code refactor

server/db/db.js

@@ -89,7 +89,7 @@ async function createTables() {
         conversation_id INT NOT NULL REFERENCES Conversations(conversation_id) ON DELETE CASCADE,
         user_id INT REFERENCES Accounts(user_id) ON DELETE CASCADE,
         joined_at TIMESTAMPTZ DEFAULT NOW(),
-        PRIMARY KEY (conversation_id, user_id)
+        PRIMARY KEY (conversation_id, user_id) -- This composite primary key ensures uniqueness, but make sure that these fields are frequently queried together to avoid unnecessary performance overhead.
       );
       CREATE INDEX IF NOT EXISTS idx_memberships_conversation_id ON Memberships (conversation_id);
       CREATE INDEX IF NOT EXISTS idx_memberships_user_id ON Memberships (user_id);
@@ -100,6 +100,7 @@ async function createTables() {
   }
 
   try {
+    // Create Contacts Table
     await client.query(`
       CREATE TABLE IF NOT EXISTS Contacts (
         contact_id SERIAL PRIMARY KEY,
@@ -113,10 +114,35 @@ async function createTables() {
       CREATE INDEX IF NOT EXISTS idx_contacts_conversation_id ON Contacts (conversation_id);
       CREATE INDEX IF NOT EXISTS idx_contacts_contact_id ON Contacts (contact_id);
     `);
-    console.log("Contacts table created successfully.");
   } catch (e) {
     console.error("Failed to create Contacts table: ", e);
   }
+
+  try {
+    // Create GroupAdmins Table
+    await client.query(`
+      CREATE TABLE IF NOT EXISTS GroupAdmins (
+        conversation_id INT NOT NULL REFERENCES Conversations(conversation_id) ON DELETE CASCADE,
+        user_id INT NOT NULL REFERENCES Accounts(user_id) ON DELETE CASCADE,
+        granted_by INT NOT NULL REFERENCES Accounts(user_id) ON DELETE CASCADE,
+        granted_at TIMESTAMPTZ DEFAULT NOW(),
+        PRIMARY KEY (conversation_id, user_id),
+        CONSTRAINT group_conversation_only CHECK (conversation_type = 'group'),
+        CONSTRAINT admin_grants_admin CHECK (
+          granted_by = user_id OR 
+          EXISTS (
+            SELECT 1 FROM GroupAdmins ga 
+            WHERE ga.conversation_id = GroupAdmins.conversation_id 
+            AND ga.user_id = GroupAdmins.granted_by
+          )
+        )
+      );
+      CREATE INDEX IF NOT EXISTS idx_group_admins_conversation_id ON GroupAdmins (conversation_id);
+      CREATE INDEX IF NOT EXISTS idx_group_admins_user_id ON GroupAdmins (user_id);
+    `);
+  } catch (e) {
+    console.error("Failed to create GroupAdmins table: ", e);
+  }
 }
 
 async function insertUser(username, passwordHash) {