'use strict';

async function upsert(table, items, duplicatesById, identifier = 'id', knex) {
    const { insert, update } = items.reduce((acc, item) => {
        if (duplicatesById[item[identifier]]) {
            return {
                ...acc,
                update: [
                    ...acc.update,
                    {
                        ...duplicatesById[item[identifier]],
                        ...item,
                    },
                ],
            };
        }

        return {
            ...acc,
            insert: [
                ...acc.insert,
                item,
            ],
        };
    },
    {
        insert: [],
        update: [],
    });

    if (knex) {
        console.log(`${table}: Inserting ${insert.length}`);
        console.log(`${table}: Updating ${update.length}`);

        return Promise.all([
            knex(table).insert(insert),
            knex.transaction(async trx => Promise.all(update.map(item => trx
                .where({ id: item.id })
                .update(item)
                .into(table)))),
        ]);
    }

    return { insert, update };
}

module.exports = upsert;