How to add an Islamic calendar to a public calendar? - php

Question

I have this script. The code below shows the usual calendar
<table cellspacing="0" cellpadding="0" border="0" width="100%" class="view-calendar">
<tr>
<td valign="top" width="14.2857%">Monday</td>
<td valign="top" width="14.2857%">Tuesday</td>
<td valign="top" width="14.2857%">Wednesday</td>
<td valign="top" width="14.2857%">Thursday</td>
<td valign="top" width="14.2857%">Friday</td>
<td valign="top" width="14.2857%">Saturday</td>
<td valign="top" width="14.2857%">Sunday</td>
</tr>
<?php
date_default_timezone_set('Asia/Jakarta');
$days_count = date('t');
$current_day = date('d');
// save time of first day for later use
$time_first_day_of_month = mktime(0, 0, 0, date('m'), 1, date('Y'));
$week_day_first = date('N', $time_first_day_of_month);
// Get next month dates
$next_start = strtotime(date("Y-m-00", strtotime("+1 month")));
$next_dates = array();
for ($w = 1 - $week_day_first + 1; $w <= $days_count; $w = $w + 7){
echo '<tr>';
$counter = 0;
for ($d = $w; $d <= $w + 6; $d++){
if($d < 10){
$current_date = date("Y").date("m").'0'.$d;
}else{
$current_date = date("Y").date("m").$d;
}
echo '<td valign="top" width="14.2857%"'.(($d > 0 ? ($d > $days_count ? ' class="disabled"' : '') : ' class="disabled"')).(($counter > 4 ? ' class="week-day"' : '')).'>';
if($d > 0){
// next month's dates
if($d > $days_count){
for($in = 1; $in <= 1; $in++){
echo array_push($next_dates, date('j', strtotime("+ $in day", $next_start)));
}
}
// today
else if($current_day == $d){
echo '<div class="current-day" style="font-weight: bold;color:red;"><span class="given-date">'.$d.'</span></div>';
}
// this month's dates
else{
echo '<span class="given-date">'.$d.'</span>';
}
}
// last month's dates
else{
//Here comes previous dates
$offset = $d - 1;
echo '<span class="given-date">'.date('d', strtotime("$offset day",$time_first_day_of_month)).'</span>';
}
echo '</td>';
$counter++;
}
echo '</tr>';
}
?>
</table>
I want to create an Islamic calendar like this https://www.islamicfinder.org/islamic-calendar/. How to combine it with islamic calendar? And I do not know how to calculate to get the calendar result of Islam