const leaderboards  = require("../Data/leaderboard");

const BATCH_SIZE    = 1000;
const INTERVAL_TIME = 60000;   

async function leaderboardLoop() {
    for (let i = 0, length = leaderboards.length; i < length; i++) {
        const leaderboard = leaderboards[i];
        const databaseName = `leaderboard_${i + 1}`;
        const queries = [];
        const entries = [];

        const dbConnection = await db.getConnection();
        await dbConnection.beginTransaction();

        leaderboard.list.clearEach((key, value) => entries.push([key, value]));

        for (let j = 0, length = Math.ceil(entries.length / BATCH_SIZE); j < length; j++) {
            const batch = entries.slice(j * BATCH_SIZE, (j + 1) * BATCH_SIZE);
            let leaderboardFromDB = null;

            if (i === 0) leaderboardFromDB = dbConnection.query(`INSERT INTO ${databaseName} (id, amount) VALUES ? ON DUPLICATE KEY UPDATE amount = VALUES(amount)`, [batch]);
            else leaderboardFromDB = dbConnection.query(`INSERT INTO ${databaseName} (id, amount) VALUES ? ON DUPLICATE KEY UPDATE amount = amount + VALUES(amount)`, [batch]);

            queries.push(leaderboardFromDB);
        };

        try {
            await Promise.all(queries);
            await dbConnection.commit();
        } catch {
            await dbConnection.rollback();
        } finally {
            dbConnection.release();
        };

        const leaderboardSizeFromDB = await execute(`SELECT COUNT(*) AS size FROM ${databaseName}`);
        leaderboard.size = leaderboardSizeFromDB.data ? leaderboardSizeFromDB.data[0].size : 0;
        leaderboard.cache = {};
    };
};

setInterval(leaderboardLoop, INTERVAL_TIME);

module.exports = leaderboardLoop;

/*
    Periodically saves leaderboard changes to disk in batches
*/