UserManager.java

package Q7_07_Chat_Server;

import java.util.Date;
import java.util.HashMap;

/* UserManager serves as the central place for the core user actions. */
public class UserManager {
	private static UserManager instance;
	private HashMap<Integer, User> usersById = new HashMap<Integer, User>();
	private HashMap<String, User> usersByAccountName = new HashMap<String, User>();
	private HashMap<Integer, User> onlineUsers = new HashMap<Integer, User>();
	
	public static UserManager getInstance() {
		if (instance == null) {
			instance = new UserManager();
		}
		return instance;
	}
	
	public void addUser(User fromUser, String toAccountName) {
		User toUser = usersByAccountName.get(toAccountName);
		AddRequest req = new AddRequest(fromUser, toUser, new Date());
		toUser.receivedAddRequest(req);
		fromUser.sentAddRequest(req);
	}
	
	public void approveAddRequest(AddRequest req) {
		req.status = RequestStatus.Accepted;
		User from = req.getFromUser();
		User to = req.getToUser();
		from.addContact(to);
		to.addContact(from);
	}
	
	public void rejectAddRequest(AddRequest req) {
		req.status = RequestStatus.Rejected;
		User from = req.getFromUser();
		User to = req.getToUser();
		from.removeAddRequest(req);
		to.removeAddRequest(req);		
	}
	
	public void userSignedOn(String accountName) {
		User user = usersByAccountName.get(accountName);
		if (user != null) {
			user.setStatus(new UserStatus(UserStatusType.Available, ""));			
			onlineUsers.put(user.getId(), user);
		}
	}
	
	public void userSignedOff(String accountName) {
		User user = usersByAccountName.get(accountName);
		if (user != null) {
			user.setStatus(new UserStatus(UserStatusType.Offline, ""));
			onlineUsers.remove(user.getId());
		}
	}	
}