Finding differently lengthed time intervals between two dates - php

Question

I want users to be able to select a date range and an interval to display results from, such as "show me results between Jan 1, 2017 and Apr 1, 2017, listed by day|week|month"
So if they selected day, I'd group results by Jan 1, 2017; Jan 2, 2017; Jan 3, 2017; etc...
If they selected week, it'd be Jan 1, 2017; Jan 8, 2017; Jan 15, 2017; etc...
The method I'm using now is as follows:
if(isset($chosenInterval) && ($chosenInterval == "week" || $chosenInterval == "day") ) {
$timeFormat = "F j, Y";
} else {
$timeFormat = "F Y";
$chosenInterval = "month";
}
$start = (new DateTime($start))->modify('first day of this month');
$end = (new DateTime($stop))->modify('first day of next month');
$interval = DateInterval::createFromDateString('1 '.$chosenInterval);
$period = new DatePeriod($start, $interval, $end);
foreach($period as $dt) {
$dataLabels[] = $dt->format($timeFormat);
}
The problem is that if the user selects Jan 8, 2017 - Jan 20, 2017, it still includes all the dates in January.
Ideally it would show:
Day: Jan 8, 2017; Jan 9, 2017; ... Jan 19, 2017; Jan 20, 2017
Week: Jan 8, 2017; Jan 15, 2017
Month: Jan, 2017
Any suggestions on how to accomplish this? Thanks!

Answer 1

You need to check when adding your DateTime objects to $dataLabels if the date is before the start or after the end. If it is (and the $chosenInterval is not a month), don't add them:
<?php
$start = "2017-01-08";
$stop = "2017-01-20";
$chosenInterval = "week";
function getDates($start, $stop, $chosenInterval = "week") {
$startDT = new DateTime($start); // make a DateTime out of the date to later compare it
$stopDT = new DateTime($stop); // make a DateTime out of the date to later compare it
if(isset($chosenInterval) && ($chosenInterval == "week" || $chosenInterval == "day") ) {
$timeFormat = "F j, Y";
} else {
$timeFormat = "F Y";
$chosenInterval = "month";
}
$begin = (new DateTime($start))->modify('first day of this month');
$end = (new DateTime($stop))->modify('first day of next month');
$interval = DateInterval::createFromDateString('1 '.$chosenInterval);
$period = new DatePeriod($begin, $interval, $end);
foreach($period as $dt) {
if ($chosenInterval !== "month" && ($dt < $startDT || $dt > $stopDT)) continue; // if date is before start or after end, skip
$dataLabels[] = $dt->format($timeFormat);
}
return $dataLabels;
}
var_dump(getDates($start, $stop));
var_dump(getDates($start, $stop, "day"));
var_dump(getDates($start, $stop, "month"));
Demo