Format time from seconds

'use strict';

/**
 * Format Time
 *
 * Format seconds as a time string, H:MM:SS or M:SS
 * Supplying a guide (in seconds) will force a number of leading zeros
 * to cover the length of the guide
 *
 * https://github.com/videojs/video.js/blob/master/src/js/utils/format-time.js
 *
 * @param  {Number} seconds Number of seconds to be turned into a string
 * @param  {Number} guide   Number (in seconds) to model the string after
 * @return {String}         Time formatted as H:MM:SS or M:SS
 * @private
 * @function formatTime
 */
function formatTime(seconds) {
    var guide = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : seconds;

    seconds = seconds < 0 ? 0 : seconds;
    var s = Math.floor(seconds % 60);
    var m = Math.floor(seconds / 60 % 60);
    var h = Math.floor(seconds / 3600);
    var gm = Math.floor(guide / 60 % 60);
    var gh = Math.floor(guide / 3600);

    // handle invalid times
    if (isNaN(seconds) || seconds === Infinity) {
        // '-' is false for all relational operators (e.g. <, >=) so this setting
        // will add the minimum number of fields specified by the guide
        h = m = s = '-';
    }

    // Check if we need to show hours
    h = h > 0 || gh > 0 ? h + ':' : '';

    // If hours are showing, we may need to add a leading zero.
    // Always show at least one digit of minutes.
    m = ((h || gm >= 10) && m < 10 ? '0' + m : m) + ':';

    // Check if leading zero is need for seconds
    s = s < 10 ? '0' + s : s;

    return h + m + s;
}