PHP - Get start and end date of current date interval - php

Question

I have as unix timestamps
$now = strtotime("2013-12-10");
$start_date = strtotime("2013-01-01");
$end_date = strtotime("2013-12-31");
The $start date and $end date span a period of time and the $now timestamp sits in the middle of the two.
I also have a variable date interval like so:
$interval = new DateInterval('P1W');
// or
$interval = new DateInterval('P3D');
Given the above how do I get the start and end timestamps of the interval that now sits in?
The $now, $start_date, $end_date and the interval will be dynamic.
Example
Lets say I have these parameters:
$start_date = '2013-01-01 00:00:00';
$end_date = '2013-12-31 23:59:59';
$now = '2013-12-10 15:45:34';
$interval = new DateInterval( 'P1W' );
I want to know the start and end date of the interval $now sits in. The output I would expect from the above params is:
$int_start_date = '2013-12-10 00:00:00';
$int_end_date = '2013-12-16 23:59:59';

Answer 1

I think this is a less hacky and cleaner approach than yours.
$start_date = new DateTime( '2013-01-01 00:00:00' );
$end_date = new DateTime( '2013-12-31 23:59:59' );
$end_date_ts = $end_date->getTimestamp();
$now = new DateTime( '2013-12-10 15:45:34' );
$now_ts = $now->getTimestamp();
$interval = new DateInterval( 'P1W' );
$periods = new DatePeriod( $start_date, $interval, $end_date );
/** #var \DateTime $period */
foreach($periods as $period){
$periodEnd = clone $period;
$periodEnd->add($interval);
if($period < $now && $now < $periodEnd){
$result = iterator_to_array(new \DatePeriod($period, $interval, $periodEnd->add($interval)));
$int_start_date = $result[0];
$int_end_date = $result[1];
break;
}
}
/** #var DateTime $int_start_date */
/** #var DateTime $int_end_date */
var_dump( $int_start_date->format( 'Y-m-d H:i:s' ) );
var_dump( $int_end_date->modify( '-1 Second' )->format( 'Y-m-d H:i:s' ) );

Answer 2

I have figured the problem myself however is hacky
$start_date = new DateTime( '2013-01-01 00:00:00' );
$end_date = new DateTime( '2013-12-31 23:59:59' );
$end_date_ts = $end_date->getTimestamp();
$now = new DateTime( '2013-12-10 15:45:34' );
$now_ts = $now->getTimestamp();
$interval = new DateInterval( 'P1W' );
$period = new DatePeriod( $start_date, $interval, $end_date );
$intervals = array();
foreach ( $period as $dt ) {
$intervals[] = $dt->getTimestamp();
}
$intervals[] = $end_date_ts;
$int_start_date = new DateTime();
$int_end_date = new DateTime();
for ( $i = 0; $i < count( $intervals ); $i++ ) {
if ( $now_ts >= $intervals[$i] && $now_ts <= $intervals[$i+1]) {
$int_start_date->setTimestamp($intervals[$i]);
$int_end_date->setTimestamp($intervals[$i+1]-1);
break;
}
}
var_dump( $int_start_date->format( 'Y-m-d H:i:s' ) );
var_dump( $int_end_date->format( 'Y-m-d H:i:s' ) );
I gladly accept better approaches if anyone has them.

Answer 3

You could try:
$now = time();
$interval = new DateInterval('P1W');
$interval_seconds = $interval->s + ($interval->i * 60) + ($interval->h * 60 * 60) + ($interval->d * 60 * 60 * 24);
$half_interval = round($interval_seconds / 2);
// Unix timestamps
$interval_start = $now - $half_interval;
$interval_end = $now + $half_interval;
EDIT: 2nd answer following on from comments
This only works for intervals of length 1 - eg 1 week, 1 year etc.
If your interval is > 1 then you'll need to somehow determine how far through the interval you are... e.g for a 2 week interval, are you in the first week or the second week?
$now = time();
$interval = "week";
switch ($interval) {
case "year":
$start_int = strtotime(date("Y", $now)."-01-01 00:00:00");
$end_int = strtotime(date("Y", $now)."-12-31 23:59:59");
break;
case "month":
$start_int = strtotime(date("Y-m", $now)."-01 00:00:00");
$end_int = strtotime(date("Y-m-t", $now)." 23:59:59");
break;
case "week":
$start_week = date("Y-m-d", strtotime("previous Monday", $now));
$end_week = date("Y-m-d", strtotime("next Sunday", $now));
$start_int = strtotime($start_week." 00:00:00");
$end_int = strtotime($end_week." 23:59:59");
break;
case "day":
$start_int = strtotime(date("Y-m-d", $now)." 00:00:00");
$end_int = strtotime(date("Y-m-d", $now)." 23:59:59");
break;
case "hour":
$start_int = strtotime(date("Y-m-d H", $now).":00:00");
$end_int = strtotime(date("Y-m-d H", $now).":59:59");
break;
case "minute":
$start_int = strtotime(date("Y-m-d H:i", $now).":00");
$end_int = strtotime(date("Y-m-d H:i", $now).":59");
break;
}
echo date("Y-m-d H:i:s", $start_int), "<br>";
echo date("Y-m-d H:i:s", $end_int), "<br>";
Update 3
I've put the logic from your answer into a single loop:
$start_date = new DateTime( '2013-01-01 00:00:00' );
$end_date = new DateTime( '2013-12-31 23:59:59' );
$end_date_ts = $end_date->getTimestamp();
$now = new DateTime( '2013-12-10 15:45:34' );
$now_ts = $now->getTimestamp();
$interval = new DateInterval( 'P1W' );
$period = new DatePeriod( $start_date, $interval, $end_date );
$int_start_date = $start_date;
$int_end_date = $end_date;
foreach ( $period as $dt ) {
$timestamp = $dt->getTimestamp();
if ($now_ts >= $timestamp) {
$int_start_date->setTimestamp($timestamp);
}
if ($now_ts < $timestamp and $timestamp < $int_end_date->getTimestamp()) {
$int_end_date->setTimestamp($timestamp - 1);
}
}
var_dump( $int_start_date->format( 'Y-m-d H:i:s' ) );
var_dump( $int_end_date->format( 'Y-m-d H:i:s' ) );