import 'dart:async';
import 'dart:io';
import 'dart:math';

import 'package:firebase_analytics/firebase_analytics.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_database/firebase_database.dart';
import 'package:firebase_database/ui/firebase_animated_list.dart';
import 'package:firebase_storage/firebase_storage.dart';

import 'package:flutter/cupertino.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

import 'package:google_sign_in/google_sign_in.dart';
import 'package:image_picker/image_picker.dart';


final auth = FirebaseAuth.instance;
final analytics = new FirebaseAnalytics();
final googleSignIn = new GoogleSignIn();
final reference = FirebaseDatabase.instance.reference().child('messages');

void main() => runApp(new FriendlychatApp());

final ThemeData kIOSTheme = new ThemeData(
  primarySwatch: Colors.orange,
  primaryColor: Colors.grey[100],
  primaryColorBrightness: Brightness.light,
);

final ThemeData kDefaultTheme = new ThemeData(
  primarySwatch: Colors.purple,
  accentColor: Colors.orangeAccent[400],
);

class FriendlychatApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: "Friendlychat",
      theme: defaultTargetPlatform == TargetPlatform.iOS
          ? kIOSTheme : kDefaultTheme,
      home: new ChatScreen(),
    );
  }
}

class ChatMessage extends StatelessWidget {
  ChatMessage({this.snapshot, this.animation});
  final DataSnapshot snapshot;
  final Animation animation;

  @override
  Widget build(BuildContext context) {
    return new FadeTransition(
      opacity: new CurvedAnimation(
        parent: animation, curve: Curves.easeOut
      ),
      child: new Container(
        margin: const EdgeInsets.symmetric(vertical: 10.0),
        child: new Row(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            new Container(
              margin: const EdgeInsets.only(right: 16.0),
              child: new CircleAvatar(
                backgroundImage: new NetworkImage(snapshot.value['senderPhotoUrl']),
              ),
            ),
            new Expanded(
              child: new Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: <Widget>[
                  new Text(
                    snapshot.value['senderName'],
                    style: Theme.of(context).textTheme.subhead
                  ),
                  new Container(
                    margin: const EdgeInsets.only(top: 5.0),
                    child: snapshot.value['imageUrl'] != null ?
                            new Image.network(
                              snapshot.value['imageUrl'],
                              width: 250.0,
                            ) : new Text(snapshot.value['text']),
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class ChatScreen extends StatefulWidget {
  @override
  State createState() => new ChatScreenState();
}

class ChatScreenState extends State<ChatScreen> {
  final TextEditingController _textController = new TextEditingController();
  bool _isComposing = false;

  Future<Null> _ensureLoggedIn() async {
    GoogleSignInAccount user = googleSignIn.currentUser;
    if (user == null) {
      user = await googleSignIn.signInSilently();
    }
    if (user == null) {
      await googleSignIn.signIn();
      analytics.logLogin();
    }
    if (await auth.currentUser() == null) {
      GoogleSignInAuthentication credentials = await googleSignIn.currentUser.authentication;
      await auth.signInWithGoogle(
        idToken: credentials.idToken,
        accessToken: credentials.accessToken,
      );
    }
  }

  void _handleSubmitted(String text) async {
    _textController.clear();

    setState(() {
      _isComposing = false;
    });

    await _ensureLoggedIn();
    _sendMessage(text: text);
  }

  void _sendMessage({ String text, String imageUrl }) {
    reference.push().set({
      'text': text,
      'imageUrl': imageUrl,
      'senderName': googleSignIn.currentUser.displayName,
      'senderPhotoUrl': googleSignIn.currentUser.photoUrl,
    });

    // ChatMessage message = new ChatMessage(
    //   text: text,
    //   animationController: new AnimationController(
    //     duration: new Duration(milliseconds: 700),
    //     vsync: this,
    //   ),
    // );

    // setState(() { _messages.insert(0, message); });
    // message.animationController.forward();

    analytics.logEvent(name: "send_message");
  }

  Widget _buildTextComposer() {
    return new IconTheme(
      data: new IconThemeData(color: Theme.of(context).accentColor),
      child: new Container(
        margin: const EdgeInsets.symmetric(horizontal: 8.0),
        child: new Row(
          children: <Widget>[
            new Container(
              margin: const EdgeInsets.symmetric(horizontal: 8.0),
              child: new IconButton(
                icon: new Icon(Icons.photo_camera),
                onPressed: () async {
                  await _ensureLoggedIn();
                  File imageFile = await ImagePicker.pickImage(source: ImageSource.gallery);
                  int random = new Random().nextInt(100000);
                  StorageReference ref = FirebaseStorage.instance.ref().child("image_$random.jpg");
                  StorageUploadTask uploadTask = ref.putFile(imageFile);
                  Uri downloadUrl = (await uploadTask.future).downloadUrl;
                  _sendMessage(imageUrl: downloadUrl.toString());
                },
              ),
            ),
            new Flexible(
              child: new TextField(
                controller: _textController,
                onChanged: (String text) {
                  setState(() {
                    _isComposing = text.length > 0;
                  });
                },
                onSubmitted: _handleSubmitted,
                decoration: new InputDecoration.collapsed(
                  hintText: "Send a message",
                ),
              ),
            ),
            new Container(
              margin: new EdgeInsets.symmetric(horizontal: 4.0),
              child: Theme.of(context).platform == TargetPlatform.iOS ?
                new CupertinoButton(
                  child: new Text("Send"),
                  onPressed: _isComposing
                      ? () => _handleSubmitted(_textController.text) : null,
                )
                :
                new IconButton(
                  icon: new Icon(Icons.send),
                  onPressed: _isComposing
                      ? () => _handleSubmitted(_textController.text) : null,
                ),
            ),
          ],
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("Friendlychat"),
        elevation: Theme.of(context).platform == TargetPlatform.iOS ? 0.0 : 4.0,
      ),
      body: new Column(
        children: <Widget>[
          new Flexible(
            child: new FirebaseAnimatedList(
              query: reference,
              sort: (a, b) => b.key.compareTo(a.key),
              padding: new EdgeInsets.all(8.0),
              reverse: true,
              itemBuilder: (_, DataSnapshot snapshot, Animation<double> animation, int index) {
                return new ChatMessage(
                  snapshot: snapshot,
                  animation: animation,
                );
              },
            ),
          ),
          new Divider(height: 1.0),
          new Container(
            decoration: new BoxDecoration(color: Theme.of(context).cardColor),
            child: _buildTextComposer(),
          ),
        ],
      ),
    );
  }
}