Delete group by owner, transfer ownership, leave group

src/main/java/org/to/telegramfinalproject/Client/ActionHandler.java

@@ -713,8 +713,11 @@ public class ActionHandler {
         }
         if (isOwner) {
             System.out.println("8. Delete Group");
-        }
+            System.out.println("9. Leave Group (Transfer ownership required)");
+        } else {
             System.out.println("9. Leave Group");
+        }
+
         System.out.println("0. Back to Chat List");
 
         String input = scanner.nextLine();
@@ -747,9 +750,16 @@ public class ActionHandler {
                 return false;
             }
             case "9" -> {
+                if (isOwner) {
+                    transferOwnershipAndLeave(chat.getId());
+                    refreshChatList();
+                } else {
                     leaveChat(chat.getId(), "group");
+                    refreshChatList();
+                }
                 return false;
             }
+
             case "0" -> {
                 return false;
             }
@@ -811,6 +821,57 @@ public class ActionHandler {
 
 
 
+    private void transferOwnershipAndLeave(UUID groupId) {
+        JSONObject req = new JSONObject();
+        req.put("action", "view_group_admins");
+        req.put("group_id", groupId.toString());
+
+        JSONObject res = sendWithResponse(req);
+        if (res == null || !res.getString("status").equals("success")) {
+            System.out.println("❌ Failed to fetch admins.");
+            return;
+        }
+
+        JSONArray admins = res.getJSONObject("data").getJSONArray("admins");
+
+        if (admins.length() == 0) {
+            System.out.println("⚠️ No other admins available. You cannot leave without promoting someone to owner.");
+            return;
+        }
+
+        System.out.println("--- Admins List ---");
+        for (int i = 0; i < admins.length(); i++) {
+            JSONObject admin = admins.getJSONObject(i);
+            System.out.printf("%d. %s (%s)\n", i + 1, admin.getString("profile_name"), admin.getString("user_id"));
+        }
+
+        System.out.print("Select a new owner by number: ");
+        int choice = Integer.parseInt(scanner.nextLine()) - 1;
+
+        if (choice < 0 || choice >= admins.length()) {
+            System.out.println("Invalid selection.");
+            return;
+        }
+
+        JSONObject selected = admins.getJSONObject(choice);
+        String newOwnerId = selected.getString("user_id");
+
+        JSONObject promoteReq = new JSONObject();
+        promoteReq.put("action", "transfer_group_ownership");
+        promoteReq.put("group_id", groupId.toString());
+        promoteReq.put("new_owner_user_id", newOwnerId);
+
+        JSONObject promoteRes = sendWithResponse(promoteReq);
+        if (promoteRes == null || !promoteRes.getString("status").equals("success")) {
+            System.out.println("❌ Failed to transfer ownership.");
+            return;
+        }
+
+        System.out.println("✅ Ownership transferred successfully.");
+        leaveChat(groupId, "group");
+    }
+
+
     private void removeMemberFromGroup(UUID groupId) {
         JSONObject req = new JSONObject();
         req.put("action", "view_group_members");
@@ -1046,13 +1107,17 @@ public class ActionHandler {
         JSONObject res = sendWithResponse(req);
         if (res == null) return;
 
-        if (res.getBoolean("success")) {
+        String status = res.getString("status");
+        String message = res.getString("message");
+
+        if (status.equals("success")) {
             System.out.println("✅ You left the chat.");
         } else {
-            System.out.println("❌ " + res.getString("message"));
+            System.out.println("❌ " + message);
         }
     }
 
+
     private void sendMessageTo(UUID id, String type) {
         System.out.print("Enter message: ");
         String text = scanner.nextLine().trim();
@@ -1120,8 +1185,8 @@ public class ActionHandler {
 
         String currentId = data.getString("id");
         String currentName = data.getString("name");
-        String currentDesc = data.optString("description", "None");
+        String currentDesc = data.optString("description", null);
-        String currentImage = data.optString("image_url", "None");
+        String currentImage = data.optString("image_url", null);
 
         System.out.println("\n--- Current Group Info ---");
         System.out.println("1. Group ID: " + currentId);

src/main/java/org/to/telegramfinalproject/Database/ChannelDatabase.java

@@ -435,5 +435,22 @@ public class ChannelDatabase {
     }
 
 
+    public static boolean removeSubscriberFromChannel(UUID channelId, UUID userId) {
+        String sql = "DELETE FROM channel_subscribers WHERE channel_id = ? AND user_id = ?";
+
+        try (Connection conn =ConnectionDb.connect();
+             PreparedStatement stmt = conn.prepareStatement(sql)) {
+
+            stmt.setObject(1, channelId);
+            stmt.setObject(2, userId);
+
+            int affectedRows = stmt.executeUpdate();
+            return affectedRows > 0;
+
+        } catch (SQLException e) {
+            System.err.println("Error removing subscriber from channel: " + e.getMessage());
+            return false;
+        }
+    }
 
 }

src/main/java/org/to/telegramfinalproject/Database/GroupDatabase.java

@@ -404,22 +404,32 @@ public class GroupDatabase {
 
 
     public static List<JSONObject> getGroupAdminsAndOwner(UUID groupId) {
-        String sql = "SELECT user_id, role, permissions FROM group_members WHERE group_id = ? AND role IN ('owner', 'admin')";
         List<JSONObject> admins = new ArrayList<>();
+
+        String sql = "SELECT gm.user_id, gm.role, gm.permissions, u.profile_name " +
+                "FROM group_members gm " +
+                "JOIN users u ON gm.user_id = u.internal_uuid " +
+                "WHERE gm.group_id = ? AND gm.role IN ('owner', 'admin')";
+
         try (Connection conn = ConnectionDb.connect();
              PreparedStatement stmt = conn.prepareStatement(sql)) {
+
             stmt.setObject(1, groupId);
             ResultSet rs = stmt.executeQuery();
+
             while (rs.next()) {
                 JSONObject obj = new JSONObject();
                 obj.put("user_id", rs.getObject("user_id").toString());
                 obj.put("role", rs.getString("role"));
                 obj.put("permissions", new JSONObject(rs.getString("permissions")));
+                obj.put("profile_name", rs.getString("profile_name"));
                 admins.add(obj);
             }
-        } catch (Exception e) {
+
+        } catch (SQLException e) {
             e.printStackTrace();
         }
+
         return admins;
     }
 
@@ -544,4 +554,50 @@ public class GroupDatabase {
     }
 
 
+    public static boolean transferOwnership(UUID groupId, UUID newOwnerId) {
+        String demoteOldOwner = "UPDATE group_members SET role = 'admin' WHERE group_id = ? AND role = 'owner'";
+        String promoteNewOwner = "UPDATE group_members SET role = 'owner' WHERE group_id = ? AND user_id = ?";
+
+        try (Connection conn = ConnectionDb.connect()) {
+            conn.setAutoCommit(false);
+
+            try (PreparedStatement demoteStmt = conn.prepareStatement(demoteOldOwner);
+                 PreparedStatement promoteStmt = conn.prepareStatement(promoteNewOwner)) {
+
+                demoteStmt.setObject(1, groupId);
+                demoteStmt.executeUpdate();
+
+                promoteStmt.setObject(1, groupId);
+                promoteStmt.setObject(2, newOwnerId);
+                promoteStmt.executeUpdate();
+
+                conn.commit();
+                return true;
+            } catch (SQLException e) {
+                conn.rollback();
+                e.printStackTrace();
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        return false;
+    }
+
+
+    public static boolean deleteGroup(UUID groupId) {
+        try (Connection conn = ConnectionDb.connect();
+             PreparedStatement stmt = conn.prepareStatement("DELETE FROM groups WHERE internal_uuid = ?")) {
+
+            stmt.setObject(1, groupId);
+            int affectedRows = stmt.executeUpdate();
+
+            return affectedRows > 0;
+
+        } catch (SQLException e) {
+            e.printStackTrace();
+            return false;
+        }
+    }
+
+
 }

src/main/java/org/to/telegramfinalproject/Server/ClientHandler.java

@@ -912,6 +912,36 @@ public class ClientHandler implements Runnable {
 
 
 
+                    case "transfer_group_ownership": {
+                        UUID groupId = UUID.fromString(requestJson.getString("group_id"));
+                        UUID newOwnerUserId = UUID.fromString(requestJson.getString("new_owner_user_id"));
+
+                        User newOwner = userDatabase.findByInternalUUID(newOwnerUserId);
+                        if (newOwner == null) {
+                            response = new ResponseModel("error", "New owner not found.");
+                            break;
+                        }
+
+                        if (!GroupDatabase.isOwner(groupId, currentUser.getInternal_uuid())) {
+                            response = new ResponseModel("error", "Only current owner can transfer ownership.");
+                            break;
+                        }
+
+                        if (!GroupDatabase.isAdmin(groupId, newOwner.getInternal_uuid())) {
+                            response = new ResponseModel("error", "Selected user is not an admin.");
+                            break;
+                        }
+
+                        boolean success = GroupDatabase.transferOwnership(groupId, newOwner.getInternal_uuid());
+
+                        response = success
+                                ? new ResponseModel("success", "Ownership transferred.")
+                                : new ResponseModel("error", "Failed to transfer ownership.");
+
+                        break;
+                    }
+
+
                     case "view_group_members" : {
                         UUID groupId = UUID.fromString(requestJson.getString("group_id"));
 
@@ -948,7 +978,47 @@ public class ClientHandler implements Runnable {
                     }
 
 
+                    case "leave_chat": {
+                        String chatType = requestJson.getString("chat_type");
+                        UUID chatId = UUID.fromString(requestJson.getString("chat_id"));
+                         userId = UUID.fromString(requestJson.getString("user_id"));
 
+                        boolean success = false;
+
+                        switch (chatType) {
+                            case "group" -> success = GroupDatabase.removeMemberFromGroup(chatId, userId);
+                            case "channel" -> success = ChannelDatabase.removeSubscriberFromChannel(chatId, userId);
+                            default -> {
+                                response = new ResponseModel("error", "Unsupported chat type.");
+                                break;
+                            }
+                        }
+
+                        if (response == null) {
+                            response = success
+                                    ? new ResponseModel("success", "Left the " + chatType + " successfully.")
+                                    : new ResponseModel("error", "Failed to leave the " + chatType + ".");
+                        }
+
+                        break;
+                    }
+
+
+                    case "delete_group": {
+                        UUID groupId = UUID.fromString(requestJson.getString("group_id"));
+
+                        if (!GroupDatabase.isOwner(groupId, currentUser.getInternal_uuid())) {
+                            response = new ResponseModel("error", "Only the group owner can delete the group.");
+                            break;
+                        }
+
+                        boolean success = GroupDatabase.deleteGroup(groupId);
+
+                        response = success
+                                ? new ResponseModel("success", "Group deleted successfully.")
+                                : new ResponseModel("error", "Failed to delete group.");
+                        break;
+                    }