mobile-app/lib/presentation/screens/login/view/login_form.dart

import 'package:farm_tpf/authentication/authentication.dart';
import 'package:farm_tpf/data/repository/authentication_repository.dart';
import 'package:farm_tpf/presentation/custom_widgets/widget_loading.dart';
import 'package:farm_tpf/presentation/screens/login/bloc/login_bloc.dart';
import 'package:flutter/material.dart';
import 'package:formz/formz.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

class LoginForm extends StatelessWidget {
  AuthenticationBloc _authenticationBloc;

  @override
  Widget build(BuildContext context) {
    _authenticationBloc = BlocProvider.of<AuthenticationBloc>(context);
    return BlocListener<LoginBloc, LoginState>(
      listener: (context, state) {
        if (state.status.isSubmissionFailure) {
          LoadingDialog.hideLoadingDialog(context);
          Scaffold.of(context)
            ..hideCurrentSnackBar()
            ..showSnackBar(
              const SnackBar(content: Text('Authentication Failure')),
            );
        }
        if (state.status.isSubmissionSuccess) {
          LoadingDialog.hideLoadingDialog(context);
          _authenticationBloc.add(
              AuthenticationStatusChanged(AuthenticationStatus.authenticated));
        }
        if (state.status.isSubmissionInProgress) {
          LoadingDialog.showLoadingDialog(context);
        }
      },
      child: Align(
        alignment: const Alignment(0, -1 / 3),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            _UsernameInput(),
            const Padding(padding: EdgeInsets.all(12)),
            _PasswordInput(),
            const Padding(padding: EdgeInsets.all(12)),
            _LoginButton(),
          ],
        ),
      ),
    );
  }
}

class _UsernameInput extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocBuilder<LoginBloc, LoginState>(
      buildWhen: (previous, current) => previous.username != current.username,
      builder: (context, state) {
        return TextField(
          key: const Key('loginForm_usernameInput_textField'),
          onChanged: (username) =>
              context.bloc<LoginBloc>().add(LoginUsernameChanged(username)),
          decoration: InputDecoration(
            labelText: 'Tên đăng nhập',
            errorText:
                state.username.invalid ? 'Vui lòng nhập tên đăng nhập' : null,
          ),
        );
      },
    );
  }
}

class _PasswordInput extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocBuilder<LoginBloc, LoginState>(
      buildWhen: (previous, current) => previous.password != current.password,
      builder: (context, state) {
        return TextField(
          key: const Key('loginForm_passwordInput_textField'),
          onChanged: (password) =>
              context.bloc<LoginBloc>().add(LoginPasswordChanged(password)),
          obscureText: true,
          decoration: InputDecoration(
            labelText: 'Mật khẩu',
            errorText: state.password.invalid ? 'Vui lòng nhập mật khẩu' : null,
          ),
        );
      },
    );
  }
}

class _LoginButton extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocBuilder<LoginBloc, LoginState>(
      buildWhen: (previous, current) => previous.status != current.status,
      builder: (context, state) {
        return state.status.isSubmissionInProgress
            ? const CircularProgressIndicator()
            : RaisedButton(
                key: const Key('loginForm_continue_raisedButton'),
                child: const Text('Đăng nhập'),
                onPressed: state.status.isValidated
                    ? () {
                        context.bloc<LoginBloc>().add(const LoginSubmitted());
                      }
                    : null,
              );
      },
    );
  }
}