NodeBB/NodeBB

'use strict';

const plugins = require('../plugins');
const posts = require('../posts');

module.exports = function (Topics) {
    Topics.merge = async function (tids, uid, options) {
        options = options || {};

        const topicsData = await Topics.getTopicsFields(tids, ['scheduled']);
        if (topicsData.some(t => t.scheduled)) {
            throw new Error('[[error:cant-merge-scheduled]]');
        }

        const oldestTid = findOldestTopic(tids);
        let mergeIntoTid = oldestTid;
        if (options.mainTid) {
            mergeIntoTid = options.mainTid;
        } else if (options.newTopicTitle) {
            mergeIntoTid = await createNewTopic(options.newTopicTitle, oldestTid);
        }

        const otherTids = tids.sort((a, b) => a - b)
            .filter(tid => tid && parseInt(tid, 10) !== parseInt(mergeIntoTid, 10));

        for (const tid of otherTids) {
            /* eslint-disable no-await-in-loop */
            const pids = await Topics.getPids(tid);
            for (const pid of pids) {
                await Topics.movePostToTopic(uid, pid, mergeIntoTid);
            }

            await Topics.setTopicField(tid, 'mainPid', 0);
            await Topics.delete(tid, uid);
            await Topics.setTopicFields(tid, {
                mergeIntoTid: mergeIntoTid,
                mergerUid: uid,
                mergedTimestamp: Date.now(),
            });
        }

        await Promise.all([
            posts.updateQueuedPostsTopic(mergeIntoTid, otherTids),
            updateViewCount(mergeIntoTid, tids),
        ]);

        plugins.hooks.fire('action:topic.merge', {
            uid: uid,
            tids: tids,
            mergeIntoTid: mergeIntoTid,
            otherTids: otherTids,
        });
        return mergeIntoTid;
    };

    async function createNewTopic(title, oldestTid) {
        const topicData = await Topics.getTopicFields(oldestTid, ['uid', 'cid']);
        const params = {
            uid: topicData.uid,
            cid: topicData.cid,
            title: title,
        };
        const result = await plugins.hooks.fire('filter:topic.mergeCreateNewTopic', {
            oldestTid: oldestTid,
            params: params,
        });
        const tid = await Topics.create(result.params);
        return tid;
    }

    async function updateViewCount(mergeIntoTid, tids) {
        const topicData = await Topics.getTopicsFields(tids, ['viewcount']);
        const totalViewCount = topicData.reduce(
            (count, topic) => count + parseInt(topic.viewcount, 10), 0
        );
        await Topics.setTopicField(mergeIntoTid, 'viewcount', totalViewCount);
    }

    function findOldestTopic(tids) {
        return Math.min.apply(null, tids);
    }
};