/// 相册列表页签（P3 计划 Task 4）：游标加载更多、下拉刷新、卡片标签行
/// （状态 + 四开关）、时区感知的时间展示、公开令牌短显、FAB 新建；
/// 加载/空/错误态齐备。详情/编辑由卡片与列表级刷新联动。
library;

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

import '../core/error_l10n.dart';
import '../features/albums/album_format.dart';
import '../features/albums/models.dart';
import '../features/albums/providers.dart';
import '../l10n/app_localizations.dart';
import 'album_detail_page.dart';
import 'album_form_page.dart';

/// 首页「相册」页签。
class AlbumsTab extends ConsumerWidget {
  const AlbumsTab({super.key});

  Future<void> _openCreate(BuildContext context, WidgetRef ref) async {
    final changed = await Navigator.of(context).push<bool>(
      MaterialPageRoute<bool>(builder: (_) => const AlbumFormPage()),
    );
    if (changed == true) {
      ref.read(albumListProvider.notifier).refresh();
    }
  }

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final l10n = AppLocalizations.of(context);
    final state = ref.watch(albumListProvider);
    return Scaffold(
      appBar: AppBar(title: Text(l10n.albums)),
      floatingActionButton: FloatingActionButton.extended(
        onPressed: () => _openCreate(context, ref),
        icon: const Icon(Icons.add),
        label: Text(l10n.albumCreate),
      ),
      body: AlbumListBody(state: state),
    );
  }
}

/// 列表主体：按状态分发 加载/错误/空/列表（含加载更多页脚）。
class AlbumListBody extends ConsumerWidget {
  const AlbumListBody({required this.state, super.key});

  final AlbumListState state;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final l10n = AppLocalizations.of(context);
    final notifier = ref.read(albumListProvider.notifier);

    if (state.loading) {
      return const Center(child: CircularProgressIndicator());
    }
    if (state.items.isEmpty) {
      if (state.errorCode != null) {
        return _ErrorView(
          message: l10n.messageForErrorCode(state.errorCode!),
          onRetry: notifier.refresh,
        );
      }
      return _EmptyView(message: l10n.albumsEmpty);
    }

    final hasFooter = state.hasMore || state.loadMoreFailed;
    return RefreshIndicator(
      onRefresh: notifier.refresh,
      child: ListView.builder(
        physics: const AlwaysScrollableScrollPhysics(),
        itemCount: state.items.length + (hasFooter ? 1 : 0),
        itemBuilder: (context, index) {
          if (index >= state.items.length) {
            if (state.loadMoreFailed) {
              return ListTile(
                contentPadding: const EdgeInsets.symmetric(horizontal: 16),
                leading: const Icon(Icons.error_outline),
                title: Text(l10n.loadMoreFailed),
                onTap: notifier.loadMore,
              );
            }
            return const Padding(
              padding: EdgeInsets.symmetric(vertical: 16),
              child: Center(
                child: SizedBox(
                  height: 24,
                  width: 24,
                  child: CircularProgressIndicator(strokeWidth: 2),
                ),
              ),
            );
          }
          // 接近底部时预取下一页（loadMore 自带并发/末页守卫）。
          if (index >= state.items.length - 3 &&
              state.hasMore &&
              !state.loadingMore) {
            WidgetsBinding.instance.addPostFrameCallback(
              (_) => notifier.loadMore(),
            );
          }
          return AlbumCard(album: state.items[index]);
        },
      ),
    );
  }
}

/// 首屏错误视图（重试按钮触发整页刷新）。
class _ErrorView extends StatelessWidget {
  const _ErrorView({required this.message, required this.onRetry});

  final String message;
  final Future<void> Function() onRetry;

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          const Icon(Icons.cloud_off, size: 48),
          const SizedBox(height: 12),
          Text(message, textAlign: TextAlign.center),
          const SizedBox(height: 12),
          FilledButton.icon(
            onPressed: onRetry,
            icon: const Icon(Icons.refresh),
            label: Text(l10n.retry),
          ),
        ],
      ),
    );
  }
}

/// 空列表视图。
class _EmptyView extends StatelessWidget {
  const _EmptyView({required this.message});

  final String message;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          const Icon(Icons.photo_library_outlined, size: 48),
          const SizedBox(height: 12),
          Text(message, textAlign: TextAlign.center),
        ],
      ),
    );
  }
}

/// 相册卡片：默认语言标题、状态 + 四开关标签行、相册时区的时间区间、
/// 公开令牌短显。
class AlbumCard extends StatelessWidget {
  const AlbumCard({required this.album, super.key});

  final AlbumSummary album;

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    final theme = Theme.of(context);
    final time = _timeRange(l10n);
    return Card(
      margin: const EdgeInsets.symmetric(horizontal: 12, vertical: 6),
      child: InkWell(
        borderRadius: BorderRadius.circular(12),
        onTap: () => Navigator.of(context).push(
          MaterialPageRoute<void>(
            builder: (_) => AlbumDetailPage(albumId: album.id),
          ),
        ),
        child: Padding(
          padding: const EdgeInsets.all(12),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Row(
                children: [
                  Expanded(
                    child: Text(
                      _title,
                      maxLines: 1,
                      overflow: TextOverflow.ellipsis,
                      style: theme.textTheme.titleMedium
                          ?.copyWith(fontWeight: FontWeight.w600),
                    ),
                  ),
                  const SizedBox(width: 8),
                  _StatusChip(status: album.status),
                ],
              ),
              const SizedBox(height: 8),
              Wrap(
                spacing: 6,
                runSpacing: 4,
                children: [
                  _SwitchChip(label: l10n.tagUpload, on: album.uploadEnabled),
                  _SwitchChip(label: l10n.tagPublic, on: album.publicEnabled),
                  _SwitchChip(
                    label: l10n.tagDownload,
                    on: album.downloadEnabled,
                  ),
                  _SwitchChip(
                    label: l10n.tagOriginal,
                    on: album.originalDownloadEnabled,
                  ),
                ],
              ),
              const SizedBox(height: 8),
              Row(
                children: [
                  Icon(
                    Icons.schedule,
                    size: 14,
                    color: theme.colorScheme.onSurfaceVariant,
                  ),
                  const SizedBox(width: 4),
                  Expanded(
                    child: Text(
                      time,
                      style: theme.textTheme.bodySmall?.copyWith(
                        color: theme.colorScheme.onSurfaceVariant,
                      ),
                    ),
                  ),
                ],
              ),
              const SizedBox(height: 2),
              Text(
                album.publicToken.length > 10
                    ? '${album.publicToken.substring(0, 10)}…'
                    : album.publicToken,
                style: theme.textTheme.bodySmall?.copyWith(
                  fontFeatures: const [FontFeature.tabularFigures()],
                  color: theme.colorScheme.onSurfaceVariant,
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  /// 默认语言标题（缺失时回退首个条目；无翻译时显示 ID 兜底）。
  String get _title {
    for (final t in album.translations) {
      if (t.locale == album.defaultLocale) return t.title;
    }
    if (album.translations.isNotEmpty) return album.translations.first.title;
    return album.id;
  }

  /// 相册时区的时间区间（结束未定显示「未定」占位）。
  String _timeRange(AppLocalizations l10n) {
    final locale = l10n.localeName;
    final start = formatAlbumDateTime(album.startAt, album.timezone, locale);
    final end = album.endAt == null
        ? l10n.notSet
        : formatAlbumDateTime(album.endAt!, album.timezone, locale);
    return '$start ~ $end';
  }
}

/// 状态标签：active 正常 / offline 下线。
class _StatusChip extends StatelessWidget {
  const _StatusChip({required this.status});

  final AlbumStatus status;

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    final theme = Theme.of(context);
    final active = status == AlbumStatus.active;
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 2),
      decoration: BoxDecoration(
        color: active
            ? theme.colorScheme.secondaryContainer
            : theme.colorScheme.errorContainer,
        borderRadius: BorderRadius.circular(999),
      ),
      child: Text(
        active ? l10n.albumStatusActive : l10n.albumStatusOffline,
        style: theme.textTheme.labelSmall?.copyWith(
          color: active
              ? theme.colorScheme.onSecondaryContainer
              : theme.colorScheme.onErrorContainer,
        ),
      ),
    );
  }
}

/// 开关标签：色调区分开/关。
class _SwitchChip extends StatelessWidget {
  const _SwitchChip({required this.label, required this.on});

  final String label;
  final bool on;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 2),
      decoration: BoxDecoration(
        color: on
            ? theme.colorScheme.primaryContainer
            : theme.colorScheme.surfaceContainerHighest,
        borderRadius: BorderRadius.circular(999),
      ),
      child: Text(
        label,
        style: theme.textTheme.labelSmall?.copyWith(
          color: on
              ? theme.colorScheme.onPrimaryContainer
              : theme.colorScheme.onSurfaceVariant,
        ),
      ),
    );
  }
}