<?php

//By Dominic Gannaway

/**
 * Check they're set and valid strings
 * @param string $time1
 * @param string $time2
 *
 * @return boolean
 */
function validateTimestamps($time1, $time2) {

    return isset($time1) && is_string($time1) && isset($time2) && is_string($time2);
}

/**
 * PHP 5.2 method - plus it's using math
 * @param string $time1
 * @param string $time2
 *
 * @return int
 */
function getTimeBetween($time1, $time2) {

    //check the times are valid
    if(validateTimestamps($time1, $time2)) {
    //convert to PHP timestamp
        $time1 = strtotime($time1);
        $time2 = strtotime($time2);
    } else {
        return 'You need to enter some timestamps';
    }

    //find the difference of the two times, taking into consideration the absolute value
    $diff = abs($time1 - $time2);

    //now we need to calculate the minutes, rounding down
    $diff_minutes = floor($diff / 60);

    //return minutes
    return $diff_minutes;
}


/**
 * PHP 5.3 method - using the standard DateTime component
 * @param string $time1
 * @param string $time2
 *
 * @return int
 */
function getTimeBetween2($time1, $time2) {

    //check the times are valid
    if(validateTimestamps($time1, $time2)) {
        $start = new DateTime($time1);
        $end = new DateTime($time2);
    } else {
        return 'You need to enter some timestamps';
    }

    $diff = $start->diff($end);
    //now we have the diff in segments, we need to put them back together
    $diff_minutes = (($diff->days * 24 * 60) + ($diff->h * 60) + $diff->i);

    //return minutes
    return $diff_minutes;
}


//should be 60 minutes
echo getTimeBetween('Thu, 21 Dec 2000 16:01:07 +0200', 'Thu, 21 Dec 2000 17:01:07 +0200') . ' minutes<br>';
echo getTimeBetween2('Thu, 21 Dec 2000 16:01:07 +0200', 'Thu, 21 Dec 2000 17:01:07 +0200') . ' minutes<br>';

//should be 120 minutes
echo getTimeBetween('Thu, 21 Dec 2000 16:01:07 +0200', 'Thu, 21 Dec 2000 19:01:07 +0300') . ' minutes<br>';
echo getTimeBetween2('Thu, 21 Dec 2000 16:01:07 +0200', 'Thu, 21 Dec 2000 19:01:07 +0300') . ' minutes<br>';

//should be 6310860 minutes
echo getTimeBetween('Thu, 7 Dec 2000 16:01:07 +0200', 'Thu, 6 Dec 2012 19:01:07 -0800') . ' minutes<br>';
echo getTimeBetween2('Thu, 7 Dec 2000 16:01:07 +0200', 'Thu, 6 Dec 2012 19:01:07 -0800') . ' minutes<br>';


?>