'use strict';

const knex = require('./knex');

async function matchTags(rawTags) {
    const tagQuery = knex('tags')
        .select(knex.raw('ifnull(original.tag, tags.tag) as tag'), knex.raw('ifnull(original.tag, tags.tag) as tag'))
        .whereIn('tags.tag', rawTags)
        .leftJoin('tags as original', 'tags.alias_for', 'original.tag')
        .toString()
        .replace('where `tags`.`tag` in', 'where `tags`.`tag` collate NOCASE in');

    const tagEntries = await knex.raw(tagQuery);

    return Array.from(new Set(tagEntries.map(({ tag }) => tag))).sort(); // reduce to tag name and filter duplicates
}

module.exports = { matchTags };