const BluetoothHciSocket = require('@abandonware/bluetooth-hci-socket');

var HCI_COMMAND_PKT = 0x01;
var HCI_EVENT_PKT = 0x04;

var EVT_LE_META_EVENT = 0x3e;

var OGF_LE_CTL = 0x08;
var OCF_LE_SET_SCAN_PARAMETERS = 0x000b;
var OCF_LE_SET_SCAN_ENABLE = 0x000c;
var OCF_LE_SET_ADVERTISING_PARAMETERS = 0x0006;
var OCF_LE_SET_ADVERTISING_DATA = 0x0008;
var OCF_LE_SET_ADVERTISE_ENABLE = 0x000a;

var LE_SET_SCAN_PARAMETERS_CMD = OCF_LE_SET_SCAN_PARAMETERS | OGF_LE_CTL << 10;
var LE_SET_SCAN_ENABLE_CMD = OCF_LE_SET_SCAN_ENABLE | OGF_LE_CTL << 10;
var LE_SET_ADVERTISING_PARAMETERS_CMD = OCF_LE_SET_ADVERTISING_PARAMETERS | OGF_LE_CTL << 10;
var LE_SET_ADVERTISING_DATA_CMD = OCF_LE_SET_ADVERTISING_DATA | OGF_LE_CTL << 10;
var LE_SET_ADVERTISE_ENABLE_CMD = OCF_LE_SET_ADVERTISE_ENABLE | OGF_LE_CTL << 10;


class PybricksBroadcast extends BluetoothHciSocket {

  constructor(...args) {
    super(...args);

    this.on('data', function(data) {
      //console.log(data.toString('hex'));
      if(data.length < 19) return;
      if(data.readUInt8(15) === 0xff) { // manufacturer data
        if(data.readUInt16LE(16) === 0x0397) { // lego
          this.emit('observe', {channel: data.readUInt8(18), data: data.slice(19, data.length -1), rssi: data.readInt8(data.length -1)})
        }
      }
    });

    this.on('error', function(error) {console.error(error);});

    this.bindRaw();

    var filter = Buffer.allocUnsafe(14).fill(0);
    var typeMask = (1 << HCI_EVENT_PKT);
    var eventMask2 = (1 << (EVT_LE_META_EVENT - 32));
    filter.writeUInt32LE(typeMask, 0);
    filter.writeUInt32LE(eventMask2, 8);
    this.setFilter(filter);

    this.start();

    this.setScanEnable(false);
    this.setAdvertiseEnable(false);
    this.setScanParameters();
    this.setAdvertiseParameters();
    this.setScanEnable(true);
    this.setAdvertiseEnable(true);
  }


  destructor() {
    this.setScanEnable(false);
    this.setAdvertiseEnable(false);

    this.stop();
  }


  setScanParameters() {
    var cmd = Buffer.allocUnsafe(11);
    cmd.writeUInt8(HCI_COMMAND_PKT, 0);
    cmd.writeUInt16LE(LE_SET_SCAN_PARAMETERS_CMD, 1); // command
    cmd.writeUInt8(0x07, 3); // length

    cmd.writeUInt8(0x00, 4); // type: 0 -> passive, 1 -> active
    cmd.writeUInt16LE(0x003e, 5); // internal, ms * 1.6
    cmd.writeUInt16LE(0x003e, 7); // window, ms * 1.6
    cmd.writeUInt8(0x00, 9); // own address type: 0 -> public, 1 -> random
    cmd.writeUInt8(0x00, 10); // filter: 0 -> all event types

    this.write(cmd);
  }


  setScanEnable(enabled) {
    var cmd = Buffer.allocUnsafe(6);
    cmd.writeUInt8(HCI_COMMAND_PKT, 0);
    cmd.writeUInt16LE(LE_SET_SCAN_ENABLE_CMD, 1); // command
    cmd.writeUInt8(0x02, 3); // length

    cmd.writeUInt8(enabled ? 0x01 : 0x00, 4); // enable: 0 -> disabled, 1 -> enabled
    cmd.writeUInt8(0x01, 5); // duplicates: 0 -> no duplicates, 1 -> duplicates

    this.write(cmd);
  }


  setAdvertiseParameters() {
    var cmd = Buffer.allocUnsafe(19).fill(0);
    cmd.writeUInt8(HCI_COMMAND_PKT, 0);
    cmd.writeUInt16LE(LE_SET_ADVERTISING_PARAMETERS_CMD, 1); // command
    cmd.writeUInt8(15, 3); // length

    cmd.writeUInt16LE(0x00a0, 4); // min interval
    cmd.writeUInt16LE(0x00a0, 6); // max interval
    cmd.writeUInt8(0x03, 8); // adv type: 3 -> ADV_NONCONN_IND
    cmd.writeUInt8(0x07, 17);

    this.write(cmd);
  };


  setAdvertiseData(data) {
    var cmd = Buffer.allocUnsafe(36).fill(0);
    cmd.writeUInt8(HCI_COMMAND_PKT, 0);
    cmd.writeUInt16LE(LE_SET_ADVERTISING_DATA_CMD, 1); // command
    cmd.writeUInt8(32, 3); // length

    cmd.writeUInt8(data.length, 4);
    data.copy(cmd, 5);

    this.write(cmd);
  }


  setAdvertiseEnable(enabled) {
    var cmd = Buffer.allocUnsafe(5).fill(0);
    cmd.writeUInt8(HCI_COMMAND_PKT, 0);
    cmd.writeUInt16LE(LE_SET_ADVERTISE_ENABLE_CMD, 1); // command
    cmd.writeUInt8(0x01, 3); // length

    cmd.writeUInt8(enabled ? 0x01 : 0x00, 4); // enable: 0 -> disabled, 1 -> enabled

    this.write(cmd);
  }


  setBroadcast(channel, data) {
    var header = Buffer.allocUnsafe(5);
    header.writeUInt8(data.length + 4, 0); // length
    header.writeUInt8(0xff, 1); // manufacturer data
    header.writeUInt16LE(0x0397, 2); // lego
    header.writeUInt8(channel, 4); // pybricks channel nr

    this.setAdvertiseData(Buffer.concat([header, data]));
  }

}

broadcaster = new PybricksBroadcast();
broadcaster.on('observe', (arg) => {console.log(arg)});
broadcaster.setBroadcast(0, Buffer.from([0x61, 0x64, 0x84, 0x00, 0x00, 0x80, 0x3f, 0xA2, 0x68, 0x69, 0x20]));

['SIGINT', 'SIGTERM', 'SIGQUIT'].forEach(signal => process.on(signal, () => {broadcaster.destructor();}));