'use strict';

var async = require('async'),
	db = require('../database'),
	privileges = require('../privileges');


module.exports = function(Topics) {

	Topics.getPopular = function(term, uid, count, callback) {
		count = parseInt(count, 10) || 20;

		if (term === 'alltime') {
			return getAllTimePopular(uid, count, callback);
		}

		async.waterfall([
			function(next) {
				Topics.getLatestTidsFromSet('topics:tid', 0, -1, term, next);
			},
			function(tids, next) {
				getTopics(tids, uid, count, next);
			}
		], callback);
	};

	function getAllTimePopular(uid, count, callback) {
		Topics.getTopicsFromSet('topics:posts', uid, 0, count - 1, function(err, data) {
			callback(err, data ? data.topics : null);
		});
	}

	function getTopics(tids, uid, count, callback) {
		async.waterfall([
			function(next) {
				Topics.getTopicsFields(tids, ['tid', 'postcount', 'deleted'], next);
			},
			function(topics, next) {
				tids = topics.filter(function(topic) {
					return topic && parseInt(topic.deleted, 10) !== 1;
				}).sort(function(a, b) {
					return b.postcount - a.postcount;
				}).slice(0, count).map(function(topic) {
					return topic.tid;
				});
				privileges.topics.filter('read', tids, uid, next);
			},
			function(tids, next) {
				Topics.getTopicsByTids(tids, uid, next);
			}
		], callback);
	}
};