Calculate UK Fiscal calendar week, period and year in PHP - php

Question

I would like to determine the current Fiscal week period and year with a function when you pass it an empty argument, or the week, period and year of a datestring you include in the argument.
I have a function like this so far.
function FiscalDates($date){
$basedate=date_create("2018-04-29");
$querydate=date_create($date);
$diff=date_diff($basedate,$querydate);
$days = $diff->format('%a');
if(fmod($days,7)==0){
$weekno = ($days/7)+1;
} else {
$weekno = ceil($days/7);
}
if(fmod($weekno,4)==0){
$period = ($weekno/4);
} else {
$period = ceil($weekno/4);
}
if(fmod($period,13)==0){
$year = ($period/13)-1;
} else {
$year = (ceil($period/13))-1;
}
$period = $period-(13*$year);
$year = $year+2018;
return array($weekno,$period,$year);
}
This works for the most part, but the only problem is that it does not account for the 'leap week' that happens every 5-6 years. (Where there is 53 weeks in the year) see 2nd paragraph of this page about that. Every time this happens, the calculations will be off by another week.
How can I achieve a similar thing, but account for the 53 weeks in a year years and keep it accurate?

Answer 1

Might be too late or not exactly a direct reply, but had similar issues a few years back for a UK business, so decided to work on a library that could prove helpful for you.
https://github.com/RoussKS/financial-year
It can get period/weeks for a financial year.
It handles 2 types of financial year. The standard 12 month (period) one, named calendar as a library convention, and business for 13 period financial years (for 52/53 weeks). Business is the one you would want to use.
It does not check when a year should be a 53 week year as this depends on the business, so you would need to provide that as a param (defaults to false aka 52).
Example use to fetch the period & week
require_once __DIR__ . '/vendor/autoload.php';
// DateTimeAdapter
// If instantiating with string, it must be of ISO-8601 format 'YYYY-MM-DD'.
// This is your business's financial year start date.
$startDate = new \DateTime('2018-04-01');
$fy = new \RoussKS\FinancialYear\DateTimeAdapter('business', $startDate, false); // false for 52 weeks, true for 53 weeks
$dateToExamine = '2018-04-29';
// Get period of the date in question
echo $fy->getPeriodIdByDate($dateToExamine); // 1
// Get week of the date in question
echo $fy->getBusinessWeekIdIdByDate($dateToExamine); // 5
Not sure though what you mean by year, is it like naming the year as per 2018/2019?