/*
 * This script uses the BLE scan functionality in scripting to pass scan reults to openHAB
 * Supported BLU Devices: SBBT , SBDW
 * Version 0.2
 */

let ALLTERCO_DEVICE_NAME_PREFIX = ["SBBT", "SBDW"];
let ALLTERCO_MFD_ID_STR = "0ba9";
let BTHOME_SVC_ID_STR = "fcd2";

let ALLTERCO_MFD_ID = JSON.parse("0x" + ALLTERCO_MFD_ID_STR);
let BTHOME_SVC_ID = JSON.parse("0x" + BTHOME_SVC_ID_STR);
let SCAN_DURATION = BLE.Scanner.INFINITE_SCAN;

let SHELLY_BLU_CACHE = {};
let LAST_PID = {};

let uint8 = 0;
let int8 = 1;
let uint16 = 2;
let int16 = 3;
let uint24 = 4;
let int24 = 5;

let BTH = [];
BTH[0x00] = { n: "pid", t: uint8 };
BTH[0x01] = { n: "Battery", t: uint8, u: "%" };
BTH[0x05] = { n: "Illuminance", t: uint24, f: 0.01 };
BTH[0x1a] = { n: "Door", t: uint8 };
BTH[0x20] = { n: "Moisture", t: uint8 };
BTH[0x2d] = { n: "Window", t: uint8 };
BTH[0x3a] = { n: "Button", t: uint8 };
BTH[0x3f] = { n: "Rotation", t: int16, f: 0.1 };

function getByteSize(type) {
  if (type === uint8 || type === int8) return 1;
  if (type === uint16 || type === int16) return 2;
  if (type === uint24 || type === int24) return 3;
  //impossible as advertisements are much smaller;
  return 255;
}

let BTHomeDecoder = {
  utoi: function (num, bitsz) {
    let mask = 1 << (bitsz - 1);
    return num & mask ? num - (1 << bitsz) : num;
  },
  getUInt8: function (buffer) {
    return buffer.at(0);
  },
  getInt8: function (buffer) {
    return this.utoi(this.getUInt8(buffer), 8);
  },
  getUInt16LE: function (buffer) {
    return 0xffff & ((buffer.at(1) << 8) | buffer.at(0));
  },
  getInt16LE: function (buffer) {
    return this.utoi(this.getUInt16LE(buffer), 16);
  },
  getUInt24LE: function (buffer) {
    return (
      0x00ffffff & ((buffer.at(2) << 16) | (buffer.at(1) << 8) | buffer.at(0))
    );
  },
  getInt24LE: function (buffer) {
    return this.utoi(this.getUInt24LE(buffer), 24);
  },
  getBufValue: function (type, buffer) {
    if (buffer.length < getByteSize(type)) return null;
    let res = null;
    if (type === uint8) res = this.getUInt8(buffer);
    if (type === int8) res = this.getInt8(buffer);
    if (type === uint16) res = this.getUInt16LE(buffer);
    if (type === int16) res = this.getInt16LE(buffer);
    if (type === uint24) res = this.getUInt24LE(buffer);
    if (type === int24) res = this.getInt24LE(buffer);
    return res;
  },
  unpack: function (buffer) {
    // beacons might not provide BTH service data
    if (typeof buffer !== "string" || buffer.length === 0) return null;
    let result = {};
    let _dib = buffer.at(0);
    result["encryption"] = _dib & 0x1 ? true : false;
    result["BTHome_version"] = _dib >> 5;
    if (result["BTHome_version"] !== 2) return null;
    //Can not handle encrypted data
    if (result["encryption"]) return result;
    buffer = buffer.slice(1);

    let _bth;
    let _value;
    while (buffer.length > 0) {
      _bth = BTH[buffer.at(0)];
      if (_bth === "undefined") {
        console.log("BTH: unknown type");
        break;
      }
      buffer = buffer.slice(1);
      _value = this.getBufValue(_bth.t, buffer);
      if (_value === null) break;
      if (typeof _bth.f !== "undefined") _value = _value * _bth.f;
      result[_bth.n] = _value;
      buffer = buffer.slice(getByteSize(_bth.t));
    }
    return result;
  },
};

let ShellyBLUParser = {
  getData: function (res) {
    let result = BTHomeDecoder.unpack(res.service_data[BTHOME_SVC_ID_STR]);
    result.addr = res.addr;
    result.rssi = res.rssi;
    return result;
  },
};

function scanCB(ev, res) {
  if (ev !== BLE.Scanner.SCAN_RESULT) return;
  // skip if there is no service_data member
  if (typeof res.service_data === 'undefined' || typeof res.service_data[BTHOME_SVC_ID_STR] === 'undefined') return;
  // skip if we have already found this device
  if (typeof SHELLY_BLU_CACHE[res.addr] === 'undefined') {
   if (typeof res.local_name === "undefined") console.log("res.local_name undefined")
   if (typeof res.local_name !== 'string') return;
    let shellyBluNameIdx = 0; 
    for (shellyBluNameIdx in ALLTERCO_DEVICE_NAME_PREFIX) {
      if (res.local_name.indexOf(ALLTERCO_DEVICE_NAME_PREFIX[shellyBluNameIdx]) === 0) {
        console.log('New device found: address=', res.addr, ', name=', res.local_name);
        Shelly.emitEvent("oh-blu.scan_result", {"addr":res.addr, "name":res.local_name, "rssi":res.rssi, "tx_power":res.tx_power_level});
        SHELLY_BLU_CACHE[res.addr] = res.local_name;
        }
    }
  }
  
  let BTHparsed = ShellyBLUParser.getData(res); // skip if parsing failed
    if (BTHparsed === null) {
    console.log("Failed to parse BTH data");
    return;
  }
  
  // skip, we are deduping results
  if (typeof LAST_PID[res.addr] === 'undefined' ||
      BTHparsed.pid !== LAST_PID[res.addr]) {
    Shelly.emitEvent("oh-blu.data", BTHparsed);
    LAST_PID[res.addr] = BTHparsed.pid;
  }
}

let BLEConfig = Shelly.getComponentConfig('ble');
if(BLEConfig.enable === false) {
  console.log('Error: BLE not enabled, unable to start OH-BLU Scanner');
} else {
    BLE.Scanner.Start({ duration_ms: SCAN_DURATION, active: true }, scanCB);
    console.log('OH-BLU Event Gateway running');
}