// Author: fruit.com.cn

import 'dart:async';

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

import '../../core/data/remote/api_client.dart';
import '../../core/data/services/auth_controller.dart';
import '../../core/platform/haptics.dart';
import '../../core/theme/app_colors.dart';
import '../../core/theme/app_theme.dart';
import '../../l10n/app_localizations.dart';
import 'auth_logic.dart';

part 'auth_widgets.dart';
part 'auth_form_widgets.dart';

const double _minTapTarget = 44;
const double _brandMarkSize = 48;
const double _contentMaxWidth = 440;
const double _cardRadius = 20;
const double _cardPadding = 20;
const double _cardBorderWidth = 1;
const double _fieldHeight = 52;
const double _fieldRadius = 14;
const double _fieldBorderWidth = 1.5;
const double _buttonHeight = 52;
const double _buttonRadius = 26;
const double _glowOpacity = 0.18;
const double _errorOpacity = 0.10;
const double _errorBorderOpacity = 0.28;
const double _enterSlideDistance = 16;
const Duration _enterDuration = Duration(milliseconds: 220);
const Duration _segmentDuration = Duration(milliseconds: 160);

/// 登录 / 注册页：邮箱 + 密码。
class AuthPage extends StatefulWidget {
  const AuthPage({super.key, this.signUpMode = false});

  final bool signUpMode;

  @override
  State<AuthPage> createState() => _AuthPageState();
}

class _AuthPageState extends State<AuthPage> {
  late AuthLogic _logic;
  late final TextEditingController _emailController;
  late final TextEditingController _passwordController;
  late final FocusNode _emailFocus;
  late final FocusNode _passwordFocus;
  bool _obscurePassword = true;

  @override
  void initState() {
    super.initState();
    _logic = AuthLogic(signUpMode: widget.signUpMode);
    _emailController = TextEditingController();
    _passwordController = TextEditingController();
    _emailFocus = FocusNode(debugLabel: 'auth-email-focus');
    _passwordFocus = FocusNode(debugLabel: 'auth-password-focus');
  }

  @override
  void dispose() {
    _emailController.dispose();
    _passwordController.dispose();
    _emailFocus.dispose();
    _passwordFocus.dispose();
    super.dispose();
  }

  String _errorText(AppLocalizations l10n, AuthFieldError error) {
    switch (error) {
      case AuthFieldError.emailRequired:
        return l10n.authEmailRequired;
      case AuthFieldError.emailInvalid:
        return l10n.authEmailInvalid;
      case AuthFieldError.passwordRequired:
        return l10n.authPasswordRequired;
      case AuthFieldError.passwordLength:
        return l10n.authPasswordLength;
      case AuthFieldError.passwordWeak:
        return l10n.authPasswordWeak;
    }
  }

  Future<void> _submit() async {
    final l10n = AppLocalizations.of(context)!;
    final invalid = _logic.validate();
    if (invalid != null) {
      setState(() => _logic.errorMessage = _errorText(l10n, invalid));
      return;
    }
    unawaited(context.read<Haptics>().lightImpact());
    FocusScope.of(context).unfocus();
    setState(() {
      _logic.busy = true;
      _logic.errorMessage = null;
    });
    final auth = context.read<AuthController>();
    try {
      if (_logic.signUpMode) {
        await auth.register(
          email: _logic.normalizedEmail,
          password: _logic.password,
        );
      } else {
        await auth.signIn(
          email: _logic.normalizedEmail,
          password: _logic.password,
        );
      }
      if (!mounted) return;
      Navigator.of(context).maybePop();
    } on ApiException catch (error) {
      setState(() => _logic.errorMessage = error.message);
    } catch (_) {
      setState(() => _logic.errorMessage = l10n.authNetworkError);
    } finally {
      if (mounted) setState(() => _logic.busy = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    return Theme(
      data: AppTheme.dark(),
      child: Scaffold(
        resizeToAvoidBottomInset: true,
        backgroundColor: AppColors.ink,
        body: Stack(
          children: [
            Positioned(
              top: 0,
              left: 0,
              right: 0,
              height: 420,
              child: IgnorePointer(
                child: Container(
                  key: const Key('auth-background-glow'),
                  decoration: BoxDecoration(
                    gradient: LinearGradient(
                      begin: Alignment.topCenter,
                      end: Alignment.bottomCenter,
                      colors: [
                        AppColors.blue.withValues(alpha: _glowOpacity),
                        AppColors.blue.withValues(alpha: 0.05),
                        AppColors.ink.withValues(alpha: 0),
                      ],
                      stops: const [0, 0.55, 1],
                    ),
                  ),
                ),
              ),
            ),
            SafeArea(
              child: AutofillGroup(
                child: ListView(
                  key: const Key('auth-scroll'),
                  keyboardDismissBehavior:
                      ScrollViewKeyboardDismissBehavior.onDrag,
                  padding: EdgeInsets.fromLTRB(
                    20,
                    12,
                    20,
                    28 + MediaQuery.viewInsetsOf(context).bottom,
                  ),
                  children: [
                    Center(
                      child: ConstrainedBox(
                        constraints: const BoxConstraints(
                          maxWidth: _contentMaxWidth,
                        ),
                        child: TweenAnimationBuilder<double>(
                          key: const Key('auth-enter-animation'),
                          tween: Tween(begin: 0, end: 1),
                          duration: _enterDuration,
                          curve: Curves.easeOutCubic,
                          builder: (context, value, child) => Opacity(
                            opacity: value,
                            child: Transform.translate(
                              offset: Offset(
                                0,
                                _enterSlideDistance * (1 - value),
                              ),
                              child: child,
                            ),
                          ),
                          child: Column(
                            crossAxisAlignment: CrossAxisAlignment.stretch,
                            children: [
                              if (Navigator.of(context).canPop())
                                Align(
                                  alignment: Alignment.centerLeft,
                                  child: IconButton(
                                    key: const Key('auth-back'),
                                    tooltip: MaterialLocalizations.of(
                                      context,
                                    ).backButtonTooltip,
                                    onPressed: () =>
                                        Navigator.of(context).pop(),
                                    icon: const Icon(
                                      Icons.arrow_back_rounded,
                                      color: AppColors.onPrimary,
                                    ),
                                  ),
                                ),
                              _AuthBrand(tagline: l10n.authBrandTagline),
                              const SizedBox(height: 28),
                              _authCard(l10n),
                            ],
                          ),
                        ),
                      ),
                    ),
                  ],
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _authCard(AppLocalizations l10n) => _AuthCard(
    state: _AuthCardState(
      l10n: l10n,
      status: _AuthFormStatus(
        signUpMode: _logic.signUpMode,
        busy: _logic.busy,
        errorMessage: _logic.errorMessage,
        obscurePassword: _obscurePassword,
      ),
      fields: _AuthFieldControllers(
        email: _emailController,
        password: _passwordController,
        emailFocus: _emailFocus,
        passwordFocus: _passwordFocus,
      ),
    ),
    callbacks: _AuthCardCallbacks(
      onModeSelected: _selectMode,
      onEmailChanged: (value) => _logic.email = value,
      onPasswordChanged: (value) => _logic.password = value,
      onTogglePasswordVisibility: () =>
          setState(() => _obscurePassword = !_obscurePassword),
      onSubmit: _submit,
    ),
  );

  void _selectMode(bool signUpMode) {
    if (_logic.busy || _logic.signUpMode == signUpMode) return;
    setState(() => _logic.toggleMode());
  }
}