Email using cron and including attachment to email from moodle - php

Question

I would like to send emails only to users that have completed a specific course and add a pdf file (a certificate for completing the course) as attachment to the email, and do so at a specific time using moodle cron.
I have looked at some plugins to find out how it's done, but I'm still not sure how exactly I should do this.
I need:
1. to know how I would add an attachment to an email (and which API to use),
2. how I would use cron to send the emails to the desired group at a certain time,
3. how to retrieve users that have completed the course so that I could send emails (with attachment) to them.
Thanks in advance.
(I'm using moodle version 3.0)

Answer 1

This is an overview.
First create a local plugin. For example /local/yourplugin
https://docs.moodle.org/dev/Local_plugins
Then set up a message provider
https://docs.moodle.org/dev/Message_API
defined('MOODLE_INTERNAL') || die();
in local/yourplugin/db/messages.php
$messageproviders = array (
'coursecompleted' => array (
),
Then add an event observer - you will want to respond to the course_completed event
https://docs.moodle.org/dev/Event_2
in /local/yourpluginname/db/events.php
have something like
$observers = array(
array(
'eventname' => '\core\event\course_completed',
'callback' => 'local_yourplugin_observer::course_completed',
),
);
Now add the message code
Add something like this to '/local/message/classes/observer.php'
defined('MOODLE_INTERNAL') || die();
class local_yourplugin_observer {
/**
* Triggered when 'course_completed' event is triggered.
*
* #param \core\event\course_completed $event
* #return bool
*/
public static function course_completed(\core\event\course_completed $event) {
// Your code here.
$message = new \core\message\message();
$message->component = 'local_yourplugin'; // Name of your local plugin.
$message->name = 'coursecompleted'; // Name of message provider.
$message->userfrom = $USER;
$message->userto = $user;
$message->subject = 'message subject 1';
$message->fullmessage = 'message body';
$message->fullmessageformat = FORMAT_MARKDOWN;
$message->fullmessagehtml = '<p>message body</p>';
$message->smallmessage = 'small message';
$message->notification = '0';
$message->contexturl = 'http://GalaxyFarFarAway.com';
$message->contexturlname = 'Context name';
$message->replyto = "random#example.com";
$content = array('*' => array('header' => ' test ', 'footer' => ' test ')); // Extra content for specific processor
$message->set_additional_content('email', $content);
// Create a file instance.
$usercontext = context_user::instance($user->id);
$file = new stdClass;
$file->contextid = $usercontext->id;
$file->component = 'user';
$file->filearea = 'private';
$file->itemid = 0;
$file->filepath = '/';
$file->filename = '1.txt';
$file->source = 'test';
$fs = get_file_storage();
$file = $fs->create_file_from_string($file, 'file1 content');
$message->attachment = $file;
$messageid = message_send($message);
}
}