- Refactors Mailer class

- Refactors SendingQueue worker class
- Adds Maier router with a send() method + ability to specify sending method
- Updates tests
- Introduces 'stopping' and 'starting' cron states
- Improves cron control mechanism
Closes #276

lib/Mailer/Methods/SendGrid.php

@@ -0,0 +1,59 @@
+<?php
+namespace MailPoet\Mailer\Methods;
+
+if(!defined('ABSPATH')) exit;
+
+class SendGrid {
+  function __construct($apiKey, $fromEmail, $fromName) {
+    $this->url = 'https://api.sendgrid.com/api/mail.send.json';
+    $this->apiKey = $apiKey;
+    $this->fromEmail = $fromEmail;
+    $this->fromName = $fromName;
+  }
+
+  function send($newsletter, $subscriber) {
+    $result = wp_remote_post(
+      $this->url,
+      $this->request($newsletter, $subscriber)
+    );
+    return (
+      !is_wp_error($result) === true &&
+      !preg_match('!invalid!', $result['body']) === true &&
+      !isset(json_decode($result['body'], true)['errors']) === true &&
+      wp_remote_retrieve_response_code($result) === 200
+    );
+  }
+
+  function getBody($newsletter, $subscriber) {
+    $body = array(
+      'to' => $subscriber,
+      'from' => $this->fromEmail,
+      'fromname' => $this->fromName,
+      'subject' => $newsletter['subject']
+    );
+    if(!empty($newsletter['body']['html'])) {
+      $body['html'] = $newsletter['body']['html'];
+    }
+    if(!empty($newsletter['body']['text'])) {
+      $body['text'] = $newsletter['body']['text'];
+    }
+    return $body;
+  }
+
+  function auth() {
+    return 'Bearer ' . $this->apiKey;
+  }
+
+  function request($newsletter, $subscriber) {
+    $body = $this->getBody($newsletter, $subscriber);
+    return array(
+      'timeout' => 10,
+      'httpversion' => '1.1',
+      'method' => 'POST',
+      'headers' => array(
+        'Authorization' => $this->auth()
+      ),
+      'body' => urldecode(http_build_query($body))
+    );
+  }
+}