Add reading users' groups from user data database

sources/Users/User.uc

@@ -40,7 +40,8 @@ var private JSONPointer persistentSettingsPointer;
 //      Group names are stored in the lower register.
 var private array<Text> userGroups; // user groups loaded from database
 var private array<Text> localUserGroups; // user groups loaded from local files
-var private LoggerAPI.Definition errNoUserDataDatabase;
+var private LoggerAPI.Definition errNoUserDataDatabase, errCannotReadDB;
+var private LoggerAPI.Definition errInvalidUserGroups;
 
 protected function Finalizer()
 {
@@ -64,12 +65,17 @@ protected function Finalizer()
  */
 public final function Initialize(UserID initID, int initKey)
 {
+    local DBReadTask groupsReadingTask;
     id  = initID;
     key = initKey;
     if (initID != none) {
         initID.NewRef();
     }
     LoadLocalGroups();
+    groupsReadingTask = ReadPersistentData(P("Acedia"), P("UserGroups"));
+    if (groupsReadingTask != none) {
+        groupsReadingTask.connect = LoadDBGroups;
+    }
 }
 
 /**
@@ -130,6 +136,59 @@ private final function LoadLocalGroups()
     _.memory.FreeMany(availableGroups);
 }
 
+//  Loads groups defined in database with user data
+private final function LoadDBGroups(
+    Database.DBQueryResult  result,
+    AcediaObject            data,
+    Database                source)
+{
+    local int           i;
+    local MutableText   nextGroup;
+    local ArrayList     dbGroups;
+
+    if (result != DBR_Success)
+    {
+        _.logger.Auto(errCannotReadDB);
+        return;
+    }
+    _.memory.FreeMany(userGroups);
+    userGroups.length = 0;
+    dbGroups = ArrayList(data);
+    if (dbGroups == none)
+    {
+        if (data != none)
+        {
+            _.logger.Auto(errInvalidUserGroups);
+            _.memory.Free(data);
+        }
+        return;
+    }
+    for (i = 0; i < dbGroups.GetLength(); i += 1)
+    {
+        nextGroup = dbGroups.GetMutableText(i);
+        if (nextGroup == none) {
+            continue;
+        }
+        if (!class'UserGroup'.static.Exists(nextGroup))
+        {
+            nextGroup.FreeSelf();
+            continue;
+        }
+        userGroups[userGroups.length] = nextGroup.IntoText();
+    }
+    dbGroups.FreeSelf();
+}
+
+//  Save current user groups into the user data database
+private final function UpdateDBGroups()
+{
+    local ArrayList newDBData;
+
+    newDBData = _.collections.NewArrayList(userGroups);
+    WritePersistentData(P("Acedia"), P("UserGroups"), newDBData);
+    newDBData.FreeSelf();
+}
+
 /**
  *  Adds caller user into new group, specified by `newGroup`.
  *  This group must exist for the method to succeed.
@@ -150,6 +209,7 @@ public final function AddGroup(Text newGroup)
         }
     }
     userGroups[userGroups.length] = newGroup.LowerCopy();
+    UpdateDBGroups();
 }
 
 /**
@@ -172,6 +232,7 @@ public final function bool RemoveGroup(Text groupToRemove)
         {
             userGroups[i].FreeSelf();
             userGroups.Remove(i, 1);
+            UpdateDBGroups();
             return true;
         }
     }
@@ -390,5 +451,7 @@ private function bool SetupDatabaseVariables()
 
 defaultproperties
 {
+    errCannotReadDB         = (l=LOG_Error,m="Failed to read user groups from persistent user database.")
+    errInvalidUserGroups    = (l=LOG_Error,m="Invalid data is written as user groups array inside persistent user database.")
     errNoUserDataDatabase   = (l=LOG_Error,m="Failed to load persistent user database instance given by link \"%1\".")
 }