package com.commafeed.backend.services;

import java.util.List;
import java.util.Map;

import javax.ejb.ApplicationException;
import javax.inject.Inject;

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.commafeed.backend.cache.CacheService;
import com.commafeed.backend.dao.FeedEntryDAO;
import com.commafeed.backend.dao.FeedEntryStatusDAO;
import com.commafeed.backend.dao.FeedSubscriptionDAO;
import com.commafeed.backend.feeds.FeedRefreshTaskGiver;
import com.commafeed.backend.feeds.FeedUtils;
import com.commafeed.backend.model.Feed;
import com.commafeed.backend.model.FeedCategory;
import com.commafeed.backend.model.FeedEntry;
import com.commafeed.backend.model.FeedEntryStatus;
import com.commafeed.backend.model.FeedSubscription;
import com.commafeed.backend.model.Models;
import com.commafeed.backend.model.User;
import com.google.api.client.util.Lists;

public class FeedSubscriptionService {

	private static Logger log = LoggerFactory
			.getLogger(FeedSubscriptionService.class);

	@SuppressWarnings("serial")
	@ApplicationException
	public static class FeedSubscriptionException extends RuntimeException {
		public FeedSubscriptionException(String msg) {
			super(msg);
		}
	}

	@Inject
	FeedService feedService;

	@Inject
	FeedEntryDAO feedEntryDAO;

	@Inject
	FeedEntryStatusDAO feedEntryStatusDAO;

	@Inject
	FeedSubscriptionDAO feedSubscriptionDAO;

	@Inject
	ApplicationSettingsService applicationSettingsService;

	@Inject
	FeedRefreshTaskGiver taskGiver;

	@Inject
	CacheService cache;

	public Feed subscribe(User user, String url, String title,
			FeedCategory category) {

		final String pubUrl = applicationSettingsService.get().getPublicUrl();
		if (StringUtils.isBlank(pubUrl)) {
			throw new FeedSubscriptionException(
					"Public URL of this CommaFeed instance is not set");
		}
		if (url.startsWith(pubUrl)) {
			throw new FeedSubscriptionException(
					"Could not subscribe to a feed from this CommaFeed instance");
		}

		Feed feed = feedService.findOrCreate(url);

		FeedSubscription sub = feedSubscriptionDAO.findByFeed(user, feed);
		boolean newSubscription = false;
		if (sub == null) {
			sub = new FeedSubscription();
			sub.setFeed(feed);
			sub.setUser(user);
			newSubscription = true;
		}
		sub.setCategory(category);
		sub.setPosition(0);
		sub.setTitle(FeedUtils.truncate(title, 128));
		feedSubscriptionDAO.saveOrUpdate(sub);

		if (newSubscription) {
			try {
				List<FeedEntryStatus> statuses = Lists.newArrayList();
				List<FeedEntry> allEntries = feedEntryDAO.findByFeed(feed, 0,
						10);
				for (FeedEntry entry : allEntries) {
					FeedEntryStatus status = new FeedEntryStatus();
					status.setEntry(entry);
					status.setRead(false);
					status.setSubscription(sub);
					statuses.add(status);
				}
				feedEntryStatusDAO.saveOrUpdate(statuses);
			} catch (Exception e) {
				log.error(
						"could not fetch initial statuses when importing {} : {}",
						feed.getUrl(), e.getMessage());
			}
		}
		taskGiver.add(feed);
		return feed;
	}

	public Map<Long, Long> getUnreadCount(User user) {
		Map<Long, Long> map = cache.getUnreadCounts(user);
		if (map == null) {
			log.debug("unread count cache miss for {}", Models.getId(user));
			map = feedEntryStatusDAO.getUnreadCount(user);
			cache.setUnreadCounts(user, map);
		}
		return map;
	}
}