task3.php

<?php
/**
 * Created by PhpStorm.
 * User: roboter
 * Date: 10.10.2014
 * Time: 14:12
 */
date_default_timezone_set( 'UTC' );
require_once( 'tooaeg.php' );
define ( 'NEXTDAY', 24 * 60 * 60 );

$nighttime_end = strtotime( gmdate( 'd/m/Y', 0 ).' '.$SETTINGS_nighttime_end ); // 07:00
$nighttime_start   = strtotime( gmdate( 'd/m/Y', 0 ).' '.$SETTINGS_nighttime_start ); // 22:00

echo '<pre>';
foreach ( $EMPLOYEES as $employee ) {
	echo 'Name: '.$employee['name']."\n";
	echo 'Shift start: '.$employee['shift_start']."\n";
	echo 'Shift end: '.$employee['shift_end']."\n";

	echo 'Interval: '.interval( date_create( $employee['shift_start'] ), date_create( $employee['shift_end'] ) )."\n";
	$start       = strtotime( gmdate( 'd/m/Y', 0 ).' '.$employee['shift_start'] );
	$end         = strtotime( gmdate( 'd/m/Y', 0 ).' '.$employee['shift_end'] );

	echo 'Daytime: '.intersection(
			$start,
			$end,
			$nighttime_end,
			$nighttime_start)."\n";
	if ( $start > $end ) {
		$end = $end + NEXTDAY;
	}
	echo 'Nighttime: '.intersection(
			$start,
			$end,
			$nighttime_start,
			$nighttime_end + NEXTDAY )."\n";
	echo "\n";
}

echo '</pre>';

function interval( $start, $end ) {
	$start_unix = $start->getTimestamp();
	$end_unix   = $end->getTimestamp();

	if ( $end_unix > $start_unix ) {
		return gmdate( 'H:i', $end_unix - $start_unix );
	}

	return gmdate( 'H:i', 0 - $start_unix + $end_unix );
}

function intersection( $start, $end, $start_shift, $end_shift ) {

//	print_time($start);
//	print_time($end);
	if ( $start_shift > $end || $start > $end_shift || $end < $start || $end_shift < $start_shift ) {
		return '-';
	}
	$start = $start < $start_shift ? $start_shift : $start;
	$end   = $end < $end_shift ? $end : $end_shift;

	return gmdate( 'H:i', $end - $start );

}

function print_time( $time ) {
	echo gmdate( 'H:i', $time ).( gmdate( 'd', $time ) == 2 ? ' + day' : '' )."\n";
}