feat(SortByInternal): store selection in the fs

SortByInternalDifficulty/MU3.User/patch_UserDetail.cs

@@ -1,5 +1,9 @@
 using MU3.Client;
 using MU3.DB;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
 
 namespace MU3.User;
 class patch_UserDetail: UserDetail {
@@ -9,12 +13,62 @@ class patch_UserDetail: UserDetail {
 
         // Attempting to use a profile with InternalLevel sorting enabled
         // causes unpatched clients to crash thanks to enormous incompetence
-        // of Sxga's interns. So, unfortunately, this value has to be discarded.
+        // of Sxga's interns.
         // See:
         // * MusicSelectViewDataList._sort1 set
         // * UserDetail.copyFrom()
         if(userDetail.tabSetting == (int)patch_MusicSort1ID.InternalLevel) {
             userDetail.tabSetting = (int)patch_MusicSort1ID.Level;
+            stashTabSelection(userDetail.userName, true);
+        } else {
+            stashTabSelection(userDetail.userName, false);
         }
     }
+
+    public extern void orig_copyFrom(UserData userDetail);
+    public new void copyFrom(UserData userDetail) {
+        orig_copyFrom(userDetail);
+
+        if(userDetail.tabSetting == (int)patch_MusicSort1ID.Level && isStashedTabSelection(userDetail.userName)) {
+            MusicSort1 = (MusicSort1ID)patch_MusicSort1ID.InternalLevel;
+        }
+    }
+
+    private void stashTabSelection(string user, bool value) {
+        var path = getStashPath();
+        List<string> entries;
+        try {
+            entries = File.ReadAllText(path).Split('\n').ToList();
+            entries = entries.Where((val) => val.Length > 0 && val != user).ToList();
+        } catch(Exception) {
+            entries = [];
+        }
+
+        if(value) {
+            entries.Add(user);
+        }
+
+        try {
+            File.WriteAllText(path, entries.Aggregate("", (acc, s) => acc + s + "\n").Trim());
+        } catch(Exception e) {
+            UnityEngine.Debug.Log("Unable to write tab selection: " + e.ToString());
+        }
+    }
+
+    private bool isStashedTabSelection(string user) {
+        try {
+            var entries = File.ReadAllText(getStashPath()).Split('\n').ToList();
+            return entries.Contains(user);
+        } catch(Exception) {
+            // Whatever, this is not mission critical
+            return false;
+        }
+    }
+
+    private string getStashPath() {
+        using IniFile iniFile = new("mu3.ini");
+        var dir = iniFile.getValue("Extra", "CacheDir", ".");
+        Directory.CreateDirectory(dir);
+        return Path.Combine(dir, "data_tab_cache.txt");
+    }
 }