import '../../share_intent/remote_file_ref.dart';
import '../file_viewer/file_kind.dart';

enum GalleryMediaKind { image, video }

/// Single rule for "is this a picture/video": the gallery and the chat bubble
/// both use it, so whatever looks like media in a chat is also in the gallery.
GalleryMediaKind? galleryMediaKindOf(String name, {String? mimeType}) {
  final mime = mimeType?.toLowerCase() ?? '';
  // Only formats the device decodes itself — image/* also covers PSD, SVG,
  // TIFF …, which would hinge on a server preview.
  if (_galleryImageMimes.contains(mime)) return GalleryMediaKind.image;
  if (mime.startsWith('video/')) return GalleryMediaKind.video;
  if (isGalleryImageName(name)) return GalleryMediaKind.image;
  if (isGalleryVideoName(name)) return GalleryMediaKind.video;
  return null;
}

const Set<String> _galleryImageMimes = {
  'image/jpeg',
  'image/png',
  'image/gif',
  'image/webp',
  'image/bmp',
  'image/x-ms-bmp',
  'image/heic',
  'image/heif',
  'image/avif',
  'image/x-icon',
  'image/vnd.microsoft.icon',
};

class GalleryItem {
  final RemoteFileRef file;
  final GalleryMediaKind kind;

  /// Talk message id: orders chat media and dedupes overlapping pages.
  final int? messageId;

  /// Second line in the app bar, e.g. sender and date.
  final String? subtitle;

  /// Part of the cache key so an overwritten file is not served stale.
  final String? eTag;

  const GalleryItem({
    required this.file,
    required this.kind,
    this.messageId,
    this.subtitle,
    this.eTag,
  });

  String get key => messageId?.toString() ?? file.path;

  bool get isVideo => kind == GalleryMediaKind.video;

  String get _extension => file.name.split('.').last.toLowerCase();

  /// Server previews of a GIF are a single still frame.
  bool get needsOriginal => _extension == 'gif';
}

/// Adds [incoming] to [current], dropping duplicates by [GalleryItem.key] and
/// keeping chat media in chronological (message id) order.
List<GalleryItem> mergeGalleryItems(
  List<GalleryItem> current,
  Iterable<GalleryItem> incoming,
) {
  final byKey = {for (final item in current) item.key: item};
  for (final item in incoming) {
    byKey.putIfAbsent(item.key, () => item);
  }
  final merged = byKey.values.toList();
  if (merged.every((item) => item.messageId != null)) {
    merged.sort((a, b) => a.messageId!.compareTo(b.messageId!));
  }
  return merged;
}