/// 修改密码页（UI-03 页面 03 重设计，图01；入口在设置页）。
///
/// 返回标题 + 简短安全提示 + 当前/新/确认三字段 + Save password。
/// 客户端校验（新密码 ≥8 位、两次一致）先行——新密码变更时若确认字段
/// 已填写会即时复验（不匹配当场提示）；服务端
/// [ApiClient.changePassword] 成功后 204——当前会话被服务端保留，
/// 无需重登录：toast 提示后直接 pop 回设置页。失败以内联 StateBadge
/// （图标 + 文案 + 错误色）展示；AUTH_INVALID_CREDENTIALS 在本页语义为
/// 「当前密码错误」（覆写通用映射）。提交中防重复。
library;

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

import '../core/api_client.dart';
import '../core/app_exception.dart';
import '../core/error_codes.dart';
import '../core/error_l10n.dart';
import '../l10n/app_localizations.dart';
import '../ui/components/state_badge.dart';
import '../ui/tokens.dart';

/// 修改密码页。
class PasswordChangePage extends ConsumerStatefulWidget {
  const PasswordChangePage({super.key});

  @override
  ConsumerState<PasswordChangePage> createState() =>
      _PasswordChangePageState();
}

class _PasswordChangePageState extends ConsumerState<PasswordChangePage> {
  final _formKey = GlobalKey<FormState>();
  final _oldController = TextEditingController();
  final _newController = TextEditingController();
  final _confirmController = TextEditingController();

  bool _obscureOld = true;
  bool _obscureNew = true;
  bool _obscureConfirm = true;
  bool _submitting = false;

  /// 最近一次提交失败文案（内联 StateBadge 展示；null = 无错误）。
  String? _errorText;

  @override
  void initState() {
    super.initState();
    // 新密码变更 → 确认字段已填写时即时复验（不匹配当场提示，不等提交）。
    _newController.addListener(_revalidateConfirm);
  }

  void _revalidateConfirm() {
    if (_confirmController.text.isEmpty) return;
    _formKey.currentState?.validate();
  }

  @override
  void dispose() {
    _newController.removeListener(_revalidateConfirm);
    _oldController.dispose();
    _newController.dispose();
    _confirmController.dispose();
    super.dispose();
  }

  Future<void> _submit() async {
    if (!_formKey.currentState!.validate()) return;
    setState(() {
      _submitting = true;
      _errorText = null;
    });
    final l10n = AppLocalizations.of(context);
    final messenger = ScaffoldMessenger.of(context);
    final navigator = Navigator.of(context);
    try {
      await ref.read(apiClientProvider).changePassword(
            _oldController.text,
            _newController.text,
          );
      // 成功路径：先弹提示再 pop；pop 后 SnackBar 仍挂在根 messenger 上可见。
      messenger.showSnackBar(
        SnackBar(content: Text(l10n.passwordChangeSuccess)),
      );
      navigator.pop();
    } on AppException catch (error) {
      if (mounted) {
        setState(
          () => _errorText =
              error.code == ErrorCodes.authInvalidCredentials
                  ? l10n.errorOldPasswordIncorrect
                  : l10n.messageForError(error),
        );
      }
    } on Object {
      if (mounted) setState(() => _errorText = l10n.errorGeneric);
    } finally {
      if (mounted) setState(() => _submitting = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    final theme = Theme.of(context);
    return Scaffold(
      appBar: AppBar(title: Text(l10n.passwordChangeTitle)),
      body: Center(
        child: ConstrainedBox(
          constraints: const BoxConstraints(maxWidth: 420),
          child: SingleChildScrollView(
            child: Padding(
              padding: const EdgeInsets.all(kSpace24),
              child: Form(
                key: _formKey,
                autovalidateMode: AutovalidateMode.onUserInteraction,
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: [
                    Text(
                      l10n.passwordSecurityHint,
                      style: theme.textTheme.bodySmall?.copyWith(
                        color: theme.colorScheme.onSurfaceVariant,
                      ),
                    ),
                    const SizedBox(height: kSpace16),
                    TextFormField(
                      controller: _oldController,
                      obscureText: _obscureOld,
                      enableSuggestions: false,
                      autocorrect: false,
                      textInputAction: TextInputAction.next,
                      autofillHints: const [AutofillHints.password],
                      decoration: InputDecoration(
                        labelText: l10n.currentPassword,
                        suffixIcon: _visibilityToggle(
                          obscure: _obscureOld,
                          onPressed: () => setState(
                            () => _obscureOld = !_obscureOld,
                          ),
                        ),
                      ),
                      validator: (value) => (value == null || value.isEmpty)
                          ? l10n.fieldRequired
                          : null,
                    ),
                    const SizedBox(height: kSpace16),
                    TextFormField(
                      controller: _newController,
                      obscureText: _obscureNew,
                      enableSuggestions: false,
                      autocorrect: false,
                      textInputAction: TextInputAction.next,
                      autofillHints: const [AutofillHints.newPassword],
                      decoration: InputDecoration(
                        labelText: l10n.newPassword,
                        suffixIcon: _visibilityToggle(
                          obscure: _obscureNew,
                          onPressed: () => setState(
                            () => _obscureNew = !_obscureNew,
                          ),
                        ),
                      ),
                      validator: (value) {
                        if (value == null || value.isEmpty) {
                          return l10n.fieldRequired;
                        }
                        if (value.length < 8) return l10n.passwordMinLength;
                        return null;
                      },
                    ),
                    const SizedBox(height: kSpace16),
                    TextFormField(
                      controller: _confirmController,
                      obscureText: _obscureConfirm,
                      enableSuggestions: false,
                      autocorrect: false,
                      textInputAction: TextInputAction.done,
                      autofillHints: const [AutofillHints.newPassword],
                      onFieldSubmitted: (_) => _submitting ? null : _submit(),
                      decoration: InputDecoration(
                        labelText: l10n.confirmNewPassword,
                        suffixIcon: _visibilityToggle(
                          obscure: _obscureConfirm,
                          onPressed: () => setState(
                            () => _obscureConfirm = !_obscureConfirm,
                          ),
                        ),
                      ),
                      validator: (value) {
                        if (value == null || value.isEmpty) {
                          return l10n.fieldRequired;
                        }
                        if (value != _newController.text) {
                          return l10n.passwordMismatch;
                        }
                        return null;
                      },
                    ),
                    if (_errorText != null) ...[
                      const SizedBox(height: kSpace16),
                      StateBadge(
                        variant: BadgeVariant.error,
                        label: _errorText!,
                      ),
                    ],
                    const SizedBox(height: kSpace24),
                    FilledButton(
                      onPressed: _submitting ? null : _submit,
                      child: _submitting
                          ? const SizedBox(
                              height: 20,
                              width: 20,
                              child: CircularProgressIndicator(strokeWidth: 2),
                            )
                          : Text(l10n.passwordSave),
                    ),
                  ],
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }

  /// 显示/隐藏切换（Tooltip 提供语义标签；触控目标 48）。
  Widget _visibilityToggle({
    required bool obscure,
    required VoidCallback onPressed,
  }) {
    final l10n = AppLocalizations.of(context);
    return Tooltip(
      message: obscure ? l10n.loginShowPassword : l10n.loginHidePassword,
      child: IconButton(
        onPressed: onPressed,
        icon: Icon(
          obscure ? Icons.visibility_outlined : Icons.visibility_off_outlined,
          size: 24,
        ),
      ),
    );
  }
}