package com.example.fp;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.List;

import com.example.fp.dao.UserDAO;

public class UserManagerImpl implements UserManager {

	private UserDAO userDAO;

	public void setUserDAO(UserDAO userDAO) {
		this.userDAO = userDAO;
	}

	@Override
	public void create(User user) {
		user.setPassword(calculatePasswordHash(user.getPassword()));
		userDAO.create(user);
	}

	@Override
	public User find(int uid) {
		return userDAO.find(uid);
	}

	@Override
	public List<User> findAll() {
		return userDAO.findAll();
	}

	@Override
	public void delete(int uid) {
		userDAO.delete(uid);
	}

	@Override
	public void update(User user) {
		userDAO.update(user);
	}

	@Override
	public void setPassword(int uid, String plainTextPassword) {
		User user = userDAO.find(uid);

		user.setPassword(calculatePasswordHash(plainTextPassword));

		userDAO.update(user);
	}

	public static String calculatePasswordHash(String plainText) {

		try {
			// Static getInstance method is called with hashing MD5
			MessageDigest md = MessageDigest.getInstance("MD5");

			// digest() method is called to calculate message digest
			// of an input digest() return array of byte
			byte[] messageDigest = md.digest(plainText.getBytes());

			// Convert byte array into signum representation
			BigInteger no = new BigInteger(1, messageDigest);

			// Convert message digest into hex value
			String hashtext = no.toString(16);
			while (hashtext.length() < 32) {
				hashtext = "0" + hashtext;
			}
			
			return hashtext;
		} catch (NoSuchAlgorithmException e) {
			// For specifying wrong message digest algorithms
			throw new RuntimeException(e);
		}
	}
}