electronVueDemo/static/server/ble/nobleWrapper.js

const resp = require('../util/resp')
const noble = require('noble');

let inRange = {};
let blueDeviceList = []
let blueCharacteristics = []

const ECHO_SERVICE_UUID = 'ec00';
const ECHO_CHARACTERISTIC_UUID = 'ec0e';

let connectedCharacteristic = null;
let on_data_callback = null;

noble.on('discover', function (peripheral) {
  inRange[peripheral.id] = {
    peripheral: peripheral
  };

  var blueDevice = {
    'id': peripheral.id,
    'localName': peripheral.advertisement.localName,
    'serviceUuids': JSON.stringify(peripheral.advertisement.serviceUuids),
    'address': peripheral.address,
    'addressType': peripheral.addressType,
    'connectable': peripheral.connectable,
    'rssi': peripheral.rssi,
  }

  blueDeviceList.push(blueDevice)

  explore(peripheral)
});


function explore(peripheral) {
  peripheral.connect(error => {
    peripheral.discoverServices([], function (error, services) {
      for (let serviceIndex = 0; serviceIndex < services.length; serviceIndex++) {
        (function (service) {
          service.discoverCharacteristics([], function (error, characteristics) {
            for (let charIndex = 0; charIndex < characteristics.length; charIndex++) {
              let c = characteristics[charIndex];

              let info = {
                id: peripheral.id,
                uuid: service.uuid,
                name: service.name,
                characteristic: {
                  'uuid': c.uuid,
                  'properties': c.properties
                }
              }

              blueCharacteristics.push(info)
            }
          })
        })(services[serviceIndex])

      }

      setTimeout(function () {
        peripheral.disconnect()
      }, 1000)
    })
  })
}

function merge_scan_result() {
  for (let i = 0; i < blueDeviceList.length; i++) {
    let device = blueDeviceList[i]
    device.characteristics = []

    for (let j = 0; j < blueCharacteristics.length; j++) {
      let character = blueCharacteristics[j]
      if (device.id === character.id) {
        device.characteristics.push(character)
      }
    }
  }

  return blueDeviceList
}

function connectAndSetUp(peripheral) {
  peripheral.connect(error => {
    console.log('Connected to', peripheral.id);

    // specify the services and characteristics to discover
    const serviceUUIDs = [ECHO_SERVICE_UUID];
    const characteristicUUIDs = [ECHO_CHARACTERISTIC_UUID];

    peripheral.discoverSomeServicesAndCharacteristics(
      serviceUUIDs,
      characteristicUUIDs,
      onServicesAndCharacteristicsDiscovered
    );
  });

  peripheral.on('disconnect', () => console.log('disconnected'));
}

function onServicesAndCharacteristicsDiscovered(error, services, characteristics) {
  console.log('Discovered services and characteristics');
  const echoCharacteristic = characteristics[0];

  // data callback receives notifications
  echoCharacteristic.on('data', (data, isNotification) => {
    if (on_data_callback) {
      on_data_callback(data)
    }
  });

  // subscribe to be notified whenever the peripheral update the characteristic
  echoCharacteristic.subscribe(error => {
    if (error) {
      console.error('Error subscribing to echoCharacteristic');
    } else {
      console.log('Subscribed for echoCharacteristic notifications');
    }
  });

  connectedCharacteristic = echoCharacteristic
}

module.exports = {
  scan: function (resp_callback) {

    try {
      blueDeviceList = []
      blueCharacteristics = []

      setTimeout(() => {
        noble.stopScanning()
        resp_callback(resp.ok_resp(merge_scan_result()))
      }, 2000);
      noble.startScanning()
    } catch (e) {
      resp_callback(resp.fail_resp(e.message))
    }
  },
  connect: function (id, on_data_cb, resp_callback) {
    on_data_callback = on_data_cb;
    connectAndSetUp(inRange[id].peripheral)
  },
  write: function (msg, resp_callback) {
    try {
      const buffer = new Buffer(msg, 'utf-8');
      if (connectedCharacteristic) {
        connectedCharacteristic.write(buffer);
      }
    } catch (e) {
      resp_callback(resp.fail_resp(e.message))
    }
  }
}