import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:worldhopper/models/entry.dart';
import 'package:worldhopper/providers/feed_provider.dart';

// Request object for resolving the next entry in a series feed
class NextInSeriesRequest {
  final String serverId;
  final String feedUrl;
  final String currentEntryId;

  const NextInSeriesRequest({
    required this.serverId,
    required this.feedUrl,
    required this.currentEntryId,
  });

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
      other is NextInSeriesRequest &&
          runtimeType == other.runtimeType &&
          serverId == other.serverId &&
          feedUrl == other.feedUrl &&
          currentEntryId == other.currentEntryId;

  @override
  int get hashCode =>
      serverId.hashCode ^ feedUrl.hashCode ^ currentEntryId.hashCode;
}

/// Provider that fetches a feed and returns the next entry after the current one.
/// Returns null if the current entry is the last in the feed or not found.
final nextInSeriesProvider = FutureProvider.family<Entry?, NextInSeriesRequest>(
  (ref, request) async {
    final repository = ref.watch(feedRepositoryProvider);
    final feed = await repository.fetchFeed(
      request.serverId,
      request.feedUrl,
    );

    final entries = feed.entries;
    for (var i = 0; i < entries.length; i++) {
      if (entries[i].id == request.currentEntryId) {
        if (i + 1 < entries.length) {
          return entries[i + 1];
        }
        // TODO: If this is the last entry on a paginated page,
        // fetch feed.nextLink to find the next entry.
        return null;
      }
    }
    return null;
  },
);