chat_screen.dart

import 'package:flutter/material.dart';
import 'package:flash_chat/constants.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';

final FirebaseAuth _auth = FirebaseAuth.instance;
final _firestore = FirebaseFirestore.instance;
User loggedInUser;

class ChatScreen extends StatefulWidget {
  static const String id = 'chat_screen';
  @override
  _ChatScreenState createState() => _ChatScreenState();
}

class _ChatScreenState extends State<ChatScreen> {

  final messageTextController = TextEditingController();


  String messageText;
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    getCurrentUser();
  }

  void getCurrentUser() async {
    try {
      final User user = _auth.currentUser;
      if(user!=null) {
        loggedInUser = user;
        print(loggedInUser.email);
      }
    }
    catch(e) {
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        leading: null,
        actions: <Widget>[
          IconButton(
              icon: Icon(Icons.close),
              onPressed: () {

                _auth.signOut();
                Navigator.pop(context);
              }),
        ],
        title: Text('⚡️Chat'),
        backgroundColor: Colors.lightBlueAccent,
      ),
      body: SafeArea(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: <Widget>[
            MessagesStream(),

            Container(
              decoration: kMessageContainerDecoration,
              child: Row(
                crossAxisAlignment: CrossAxisAlignment.center,
                children: <Widget>[
                  Expanded(
                    child: TextField(
                      controller: messageTextController,
                      onChanged: (value) {
                        messageText=value;

                      },
                      decoration: kMessageTextFieldDecoration,
                    ),
                  ),
                  FlatButton(
                    onPressed: () {
                      messageTextController.clear();
                      _firestore.collection('messages').add({
                        'text': messageText,
                        'sender': loggedInUser.email,
                        'timestamp': FieldValue.serverTimestamp(),
                      });
                    },
                    child: Text(
                      'Send',
                      style: kSendButtonTextStyle,
                    ),
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class MessagesStream extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return StreamBuilder<QuerySnapshot>(
      stream: _firestore.collection('messages').orderBy('timestamp', descending: false).snapshots(),
      builder: (context,snapshot) {
        if(!snapshot.hasData) {
          return Center(
            child: CircularProgressIndicator(
              backgroundColor: Colors.lightBlueAccent,
            ),
          );
        }
        final messages = snapshot.data.docs.reversed;
        List<MessageBubble> messageBubbles=[];
        for(var message in messages) {
          final messageText = message.data()['text'];
          final messageSender = message.data()['sender'];

          final currentUser = loggedInUser.email;

          final messageBubble = MessageBubble(
            sender: messageSender,
            text: messageText,
            isMe: currentUser==messageSender,

          );
          messageBubbles.add(messageBubble);

        }
        return Expanded(
          child: ListView(
            reverse: true,
            padding: EdgeInsets.symmetric(horizontal: 10.0,vertical: 20.0),
            children: messageBubbles,
          ),
        );
      },
    );
  }
}


class MessageBubble extends StatelessWidget {

  MessageBubble({this.sender,this.text,this.isMe});
  final String sender;
  final String text;
  final bool isMe;

  @override
  Widget build(BuildContext context) {

    return Padding(
      padding: EdgeInsets.all(10.0),
      child: Column(
        crossAxisAlignment: isMe?CrossAxisAlignment.end:CrossAxisAlignment.start,
        children: [
          Text(sender,style: TextStyle(
            fontSize: 11.0,
            color: Colors.black54,
          ),),
          Material(
            borderRadius: isMe? BorderRadius.only(topLeft: Radius.circular(30.0),bottomLeft: Radius.circular(30.0),bottomRight: Radius.circular(30.0)):BorderRadius.only(topRight: Radius.circular(30.0),bottomLeft: Radius.circular(30.0),bottomRight: Radius.circular(30.0)),
            elevation: 5.0,
            color: isMe ? Colors.blue:Colors.lightGreen,
            child: Padding(
              padding: EdgeInsets.symmetric(vertical: 10.0,horizontal: 20.0),
              child: Text(
                text,
                style: TextStyle(
                  color: Colors.white,
                  fontSize: 15.0,
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}






























//import 'package:flutter/material.dart';
//import 'package:flash_chat/constants.dart';
//import 'package:firebase_auth/firebase_auth.dart';
//import 'package:cloud_firestore/cloud_firestore.dart';
//
//
//class ChatScreen extends StatefulWidget {
//  static String id = 'chat_screen';
//  @override
//  _ChatScreenState createState() => _ChatScreenState();
//}
//
//class _ChatScreenState extends State<ChatScreen> {
//  final _firestore = FirebaseFirestore.instance;
//  final FirebaseAuth _auth = FirebaseAuth.instance;
//  User loggedInUser;
//  String messageText;
//
//
//
//  @override
//  void initState() {
//    // TODO: implement initState
//    super.initState();
//    getCurrentUser();
//  }
//  void getCurrentUser() async{
//    try{
//    final user = await _auth.currentUser;
//    if(user != null){
//      loggedInUser = user;
//      print(loggedInUser.email);
//    }}
//    catch(e){
//      print(e);
//
//    }
//  }
//
//
////  void getMessages() async{
////    final messages = await _firestore.collection('messages').getDocuments();
////    for (var message in messages.){
////      print(message.data);
////    }
////  }
//
//  void messagesStream()async{
//    await for (var snapshot in _firestore.collection('messages').snapshots()){
//      for (var message in snapshot.docs){
//        print(message.data);
//      }
//    }
//  }
//
//
//  @override
//  Widget build(BuildContext context) {
//    return Scaffold(
//      appBar: AppBar(
//        leading: null,
//        actions: <Widget>[
//          IconButton(
//              icon: Icon(Icons.close),
//              onPressed: () {
//                messagesStream();
////                _auth.signOut();
////                Navigator.pop(context);
//                //Implement logout functionality
//              }),
//        ],
//        title: Text('⚡️Chat'),
//        backgroundColor: Colors.lightBlueAccent,
//      ),
//      body: SafeArea(
//        child: Column(
//          mainAxisAlignment: MainAxisAlignment.spaceBetween,
//          crossAxisAlignment: CrossAxisAlignment.stretch,
//          children: <Widget>[
//            StreamBuilder<QuerySnapshot>(
//              stream: _firestore.collection('messages').snapshots(),
//              builder: (context, snapshot){
//                if(snapshot.hasData){
//                  final messages = snapshot.data.docs;
//                  List<Text> messageWidgets = [];
//                  for (var message in messages){
//                    final messageText = message.data['text'];
//                    final messageSender = message.data['sender'];
//
//                    final messageWidget = Text('$messageText from $messageSender');
//                    messageWidgets.add(messageWidget);
//                  }
//
//                  return Column(
//                    children: messageWidgets,
//                  );
//                }
//              },
//            ),
//            Container(
//              decoration: kMessageContainerDecoration,
//              child: Row(
//                crossAxisAlignment: CrossAxisAlignment.center,
//                children: <Widget>[
//                  Expanded(
//                    child: TextField(
//                      onChanged: (value) {
//                        messageText =value;
//                        //Do something with the user input.
//                      },
//                      decoration: kMessageTextFieldDecoration,
//                    ),
//                  ),
//                  FlatButton(
//                    onPressed: () {
//                      _firestore.collection('messages').add({
//                        'text': messageText,
//                        'sender': loggedInUser.email,
//                      });
//
//                      //Implement send functionality.
//                    },
//                    child: Text(
//                      'Send',
//                      style: kSendButtonTextStyle,
//                    ),
//                  ),
//                ],
//              ),
//            ),
//          ],
//        ),
//      ),
//    );
//  }
//}
//