Move common interface implementations to extension methods

osu.Game/Beatmaps/BeatmapInfoExtensions.cs

@@ -0,0 +1,37 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Linq;
+using osu.Framework.Localisation;
+
+namespace osu.Game.Beatmaps
+{
+    public static class BeatmapInfoExtensions
+    {
+        /// <summary>
+        /// A user-presentable display title representing this beatmap.
+        /// </summary>
+        public static string GetDisplayTitle(this IBeatmapInfo beatmapInfo) => $"{getClosestMetadata(beatmapInfo)} {getVersionString(beatmapInfo)}".Trim();
+
+        /// <summary>
+        /// A user-presentable display title representing this beatmap, with localisation handling for potentially romanisable fields.
+        /// </summary>
+        public static RomanisableString GetDisplayTitleRomanisable(this IBeatmapInfo beatmapInfo)
+        {
+            var metadata = getClosestMetadata(beatmapInfo).GetDisplayTitleRomanisable();
+            var versionString = getVersionString(beatmapInfo);
+
+            return new RomanisableString($"{metadata.GetPreferred(true)} {versionString}".Trim(), $"{metadata.GetPreferred(false)} {versionString}".Trim());
+        }
+
+        public static string[] GetSearchableTerms(this IBeatmapInfo beatmapInfo) => new[]
+        {
+            beatmapInfo.DifficultyName
+        }.Concat(getClosestMetadata(beatmapInfo).GetSearchableTerms()).Where(s => !string.IsNullOrEmpty(s)).ToArray();
+
+        private static string getVersionString(IBeatmapInfo beatmapInfo) => string.IsNullOrEmpty(beatmapInfo.DifficultyName) ? string.Empty : $"[{beatmapInfo.DifficultyName}]";
+
+        // temporary helper methods until we figure which metadata should be where.
+        private static IBeatmapMetadataInfo getClosestMetadata(IBeatmapInfo beatmapInfo) => (beatmapInfo.Metadata ?? beatmapInfo.BeatmapSet.Metadata)!;
+    }
+}