Create range of date with exception - php

Question

Having two arrays of date (mm/dd/yyyy)
array(2) {
["useless_range"]=>
array(4) {
[0]=>
string(10) "08/15/2014"
[1]=>
string(10) "08/30/2014"
[2]=>
string(10) "09/10/2014"
[3]=>
string(10) "09/20/2014"
}
["range"]=>
array(2) {
[0]=>
string(10) "08/01/2014"
[1]=>
string(10) "10/31/2014"
}
}
Consider that the array range_useless is holiday, strike, or anything like this. It's sorted already.
How can I get a useful range from the given array range?
For that example, I want the range to be
'08/01/2014 to 08/14/2014 **and** 08/31/2014 to 09/09/2014 **and** 09/21/2014 to 10/31/2014'
My first solution was create an array of all dates between the ranges and then create the full string looping using in_array, but I think there might exists a better solution
Code that create all dates between all ranges
$strDateFrom = '2014/08/15';
$strDateTo = '2014/08/30';
// takes two dates formatted as YYYY-MM-DD and creates an
// inclusive array of the dates between the from and to dates.
$aryRange=array();
$iDateFrom=mktime(1,0,0,substr($strDateFrom,5,2), substr($strDateFrom,8,2),substr($strDateFrom,0,4));
$iDateTo=mktime(1,0,0,substr($strDateTo,5,2), substr($strDateTo,8,2),substr($strDateTo,0,4));
if ($iDateTo>=$iDateFrom) {
array_push($aryRange,date('Y-m-d',$iDateFrom)); // first entry
while ($iDateFrom<$iDateTo) {
$iDateFrom+=86400; // add 24 hours
array_push($aryRange,date('Y-m-d',$iDateFrom));
}
}
print_r($aryRange);

Answer 1

Interesting challenge :) ! So I tried something :
$myDates = array(
"useless_range" => array(
"01/08/2015",
"01/15/2015",
"09/10/2015",
"09/20/2015"
),
"range" => array(
"08/01/2015",
"10/31/2015"
)
);
// results of strotime
$dateStart = 1420066800; //01/01/2015
$dateTo = 1422658800; // 31/01/2015
$tab = $myDates['useless_range'];
$len = count($tab);
$result = array();
$previous = $dateStart;
for($i = 0; $i < $len; $i++){
$position = $tab[$i]; // we get the current element
$iPosition = strtotime($position); // strotime it
if($previous < $iPosition && $iPosition < $dateTo){ // if the useless date is in the range
if($i % 2 == 0){ //if start of range
$result[] = array("start" => date("Y-m-d", $previous + 3600*24), "end" => date("Y-m-d", $iPosition));
}
$previous = $iPosition;
}
else { // the date is out of range, we finish the result and leave the loop
$result[] = array("start" => date("Y-m-d", $previous), "end" => date("Y-m-d", $dateTo + 3600*24));
break; //end of search
}
}
print_r($result);
The output result :
Array
(
[0] => Array
(
[start] => 2015-01-01
[end] => 2015-01-08
)
[1] => Array
(
[start] => 2015-01-15
[end] => 2015-01-31
)
)
Now to create the sentence :
$sentences = array();
foreach($result as $elem){
$sentences[] = $elem['start']." to ".$elem['end'];
}
echo implode(' **and** ', $sentences);

Answer 2

OK, this is not very different from what you've got but it's another point of view and I'm using the strtotime() function instead of mktime() which at least looks nicer.
I'm assuming the inputs have been validated and I have ignored the corner cases such as when the start date of the desired range/period is inside the first 'useless' range, or the end date is in a 'useless' range, but this could be easily verified if necessary.
I just wanted you to share how I would go for solving this problem.
Here's my code:
<?php
$uselessRanges = [ "08/15/2014", "08/30/2014", "09/10/2014", "09/20/2014" ];
$range = [ "08/01/2014", "10/31/2014" ];
// Convert to timestamps for easier manipulation
$rangeTs = array_map( 'strtotime', $range );
$uselessRangesTs = array_map( 'strtotime', $uselessRanges );
// Let the first date be the start of the whole range
$finalResult = [ array_shift( $rangeTs ) ];
/**
* Assuming that the useless ranges array is of the following format:
* $useless = [ 'start_useless_range_1', 'end_useless_range_1', 'start_useless_range_2', 'end_useless_range_2', ... ]
*
* For each of the useless range entries we decide whether to take the previous or the next day based on the parity of the index
*/
for( $i = 0; $i < count( $uselessRangesTs); $i++ ){
// Whether we should take the previous or the next day
$diff = $i % 2 === 0 ? -86400 : 86400;
$finalResult[] = $uselessRangesTs[$i] + $diff;
}
// Finally add the end of the whole range
$finalResult[] = array_shift( $rangeTs );
foreach( $finalResult as $date ){
echo date('m/d/Y', $date) . '<br />';
}

Answer 3

Assuming you only need to generate a string, and the dates are already validated and in order, I wouldn't bother with date functions. Here is a quick example of how I would do it:
$dates = array(
"useless_range" => array(
"08/15/2014",
"08/30/2014",
"09/10/2014",
"09/20/2014"
),
"range" => array(
"08/01/2015",
"10/31/2015"
)
);
$str = array();
for ( $i = 0; $i < sizeof($dates['useless_range']); $i += 2 ) {
$str[] = sprintf('%s and %s', $dates['useless_range'][$i], $dates['useless_range'][$i+1]);
}
array_unshift($str, $dates['range'][0]);
$str[] = $dates['range'][1];
$str = implode(' to ',$str);
echo $str;
// 08/01/2015 to 08/15/2014 and 08/30/2014 to 09/10/2014 and 09/20/2014 to 10/31/2015
Explanations:
The general idea is to build a sentence, so I do not bother with dates or range or anything. Just imagine words that need to be pieced together. The final result needs to be :
"range0 to useless_range0 and useless_range1 to useless_range2 and useless_range3 to range1"
This can be broken down like this:
[range0] to [useless_range0 and useless_range1] to [useless_range2 and useless_range3] to [range1]
This can be achieved very easily with implode using " to " as a separator. We just need to generate the array with range0 as first element, range1 as last element, and every piece of sentence (two consecutives dates + " and ") in between. This is a simple loop + array_shift/unshift.
Note: if your dates are not validated, or if you need to check for overlap, or anything fancy like that, then you will very probably have to build an array of dates like you are doing.