Add 'export' option to ICS generation to allow exporting the ICS source rather than creating a base64 link

[kodie]

This should basically take care of #125, #126, and #129.

I've noticed that calendar links on Apple devices can be kind of tricky, and the way that seems to work the best and most consistently is serving a generated ICS file. Currently, this isn't possible because the ICS generator returns a base64 encoded string, however with this newly added option you'd be able to have it return the ICS contents.

For example:

generate-ics.php:

<?php
require_once('autoload.php');
header('Content-type: text/calendar; charset=utf-8');
header('Content-Disposition: attachment; filename=event.ics');
$link = new Spatie\CalendarLinks\Link($title, $start_date, $end_date);
echo $link->ics(array('export' => true));
exit;
?>

Then you could link to that file like this: webcal://mywebsite.com/generate-ics.php and it should work fine for Apple devices.

It should be noted that not all browsers support the webcal protocol, so I use a piece of JavaScript to update my links depending on the browser:

function webcalify(selector) {
  var isApple = /(Mac|iPhone|iPod|iPad)/i.test(navigator.platform)
  
  if (isApple) {
    var links = document.querySelectorAll(selector || 'a.webcal')
    
    for (var i = 0; i < links.length; i++) {
      var link = links[i]
      var url = link.href
      
      link.href = url.replace(/(^\w+:|^)\/\//, 'webcal://')
    }
  }
}

[spatie-bot]

Dear contributor,

because this pull request seems to be inactive for quite some time now, I've automatically closed it. If you feel this pull request deserves some attention from my human colleagues feel free to reopen it.