/// 相册列表页签：游标加载更多、下拉刷新、封面卡片（UI-01 §4.1）。
///
/// 卡片顺序：封面（16:9，无封面中性占位）→ 标题（≤2 行，语言回退链）→
/// 时间/场地单行 → 公开/上传状态徽章（图标+文案，不只靠颜色）。手机单列；
/// 可用宽度 > 600 双列（行内卡片等高，不挤压英文标题）。publicToken 与
/// 四开关堆叠不在主卡片（完整配置在详情设置）。
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 '../ui/components/empty_state.dart';
import '../ui/components/error_state.dart';
import '../ui/components/photo_thumbnail.dart';
import '../ui/components/state_badge.dart';
import '../ui/tokens.dart';
import 'album_detail_page.dart';
import 'album_form_page.dart';

/// 双列布局的可用宽度阈值（方案 §4.1「平板按可用宽度使用两列」）。
const double kAlbumTwoColumnMinWidth = 600;

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

  /// 打开创建表单；成功后刷新列表（空态 CTA 与 FAB 共用）。
  static 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）。
///
/// 空态带「新建相册」入口；错误态带重试。列表按可用宽度切换单/双列，
/// 行结构 [ListView.builder]（行 = 1-2 张卡片），保证下拉刷新与游标
/// 加载更多行为与旧版一致。
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 ErrorState(
          message: l10n.messageForErrorCode(state.errorCode!),
          onRetry: notifier.refresh,
        );
      }
      return EmptyState(
        icon: Icons.photo_library_outlined,
        title: l10n.albumsEmpty,
        actionLabel: l10n.albumCreate,
        onAction: () => AlbumsTab.openCreate(context, ref),
      );
    }

    return LayoutBuilder(
      builder: (context, constraints) {
        final twoColumns = constraints.maxWidth > kAlbumTwoColumnMinWidth;
        final rowCount = (state.items.length / (twoColumns ? 2 : 1)).ceil();
        final hasFooter = state.hasMore || state.loadMoreFailed;
        return RefreshIndicator(
          onRefresh: notifier.refresh,
          child: ListView.builder(
            physics: const AlwaysScrollableScrollPhysics(),
            padding: const EdgeInsets.fromLTRB(
              kSpace16,
              kSpace8,
              kSpace16,
              kSpace32,
            ),
            itemCount: rowCount + (hasFooter ? 1 : 0),
            itemBuilder: (context, index) {
              if (index >= rowCount) {
                if (state.loadMoreFailed) {
                  return ListTile(
                    contentPadding: EdgeInsets.zero,
                    leading: const Icon(Icons.error_outline),
                    title: Text(l10n.loadMoreFailed),
                    onTap: notifier.loadMore,
                  );
                }
                return const Padding(
                  padding: EdgeInsets.symmetric(vertical: kSpace16),
                  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 >= rowCount - 2 && state.hasMore && !state.loadingMore) {
                WidgetsBinding.instance.addPostFrameCallback(
                  (_) => notifier.loadMore(),
                );
              }
              if (!twoColumns) {
                return AlbumCard(album: state.items[index]);
              }
              final first = index * 2;
              final hasSecond = first + 1 < state.items.length;
              return IntrinsicHeight(
                child: Row(
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: [
                    Expanded(child: AlbumCard(album: state.items[first])),
                    if (hasSecond) ...[
                      const SizedBox(width: kSpace12),
                      Expanded(child: AlbumCard(album: state.items[first + 1])),
                    ],
                  ],
                ),
              );
            },
          ),
        );
      },
    );
  }
}

/// 相册卡片（UI-01 §4.1 样板）：封面 → 标题 → 时间/场地 → 状态徽章。
///
/// 标题按「界面语言 → 相册默认语言 → 首个条目」回退；时间用相册时区；
/// 公开/上传分别显示（关闭不等于不公开）。publicToken 与四开关堆叠已从
/// 主卡片移除（完整配置在详情设置）。
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 venue = albumDisplayVenue(album, l10n.localeName);
    final meta = venue == null
        ? _timeRange(l10n)
        : '${_timeRange(l10n)} · $venue';
    return Card(
      margin: const EdgeInsets.symmetric(vertical: kSpace8),
      clipBehavior: Clip.antiAlias,
      child: InkWell(
        onTap: () => Navigator.of(context).push(
          MaterialPageRoute<void>(
            builder: (_) => AlbumDetailPage(albumId: album.id),
          ),
        ),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          mainAxisSize: MainAxisSize.min,
          children: [
            PhotoThumbnail(url: album.cover?.url, aspectRatio: 16 / 9),
            Padding(
              padding: const EdgeInsets.all(kSpace16),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    albumDisplayTitle(album, l10n.localeName),
                    maxLines: 2,
                    overflow: TextOverflow.ellipsis,
                    style: theme.textTheme.titleMedium,
                  ),
                  const SizedBox(height: kSpace4),
                  Text(
                    meta,
                    maxLines: 1,
                    overflow: TextOverflow.ellipsis,
                    style: theme.textTheme.bodySmall,
                  ),
                  const SizedBox(height: kSpace12),
                  Row(
                    children: [
                      StateBadge(
                        variant: album.publicEnabled
                            ? BadgeVariant.info
                            : BadgeVariant.neutral,
                        label: album.publicEnabled
                            ? l10n.tagPublic
                            : l10n.albumPublicOff,
                        compact: true,
                      ),
                      const SizedBox(width: kSpace8),
                      StateBadge(
                        variant: album.uploadEnabled
                            ? BadgeVariant.success
                            : BadgeVariant.neutral,
                        label: album.uploadEnabled
                            ? l10n.albumUploadsOn
                            : l10n.albumUploadsOff,
                        compact: true,
                      ),
                    ],
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }

  /// 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';
  }
}