'use strict';

const db = require('../database');
const notifications = require('../notifications');
const privileges = require('../privileges');
const plugins = require('../plugins');
const utils = require('../utils');

module.exports = function (Topics) {
	Topics.toggleFollow = async function (tid, uid) {
		const exists = await Topics.exists(tid);
		if (!exists) {
			throw new Error('[[error:no-topic]]');
		}
		const isFollowing = await Topics.isFollowing([tid], uid);
		if (isFollowing[0]) {
			await Topics.unfollow(tid, uid);
		} else {
			await Topics.follow(tid, uid);
		}
		return !isFollowing[0];
	};

	Topics.follow = async function (tid, uid) {
		await setWatching(follow, unignore, 'action:topic.follow', tid, uid);
	};

	Topics.unfollow = async function (tid, uid) {
		await setWatching(unfollow, unignore, 'action:topic.unfollow', tid, uid);
	};

	Topics.ignore = async function (tid, uid) {
		await setWatching(ignore, unfollow, 'action:topic.ignore', tid, uid);
	};

	async function setWatching(method1, method2, hook, tid, uid) {
		if (parseInt(uid, 10) <= 0) {
			return;
		}
		const exists = await Topics.exists(tid);
		if (!exists) {
			throw new Error('[[error:no-topic]]');
		}
		await method1(tid, uid);
		await method2(tid, uid);
		plugins.hooks.fire(hook, { uid: uid, tid: tid });
	}

	async function follow(tid, uid) {
		await addToSets(`tid:${tid}:followers`, `uid:${uid}:followed_tids`, tid, uid);
	}

	async function unfollow(tid, uid) {
		await removeFromSets(`tid:${tid}:followers`, `uid:${uid}:followed_tids`, tid, uid);
	}

	async function ignore(tid, uid) {
		await addToSets(`tid:${tid}:ignorers`, `uid:${uid}:ignored_tids`, tid, uid);
	}

	async function unignore(tid, uid) {
		await removeFromSets(`tid:${tid}:ignorers`, `uid:${uid}:ignored_tids`, tid, uid);
	}

	async function addToSets(set1, set2, tid, uid) {
		await db.setAdd(set1, uid);
		await db.sortedSetAdd(set2, Date.now(), tid);
	}

	async function removeFromSets(set1, set2, tid, uid) {
		await db.setRemove(set1, uid);
		await db.sortedSetRemove(set2, tid);
	}

	Topics.isFollowing = async function (tids, uid) {
		return await isIgnoringOrFollowing('followers', tids, uid);
	};

	Topics.isIgnoring = async function (tids, uid) {
		return await isIgnoringOrFollowing('ignorers', tids, uid);
	};

	Topics.getFollowData = async function (tids, uid) {
		if (!Array.isArray(tids)) {
			return;
		}
		if (parseInt(uid, 10) <= 0) {
			return tids.map(() => ({ following: false, ignoring: false }));
		}
		const keys = [];
		tids.forEach(tid => keys.push(`tid:${tid}:followers`, `tid:${tid}:ignorers`));

		const data = await db.isMemberOfSets(keys, uid);

		const followData = [];
		for (let i = 0; i < data.length; i += 2) {
			followData.push({
				following: data[i],
				ignoring: data[i + 1],
			});
		}
		return followData;
	};

	async function isIgnoringOrFollowing(set, tids, uid) {
		if (!Array.isArray(tids)) {
			return;
		}
		if (parseInt(uid, 10) <= 0) {
			return tids.map(() => false);
		}
		const keys = tids.map(tid => `tid:${tid}:${set}`);
		return await db.isMemberOfSets(keys, uid);
	}

	Topics.getFollowers = async function (tid) {
		return await db.getSetMembers(`tid:${tid}:followers`);
	};

	Topics.getIgnorers = async function (tid) {
		return await db.getSetMembers(`tid:${tid}:ignorers`);
	};

	Topics.filterIgnoringUids = async function (tid, uids) {
		const isIgnoring = await db.isSetMembers(`tid:${tid}:ignorers`, uids);
		const readingUids = uids.filter((uid, index) => uid && !isIgnoring[index]);
		return readingUids;
	};

	Topics.filterWatchedTids = async function (tids, uid) {
		if (parseInt(uid, 10) <= 0) {
			return [];
		}
		const scores = await db.sortedSetScores(`uid:${uid}:followed_tids`, tids);
		return tids.filter((tid, index) => tid && !!scores[index]);
	};

	Topics.filterNotIgnoredTids = async function (tids, uid) {
		if (parseInt(uid, 10) <= 0) {
			return tids;
		}
		const scores = await db.sortedSetScores(`uid:${uid}:ignored_tids`, tids);
		return tids.filter((tid, index) => tid && !scores[index]);
	};

	Topics.notifyFollowers = async function (postData, exceptUid, notifData) {
		notifData = notifData || {};
		let followers = await Topics.getFollowers(postData.topic.tid);
		const index = followers.indexOf(String(exceptUid));
		if (index !== -1) {
			followers.splice(index, 1);
		}

		followers = await privileges.topics.filterUids('topics:read', postData.topic.tid, followers);
		if (!followers.length) {
			return;
		}

		let { title } = postData.topic;
		if (title) {
			title = utils.decodeHTMLEntities(title);
		}

		const notification = await notifications.create({
			subject: title,
			bodyLong: postData.content,
			pid: postData.pid,
			path: `/post/${postData.pid}`,
			tid: postData.topic.tid,
			from: exceptUid,
			topicTitle: title,
			...notifData,
		});
		notifications.push(notification, followers);
	};
};