Added a method to get a user's chats

Author: amyyong11

src/main/java/data_access/UserDatabase.java

@@ -1,17 +1,19 @@
 package data_access;
 
+import entities.chat.Chat;
 import interface_adapters.User_search_IA.IRetrieveList;
 import interface_adapters.user_registration_interface_adapters.UserExists;
 import entities.user_entities.User;
 import interface_adapters.profile_modification_IA.UserModificationGateway;
 import use_cases.user_registration_use_cases.UserCreator;
 import entities.user_entities.UserFactory;
+import interface_adapters.Chat.UserChatGateway;
 import interface_adapters.User_search_IA.UserRetriever;
 
 import java.io.*;
 import java.util.ArrayList;
 import java.util.List;
-public class UserDatabase implements UserExists, UserRetriever, UserCreator, IRetrieveList, UserModificationGateway {
+public class UserDatabase implements UserExists, UserRetriever, UserCreator, IRetrieveList, UserModificationGateway, UserChatGateway {
     File accounts;
     List<User> accountList;
     public UserDatabase(){
@@ -125,6 +127,16 @@ public void modifyUser(String oldUsername, User modified){
         }
     }
 
+    @Override
+    public ArrayList<Chat> getUserChats(String username) {
+        for (User user: accountList){
+            if (getUser(username).equals(user)){
+                return user.getUserChats();
+            }
+        }
+        throw new RuntimeException("Invalid username");
+    }
+
     // Below two methods are used by conversation history-related interactors
     // (Commented as objects are not found)
 //    /**