import 'package:flutter/material.dart';
import 'package:font_awesome_flutter/font_awesome_flutter.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_database/firebase_database.dart';
import '../util/authentication.dart' as auth;

bool buttons_visible = false;
bool loader_visible = true;
FirebaseUser _firebaseUser = null;
final databaseReference = FirebaseDatabase.instance.reference();

class Login extends StatefulWidget {
  @override
  LoginState createState() => new LoginState();
}

class LoginState extends State<Login> {
  @override
  void initState() {
    super.initState();
    _checkAuthStatus();
  }

  _swapvisibility(){
    setState((){
      buttons_visible = !buttons_visible;
      loader_visible = !loader_visible;
    });
  }

  _checkAuthStatus() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    print('will attempt auto sign in');
    _performSignin(prefs.getString("auth_provider"));
  }

  _performSignin(String auth_provider) async {
    if(auth_provider==null){
      print('no auth info yet');
      _swapvisibility();
      return;
    }

    print('display buttons');
    _swapvisibility();

    if (auth_provider == 'facebook') _firebaseUser = await auth.signInWithFacebook();
    if (auth_provider == 'google') _firebaseUser = await auth.signInWithGoogle();
  }

  var linearGradient = new BoxDecoration(
    gradient: new LinearGradient(
      begin: FractionalOffset.centerRight,
      end: FractionalOffset.bottomLeft,
      colors: [
        const Color(0xFFCFD8DC),
        const Color(0xFF607D8B),
      ],
    ),
  );

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: new Container(
        decoration: linearGradient,
        child: new Center(
          child: new Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              new Opacity(
                  opacity: loader_visible ? 1.0 : 0.0,
                  child:
                  new Container(
                      padding: const EdgeInsets.all(32.0),
                      child: new CircularProgressIndicator()
                  )
              ),
              new Opacity(
                  opacity: buttons_visible ? 1.0 : 0.0,
                  child:
                  new Column(

                      mainAxisAlignment: MainAxisAlignment.center,
                      children: <Widget>[
                        new Container(
                            width: 240.0,
                            padding: const EdgeInsets.all(8.0),
                            child:
                            new RaisedButton.icon(
                                icon: new Icon(FontAwesomeIcons.facebook),
                                label: new Text('Sign in with Facebook'),
                                onPressed: () {
                                  _performSignin('facebook');
                                }
                            )
                        ),
                        new Container(
                            width: 240.0,
                            padding: const EdgeInsets.all(8.0),
                            child:
                            new RaisedButton.icon(
                                icon: new Icon(FontAwesomeIcons.google),
                                label: new Text('Sign in with Google'),
                                onPressed: () {
                                  _performSignin('google');
                                }
                            ),
                        ),

                      ]
                  )
              )
            ]
          )
        )
      )
    );
  }
}