plezy/test/media/media_item_merge_test.dart

import 'package:flutter_test/flutter_test.dart';
import 'package:plezy/media/ids.dart';
import 'package:plezy/media/media_backend.dart';
import 'package:plezy/media/media_item.dart';
import 'package:plezy/media/media_item_merge.dart';
import 'package:plezy/media/media_kind.dart';
import 'package:plezy/media/media_version.dart';
import '../test_helpers/media_items.dart';

void main() {
  MediaItem item({String? serverId, String? serverName, String? libraryId, String? libraryTitle}) => testMediaItem(
    id: 'item',
    backend: MediaBackend.plex,
    kind: MediaKind.movie,
    serverId: serverId,
    serverName: serverName,
    libraryId: libraryId,
    libraryTitle: libraryTitle,
  );

  test('uses the authoritative fallback when both items omit server identity', () {
    final merged = mergeFetchedMediaItem(fetched: item(), fallbackServerId: ServerId('fallback'));

    expect(merged.serverId, 'fallback');
    expect(merged.globalKey, 'fallback:item');
  });

  test('preserves existing identity while preferring fetched library context', () {
    final merged = mergeFetchedMediaItem(
      fetched: item(serverId: 'fetched', serverName: 'Fetched', libraryId: 'new-lib', libraryTitle: 'New'),
      existing: item(serverId: 'existing', serverName: 'Existing', libraryId: 'old-lib', libraryTitle: 'Old'),
      fallbackServerId: ServerId('fallback'),
    );

    expect(merged.serverId, 'existing');
    expect(merged.serverName, 'Existing');
    expect(merged.libraryId, 'new-lib');
    expect(merged.libraryTitle, 'New');
  });

  test('fills missing fetched library context from the existing item', () {
    final merged = mergeFetchedMediaItem(
      fetched: item(),
      existing: item(libraryId: 'old-lib', libraryTitle: 'Old'),
      fallbackServerId: ServerId('fallback'),
    );

    expect(merged.libraryId, 'old-lib');
    expect(merged.libraryTitle, 'Old');
  });

  MediaItem copy({
    required String id,
    String? libraryTitle,
    String? videoResolution,
    List<MediaVersion>? mediaVersions,
  }) => testMediaItem(
    id: id,
    serverId: 'server-1',
    serverName: 'Living Room',
    libraryId: libraryTitle == null ? null : '$id-lib',
    libraryTitle: libraryTitle,
    mediaVersions:
        mediaVersions ??
        (videoResolution == null ? null : [MediaVersion(id: '$id-v', videoResolution: videoResolution)]),
  );

  test('orders library copies by resolution, best first', () {
    final merged = mergeLibraryCopies(const [], [
      copy(id: 'hd', libraryTitle: 'Movies', videoResolution: '1080'),
      copy(id: 'uhd', libraryTitle: '4K Movies', videoResolution: '4k'),
    ]);

    expect(merged.map((item) => item.id), ['uhd', 'hd']);
  });

  test('keeps copies a later pass did not return', () {
    final merged = mergeLibraryCopies([copy(id: 'hd', libraryTitle: 'Movies')], const []);

    expect(merged.map((item) => item.id), ['hd']);
  });

  test('an unstamped re-resolve does not strip a copy of its library', () {
    // Jellyfin's library stamp is a best-effort ancestors lookup that returns
    // the item unstamped when it fails. Losing the title would make this copy
    // indistinguishable from its sibling in the server's other library.
    final merged = mergeLibraryCopies(
      [copy(id: 'hd', libraryTitle: 'Movies', videoResolution: '1080')],
      [copy(id: 'hd')],
    );

    expect(merged.single.libraryId, 'hd-lib');
    expect(merged.single.libraryTitle, 'Movies');
    expect(merged.single.serverName, 'Living Room');
    expect(merged.single.mediaVersions?.single.videoResolution, '1080');
  });

  test('a re-resolve carrying fresher library context wins', () {
    final merged = mergeLibraryCopies(
      [copy(id: 'hd', libraryTitle: 'Movies', videoResolution: '1080')],
      [copy(id: 'hd', libraryTitle: 'Renamed Movies', videoResolution: '4k')],
    );

    expect(merged.single.libraryTitle, 'Renamed Movies');
    expect(merged.single.mediaVersions?.single.videoResolution, '4k');
  });

  test('an empty version list is treated as absent, not as a downgrade', () {
    final merged = mergeLibraryCopies(
      [copy(id: 'hd', libraryTitle: 'Movies', videoResolution: '1080')],
      [copy(id: 'hd', libraryTitle: 'Movies', mediaVersions: const [])],
    );

    expect(merged.single.mediaVersions?.single.videoResolution, '1080');
  });
}