flutter/lib/screens/auth_screen.dart

import 'dart:math';
import '../models/http_exception.dart';

import 'package:flutter/material.dart';

enum AuthMode { Signup, Login }

class AuthScreen extends StatelessWidget {
  static const routeName = '/auth';

  @override
  Widget build(BuildContext context) {
    final deviceSize = MediaQuery.of(context).size;
    // final transformConfig = Matrix4.rotationZ(-8 * pi / 180);
    // transformConfig.translate(-10.0);
    return Scaffold(
      // resizeToAvoidBottomInset: false,
      body: Stack(
        children: <Widget>[
          Container(
            decoration: BoxDecoration(
              color: const Color(0xff222000),
              image: new DecorationImage(
                fit: BoxFit.cover,
                colorFilter: ColorFilter.mode(
                    Colors.black.withOpacity(0.2), BlendMode.dstATop),
                image: new AssetImage(
                  'assets/images/main.jpg',
                ),
              ),
            ),
          ),
          SingleChildScrollView(
            child: Container(
              height: deviceSize.height,
              width: deviceSize.width,
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                crossAxisAlignment: CrossAxisAlignment.center,
                children: <Widget>[
                  Flexible(
                    child: Container(
                      margin: EdgeInsets.only(bottom: 20.0),
                      padding:
                          EdgeInsets.symmetric(vertical: 8.0, horizontal: 94.0),
                      // ..translate(-10.0),
                      child: Text(
                        'WGER',
                        style: TextStyle(
                          color: Theme.of(context).accentTextTheme.title.color,
                          fontSize: 50,
                          fontFamily: 'Anton',
                          fontWeight: FontWeight.normal,
                        ),
                      ),
                    ),
                  ),
                  Flexible(
                    flex: deviceSize.width > 600 ? 2 : 1,
                    child: AuthCard(),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }
}

class AuthCard extends StatefulWidget {
  const AuthCard({
    Key key,
  }) : super(key: key);

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

class _AuthCardState extends State<AuthCard> {
  final GlobalKey<FormState> _formKey = GlobalKey();
  AuthMode _authMode = AuthMode.Login;
  Map<String, String> _authData = {
    'username': '',
    'email': '',
    'password': '',
  };
  var _isLoading = false;
  final _passwordController = TextEditingController();

  void _showErrorDialog(String message) {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        title: Text('An Error Occured!'),
        content: Text(message),
        actions: [
          FlatButton(
            child: Text('Dismiss'),
            onPressed: () {
              Navigator.of(ctx).pop();
            },
          )
        ],
      ),
    );
  }

  void _submit() async {
    if (!_formKey.currentState.validate()) {
      // Invalid!
      return;
    }
    _formKey.currentState.save();
    setState(() {
      _isLoading = true;
    });
    try {
      if (_authMode == AuthMode.Login) {
        // await Provider.of<Auth>(context, listen: false)
        // .signIn(_authData['email'], _authData['password']);
      } else {
        // await Provider.of<Auth>(context, listen: false)
        // .signUp(_authData['email'], _authData['password']);
        // Sign user up
      }
    } on HttpException catch (error) {
      var errorMessage = 'Authentication Failed';

      if (error.toString().contains('EMAIL_EXISTS')) {
        errorMessage = 'This email address is already in use';
      } else if (error.toString().contains('INVALID_EMAIL')) {
        errorMessage = 'This is not a valid email address';
      } else if (error.toString().contains('WEAK_PASSWORD')) {
        errorMessage = 'This password is too weak';
      } else if (error.toString().contains('EMAIL_NOT_FOUND')) {
        errorMessage = 'Could not find a user with that email';
      } else if (error.toString().contains('INVALID_PASSWORD')) {
        errorMessage = 'Your password is incorrect';
      }
      _showErrorDialog(errorMessage);
    } catch (error) {
      var errorMessage = 'Could not authenticate you. Please try again later';
      _showErrorDialog(errorMessage);
    }

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

  void _switchAuthMode() {
    if (_authMode == AuthMode.Login) {
      setState(() {
        _authMode = AuthMode.Signup;
      });
    } else {
      setState(() {
        _authMode = AuthMode.Login;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    final deviceSize = MediaQuery.of(context).size;
    return Card(
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(10.0),
      ),
      elevation: 8.0,
      child: Container(
        height: _authMode == AuthMode.Signup ? 450 : 260,
        constraints:
            BoxConstraints(minHeight: _authMode == AuthMode.Signup ? 450 : 260),
        width: deviceSize.width * 0.75,
        padding: EdgeInsets.all(16.0),
        child: Form(
          key: _formKey,
          child: SingleChildScrollView(
            child: Column(
              children: <Widget>[
                if (_authMode == AuthMode.Signup)
                  TextFormField(
                    decoration: InputDecoration(labelText: 'Username'),
                    keyboardType: TextInputType.emailAddress,
                    validator: (value) {
                      if (value.isEmpty) {
                        return 'Invalid Username!';
                      }
                    },
                    onSaved: (value) {
                      _authData['username'] = value;
                    },
                  ),
                TextFormField(
                  decoration: InputDecoration(labelText: 'E-Mail'),
                  keyboardType: TextInputType.emailAddress,
                  validator: (value) {
                    if (value.isEmpty || !value.contains('@')) {
                      return 'Invalid email!';
                    }
                  },
                  onSaved: (value) {
                    _authData['email'] = value;
                  },
                ),
                TextFormField(
                  decoration: InputDecoration(labelText: 'Password'),
                  obscureText: true,
                  controller: _passwordController,
                  validator: (value) {
                    if (value.isEmpty || value.length < 5) {
                      return 'Password is too short!';
                    }
                  },
                  onSaved: (value) {
                    _authData['password'] = value;
                  },
                ),
                if (_authMode == AuthMode.Signup)
                  TextFormField(
                    enabled: _authMode == AuthMode.Signup,
                    decoration: InputDecoration(labelText: 'Confirm Password'),
                    obscureText: true,
                    validator: _authMode == AuthMode.Signup
                        ? (value) {
                            if (value != _passwordController.text) {
                              return 'Passwords do not match!';
                            }
                          }
                        : null,
                  ),
                SizedBox(
                  height: 20,
                ),
                if (_isLoading)
                  CircularProgressIndicator()
                else
                  RaisedButton(
                    child:
                        Text(_authMode == AuthMode.Login ? 'LOGIN' : 'SIGN UP'),
                    onPressed: _submit,
                    shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(30),
                    ),
                    padding:
                        EdgeInsets.symmetric(horizontal: 30.0, vertical: 8.0),
                    color: const Color(0xff204a87),
                    textColor: Theme.of(context).primaryTextTheme.button.color,
                  ),
                FlatButton(
                  child: Text(
                      '${_authMode == AuthMode.Login ? 'SIGNUP' : 'LOGIN'} INSTEAD'),
                  onPressed: _switchAuthMode,
                  padding: EdgeInsets.symmetric(horizontal: 30.0, vertical: 4),
                  materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
                  textColor: const Color(0xff204a87),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}