// Copyright 2017 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:async';

import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/material.dart';

final Map<String, Item> _items = <String, Item>{};
Item _itemForMessage(Map<String, dynamic> message) {
  final String itemId = message['data']['id'];
  final Item item = _items.putIfAbsent(itemId, () => Item(itemId: itemId))
    ..status = message['data']['status'];
  return item;
}

class Item {
  Item({this.itemId});
  final String itemId;

  StreamController<Item> _controller = StreamController<Item>.broadcast();
  Stream<Item> get onChanged => _controller.stream;

  String _status;
  String get status => _status;
  set status(String value) {
    _status = value;
    _controller.add(this);
  }

  static final Map<String, Route<void>> routes = <String, Route<void>>{};
  Route<void> get route {
    final String routeName = '/detail/$itemId';
    return routes.putIfAbsent(
      routeName,
      () => MaterialPageRoute<void>(
            settings: RouteSettings(name: routeName),
            builder: (BuildContext context) => DetailPage(itemId),
          ),
    );
  }
}

class DetailPage extends StatefulWidget {
  DetailPage(this.itemId);
  final String itemId;
  @override
  _DetailPageState createState() => _DetailPageState();
}

class _DetailPageState extends State<DetailPage> {
  Item _item;
  StreamSubscription<Item> _subscription;

  @override
  void initState() {
    super.initState();
    _item = _items[widget.itemId];
    _subscription = _item.onChanged.listen((Item item) {
      if (!mounted) {
        _subscription.cancel();
      } else {
        setState(() {
          _item = item;
        });
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Item ${_item.itemId}"),
      ),
      body: Material(
        child: Center(child: Text("Item status: ${_item.status}")),
      ),
    );
  }
}

class PushMessagingExample extends StatefulWidget {
  @override
  _PushMessagingExampleState createState() => _PushMessagingExampleState();
}

class _PushMessagingExampleState extends State<PushMessagingExample> {
  String _homeScreenText = "Waiting for token...";
  bool _topicButtonsDisabled = false;

  final FirebaseMessaging _firebaseMessaging = FirebaseMessaging();
  final TextEditingController _topicController =
      TextEditingController(text: 'topic');

  Widget _buildDialog(BuildContext context, Item item) {
    return AlertDialog(
      content: Text("Item ${item.itemId} has been updated"),
      actions: <Widget>[
        FlatButton(
          child: const Text('CLOSE'),
          onPressed: () {
            Navigator.pop(context, false);
          },
        ),
        FlatButton(
          child: const Text('SHOW'),
          onPressed: () {
            Navigator.pop(context, true);
          },
        ),
      ],
    );
  }

  void _showItemDialog(Map<String, dynamic> message) {
    showDialog<bool>(
      context: context,
      builder: (_) => _buildDialog(context, _itemForMessage(message)),
    ).then((bool shouldNavigate) {
      if (shouldNavigate == true) {
        _navigateToItemDetail(message);
      }
    });
  }

  void _navigateToItemDetail(Map<String, dynamic> message) {
    final Item item = _itemForMessage(message);
    // Clear away dialogs
    Navigator.popUntil(context, (Route<dynamic> route) => route is PageRoute);
    if (!item.route.isCurrent) {
      Navigator.push(context, item.route);
    }
  }

  @override
  void initState() {
    super.initState();
    _firebaseMessaging.configure(
      onMessage: (Map<String, dynamic> message) async {
        print("onMessage: $message");
        _showItemDialog(message);
      },
      onLaunch: (Map<String, dynamic> message) async {
        print("onLaunch: $message");
        _navigateToItemDetail(message);
      },
      onResume: (Map<String, dynamic> message) async {
        print("onResume: $message");
        _navigateToItemDetail(message);
      },
    );
    _firebaseMessaging.requestNotificationPermissions(
        const IosNotificationSettings(sound: true, badge: true, alert: true));
    _firebaseMessaging.onIosSettingsRegistered
        .listen((IosNotificationSettings settings) {
      print("Settings registered: $settings");
    });
    _firebaseMessaging.getToken().then((String token) {
      assert(token != null);
      setState(() {
        _homeScreenText = "Push Messaging token: $token";
      });
      print(_homeScreenText);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text('Push Messaging Demo'),
        ),
        // For testing -- simulate a message being received
        floatingActionButton: FloatingActionButton(
          onPressed: () => _showItemDialog(<String, dynamic>{
                "data": <String, String>{
                  "id": "2",
                  "status": "out of stock",
                },
              }),
          tooltip: 'Simulate Message',
          child: const Icon(Icons.message),
        ),
        body: Material(
          child: Column(
            children: <Widget>[
              Center(
                child: Text(_homeScreenText),
              ),
              Row(children: <Widget>[
                Expanded(
                  child: TextField(
                      controller: _topicController,
                      onChanged: (String v) {
                        setState(() {
                          _topicButtonsDisabled = v.isEmpty;
                        });
                      }),
                ),
                FlatButton(
                  child: const Text("subscribe"),
                  onPressed: _topicButtonsDisabled
                      ? null
                      : () {
                          _firebaseMessaging
                              .subscribeToTopic(_topicController.text);
                          _clearTopicText();
                        },
                ),
                FlatButton(
                  child: const Text("unsubscribe"),
                  onPressed: _topicButtonsDisabled
                      ? null
                      : () {
                          _firebaseMessaging
                              .unsubscribeFromTopic(_topicController.text);
                          _clearTopicText();
                        },
                ),
              ])
            ],
          ),
        ));
  }

  void _clearTopicText() {
    setState(() {
      _topicController.text = "";
      _topicButtonsDisabled = true;
    });
  }
}

void main() {
  runApp(
    MaterialApp(
      home: PushMessagingExample(),
    ),
  );
}