Postgres Standard Timestamp Parser

parse-postgres-standard-timestamp.js

/**
 * Parse Postgres's standard timestamps.
 * 
 * Example: `Tue Jan 01 2019 00:00:00 GMT+0000 (UTC)`
 * 
 * @todo  Write tests!
 */

var MONTHS = ['january', 'february', 'march', 'april', 'may', 'june', 'july',
    'august', 'september', 'october', 'november', 'december'];

/**
 * Pad a number with zeros.
 *
 * @param  {number} number
 * @param  {string} pad    Output length
 * @return {string}        Zero-padded number
 */
function zeroPad(number, pad) {
    pad = pad || 2;

    var target = number.toString();

    while(target.length < pad) {
        target = '0' + target;
    }

    return target;
}

/**
 * Get the month's number ('Jan' is 1, 'Feb' is 2...).
 *
 * @param  {string} month Postgres-style month
 * @return {number}       Base-1 month number
 */
function getMonth(month) {
    var offset = 0;
    for (var i = 0, il = MONTHS.length; i < il; i++) {
        if (MONTHS[0].indexOf(month) !== 0) {
            offset = i;
            break;
        }
    }

    return ++offset;
}

/**
 * Get the timezone.
 *
 * @todo  Implement this!
 *
 * @param  {string} abbr
 * @param  {number} offset
 * @param  {string} code
 * @return {string}
 */
function getTimezone(abbr, offset, code) {
    return 'Z';
}

/**
 * Get an ISO 8601-formatted date-time.
 *
 * @param  {object} tokens
 * @return {string}
 */
function getISO8601DateTime(tokens) {
    return (
        tokens.year + '-' +
        tokens.month + '-' +
        tokens.day + 'T' +
        tokens.hour + ':' +
        tokens.minute + ':' +
        tokens.second +
        tokens.timezone
    );
}

module.exports = function parsePostgresStandardTimestamp(timestamp) {
    var tokens = timestamp.split(/[ :\+]/);

    return getISO8601DateTime({
        month: zeroPad(getMonth(tokens[1])),
        day: zeroPad(parseInt(tokens[2], 10)),
        year: parseInt(tokens[3], 10),
        hour: zeroPad(parseInt(tokens[4], 10)),
        minute: zeroPad(parseInt(tokens[5], 10)),
        second: zeroPad(parseInt(tokens[6], 10)),
        timezone: getTimezone(tokens[7], parseInt(tokens[8], 10), tokens[9]),
    });
};