From 2b0fd3558f2f7f1c6a79dbba62ab80f40d656ca9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bart=C5=82omiej=20Dach?= <dach.bartlomiej@gmail.com>
Date: Wed, 30 Oct 2024 08:44:23 +0100
Subject: [PATCH] Remove more no-longer-required checks

The scenario that remaining guard was trying to protect against is
obviated by and no longer possible after
776fabd77c5a6225e69a0b14e79b9e097692320c.
---
 .../BeatmapUpdaterMetadataLookupTest.cs       | 28 -------------------
 .../Beatmaps/BeatmapUpdaterMetadataLookup.cs  | 24 ++++------------
 2 files changed, 5 insertions(+), 47 deletions(-)

diff --git a/osu.Game.Tests/Beatmaps/BeatmapUpdaterMetadataLookupTest.cs b/osu.Game.Tests/Beatmaps/BeatmapUpdaterMetadataLookupTest.cs
index 2e1bb3a1c6..82e54875ef 100644
--- a/osu.Game.Tests/Beatmaps/BeatmapUpdaterMetadataLookupTest.cs
+++ b/osu.Game.Tests/Beatmaps/BeatmapUpdaterMetadataLookupTest.cs
@@ -273,34 +273,6 @@ namespace osu.Game.Tests.Beatmaps
             Assert.That(beatmap.OnlineID, Is.EqualTo(654321));
         }
 
-        [Test]
-        public void TestMetadataLookupForBeatmapWithoutPopulatedIDAndIncorrectHash([Values] bool preferOnlineFetch)
-        {
-            var lookupResult = new OnlineBeatmapMetadata
-            {
-                BeatmapID = 654321,
-                BeatmapStatus = BeatmapOnlineStatus.Ranked,
-                MD5Hash = @"cafebabe",
-            };
-
-            var targetMock = preferOnlineFetch ? apiMetadataSourceMock : localCachedMetadataSourceMock;
-            targetMock.Setup(src => src.Available).Returns(true);
-            targetMock.Setup(src => src.TryLookup(It.IsAny<BeatmapInfo>(), out lookupResult))
-                      .Returns(true);
-
-            var beatmap = new BeatmapInfo
-            {
-                MD5Hash = @"deadbeef"
-            };
-            var beatmapSet = new BeatmapSetInfo(beatmap.Yield());
-            beatmap.BeatmapSet = beatmapSet;
-
-            metadataLookup.Update(beatmapSet, preferOnlineFetch);
-
-            Assert.That(beatmap.Status, Is.EqualTo(BeatmapOnlineStatus.None));
-            Assert.That(beatmap.OnlineID, Is.EqualTo(-1));
-        }
-
         [Test]
         public void TestReturnedMetadataHasDifferentHash([Values] bool preferOnlineFetch)
         {
diff --git a/osu.Game/Beatmaps/BeatmapUpdaterMetadataLookup.cs b/osu.Game/Beatmaps/BeatmapUpdaterMetadataLookup.cs
index 42d8e07432..dd17ee784b 100644
--- a/osu.Game/Beatmaps/BeatmapUpdaterMetadataLookup.cs
+++ b/osu.Game/Beatmaps/BeatmapUpdaterMetadataLookup.cs
@@ -5,7 +5,6 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
-using osu.Framework.Logging;
 using osu.Framework.Platform;
 using osu.Game.Online.API;
 
@@ -44,10 +43,14 @@ namespace osu.Game.Beatmaps
 
             foreach (var beatmapInfo in beatmapSet.Beatmaps)
             {
+                // note that it is KEY that the lookup here only uses MD5 inside
+                // (see implementations of underlying `IOnlineBeatmapMetadataSource`s).
+                // anything else like online ID or filename can be manipulated, thus being inherently unreliable,
+                // thus being unusable here for any purpose.
                 if (!tryLookup(beatmapInfo, preferOnlineFetch, out var res))
                     continue;
 
-                if (res == null || shouldDiscardLookupResult(res, beatmapInfo))
+                if (res == null)
                 {
                     beatmapInfo.ResetOnlineInfo();
                     lookupResults.Add(null); // mark lookup failure
@@ -83,23 +86,6 @@ namespace osu.Game.Beatmaps
             }
         }
 
-        private bool shouldDiscardLookupResult(OnlineBeatmapMetadata result, BeatmapInfo beatmapInfo)
-        {
-            // previously this used to check whether the `OnlineID` of the looked-up beatmap matches the local `OnlineID`.
-            // unfortunately it appears that historically stable mappers would apply crude hacks to fix unspecified "issues" with submission
-            // which would amount to reusing online IDs of other beatmaps.
-            // this means that the online ID in the `.osu` file is not reliable, and this cannot be fixed server-side
-            // because updating the maps retroactively would break stable (by losing all of users' local scores).
-
-            if (beatmapInfo.OnlineID == -1 && result.MD5Hash != beatmapInfo.MD5Hash)
-            {
-                Logger.Log($"Discarding metadata lookup result due to mismatching hash (expected: {beatmapInfo.MD5Hash} actual: {result.MD5Hash})", LoggingTarget.Database);
-                return true;
-            }
-
-            return false;
-        }
-
         /// <summary>
         /// Attempts to retrieve the <see cref="OnlineBeatmapMetadata"/> for the given <paramref name="beatmapInfo"/>.
         /// </summary>