Timer class

Timer.php

<?php
/**
 * Class Timer
 */
class Timer
{
    /**
     * @var float|null
     */
    protected $startTime;
    /**
     * @var float|null
     */
    protected $endTime;

    public function __construct($start = false)
    {
        if ($start) {
            $this->start();
        }
    }

    public function start()
    {
        $this->startTime = $this->getCurrentTime();
    }

    public function stop()
    {
        $this->endTime = $this->getCurrentTime();
    }

    public function reset()
    {
        $this->startTime = null;
        $this->endTime = null;
    }

    public function getCurrentTime()
    {
        return microtime(true);
    }

    public function getElapsedTime($unit = 's')
    {
        $startTime = is_null($this->startTime) ? $this->getCurrentTime() : $this->getStartTime();
        $endTime = $this->isTimerRunning() ? $this->getCurrentTime() : $this->getEndTime();

        return ($endTime - $startTime) * $this->getMultiplicationFactorForUnit($unit);
    }

    /**
     * @return float
     */
    public function getStartTime()
    {
        return $this->startTime;
    }

    /**
     * @return float
     */
    public function getEndTime()
    {
        return $this->endTime;
    }

    /**
     * @param $unit
     * @return float|int
     */
    protected function getMultiplicationFactorForUnit($unit)
    {
        $multiplicationFactor = 1;

        switch ($unit) {
            // milliseconds
            case 'ms':
                $multiplicationFactor = 1000;
                break;
            // seconds
            case 's':
                $multiplicationFactor = 1;
                break;
            // minutes
            case 'm':
                $multiplicationFactor = 1 / 60;
                break;
        }

        return $multiplicationFactor;
    }

    protected function isTimerRunning()
    {
        return is_null($this->endTime);
    }
}