class Timing

class Timing {
    
    /**
     * Number of milliseconds in a minute.
     *
     * @var int
     */
    const MINUTE_IN_MS = 60000;
    
    /**
     * Number of milliseconds in a second.
     *
     * @var int
     */
    const SECOND_IN_MS = 1000;
    
    /**
     * The start time of the run in microseconds.
     *
     * @var float
     */
    private static $startTime;
    
    /**
     * Used to make sure we only print the run time once per run.
     *
     * @var boolean
     */
    private static $printed = false;
    
    /**
     * Start recording time for the run.
     *
     * @return void
     */
    public static function startTiming() {
        self::$startTime = microtime(true);
    }
    
    //end startTiming()
    
    /**
     * Get the duration of the run up to "now".
     *
     * @return float Duration in milliseconds.
     */
    public static function getDuration() {
        if (self::$startTime === null) {
            // Timing was never started.
            return 0;
        }
        return (microtime(true) - self::$startTime) * 1000;
    }
    
    //end getDuration()
    
    /**
     * Convert a duration in milliseconds to a human readable duration string.
     *
     * @param float $duration Duration in milliseconds.
     *
     * @return string
     */
    public static function getHumanReadableDuration($duration) {
        $timeString = '';
        if ($duration >= self::MINUTE_IN_MS) {
            $mins = floor($duration / self::MINUTE_IN_MS);
            $secs = round(fmod($duration, self::MINUTE_IN_MS) / self::SECOND_IN_MS, 2);
            $timeString = $mins . ' mins';
            if ($secs >= 0.01) {
                $timeString .= ", {$secs} secs";
            }
        }
        else {
            if ($duration >= self::SECOND_IN_MS) {
                $timeString = round($duration / self::SECOND_IN_MS, 2) . ' secs';
            }
            else {
                $timeString = round($duration) . 'ms';
            }
        }
        return $timeString;
    }
    
    //end getHumanReadableDuration()
    
    /**
     * Print information about the run.
     *
     * @param boolean $force If TRUE, prints the output even if it has
     *                       already been printed during the run.
     *
     * @return void
     */
    public static function printRunTime($force = false) {
        if ($force === false && self::$printed === true) {
            // A double call.
            return;
        }
        if (self::$startTime === null) {
            // Timing was never started.
            return;
        }
        $duration = self::getDuration();
        $duration = self::getHumanReadableDuration($duration);
        $mem = round(memory_get_peak_usage(true) / (1024 * 1024), 2) . 'MB';
        echo "Time: {$duration}; Memory: {$mem}" . PHP_EOL . PHP_EOL;
        self::$printed = true;
    }
    
    //end printRunTime()

}