How to summarize multiple Intervals in PHP - php

Question

In my app I can create projects and for each project I can record work reports. Each report has a start and an end timestamp. A table in the project description shows every report for this project and it also calculates the duration (with DateTime and the diff() function used between start and end timestamp). Now I want to calculate the total work time on the projects but I have no idea how I can do this. I already tried looping through all reports somehow and then use DateTime functions, but I'm getting nowhere... My last desperate attempt was this:
public static function calculateDuration($start, $end)
{
$start = date('Y-m-d H:i:s', $start);
$end = date('Y-m-d H:i:s', $end);
$s = new \DateTime($start);
$e = new \DateTime($end);
$interval = $e->diff($s);
return $interval->format('%H:%I');
}
public static function calculateTotal($idProject)
{
$reports = self::find('id_project = "' . $idProject . '"');
$totalReports = new \DateTime();
foreach ($reports as $report) {
$totalReports->add(new \DateInterval(self::calculateDuration($report->getStart(), $report->getEnd())));
}
/*echo '<pre>';
die(var_dump($totalReports));
echo '</pre>';*/
return $totalReports->format('H:I');
}
the calculateDuration functions works perfectly, but of course calculateTotal doesn't, because DateInterval does not take a string like "0:30". So that is completely useless...
I hope I provided all the needed information, just let me know if you need something else.

Answer 1

For clarity on my comments: You already have calculateDuration doing all the work, and it internally deals with a DateInterval object. So why not make use of it? Here, getInterval is a protected method that's used by both existing methods and returns the DateInterval object directly. Now calculateDuration becomes a simple formatting function, and calculateTotal has access to the DateInterval object.
protected static function getInterval($start, $end)
{
$s = new \DateTime('#' . $start);
$e = new \DateTime('#' . $end);
return $e->diff($s);
}
public static function calculateDuration($start, $end)
{
return self::getInterval($start, $end)->format('%H:%I');
}
public static function calculateTotal($idProject)
{
// ...
$totalReports = new \DateTime();
$totalReportsEnd = clone $totalReports;
foreach ($reports as $report) {
$totalReportsEnd->add(self::getInterval(
$report->getStart(),
$report->getEnd()
));
}
$totalInterval = $totalReportsEnd->diff($totalReports);
// do as you wish with the interval
}

Answer 2

Just create a valid DateInterval format instead of returning hours and minutes:
// Untested. Might need escaping.
return $interval->format('PT%HH%IM');