Facebook Events – Exporting Facebook Page Events to Google Calendar

I've solved this with a little help from my friends and iCalcreator. Code as follows:

<?php
/*
To begin with, you will need an access token. This is complicated stuff - getting a regular one is easy, but we want one that lasts permanently. As described in Scenario 5 here: https://developers.facebook.com/roadmap/offline-access-removal/ , we need to:

1. Get a regular short-lived access token
2. Exchange it for a long-lived access token
3. Using our new access token, get a permanent page access token.

First, create a new Facebook app at https://developers.facebook.com/apps/ . It can be named whatever, it's not going to be really used. Fill in a domain - it doesn't matter which, just take one that shows simple HTML and doesn't do any redirects: I used my own static web page, http://jobjorn.se/ , but http://example.org/ may work too.

As instructed by MPaulo on Stack Overflow here: https://stackoverflow.com/a/11238327/564628 , use the app id - from your newly created app - and visit this page:
https://www.facebook.com/dialog/oauth?client_id=MY_APP_ID&redirect_uri=MY_SITE_URL&scope=manage_pages&response_type=token
Be sure to replace "MY_APP_ID" and "MY_SITE_URL".

Then, exchange your short-lived access token for a long-lived access token by visiting this page:
https://graph.facebook.com/oauth/access_token?client_id=MY_APP_ID&client_secret=MY_APP_SECRET&grant_type=fb_exchange_token&fb_exchange_token=YOUR_ACCESS_TOKEN
Be sure to replace "MY_APP_ID", "MY_APP_SECRET", and "YOUR_ACCESS_TOKEN" (the last being the access token you received from the first page)

Finally, get your page access token here:
https://graph.facebook.com/me/accounts?access_token=YOUR_NEW_ACCESS_TOKEN
Be sure to replace "YOUR_NEW_ACCESS_TOKEN" (the access token you recieved from the second page)

Paste it below. It should be permanent, but due to a bug it might only last two months - see https://developers.facebook.com/bugs/151056591697025 for details. It seems to have been fixed however. You can test it here: https://developers.facebook.com/tools/debug/access_token
*/

// You will need to edit these variables.
$access_token = "";
$page = "";

// We don't want to query the Facebook Graph API over and over, so we'll cache our results. You can force the cache to update by visiting the script and appending "?f=true", otherwise it will only run (rather than display the cache) if the cache is older than 3600 seconds (one hour).
$cache = $page . ".cache";
$f = false;
if($_GET['f'] == "true"){
    $f = true;
}
if(!file_exists($cache) || filemtime($cache) <= time()-3600 || $f){

    // Get and decode the data - your page's event list - from the API
    $graph_url = "https://graph.facebook.com/" . $page . "/events?access_token=" . $access_token;
    $data = file_get_contents($graph_url);
    $data = json_decode($data);

    if(!empty($data->error)){
        echo '<b>$data error</b><br />';
        echo $data->error->type . " error (" . $data->error->code . "/" . $data->error->error_subcode . "): " . $data->error->message;
        exit;
    }

    // Go through the list of events, and get and decode more detailed information on each event.
    foreach ($data->data as $event){
        $event_data = file_get_contents("https://graph.facebook.com/" . $event->id . "?access_token=" . $access_token);
        $event_data = json_decode($event_data);

        if(!empty($event_data->error)){
            echo '<b>$event_data error</b><br />';
            echo $event_data->error->type . " error (" . $event_data->error->code . "/" . $event_data->error->error_subcode . "): " . $event_data->error->message;
            exit;
        }
        // Store it in an array for later use.
        $events[] = $event_data;
    }

    // We're now done fetching the data from Facebook's Graph API. Now we'll have to create an iCal file.

    // This requires the iCalcreator PHP class, which you can downloead from kigkonsult at kigkonsult.se/iCalcreator/index.php
    require_once("icalcreator/iCalcreator.class.php");

    // Create the calendar, set up some basic properties
    $c = new vcalendar(array('unique_id' => $page));

    $c->setProperty('X-WR-CALNAME', $page . ' events');
    $c->setProperty('X-WR-CALDESC', 'Facebook events for ' . $page);
    $c->setProperty('X-WR-TIMEZONE', $events[0]->timezone); // We assume all of the events use the same timezone.

    // Loop through the events, create event components in the calendar
    foreach($events as $key => $event){
        $e[$key] = & $c->newComponent('vevent');

        $e[$key]->setProperty('summary', $event->name);
        $e[$key]->setProperty('dtstart', $event->start_time);
        $e[$key]->setProperty('dtend', $event->end_time);
        $e[$key]->setProperty('description', $event->description . "\n\nhttp://www.facebook.com/events/" . $event->id);
        $e[$key]->setProperty('location', $event->location);
    }

    // Remove the cache if it exists
    if(file_exists($cache)){
        unlink($cache);
    }

    // Open (create) the cache file
    if(!$handle = fopen($cache, 'w')){
        echo "Cannot open output file: " . $cache;
        exit;
    }

    // Write the calendar to the cache
    if(fwrite($handle, $c->createCalendar()) === FALSE){
        echo "Cannot write to output file: " . $cache;
        exit;
    }

    // Close the cache file
    fclose($handle);
}

// Now we've got the calendar in the cache file, either newly generated and stored there just a few lines ago or from earlier. Now we'll just display it.

header("Content-Type: text/calendar; charset=UTF-8");
header("Content-Disposition: filename=" . $page . ".ics");
require($cache);
?>