Kekkai/database/main.js

const pool = require('./postgresql.js');


/**
 * Getting the currency exchange rate for a specific day
 * @param from_currency {String}
 * @param conv_currency {String}
 * @param date
 * @returns {Promise<*|Error>}
 */

async function getDay(from_currency, conv_currency, date) {
    if (!from_currency || !conv_currency) return new Error('fromCurrency and convCurrency are required');
    else if (!date) return new Error('date is required')

    const data = await pool.query('SELECT from_currency, conv_currency, date, rate FROM currency ' +
        'WHERE from_currency = $1 AND conv_currency = $2 AND date = $3', [
            from_currency.toUpperCase(),
            conv_currency.toUpperCase(),
            date
        ]);

    if (!data) return new Error('Missing data');

    return data['rows'][0];
}

/**
 * Getting the exchange rate for a certain period
 * @param {String} from_currency - The currency that is being converted
 * @param {String} conv_currency - The currency to be converted into
 * @param {String} start_date - Start date of the period
 * @param {String} end_date - End date of the period
 * @returns {Promise<*|Error>}
 */

async function getPeriod(from_currency, conv_currency, start_date, end_date) {
    if (!from_currency || !conv_currency) return new Error('from_currency and conv_currency are required');
    else if(!start_date || !end_date) return new Error('start_date and end_date are required')

    const data = await pool.query('SELECT * FROM currency WHERE ' +
        '(date BETWEEN $3 AND $4) AND from_currency = $1 AND conv_currency = $2', [
            from_currency.toUpperCase(),
            conv_currency.toUpperCase(),
            start_date,
            end_date
    ]);

    if (!data) return new Error('Missing data');

    return data['rows'];
}

module.exports = { getDay, getPeriod };