1 files changed, 112 insertions, 0 deletions
diff --git a/MediaBrowser.Providers/Plugins/MusicBrainz/MusicBrainzQueryExtensions.cs b/MediaBrowser.Providers/Plugins/MusicBrainz/MusicBrainzQueryExtensions.cs
new file mode 100644
index 0000000000..f3df41e942
--- /dev/null
+++ b/MediaBrowser.Providers/Plugins/MusicBrainz/MusicBrainzQueryExtensions.cs
@@ -0,0 +1,112 @@
+using System;
+using System.Net;
+using System.Threading;
+using System.Threading.Tasks;
+using MetaBrainz.Common;
+using MetaBrainz.MusicBrainz;
+using MetaBrainz.MusicBrainz.Interfaces.Entities;
+using Microsoft.Extensions.Logging;
+
+namespace MediaBrowser.Providers.Plugins.MusicBrainz;
+
+/// <summary>
+/// Helpers for talking to MusicBrainz with identifiers that are not guaranteed to be valid.
+/// </summary>
+internal static class MusicBrainzQueryExtensions
+{
+    /// <summary>
+    /// Parses a MusicBrainz identifier, which may come from user-supplied tags or NFO files and is therefore not
+    /// guaranteed to be a valid GUID.
+    /// </summary>
+    /// <param name="id">The identifier to parse.</param>
+    /// <param name="entityType">The type of entity the identifier refers to, used for logging.</param>
+    /// <param name="logger">The logger.</param>
+    /// <returns>The parsed identifier, or <see langword="null"/> if it is missing or malformed.</returns>
+    public static Guid? ParseMusicBrainzId(string? id, string entityType, ILogger logger)
+    {
+        if (string.IsNullOrWhiteSpace(id))
+        {
+            return null;
+        }
+
+        if (!Guid.TryParse(id, out var parsedId))
+        {
+            logger.LogDebug("Ignoring malformed MusicBrainz {EntityType} id {Id}", entityType, id);
+            return null;
+        }
+
+        return parsedId;
+    }
+
+    /// <summary>
+    /// Looks up a release, treating an unknown identifier as missing data rather than an error.
+    /// </summary>
+    /// <param name="query">The MusicBrainz query client.</param>
+    /// <param name="releaseId">The release identifier.</param>
+    /// <param name="include">The additional data to include in the lookup.</param>
+    /// <param name="logger">The logger.</param>
+    /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>The release, or <see langword="null"/> if MusicBrainz does not have it.</returns>
+    public static Task<IRelease?> LookupReleaseOrNullAsync(this Query query, Guid releaseId, Include include, ILogger logger, CancellationToken cancellationToken)
+        => NotFoundAsNullAsync(
+            () => query.LookupReleaseAsync(releaseId, include, cancellationToken),
+            "release",
+            releaseId,
+            logger);
+
+    /// <summary>
+    /// Looks up a release group, treating an unknown identifier as missing data rather than an error.
+    /// </summary>
+    /// <param name="query">The MusicBrainz query client.</param>
+    /// <param name="releaseGroupId">The release group identifier.</param>
+    /// <param name="include">The additional data to include in the lookup.</param>
+    /// <param name="logger">The logger.</param>
+    /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>The release group, or <see langword="null"/> if MusicBrainz does not have it.</returns>
+    public static Task<IReleaseGroup?> LookupReleaseGroupOrNullAsync(this Query query, Guid releaseGroupId, Include include, ILogger logger, CancellationToken cancellationToken)
+        => NotFoundAsNullAsync(
+            () => query.LookupReleaseGroupAsync(releaseGroupId, include, null, cancellationToken),
+            "release group",
+            releaseGroupId,
+            logger);
+
+    /// <summary>
+    /// Looks up an artist, treating an unknown identifier as missing data rather than an error.
+    /// </summary>
+    /// <param name="query">The MusicBrainz query client.</param>
+    /// <param name="artistId">The artist identifier.</param>
+    /// <param name="include">The additional data to include in the lookup.</param>
+    /// <param name="logger">The logger.</param>
+    /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>The artist, or <see langword="null"/> if MusicBrainz does not have it.</returns>
+    public static Task<IArtist?> LookupArtistOrNullAsync(this Query query, Guid artistId, Include include, ILogger logger, CancellationToken cancellationToken)
+        => NotFoundAsNullAsync(
+            () => query.LookupArtistAsync(artistId, include, null, null, cancellationToken),
+            "artist",
+            artistId,
+            logger);
+
+    /// <summary>
+    /// Runs a lookup, mapping a "not found" response to <see langword="null"/>. Identifiers stored on a library item
+    /// can refer to entities that no longer exist in MusicBrainz, which is not an error worth failing a refresh over.
+    /// </summary>
+    /// <typeparam name="T">The type of entity being looked up.</typeparam>
+    /// <param name="lookup">The lookup to run.</param>
+    /// <param name="entityType">The type of entity being looked up, used for logging.</param>
+    /// <param name="id">The identifier being looked up, used for logging.</param>
+    /// <param name="logger">The logger.</param>
+    /// <returns>The entity, or <see langword="null"/> if MusicBrainz does not have it.</returns>
+    private static async Task<T?> NotFoundAsNullAsync<T>(Func<Task<T>> lookup, string entityType, Guid id, ILogger logger)
+        where T : class
+    {
+        try
+        {
+            return await lookup().ConfigureAwait(false);
+        }
+        catch (HttpError ex) when (ex.Status == HttpStatusCode.NotFound)
+        {
+            logger.LogDebug("MusicBrainz has no {EntityType} with id {Id}", entityType, id);
+            return null;
+        }
+    }
+}