[+] Random old version maimai BGM

AquaMai/AquaMai.csproj

@@ -35,6 +35,9 @@
     <Reference Include="Assembly-CSharp">
       <HintPath>Libs\Assembly-CSharp.dll</HintPath>
     </Reference>
+    <Reference Include="Assembly-CSharp-firstpass">
+      <HintPath>Libs\Assembly-CSharp-firstpass.dll</HintPath>
+    </Reference>
     <Reference Include="MelonLoader">
       <HintPath>Libs\MelonLoader.dll</HintPath>
     </Reference>
@@ -274,6 +277,7 @@
     <Compile Include="UX\LoadJacketPng.cs" />
     <Compile Include="UX\LoadAssetBundleWithoutManifest.cs" />
     <Compile Include="UX\QuickSkip.cs" />
+    <Compile Include="UX\RandomBgm.cs" />
     <Compile Include="UX\SinglePlayer.cs" />
     <Compile Include="UX\SkipEventInfo.cs" />
     <Compile Include="UX\SkipWarningScreen.cs" />

AquaMai/AquaMai.toml

@@ -24,6 +24,8 @@ QuickSkip=true
 LoadAssetBundleWithoutManifest=true
 # Skip "New Event" and "Information" text boxes for new users
 SkipEventInfo=true
+# Random BGM, put Mai2Cue.{acb,awb} of old version of the game in `LocalAssets\Mai2Cue` and rename them
+RandomBgm=false
 
 [Performance]
 # Disable some useless delays to speed up the game boot process

AquaMai/Config.cs

@@ -22,6 +22,7 @@ namespace AquaMai
             public bool LoadJacketPng { get; set; }
             public bool LoadAssetBundleWithoutManifest { get; set; }
             public bool QuickSkip { get; set; }
+            public bool RandomBgm { get; set; }
             public string CustomVersionString { get; set; }
         }
         

AquaMai/UX/RandomBgm.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using HarmonyLib;
+using Mai2.Mai2Cue;
+using MAI2.Util;
+using Manager;
+using MelonLoader;
+
+namespace AquaMai.UX
+{
+    public class RandomBgm
+    {
+        private static List<CriAtomExAcb> _acbs = new List<CriAtomExAcb>();
+        private static Random _rng = new Random();
+        private static CriAtomExAcb _originalAcb;
+
+        [HarmonyPostfix]
+        [HarmonyPatch(typeof(SoundManager), "Initialize")]
+        public static void Init()
+        {
+            var files = Directory.EnumerateFiles(Path.Combine(Environment.CurrentDirectory, "LocalAssets", "Mai2Cue"));
+            foreach (var file in files)
+            {
+                if (!file.EndsWith(".acb")) continue;
+                _acbs.Add(CriAtomExAcb.LoadAcbFile(null, file, Path.ChangeExtension(file, "awb")));
+            }
+
+            MelonLogger.Msg($"Random BGM loaded {_acbs.Count} files");
+        }
+
+        [HarmonyPostfix]
+        [HarmonyPatch(typeof(CriAtomExAcb), "LoadAcbFile")]
+        public static void PostLoadAcbFile(string acbPath, CriAtomExAcb __result)
+        {
+            if (acbPath.EndsWith("SoundData/Mai2Cue.acb"))
+                _originalAcb = __result;
+        }
+
+        [HarmonyPrefix]
+        [HarmonyPatch(typeof(CriAtomExPlayer), "SetCue")]
+        [HarmonyPatch(new[] { typeof(CriAtomExAcb), typeof(int) })]
+        public static void PreSetCue(ref CriAtomExAcb acb, int id)
+        {
+            if (acb != _originalAcb) return;
+            var cueIndex = (Cue)id;
+            switch (cueIndex)
+            {
+                case Cue.BGM_ENTRY:
+                case Cue.BGM_COLLECTION:
+                case Cue.BGM_RESULT_CLEAR:
+                case Cue.BGM_RESULT:
+                    acb = _acbs[_rng.Next(_acbs.Count)];
+                    MelonLogger.Msg($"Picked random BGM for {cueIndex}");
+                    return;
+                default:
+                    return;
+            }
+        }
+    }
+}