/// 照片管理占位页（P3 计划 Task 4）：基础管理列表（可见性/处理状态
/// 标签 + 游标加载更多）；完整筛选与操作由 Task 9 队列 UI 替换。
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 '../features/albums/album_format.dart';
import '../features/albums/models.dart';
import '../features/photos/models.dart';
import '../l10n/app_localizations.dart';

/// 照片管理占位（从详情页携带 [album] 进入，时间按相册时区展示）。
class AlbumPhotosPage extends ConsumerStatefulWidget {
  const AlbumPhotosPage({required this.album, super.key});

  final Album album;

  @override
  ConsumerState<AlbumPhotosPage> createState() => _AlbumPhotosPageState();
}

class _AlbumPhotosPageState extends ConsumerState<AlbumPhotosPage> {
  static const int _pageSize = 20;

  List<AdminPhoto> _items = const <AdminPhoto>[];
  String? _nextCursor;
  bool _hasMore = false;
  bool _loading = true;
  bool _loadingMore = false;
  String? _errorCode;

  @override
  void initState() {
    super.initState();
    _reload();
  }

  Future<void> _reload() async {
    setState(() {
      _loading = true;
      _errorCode = null;
    });
    try {
      final page = await ref.read(apiClientProvider).listAlbumPhotos(
            widget.album.id,
            limit: _pageSize,
          );
      if (mounted) {
        setState(() {
          _items = page.items;
          _nextCursor = page.nextCursor;
          _hasMore = page.hasMore;
          _loading = false;
        });
      }
    } on AppException catch (e) {
      if (mounted) {
        setState(() {
          _errorCode = e.code;
          _loading = false;
        });
      }
    } on Object {
      if (mounted) {
        setState(() {
          _errorCode = ErrorCodes.internalError;
          _loading = false;
        });
      }
    }
  }

  Future<void> _loadMore() async {
    if (_loading || _loadingMore || !_hasMore) return;
    setState(() => _loadingMore = true);
    try {
      final page = await ref.read(apiClientProvider).listAlbumPhotos(
            widget.album.id,
            cursor: _nextCursor,
            limit: _pageSize,
          );
      if (mounted) {
        setState(() {
          _items = <AdminPhoto>[..._items, ...page.items];
          _nextCursor = page.nextCursor;
          _hasMore = page.hasMore;
          _loadingMore = false;
        });
      }
    } on AppException {
      if (mounted) {
        setState(() => _loadingMore = false);
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(
              AppLocalizations.of(context).messageForErrorCode(
                ErrorCodes.networkError,
              ),
            ),
          ),
        );
      }
    } on Object {
      if (mounted) {
        setState(() => _loadingMore = false);
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(AppLocalizations.of(context).errorGeneric),
          ),
        );
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    final theme = Theme.of(context);
    return Scaffold(
      appBar: AppBar(title: Text(l10n.albumPhotos)),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          // Task 9 占位横幅：完整筛选/操作届时替换本页。
          Card(
            margin: const EdgeInsets.fromLTRB(12, 12, 12, 0),
            child: Padding(
              padding: const EdgeInsets.all(12),
              child: Row(
                children: [
                  Icon(
                    Icons.construction_outlined,
                    size: 18,
                    color: theme.colorScheme.onSurfaceVariant,
                  ),
                  const SizedBox(width: 8),
                  Expanded(
                    child: Text(
                      l10n.photosTask9Placeholder,
                      style: theme.textTheme.bodySmall?.copyWith(
                        color: theme.colorScheme.onSurfaceVariant,
                      ),
                    ),
                  ),
                ],
              ),
            ),
          ),
          Expanded(
            child: _loading
                ? const Center(child: CircularProgressIndicator())
                : _items.isEmpty && _errorCode != null
                    ? Center(
                        child: Column(
                          mainAxisSize: MainAxisSize.min,
                          children: [
                            const Icon(Icons.cloud_off, size: 48),
                            const SizedBox(height: 12),
                            Text(l10n.messageForErrorCode(_errorCode!)),
                            const SizedBox(height: 12),
                            FilledButton.icon(
                              onPressed: _reload,
                              icon: const Icon(Icons.refresh),
                              label: Text(l10n.retry),
                            ),
                          ],
                        ),
                      )
                    : ListView.builder(
                  itemCount: _items.length +
                      (_items.isEmpty || _hasMore || _loadingMore ? 1 : 0),
                  itemBuilder: (context, index) {
                    if (_items.isEmpty) {
                      return Padding(
                        padding: const EdgeInsets.all(32),
                        child: Text(
                          l10n.albumPhotosEmpty,
                          textAlign: TextAlign.center,
                          style: theme.textTheme.bodySmall,
                        ),
                      );
                    }
                    if (index >= _items.length) {
                      return const Padding(
                        padding: EdgeInsets.symmetric(vertical: 16),
                        child: Center(
                          child: SizedBox(
                            height: 24,
                            width: 24,
                            child: CircularProgressIndicator(strokeWidth: 2),
                          ),
                        ),
                      );
                    }
                    if (index >= _items.length - 3 &&
                        _hasMore &&
                        !_loadingMore) {
                      WidgetsBinding.instance.addPostFrameCallback(
                        (_) => _loadMore(),
                      );
                    }
                    return _photoTile(l10n, theme, _items[index]);
                  },
                      ),
          ),
        ],
      ),
    );
  }

  Widget _photoTile(
    AppLocalizations l10n,
    ThemeData theme,
    AdminPhoto photo,
  ) {
    return ListTile(
      leading: Container(
        width: 44,
        height: 44,
        decoration: BoxDecoration(
          color: theme.colorScheme.surfaceContainerHighest,
          borderRadius: BorderRadius.circular(8),
        ),
        child: const Icon(Icons.image_outlined),
      ),
      title: Text(
        '${photo.photoId.substring(0, 8)} · ${(photo.bytes / 1024).round()} KB',
        style: theme.textTheme.bodyMedium?.copyWith(
          fontFeatures: const [FontFeature.tabularFigures()],
        ),
      ),
      subtitle: Text(
        formatAlbumDateTime(
          photo.uploadedAt,
          widget.album.timezone,
          l10n.localeName,
        ),
      ),
      trailing: Wrap(
        spacing: 6,
        runSpacing: 4,
        crossAxisAlignment: WrapCrossAlignment.center,
        children: [
          _PhotoTag(
            label: _visibilityLabel(l10n, photo.visibility),
            highlight: photo.visibility == PhotoVisibility.published,
          ),
          _PhotoTag(
            label: _processingLabel(l10n, photo.processingState),
            highlight: photo.processingState == PhotoProcessingState.ready,
          ),
        ],
      ),
    );
  }

  static String _visibilityLabel(AppLocalizations l10n, PhotoVisibility v) {
    switch (v) {
      case PhotoVisibility.published:
        return l10n.visibilityPublished;
      case PhotoVisibility.unpublished:
        return l10n.visibilityUnpublished;
      case PhotoVisibility.hidden:
        return l10n.visibilityHidden;
      case PhotoVisibility.deleted:
        return l10n.visibilityDeleted;
    }
  }

  static String _processingLabel(
    AppLocalizations l10n,
    PhotoProcessingState s,
  ) {
    switch (s) {
      case PhotoProcessingState.pendingUpload:
        return l10n.procPendingUpload;
      case PhotoProcessingState.uploaded:
        return l10n.procUploaded;
      case PhotoProcessingState.processing:
        return l10n.procProcessing;
      case PhotoProcessingState.ready:
        return l10n.procReady;
      case PhotoProcessingState.processingFailed:
        return l10n.procProcessingFailed;
    }
  }
}

/// 照片标签（可见性/处理状态）。
class _PhotoTag extends StatelessWidget {
  const _PhotoTag({required this.label, required this.highlight});

  final String label;
  final bool highlight;

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