package com.commafeed.backend.services;

import java.util.Collection;
import java.util.Date;
import java.util.UUID;

import javax.ejb.Stateless;
import javax.inject.Inject;

import org.apache.commons.codec.digest.DigestUtils;
import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.time.DateUtils;

import com.commafeed.backend.dao.FeedCategoryDAO;
import com.commafeed.backend.dao.FeedEntryStatusDAO;
import com.commafeed.backend.dao.UserDAO;
import com.commafeed.backend.dao.UserSettingsDAO;
import com.commafeed.backend.model.User;
import com.commafeed.backend.model.UserRole;
import com.commafeed.backend.model.UserRole.Role;
import com.google.common.base.Preconditions;

@Stateless
public class UserService {

	@Inject
	UserDAO userDAO;

	@Inject
	FeedEntryStatusDAO feedEntryStatusDAO;

	@Inject
	FeedCategoryDAO feedCategoryDAO;

	@Inject
	UserSettingsDAO userSettingsDAO;

	@Inject
	PasswordEncryptionService encryptionService;

	@Inject
	ApplicationSettingsService applicationSettingsService;

	@Inject
	FeedSubscriptionService feedSubscriptionService;

	public User login(String name, String password) {
		if (name == null || password == null) {
			return null;
		}

		User user = userDAO.findByName(name);
		if (user != null && !user.isDisabled()) {
			boolean authenticated = encryptionService.authenticate(password, user.getPassword(), user.getSalt());
			if (authenticated) {
				Date lastLogin = user.getLastLogin();
				Date now = new Date();

				boolean saveUser = false;
				// only update lastLogin field every hour in order to not
				// invalidate the cache everytime someone logs in
				if (lastLogin == null || lastLogin.before(DateUtils.addHours(now, -1))) {
					user.setLastLogin(now);
					saveUser = true;
				}
				if (applicationSettingsService.get().isHeavyLoad()
						&& (user.getLastFullRefresh() == null || user.getLastFullRefresh().before(DateUtils.addMinutes(now, -30)))) {
					user.setLastFullRefresh(now);
					saveUser = true;
					feedSubscriptionService.refreshAll(user);
				}
				if (saveUser) {
					userDAO.saveOrUpdate(user);
				}
				return user;
			}
		}
		return null;
	}

	public User register(String name, String password, String email, Collection<Role> roles) {
		return register(name, password, email, roles, false);
	}

	public User register(String name, String password, String email, Collection<Role> roles, boolean forceRegistration) {

		Preconditions.checkNotNull(name);
		Preconditions.checkArgument(StringUtils.length(name) <= 32, "Name too long (32 characters maximum)");
		Preconditions.checkNotNull(password);

		if (!forceRegistration) {
			Preconditions.checkState(applicationSettingsService.get().isAllowRegistrations(),
					"Registrations are closed on this CommaFeed instance");

			Preconditions.checkNotNull(email);
			Preconditions.checkArgument(StringUtils.length(name) >= 3, "Name too short (3 characters minimum)");
			Preconditions
					.checkArgument(forceRegistration || StringUtils.length(password) >= 6, "Password too short (6 characters maximum)");
			Preconditions.checkArgument(StringUtils.contains(email, "@"), "Invalid email address");
		}

		Preconditions.checkArgument(userDAO.findByName(name) == null, "Name already taken");
		if (StringUtils.isNotBlank(email)) {
			Preconditions.checkArgument(userDAO.findByEmail(email) == null, "Email already taken");
		}

		User user = new User();
		byte[] salt = encryptionService.generateSalt();
		user.setName(name);
		user.setEmail(email);
		user.setCreated(new Date());
		user.setSalt(salt);
		user.setPassword(encryptionService.getEncryptedPassword(password, salt));
		for (Role role : roles) {
			user.getRoles().add(new UserRole(user, role));
		}
		userDAO.saveOrUpdate(user);
		return user;
	}

	public void unregister(User user) {
		feedCategoryDAO.delete(feedCategoryDAO.findAll(user));
		userSettingsDAO.delete(userSettingsDAO.findByUser(user));
		userDAO.delete(user);
	}

	public String generateApiKey(User user) {
		byte[] key = encryptionService.getEncryptedPassword(UUID.randomUUID().toString(), user.getSalt());
		return DigestUtils.sha1Hex(key);
	}
}