refactored some code, started creating groups

src/Database/Handler.php

@@ -21,16 +21,26 @@ class Handler
     {
         $this->pdo = new PDO('sqlite:' . __DIR__ . '/../../storage/database.sqlite');
         $this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
-    }
-
-    public function init(): void
-    {
         $this->pdo->exec("
             CREATE TABLE IF NOT EXISTS users (
                 username VARCHAR(32) NOT NULL UNIQUE,
                 password CHAR(255) NOT NULL
             )
         ");
+        $this->pdo->exec("
+            CREATE TABLE IF NOT EXISTS chat_groups (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,                                                                                                                                                                   
+                name VARCHAR(64) NOT NULL UNIQUE
+            )
+        ");
+        $this->pdo->exec("
+            CREATE TABLE IF NOT EXISTS group_members (                                                                                                                                                                    
+                group_id INTEGER NOT NULL,
+                username VARCHAR(32) NOT NULL,                                                                                                                                                                          
+                PRIMARY KEY (group_id, username),                                                                                                                                                                         
+                FOREIGN KEY (username) REFERENCES users(username)                                                                                                                                                        
+            )    
+        ");
     }
 
     public function addUser(string $username, string $password): void