flutter_login_widget/lib/src/widgets/email_password_login.dart

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_login/flutter_login.dart';

class EmailPasswordLoginForm extends StatefulWidget {
  /// Constructs an [EmailPasswordLoginForm] widget.
  ///
  /// [onLogin]: Callback function for user login.
  /// [onForgotPassword]: Callback function for when the user
  /// forgets their password.
  /// [onRegister]: Callback function for user registration.
  /// [options]: The options for configuring the login form.
  const EmailPasswordLoginForm({
    required this.onLogin,
    super.key,
    this.onForgotPassword,
    this.onRegister,
    this.options = const LoginOptions(),
  });

  final LoginOptions options;
  final void Function(String email, BuildContext ctx)? onForgotPassword;
  final FutureOr<void> Function(
    String email,
    String password,
    BuildContext context,
  )? onRegister;
  final FutureOr<void> Function(String email, String password) onLogin;

  @override
  State<EmailPasswordLoginForm> createState() => _EmailPasswordLoginFormState();
}

class _EmailPasswordLoginFormState extends State<EmailPasswordLoginForm> {
  final _formKey = GlobalKey<FormState>();
  final ValueNotifier<bool> _formValid = ValueNotifier(false);
  bool _obscurePassword = true;

  String _currentEmail = '';
  String _currentPassword = '';

  void _updateCurrentEmail(String email) {
    _currentEmail = email;
    _validate();
  }

  void _updateCurrentPassword(String password) {
    _currentPassword = password;
    _validate();
  }

  void _validate() {
    late var isValid =
        widget.options.validations.validateEmail(_currentEmail) == null &&
            widget.options.validations.validatePassword(_currentPassword) ==
                null;
    if (isValid != _formValid.value) {
      _formValid.value = isValid;
    }
  }

  Future<void> _handleLogin() async {
    if (mounted) {
      var form = _formKey.currentState!;
      if (form.validate()) {
        await widget.onLogin(
          _currentEmail,
          _currentPassword,
        );
      }
    }
  }

  @override
  void initState() {
    super.initState();
    _currentEmail = widget.options.initialEmail;
    _currentPassword = widget.options.initialPassword;
    _validate();
  }

  @override
  Widget build(BuildContext context) {
    var theme = Theme.of(context);
    var options = widget.options;
    return CustomScrollView(
      physics: const ScrollPhysics(),
      slivers: [
        SliverFillRemaining(
          hasScrollBody: false,
          fillOverscroll: true,
          child: Column(
            children: [
              Expanded(
                flex: options.spacers.titleSpacer,
                child: Column(
                  children: [
                    if (options.spacers.spacerBeforeTitle != null) ...[
                      Spacer(flex: options.spacers.spacerBeforeTitle!),
                    ],
                    if (options.title != null) ...[
                      Align(
                        alignment: Alignment.topCenter,
                        child: wrapWithDefaultStyle(
                          options.title,
                          theme.textTheme.headlineSmall,
                        ),
                      ),
                    ],
                    if (options.spacers.spacerAfterTitle != null) ...[
                      Spacer(flex: options.spacers.spacerAfterTitle!),
                    ],
                    if (options.subtitle != null) ...[
                      Align(
                        alignment: Alignment.topCenter,
                        child: wrapWithDefaultStyle(
                          options.subtitle,
                          theme.textTheme.titleSmall,
                        ),
                      ),
                    ],
                    if (options.spacers.spacerAfterSubtitle != null) ...[
                      Spacer(flex: options.spacers.spacerAfterSubtitle!),
                    ],
                    if (options.image != null) ...[
                      Padding(
                        padding: const EdgeInsets.all(16),
                        child: options.image,
                      ),
                    ],
                    if (options.spacers.spacerAfterImage != null) ...[
                      Spacer(flex: options.spacers.spacerAfterImage!),
                    ],
                  ],
                ),
              ),
              Expanded(
                flex: options.spacers.formFlexValue,
                child: ConstrainedBox(
                  constraints: BoxConstraints(
                    maxWidth: options.maxFormWidth ?? 300,
                  ),
                  child: Form(
                    key: _formKey,
                    child: Column(
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        options.emailInputContainerBuilder(
                          TextFormField(
                            textAlign:
                                options.emailTextAlign ?? TextAlign.start,
                            onChanged: _updateCurrentEmail,
                            validator: widget.options.validations.validateEmail,
                            initialValue: options.initialEmail,
                            keyboardType: TextInputType.emailAddress,
                            textInputAction: TextInputAction.next,
                            style: options.emailTextStyle,
                            decoration: options.emailDecoration,
                          ),
                        ),
                        options.passwordInputContainerBuilder(
                          TextFormField(
                            textAlign:
                                options.passwordTextAlign ?? TextAlign.start,
                            obscureText: _obscurePassword,
                            onChanged: _updateCurrentPassword,
                            validator:
                                widget.options.validations.validatePassword,
                            initialValue: options.initialPassword,
                            keyboardType: TextInputType.visiblePassword,
                            textInputAction: TextInputAction.done,
                            style: options.passwordTextStyle,
                            onFieldSubmitted: (_) async => _handleLogin(),
                            decoration: options.passwordDecoration.copyWith(
                              suffixIcon: options.showObscurePassword
                                  ? IconButton(
                                      onPressed: () {
                                        setState(() {
                                          _obscurePassword = !_obscurePassword;
                                        });
                                      },
                                      icon: Icon(
                                        _obscurePassword
                                            ? Icons.visibility
                                            : Icons.visibility_off,
                                      ),
                                    )
                                  : null,
                            ),
                          ),
                        ),
                        if (widget.onForgotPassword != null) ...[
                          Align(
                            alignment: Alignment.topRight,
                            child: options.forgotPasswordButtonBuilder(
                              context,
                              () {
                                widget.onForgotPassword
                                    ?.call(_currentEmail, context);
                              },
                              false,
                              () {},
                              options,
                            ),
                          ),
                        ],
                        if (options.spacers.spacerAfterForm != null) ...[
                          Spacer(flex: options.spacers.spacerAfterForm!),
                        ],
                        AnimatedBuilder(
                          animation: _formValid,
                          builder: (context, _) => options.loginButtonBuilder(
                            context,
                            _handleLogin,
                            !_formValid.value,
                            () {
                              _formKey.currentState?.validate();
                            },
                            options,
                          ),
                        ),
                        if (widget.onRegister != null) ...[
                          options.registrationButtonBuilder(
                            context,
                            () async {
                              widget.onRegister?.call(
                                _currentEmail,
                                _currentPassword,
                                context,
                              );
                            },
                            false,
                            () {},
                            options,
                          ),
                        ],
                        if (options.spacers.spacerAfterButton != null) ...[
                          Spacer(flex: options.spacers.spacerAfterButton!),
                        ],
                      ],
                    ),
                  ),
                ),
              ),
            ],
          ),
        ),
      ],
    );
  }
}

Widget? wrapWithDefaultStyle(Widget? widget, TextStyle? style) {
  if (style == null || widget == null) {
    return widget;
  } else {
    return DefaultTextStyle(style: style, child: widget);
  }
}