From 8cdae790c3b0fc90996ae473ffe998206f9af51a Mon Sep 17 00:00:00 2001
From: Lucas A <game4allyt@gmail.com>
Date: Fri, 3 Apr 2020 17:32:37 +0200
Subject: [PATCH] Load user rulesets from the game data directory

---
 osu.Game/OsuGameBase.cs           |  2 +-
 osu.Game/Rulesets/RulesetStore.cs | 40 +++++++++++++++++++++++++++----
 2 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/osu.Game/OsuGameBase.cs b/osu.Game/OsuGameBase.cs
index 5487bd9320..609b6ce98e 100644
--- a/osu.Game/OsuGameBase.cs
+++ b/osu.Game/OsuGameBase.cs
@@ -168,7 +168,7 @@ private void load()
 
             var defaultBeatmap = new DummyWorkingBeatmap(Audio, Textures);
 
-            dependencies.Cache(RulesetStore = new RulesetStore(contextFactory));
+            dependencies.Cache(RulesetStore = new RulesetStore(contextFactory, Storage));
             dependencies.Cache(FileStore = new FileStore(contextFactory, Storage));
 
             // ordering is important here to ensure foreign keys rules are not broken in ModelStore.Cleanup()
diff --git a/osu.Game/Rulesets/RulesetStore.cs b/osu.Game/Rulesets/RulesetStore.cs
index a389d4ff75..c3c7b653da 100644
--- a/osu.Game/Rulesets/RulesetStore.cs
+++ b/osu.Game/Rulesets/RulesetStore.cs
@@ -7,6 +7,7 @@
 using System.Linq;
 using System.Reflection;
 using osu.Framework.Logging;
+using osu.Framework.Platform;
 using osu.Game.Database;
 
 namespace osu.Game.Rulesets
@@ -17,16 +18,20 @@ public class RulesetStore : DatabaseBackedStore, IDisposable
 
         private readonly Dictionary<Assembly, Type> loadedAssemblies = new Dictionary<Assembly, Type>();
 
-        public RulesetStore(IDatabaseContextFactory factory)
+        private readonly Storage rulesetStorage;
+
+        public RulesetStore(IDatabaseContextFactory factory, Storage storage = null)
             : base(factory)
         {
+            rulesetStorage = storage?.GetStorageForDirectory("rulesets");
+            AppDomain.CurrentDomain.AssemblyResolve += resolveRulesetDependencyAssembly;
+
             // On android in release configuration assemblies are loaded from the apk directly into memory.
             // We cannot read assemblies from cwd, so should check loaded assemblies instead.
             loadFromAppDomain();
             loadFromDisk();
+            loadUserRulesets();
             addMissingRulesets();
-
-            AppDomain.CurrentDomain.AssemblyResolve += resolveRulesetAssembly;
         }
 
         /// <summary>
@@ -48,7 +53,17 @@ public RulesetStore(IDatabaseContextFactory factory)
         /// </summary>
         public IEnumerable<RulesetInfo> AvailableRulesets { get; private set; }
 
-        private Assembly resolveRulesetAssembly(object sender, ResolveEventArgs args) => loadedAssemblies.Keys.FirstOrDefault(a => a.FullName == args.Name);
+        private Assembly resolveRulesetDependencyAssembly(object sender, ResolveEventArgs args)
+        {
+            var asm = new AssemblyName(args.Name);
+
+            // this assumes the only explicit dependency of the ruleset is the game core assembly.
+            // the ruleset dependency on the game core assembly requires manual resolving, transient dependencies should be resolved automatically
+            if (asm.Name.Equals(typeof(OsuGame).Assembly.GetName().Name, StringComparison.Ordinal))
+                return Assembly.GetExecutingAssembly();
+
+            return null;
+        }
 
         private void addMissingRulesets()
         {
@@ -120,6 +135,21 @@ private void loadFromAppDomain()
             }
         }
 
+        private void loadUserRulesets()
+        {
+            try
+            {
+                var rulesets = rulesetStorage?.GetFiles(".", $"{ruleset_library_prefix}.*.dll");
+
+                foreach (var ruleset in rulesets.Where(f => !f.Contains("Tests")))
+                    loadRulesetFromFile(rulesetStorage?.GetFullPath(ruleset));
+            }
+            catch (Exception e)
+            {
+                Logger.Error(e, "Couldn't load user rulesets");
+            }
+        }
+
         private void loadFromDisk()
         {
             try
@@ -175,7 +205,7 @@ public void Dispose()
 
         protected virtual void Dispose(bool disposing)
         {
-            AppDomain.CurrentDomain.AssemblyResolve -= resolveRulesetAssembly;
+            AppDomain.CurrentDomain.AssemblyResolve -= resolveRulesetDependencyAssembly;
         }
     }
 }