// 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/formatting/error_text.dart';
import '../../core/data/services/app_config_controller.dart';
import '../../core/data/services/auth_controller.dart';
import '../../core/platform/haptics.dart';
import '../../core/platform/keyboard_inset.dart';
import '../../core/theme/app_colors.dart';
import '../../core/theme/app_dimens.dart';
import '../../core/theme/app_theme.dart';
import '../../core/widgets/centered_toast.dart';
import '../../core/widgets/remote_image.dart';
import '../../core/widgets/subpage_header.dart';
import '../../l10n/app_localizations.dart';
import 'auth_legal_links.dart';
import 'auth_logic.dart';
import 'phone_auth_sheet.dart';

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

const double _minTapTarget = 44;
const double _brandMarkSize = 88;
const double _compactBrandMarkSize = 48;
const double _brandMarkRadius = 26;
const double _compactBrandMarkRadius = 14;
const String _appLogoAsset = 'assets/icon/ymb.png';
const double _contentMaxWidth = 440;
const double _fieldHeight = 52;
const double _fieldRadius = 12;
const double _fieldBorderWidth = 1;
const double _buttonHeight = 50;
const double _buttonRadius = 25;
const double _errorOpacity = 0.10;
const double _errorBorderOpacity = 0.28;
const double _enterSlideDistance = 16;
const double _topContentPadding = 56;
const double _bottomContentPadding = 28;
const double _compactTopContentPadding = 40;
const double _compactHeightBreakpoint = 720;
const double _compactBrandGap = 16;
const double _entryButtonHeight = 52;
const double _entryButtonRadius = 26;
const double _entryButtonFontSize = 15;
const double _entryIconSize = 20;
const Duration _enterDuration = Duration(milliseconds: 220);

Widget _brandMarkWidget({
  Key? key,
  required double size,
  required double radius,
}) {
  return ClipRRect(
    key: key,
    borderRadius: BorderRadius.circular(radius),
    child: Image.asset(
      _appLogoAsset,
      width: size,
      height: size,
      fit: BoxFit.cover,
    ),
  );
}

/// 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;
  late final ScrollController _scrollController;
  final _keyboardInset = KeyboardInsetNotifier.instance;
  double _lastKeyboardInset = 0;
  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');
    _scrollController = ScrollController();
    _emailFocus.addListener(_onFocusChanged);
    _passwordFocus.addListener(_onFocusChanged);
    _keyboardInset.addListener(_onKeyboardInsetChanged);
    unawaited(_keyboardInset.start());
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    final inset = effectiveKeyboardInset(context, _keyboardInset);
    if ((inset - _lastKeyboardInset).abs() >= 1) {
      _lastKeyboardInset = inset;
      _scheduleRevealFocusedField();
    }
  }

  @override
  void dispose() {
    _keyboardInset.removeListener(_onKeyboardInsetChanged);
    _emailFocus.removeListener(_onFocusChanged);
    _passwordFocus.removeListener(_onFocusChanged);
    _emailController.dispose();
    _passwordController.dispose();
    _emailFocus.dispose();
    _passwordFocus.dispose();
    _scrollController.dispose();
    super.dispose();
  }

  void _onKeyboardInsetChanged() {
    if (!mounted) return;
    setState(() {});
    _scheduleRevealFocusedField();
  }

  void _onFocusChanged() {
    if (_emailFocus.hasFocus || _passwordFocus.hasFocus) {
      _scheduleRevealFocusedField();
    }
  }

  /// 点在当前邮箱或密码框之外时取消焦点。
  void _releaseFieldFocus(PointerDownEvent event) {
    final focus = FocusManager.instance.primaryFocus;
    if (focus != _emailFocus && focus != _passwordFocus) return;
    final renderObject = focus?.context?.findRenderObject();
    if (renderObject is! RenderBox || !renderObject.hasSize) {
      focus?.unfocus();
      return;
    }
    final bounds = renderObject.localToGlobal(Offset.zero) & renderObject.size;
    if (!bounds.contains(event.position)) focus?.unfocus();
  }

  void _scheduleRevealFocusedField() {
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (mounted) _revealFocusedField();
    });
  }

  void _revealFocusedField() {
    if (!_scrollController.hasClients) return;
    final focus = _passwordFocus.hasFocus
        ? _passwordFocus
        : _emailFocus.hasFocus
        ? _emailFocus
        : null;
    final fieldContext = focus?.context;
    final renderObject = fieldContext?.findRenderObject();
    if (renderObject is! RenderBox || !renderObject.hasSize) return;
    final keyboardInset = effectiveKeyboardInset(context, _keyboardInset);
    if (keyboardInset <= 0) return;
    final fieldBottom = renderObject
        .localToGlobal(Offset(0, renderObject.size.height))
        .dy;
    final visibleBottom =
        MediaQuery.sizeOf(context).height - keyboardInset - 24;
    final overlap = fieldBottom - visibleBottom;
    if (overlap <= 0) return;
    final position = _scrollController.position;
    final target = (position.pixels + overlap)
        .clamp(position.minScrollExtent, position.maxScrollExtent)
        .toDouble();
    if (target <= position.pixels + 0.5) return;
    unawaited(
      _scrollController.animateTo(
        target,
        duration: const Duration(milliseconds: 200),
        curve: Curves.easeOutCubic,
      ),
    );
  }

  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>();
    String? failureMessage;
    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) {
      failureMessage = userFacingApiMessage(l10n, error.code, error.message);
    } catch (_) {
      failureMessage = l10n.authNetworkError;
    } finally {
      if (mounted) setState(() => _logic.busy = false);
    }
    if (!mounted || failureMessage == null) return;
    showCenteredToast(context, failureMessage);
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    return Theme(
      data: AppTheme.dark(),
      child: Scaffold(
        resizeToAvoidBottomInset: false,
        backgroundColor: AppColors.ink,
        body: Stack(
          children: [
            const Positioned.fill(
              child: IgnorePointer(
                child: DecoratedBox(
                  key: Key('auth-page-background'),
                  decoration: BoxDecoration(
                    gradient: LinearGradient(
                      begin: Alignment.topCenter,
                      end: Alignment.bottomCenter,
                      colors: [
                        AppColors.followingGlow,
                        AppColors.followingGlowMid,
                        AppColors.appBackground,
                      ],
                      stops: [0, 0.14, 0.3],
                    ),
                  ),
                ),
              ),
            ),
            // 全屏海报背景：压暗保证文字可读，顶部再叠品牌红光。
            Positioned.fill(child: IgnorePointer(child: _AuthPosterBackdrop())),
            const Positioned.fill(
              child: IgnorePointer(
                child: DecoratedBox(
                  key: Key('auth-poster-scrim'),
                  decoration: BoxDecoration(
                    gradient: LinearGradient(
                      begin: Alignment.topCenter,
                      end: Alignment.bottomCenter,
                      colors: [
                        Color(0x66000000),
                        Color(0x14000000),
                        Color(0xE0000000),
                      ],
                      stops: [0, 0.42, 1],
                    ),
                  ),
                ),
              ),
            ),
            const Positioned.fill(
              child: IgnorePointer(
                child: DecoratedBox(
                  key: Key('auth-red-glow'),
                  decoration: BoxDecoration(
                    gradient: RadialGradient(
                      center: Alignment(0, -1.15),
                      radius: 1.3,
                      colors: [AppColors.primaryBorder, AppColors.transparent],
                    ),
                  ),
                ),
              ),
            ),
            SafeArea(
              child: LayoutBuilder(
                builder: (context, constraints) {
                  final compact =
                      constraints.maxHeight < _compactHeightBreakpoint;
                  final top = compact
                      ? _compactTopContentPadding
                      : _topContentPadding;
                  final bottom =
                      _bottomContentPadding +
                      effectiveKeyboardInset(context, _keyboardInset);
                  final available = constraints.maxHeight - top - bottom;
                  final minHeight = available > 0 ? available : 0.0;
                  return Listener(
                    behavior: HitTestBehavior.translucent,
                    onPointerDown: _releaseFieldFocus,
                    child: AutofillGroup(
                      child: SingleChildScrollView(
                        key: const Key('auth-scroll'),
                        controller: _scrollController,
                        keyboardDismissBehavior:
                            ScrollViewKeyboardDismissBehavior.onDrag,
                        padding: EdgeInsets.fromLTRB(
                          AppDimens.pageHorizontal,
                          top,
                          AppDimens.pageHorizontal,
                          bottom,
                        ),
                        child: ConstrainedBox(
                          constraints: BoxConstraints(minHeight: minHeight),
                          child: Align(
                            alignment: Alignment.topCenter,
                            child: ConstrainedBox(
                              constraints: const BoxConstraints(
                                maxWidth: _contentMaxWidth,
                              ),
                              child: _content(
                                l10n,
                                compact: compact,
                                minHeight: minHeight,
                              ),
                            ),
                          ),
                        ),
                      ),
                    ),
                  );
                },
              ),
            ),
            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: 14, top: 8),
                      child: AppSubpageBackButton(
                        backKey: const Key('auth-back'),
                        onBack: () {
                          if (_emailEntryOpen) {
                            setState(() => _emailEntryOpen = false);
                          } else {
                            Navigator.of(context).pop();
                          }
                        },
                      ),
                    ),
                  ),
                ),
              ),
          ],
        ),
      ),
    );
  }

  Widget _content(
    AppLocalizations l10n, {
    required bool compact,
    required double minHeight,
  }) => 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, minHeight: minHeight),
  );

  /// 落地页内容需要有限高度才能用 Spacer 三段分割，这里显式钉住可用高度。
  Widget _landing(AppLocalizations l10n, {required double minHeight}) =>
      SizedBox(
        height: minHeight,
        child: Column(
          key: const Key('auth-landing'),
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            const Spacer(flex: 5),
            Center(
              child: _brandMarkWidget(
                key: const Key('auth-brand-logo'),
                size: _brandMarkSize,
                radius: _brandMarkRadius,
              ),
            ),
            const Spacer(flex: 2),
            _AuthEntryButton(
              key: const Key('auth-entry-phone'),
              label: l10n.authPhoneSignIn,
              icon: Icons.phone_android_rounded,
              primary: true,
              onTap: _openPhoneSheet,
            ),
            const SizedBox(height: 12),
            _AuthEntryButton(
              key: const Key('auth-entry-email'),
              label: l10n.authEmailSignIn,
              icon: Icons.mail_outline_rounded,
              primary: false,
              onTap: () => setState(() => _emailEntryOpen = true),
            ),
            const SizedBox(height: 14),
            const Opacity(opacity: 0.75, child: AuthLegalLinks()),
            const Spacer(flex: 6),
          ],
        ),
      );

  Future<void> _openPhoneSheet() async {
    final signedIn = await showPhoneAuthSheet(
      context,
      signUp: _logic.signUpMode,
    );
    if (signedIn == true && mounted) Navigator.of(context).maybePop();
  }

  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.primary,
    required this.onTap,
    this.icon,
  });

  final String label;
  final bool primary;
  final VoidCallback onTap;
  final IconData? icon;

  @override
  Widget build(BuildContext context) {
    // 主按钮纯品牌红；次按钮为无边框深色玻璃（白 6%），Apple 风格。
    final background = primary
        ? AppColors.brandRed
        : Colors.white.withValues(alpha: 0.06);
    final foreground = primary ? AppColors.onPrimary : AppColors.onSurface;
    return Material(
      color: background,
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(_entryButtonRadius),
      ),
      clipBehavior: Clip.antiAlias,
      child: InkWell(
        onTap: onTap,
        borderRadius: BorderRadius.circular(_entryButtonRadius),
        child: SizedBox(
          height: _entryButtonHeight,
          child: Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              if (icon != null)
                Icon(icon, size: _entryIconSize, color: foreground),
              if (icon != null) const SizedBox(width: 8),
              Flexible(
                child: Text(
                  label,
                  maxLines: 1,
                  overflow: TextOverflow.ellipsis,
                  style: TextStyle(
                    color: foreground,
                    fontSize: _entryButtonFontSize,
                    fontWeight: FontWeight.w600,
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

/// 登录页全屏海报背景（单张，无拼缝）。
///
/// 优先用后台下发的 `loginBackgroundUrl`（后台未配置或加载失败时回落到本地默认图）。
class _AuthPosterBackdrop extends StatelessWidget {
  const _AuthPosterBackdrop();

  static const String _defaultAsset = 'assets/auth/bg_3.jpg';

  @override
  Widget build(BuildContext context) {
    final remoteUrl = context.watch<AppConfigController>().loginBackgroundUrl;
    return RemoteImage(
      key: const Key('auth-poster-backdrop'),
      remoteUrl,
      fit: BoxFit.cover,
      fallbackWidget: Image.asset(
        _defaultAsset,
        key: const Key('auth-poster-default'),
        fit: BoxFit.cover,
        alignment: Alignment.center,
      ),
    );
  }
}