroom_fan/oscillation/state",
+	"oscillation_command_topic": "bedroom_fan/oscillation/set",
+	"speed_state_topic": "bedroom_fan/speed/state",
+	"speed_command_topic": "bedroom_fan/speed/set",
+	"qos": 0,
+	"payload_on": "true",
+	"payload_off": "false",
+	"payload_oscillation_on": "true",
+	"payload_oscillation_off": "false",
+	"payload_low_speed": "low",
+	"payload_medium_speed": "medium",
+	"payload_high_speed": "high",
+	"speeds": [
+		"low",
+		"medium",
+		"high"
+	]
+}