deepdrft/DeepDrftData/Repositories/TrackRepository.cs

using Data.Data.Repositories;
using Data.Errors;
using DeepDrftData.Data;
using DeepDrftModels.Entities;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

namespace DeepDrftData.Repositories;

public class TrackRepository : Repository<DeepDrftContext, TrackEntity>
{
    private readonly DeepDrftContext _context;

    public TrackRepository(
        DeepDrftContext context,
        ILogger<Repository<DeepDrftContext, TrackEntity>> logger,
        IDbExceptionClassifier? classifier = null)
        : base(context, logger, classifier: classifier)
    {
        _context = context;
    }

    // Lookup by vault entry key. The base Repository<> only exposes id-based queries, so this
    // queries the DbSet directly. Returns null on miss (service wraps in ResultContainer).
    public async Task<TrackEntity?> GetByEntryKeyAsync(string entryKey)
        => await _context.Tracks.FirstOrDefaultAsync(t => t.EntryKey == entryKey);

    // Picks one track uniformly at random. Two round-trips (count, then a single offset row)
    // rather than ORDER BY random() so the database never sorts the whole table — the catalogue
    // is small today but this keeps the cost flat as it grows. Returns null when empty so the
    // service surfaces a valid empty-library state, not an error. Queries the DbSet directly,
    // mirroring GetByEntryKeyAsync, since the base Repository<> exposes only id-based reads.
    public async Task<TrackEntity?> GetRandomAsync(CancellationToken cancellationToken = default)
    {
        var count = await _context.Tracks.CountAsync(cancellationToken);
        if (count == 0)
            return null;

        var index = Random.Shared.Next(count);
        return await _context.Tracks
            .OrderBy(t => t.Id)
            .Skip(index)
            .Take(1)
            .FirstOrDefaultAsync(cancellationToken);
    }

    protected override void UpdateEntity(TrackEntity target, TrackEntity source)
    {
        base.UpdateEntity(target, source); // copies CreatedAt, UpdatedAt, IsDeleted
        target.EntryKey = source.EntryKey;
        target.TrackName = source.TrackName;
        target.Artist = source.Artist;
        target.Album = source.Album;
        target.Genre = source.Genre;
        target.ReleaseDate = source.ReleaseDate;
        target.ImagePath = source.ImagePath;
        target.CreatedByUserId = source.CreatedByUserId;
    }
}