// 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_dimens.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;
// Auth keeps its approved 20px card silhouette.
const double _cardRadius = AppDimens.authCardRadius;
const double _cardPadding = AppDimens.cardPadding;
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 double _topContentPadding = 64;
const double _bottomContentPadding = 28;
const double _compactTopContentPadding = 48;
const double _compactHeightBreakpoint = 720;
const double _compactBrandGap = 16;
const double _warmGlowSize = 260;
const double _warmGlowOpacity = 0.06;
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;
  bool _emailEntryOpen = false;

  @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 {
    if (_logic.busy) return;
    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) {
      if (!mounted) return;
      setState(() => _logic.errorMessage = error.message);
    } catch (_) {
      if (!mounted) return;
      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],
                    ),
                  ),
                ),
              ),
            ),
            Positioned(
              top: 72,
              right: -80,
              width: _warmGlowSize,
              height: _warmGlowSize,
              child: IgnorePointer(
                child: Container(
                  key: const Key('auth-background-warm-glow'),
                  decoration: BoxDecoration(
                    shape: BoxShape.circle,
                    gradient: RadialGradient(
                      colors: [
                        AppColors.gold.withValues(alpha: _warmGlowOpacity),
                        AppColors.gold.withValues(alpha: 0),
                      ],
                    ),
                  ),
                ),
              ),
            ),
            SafeArea(
              child: LayoutBuilder(
                builder: (context, constraints) {
                  final compact =
                      constraints.maxHeight < _compactHeightBreakpoint;
                  final top = compact
                      ? _compactTopContentPadding
                      : _topContentPadding;
                  final bottom =
                      _bottomContentPadding +
                      MediaQuery.viewInsetsOf(context).bottom;
                  final available = constraints.maxHeight - top - bottom;
                  final minHeight = available > 0 ? available : 0.0;
                  return AutofillGroup(
                    child: SingleChildScrollView(
                      key: const Key('auth-scroll'),
                      keyboardDismissBehavior:
                          ScrollViewKeyboardDismissBehavior.onDrag,
                      padding: EdgeInsets.fromLTRB(
                        AppDimens.pageHorizontal,
                        top,
                        AppDimens.pageHorizontal,
                        bottom,
                      ),
                      child: ConstrainedBox(
                        constraints: BoxConstraints(minHeight: minHeight),
                        child: Center(
                          child: ConstrainedBox(
                            constraints: const BoxConstraints(
                              maxWidth: _contentMaxWidth,
                            ),
                            child: _content(l10n, compact: compact),
                          ),
                        ),
                      ),
                    ),
                  );
                },
              ),
            ),
            if (Navigator.of(context).canPop())
              Positioned(
                top: 0,
                left: 0,
                right: 0,
                child: SafeArea(
                  child: Align(
                    alignment: Alignment.topLeft,
                    child: Padding(
                      padding: const EdgeInsets.only(left: 4, top: 4),
                      child: IconButton(
                        key: const Key('auth-back'),
                        tooltip: MaterialLocalizations.of(
                          context,
                        ).backButtonTooltip,
                        onPressed: () {
                          if (_emailEntryOpen) {
                            setState(() => _emailEntryOpen = false);
                          } else {
                            Navigator.of(context).pop();
                          }
                        },
                        icon: const Icon(
                          Icons.arrow_back_rounded,
                          color: AppColors.onPrimary,
                        ),
                      ),
                    ),
                  ),
                ),
              ),
          ],
        ),
      ),
    );
  }

  Widget _content(AppLocalizations l10n, {required bool compact}) =>
      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: _emailEntryOpen
            ? Column(
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  _AuthBrand(tagline: l10n.authBrandTagline, compact: compact),
                  SizedBox(height: compact ? _compactBrandGap : 28),
                  _authCard(l10n),
                ],
              )
            : _landing(l10n),
      );

  Widget _landing(AppLocalizations l10n) => Column(
    key: const Key('auth-landing'),
    mainAxisAlignment: MainAxisAlignment.center,
    crossAxisAlignment: CrossAxisAlignment.stretch,
    children: [
      Center(
        child: Container(
          key: const Key('auth-brand-logo'),
          width: 64,
          height: 64,
          decoration: BoxDecoration(
            borderRadius: BorderRadius.circular(18),
            gradient: const LinearGradient(
              begin: Alignment.topLeft,
              end: Alignment.bottomRight,
              colors: [AppColors.blue, AppColors.secondary],
            ),
          ),
          child: const Icon(
            Icons.play_arrow_rounded,
            color: AppColors.onPrimary,
            size: 32,
          ),
        ),
      ),
      const SizedBox(height: 14),
      Text(
        l10n.fruitShortsBrand,
        textAlign: TextAlign.center,
        style: const TextStyle(
          fontFamily: 'Outfit',
          color: AppColors.onSurface,
          fontSize: 20,
          fontWeight: FontWeight.w800,
        ),
      ),
      const SizedBox(height: 6),
      Text(
        l10n.authLandingSubtitle,
        textAlign: TextAlign.center,
        style: const TextStyle(color: Color(0xFF9A96A3), fontSize: 11),
      ),
      const SizedBox(height: 22),
      _AuthEntryButton(
        key: const Key('auth-entry-google'),
        label: 'G  ${l10n.authContinueGoogle}',
        background: Colors.white,
        foreground: const Color(0xFF1A1A1A),
        leadingColor: const Color(0xFF4285F4),
        onTap: () => _comingSoon(l10n),
      ),
      const SizedBox(height: 11),
      _AuthEntryButton(
        key: const Key('auth-entry-phone'),
        label: l10n.authPhoneSignIn,
        icon: Icons.phone_android_rounded,
        background: AppColors.input,
        foreground: AppColors.onSurface,
        onTap: () => _comingSoon(l10n),
      ),
      const SizedBox(height: 11),
      _AuthEntryButton(
        key: const Key('auth-entry-email'),
        label: l10n.authEmailSignIn,
        icon: Icons.mail_outline_rounded,
        background: AppColors.input,
        foreground: AppColors.onSurface,
        onTap: () => setState(() => _emailEntryOpen = true),
      ),
      const SizedBox(height: 18),
      Text(
        l10n.authLegal,
        key: const Key('auth-legal'),
        textAlign: TextAlign.center,
        style: const TextStyle(
          color: Color(0xFF6B6772),
          fontSize: 9,
          height: 1.6,
        ),
      ),
    ],
  );

  void _comingSoon(AppLocalizations l10n) {
    ScaffoldMessenger.of(
      context,
    ).showSnackBar(SnackBar(content: Text(l10n.comingSoon)));
  }

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

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

class _AuthEntryButton extends StatelessWidget {
  const _AuthEntryButton({
    super.key,
    required this.label,
    required this.background,
    required this.foreground,
    required this.onTap,
    this.icon,
    this.leadingColor,
  });

  final String label;
  final Color background;
  final Color foreground;
  final VoidCallback onTap;
  final IconData? icon;
  final Color? leadingColor;

  @override
  Widget build(BuildContext context) {
    return Material(
      color: background,
      borderRadius: BorderRadius.circular(9),
      clipBehavior: Clip.antiAlias,
      child: InkWell(
        onTap: onTap,
        child: SizedBox(
          height: 44,
          child: Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              if (icon != null)
                Icon(icon, size: 16, color: leadingColor ?? foreground),
              if (icon != null) const SizedBox(width: 7),
              Flexible(
                child: Text(
                  label,
                  maxLines: 1,
                  overflow: TextOverflow.ellipsis,
                  style: TextStyle(
                    color: foreground,
                    fontSize: 13,
                    fontWeight: FontWeight.w600,
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}