Jany-M · September 19, 2023 03:15 · lincolnlemos · Feb 3, 2018 · marvilmedia · Feb 16, 2018
diff --git a/wp_ics.php b/wp_ics.php
 <?php

 /*  
 	For a better understanding of ics requirements and time formats
    please check https://gist.github.com/jakebellacera/635416
 */

 // UTILS

 // Check if string is a timestamp
 function isValidTimeStamp($timestamp) {
    //if($timestamp == '') return;
    return ((string) (int) $timestamp === $timestamp) 
        && ($timestamp <= PHP_INT_MAX)
        && ($timestamp >= ~PHP_INT_MAX);
 }

 // Escapes a string of characters
 function escapeString($string) {
 	return preg_replace('/([\,;])/','\\\$1', $string);
 }

 // Shorten a string to desidered characters lenght - eg. shorter_version($string, 100);
 function shorter_version($string, $lenght) {
 if (strlen($string) >= $lenght) {
 		return substr($string, 0, $lenght);
 	} else {
 		return $string;
 	}
 }

 // Add a custom endpoint "calendar"
 function add_calendar_feed(){
 	add_feed('calendar', 'export_ics');
    // Only uncomment these 2 lines the first time you load this script, to update WP rewrite rules, or in case you see a 404
    /*global $wp_rewrite;
    $wp_rewrite->flush_rules( false );*/
 }
 add_action('init', 'add_calendar_feed');

 // Calendar function
 function export_ics(){

    // Query the event
    $the_event = new WP_Query(array(
        'p' => $_REQUEST['id'],
        'post_type' => 'any',
    ));
    
    if($the_event->have_posts()) :
        
        while($the_event->have_posts()) : $the_event->the_post();
 	
 		// If your version of WP < 5.3.0 use the code below

        /*  The correct date format, for ALL dates is date_i18n('Ymd\THis\Z',time(), true)
            So if your date is not in this format, use that function    */
 	
        $start_date = date_i18n("Ymd\THis\Z", get_post_meta( get_the_ID(), 'custom-field-of-start-date', true )); // EDIT THIS WITH YOUR OWN VALUE
        $end_date = date_i18n("Ymd\THis\Z", get_post_meta( get_the_ID(), 'custom-field-of-end-date', true )); // EDIT THIS WITH YOUR OWN VALUE
        $deadline = date_i18n("Ymd\THis\Z", get_post_meta( get_the_ID(), 'custom-field-of-deadline-date', true )); // EDIT THIS WITH YOUR OWN VALUE
        
 		// Otherwise, if your version of WP >= 5.3.0 use this code
 		
 		$start_date = get_post_meta( get_the_ID(), 'custom-field-of-start-date', true ); // EDIT THIS WITH YOUR OWN VALUE
        $end_date = get_post_meta( get_the_ID(), 'custom-field-of-end-date', true ); // EDIT THIS WITH YOUR OWN VALUE
        if($start_date != '' && !isValidTimeStamp($start_date)) {
            $start_date = strtotime($start_date);
 			$start_date = wp_date("Ymd\THis", $start_date);
        }
        if($end_date != '' && !isValidTimeStamp($end_date)) {
            $end_date = strtotime($end_date);
 			$end_date = wp_date('Ymd\THis', $end_date);
 		} else {
        	$end_date = wp_date("Ymd\THis", $start_date + (1 * 60 * 60)); // 1 hour after
        }    
 		$deadline = date_i18n("Ymd\THis\Z", get_post_meta( get_the_ID(), 'custom-field-of-deadline-date', true )); // EDIT THIS WITH YOUR OWN VALUE
 		
 		// The rest is the same for any version
 		$timestamp = date_i18n('Ymd\THis\Z',time(), true);
 		$uid = get_the_ID();
 		$created_date = get_post_time('Ymd\THis\Z', true, $uid );
 		$organiser = get_bloginfo('name'); // EDIT THIS WITH YOUR OWN VALUE
        $address = ''; // EDIT THIS WITH YOUR OWN VALUE
        $url = get_the_permalink();
        $summary = get_the_excerpt();
        $content = html_entity_decode(trim(preg_replace('/\s\s+/', ' ', get_the_content()))); // removes newlines and double spaces
        $title = html_entity_decode(get_the_title());

        //Give the iCal export a filename
        $filename = urlencode( $title.'-ical-' . date('Y-m-d') . '.ics' );
        $eol = "\r\n";

        //Collect output
        ob_start();

        // Set the correct headers for this file
        header("Content-Description: File Transfer");
        header("Content-Disposition: attachment; filename=".$filename);
        header('Content-type: text/calendar; charset=utf-8');
        header("Pragma: 0");
        header("Expires: 0");

 // The below ics structure MUST NOT have spaces before each line
 // Credit for the .ics structure goes to https://gist.github.com/jakebellacera/635416
 ?>
 BEGIN:VCALENDAR
 VERSION:2.0
 PRODID:-//<?php echo get_bloginfo('name'); ?> //NONSGML Events //EN
 CALSCALE:GREGORIAN
 X-WR-CALNAME:<?php echo get_bloginfo('name').$eol;?>
 BEGIN:VEVENT
 CREATED:<?php echo $created_date.$eol;?>
 UID:<?php echo $uid.$eol;?>
 DTEND;VALUE=DATE:<?php echo $end_date.$eol; ?>
 DTSTART;VALUE=DATE:<?php echo $start_date.$eol; ?>
 DTSTAMP:<?php echo $timestamp.$eol; ?>
 LOCATION:<?php echo escapeString($address).$eol; ?>
 DESCRIPTION:<?php echo $content.$eol; ?>
 SUMMARY:<?php echo $title.$eol; ?>
 ORGANIZER:<?php echo escapeString($organiser).$eol;?>
 URL;VALUE=URI:<?php echo escapeString($url).$eol; ?>
 TRANSP:OPAQUE
 BEGIN:VALARM
 ACTION:DISPLAY
 TRIGGER;VALUE=DATE-TIME:<?php echo $deadline.$eol; ?>
 DESCRIPTION:Reminder for <?php echo escapeString(get_the_title()); echo $eol; ?>
 END:VALARM
 END:VEVENT
 <?php
        endwhile;
 ?>
 END:VCALENDAR
 <?php
        //Collect output and echo
        $eventsical = ob_get_contents();
        ob_end_clean();
        echo $eventsical;
        exit();

    endif;

 }
 ?>

 USAGE in TEMPLATE

 <a href="<?php echo get_feed_link('calendar'); ?>?id=<?php echo get_the_ID(); ?>"> Download the ics/ical </a>
	<?php

	/*
	For a better understanding of ics requirements and time formats
	please check https://gist.github.com/jakebellacera/635416
	*/

	// UTILS

	// Check if string is a timestamp
	function isValidTimeStamp($timestamp) {
	//if($timestamp == '') return;
	return ((string) (int) $timestamp === $timestamp)
	&& ($timestamp <= PHP_INT_MAX)
	&& ($timestamp >= ~PHP_INT_MAX);
	}

	// Escapes a string of characters
	function escapeString($string) {
	return preg_replace('/([\,;])/','\\\$1', $string);
	}

	// Shorten a string to desidered characters lenght - eg. shorter_version($string, 100);
	function shorter_version($string, $lenght) {
	if (strlen($string) >= $lenght) {
	return substr($string, 0, $lenght);
	} else {
	return $string;
	}
	}

	// Add a custom endpoint "calendar"
	function add_calendar_feed(){
	add_feed('calendar', 'export_ics');
	// Only uncomment these 2 lines the first time you load this script, to update WP rewrite rules, or in case you see a 404
	/*global $wp_rewrite;
	$wp_rewrite->flush_rules( false );*/
	}
	add_action('init', 'add_calendar_feed');

	// Calendar function
	function export_ics(){

	// Query the event
	$the_event = new WP_Query(array(
	'p' => $_REQUEST['id'],
	'post_type' => 'any',
	));

	if($the_event->have_posts()) :

	while($the_event->have_posts()) : $the_event->the_post();

	// If your version of WP < 5.3.0 use the code below

	/* The correct date format, for ALL dates is date_i18n('Ymd\THis\Z',time(), true)
	So if your date is not in this format, use that function */

	$start_date = date_i18n("Ymd\THis\Z", get_post_meta( get_the_ID(), 'custom-field-of-start-date', true )); // EDIT THIS WITH YOUR OWN VALUE
	$end_date = date_i18n("Ymd\THis\Z", get_post_meta( get_the_ID(), 'custom-field-of-end-date', true )); // EDIT THIS WITH YOUR OWN VALUE
	$deadline = date_i18n("Ymd\THis\Z", get_post_meta( get_the_ID(), 'custom-field-of-deadline-date', true )); // EDIT THIS WITH YOUR OWN VALUE

	// Otherwise, if your version of WP >= 5.3.0 use this code

	$start_date = get_post_meta( get_the_ID(), 'custom-field-of-start-date', true ); // EDIT THIS WITH YOUR OWN VALUE
	$end_date = get_post_meta( get_the_ID(), 'custom-field-of-end-date', true ); // EDIT THIS WITH YOUR OWN VALUE
	if($start_date != '' && !isValidTimeStamp($start_date)) {
	$start_date = strtotime($start_date);
	$start_date = wp_date("Ymd\THis", $start_date);
	}
	if($end_date != '' && !isValidTimeStamp($end_date)) {
	$end_date = strtotime($end_date);
	$end_date = wp_date('Ymd\THis', $end_date);
	} else {
	$end_date = wp_date("Ymd\THis", $start_date + (1 * 60 * 60)); // 1 hour after
	}
	$deadline = date_i18n("Ymd\THis\Z", get_post_meta( get_the_ID(), 'custom-field-of-deadline-date', true )); // EDIT THIS WITH YOUR OWN VALUE

	// The rest is the same for any version
	$timestamp = date_i18n('Ymd\THis\Z',time(), true);
	$uid = get_the_ID();
	$created_date = get_post_time('Ymd\THis\Z', true, $uid );
	$organiser = get_bloginfo('name'); // EDIT THIS WITH YOUR OWN VALUE
	$address = ''; // EDIT THIS WITH YOUR OWN VALUE
	$url = get_the_permalink();
	$summary = get_the_excerpt();
	$content = html_entity_decode(trim(preg_replace('/\s\s+/', ' ', get_the_content()))); // removes newlines and double spaces
	$title = html_entity_decode(get_the_title());

	//Give the iCal export a filename
	$filename = urlencode( $title.'-ical-' . date('Y-m-d') . '.ics' );
	$eol = "\r\n";

	//Collect output
	ob_start();

	// Set the correct headers for this file
	header("Content-Description: File Transfer");
	header("Content-Disposition: attachment; filename=".$filename);
	header('Content-type: text/calendar; charset=utf-8');
	header("Pragma: 0");
	header("Expires: 0");

	// The below ics structure MUST NOT have spaces before each line
	// Credit for the .ics structure goes to https://gist.github.com/jakebellacera/635416
	?>
	BEGIN:VCALENDAR
	VERSION:2.0
	PRODID:-//<?php echo get_bloginfo('name'); ?> //NONSGML Events //EN
	CALSCALE:GREGORIAN
	X-WR-CALNAME:<?php echo get_bloginfo('name').$eol;?>
	BEGIN:VEVENT
	CREATED:<?php echo $created_date.$eol;?>
	UID:<?php echo $uid.$eol;?>
	DTEND;VALUE=DATE:<?php echo $end_date.$eol; ?>
	DTSTART;VALUE=DATE:<?php echo $start_date.$eol; ?>
	DTSTAMP:<?php echo $timestamp.$eol; ?>
	LOCATION:<?php echo escapeString($address).$eol; ?>
	DESCRIPTION:<?php echo $content.$eol; ?>
	SUMMARY:<?php echo $title.$eol; ?>
	ORGANIZER:<?php echo escapeString($organiser).$eol;?>
	URL;VALUE=URI:<?php echo escapeString($url).$eol; ?>
	TRANSP:OPAQUE
	BEGIN:VALARM
	ACTION:DISPLAY
	TRIGGER;VALUE=DATE-TIME:<?php echo $deadline.$eol; ?>
	DESCRIPTION:Reminder for <?php echo escapeString(get_the_title()); echo $eol; ?>
	END:VALARM
	END:VEVENT
	<?php
	endwhile;
	?>
	END:VCALENDAR
	<?php
	//Collect output and echo
	$eventsical = ob_get_contents();
	ob_end_clean();
	echo $eventsical;
	exit();

	endif;

	}
	?>

	USAGE in TEMPLATE

	<a href="<?php echo get_feed_link('calendar'); ?>?id=<?php echo get_the_ID(); ?>"> Download the ics/ical </a>