// flutter bluetooth demo with adafruit bluefruit le
////////////main.dart/////////////////////
// add to pubspec.yaml
//   flutter_blue: 0.7.1+1
//
// change android/app/build.gradle
//        minSdkVersion 19
//
// troubleshooting:
//    on android - turn on bluetooth and location
//    wait a few seconds make sure device is connected
//    turn on / off bluetooth briefly
//    on android under settings - give permission to app for location
//    check with nrfconnect (from google play) correct device name, serives, and characteristics
//
// this demo shows how to send and received notification from device
// the device tested is adafruit product id: 4062
//   
//////////////// main.dart //////////////////
import 'package:flutter/material.dart';
import 'dart:async';
import './ble.dart';
import './send_ble.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(title: 'Flutter Demo Home Page'),);}}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();}

class _MyHomePageState extends State {

  static newReceivedText(String s){
    print("received: $s");}

  BLE ble = BLE(newReceivedText);

  connectToBLE() async {
    ble.init();
    await new Future.delayed(const Duration(seconds: 5));}

  @override  
  void initState() {
    super.initState();
    connectToBLE();}

  @override  
  Widget build(BuildContext ctx) {
    return Scaffold(  
      body: Container(  
          child: Column(
              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
              children: [SendBLE(),],),),);}}

///////////////// ble.dart ////////////////////
import 'package:flutter_blue/flutter_blue.dart';
import 'dart:async';

class BLE {

  final Function(String) callback;
  BLE(this.callback);

  static BluetoothCharacteristic txChar;
  static BluetoothCharacteristic notifyChar;
  static String receivedText;

  static final String baseUuid = "-b5a3-f393-e0a9-e50e24dcca9e";
  final String serviceUuid = "6e400001" + baseUuid;
  final String txCharUuid = "6e400002" + baseUuid;
  final String notifyCharUuid = "6e400003" + baseUuid;  
  final String deviceName = "Adafruit Bluefruit LE";

  FlutterBlue flutterBlue = FlutterBlue.instance;
  StreamSubscription scanSubScription;

  BluetoothDevice targetDevice;

    init(){
    scanSubScription = flutterBlue.scan().listen((scanResult) {
      if (scanResult.device.name == deviceName) {
        stopScan();
        targetDevice = scanResult.device;
        connectToDevice();
      }
    }, onDone: () => stopScan());}

  stopScan() {
    scanSubScription?.cancel();
    scanSubScription = null;}

  connectToDevice() async {
    if (targetDevice == null) return;
    await targetDevice.connect();
    print("device connectd");
    discoverServices();}

  disconnectFromDevice() {
    if (targetDevice == null) return;
    targetDevice.disconnect();}

  handle(BluetoothCharacteristic notifyChar) async {
    await notifyChar.setNotifyValue(true);
    notifyChar.value.listen((data){
      if (data.isNotEmpty) callback(String.fromCharCodes(data));
    });}

  discoverServices() async {
    if (targetDevice == null) return;
    List services = await targetDevice.discoverServices();
    services.forEach((service) {
      if (service.uuid.toString() == serviceUuid) {
        service.characteristics.forEach((characteristic) {
          if (characteristic.uuid.toString() == notifyCharUuid) {
             notifyChar = characteristic;
             handle(notifyChar);}
          if (characteristic.uuid.toString() == txCharUuid) {
            print("found txchar");
            txChar = characteristic;}});}});}}

/////////////// send_ble.dart ///////////////////
import 'dart:convert' show utf8;
import 'package:flutter/material.dart';
import './ble.dart';

class SendBLE extends StatelessWidget {
  final _writeController = TextEditingController();

  @override  
  Widget build(BuildContext context) {
    return RaisedButton(
      child: Text('write'),
      onPressed: () async {
        await showDialog(
          context: context,
          builder: (BuildContext context) {
            return AlertDialog(
              title: Text("write"),
              content: Row(
                children: [
                  Expanded(child: TextField(
                      controller: _writeController,),),],),
                 
              actions: [
                FlatButton(child: Text("Send"),
                  onPressed: () {
                    BLE.txChar.write(utf8.encode(_writeController.value.text));
                    Navigator.pop(context);},),

                FlatButton(child: Text("Cancel"),
                  onPressed: () {
                    Navigator.pop(context);},),],);});});}}