import 'package:halkyon_learn_flutter/src/feature/study/data/review_gateway.dart';

/// A [ReviewGateway] in memory; ids sort by creation, as UUID v7 ids do.
class FakeReviewGateway() implements ReviewGateway {
  var _nextId = 1;

  /// Every review stored, in order.
  final rows = <ReviewRow>[];

  /// When set, storing a review fails with it.
  Exception? failWrites;

  @override
  Future<List<ReviewRow>> reviewsOf(Set<String> cardIds) async => [
    for (final row in rows)
      if (cardIds.contains(row.cardId)) row,
  ];

  @override
  Future<List<ReviewRow>> allReviews() async => [...rows];

  @override
  Future<List<ReviewRow>> insert(Iterable<ReviewRow> reviews) async {
    if (failWrites case final error?) {
      throw error;
    }
    final stored = [
      for (final review in reviews)
        (
          id: 'review-${(_nextId++).toString().padLeft(4, '0')}',
          cardId: review.cardId,
          rating: review.rating,
          reviewedAt: review.reviewedAt,
          durationMs: review.durationMs,
          mode: review.mode,
        ),
    ];
    rows.addAll(stored);
    return stored;
  }

  @override
  Future<void> deleteReviews(
    Set<String> cardIds,
    DateTime at,
    String mode,
  ) async => rows.removeWhere(
    (row) =>
        cardIds.contains(row.cardId) &&
        row.mode == mode &&
        row.reviewedAt == at,
  );

  @override
  Stream<void> get remoteChanges => const Stream.empty();
}