- Refactors API

- Updates existing classes to use the refactored API methods

lib/API/API.php

@@ -0,0 +1,71 @@
+<?php
+namespace MailPoet\API;
+
+use MailPoet\Util\Helpers;
+
+if(!defined('ABSPATH')) exit;
+
+class API {
+  public $api_request;
+  public $endpoint;
+  public $action;
+  public $data;
+  const API_NAME = 'mailpoet_api';
+  const ENDPOINT_NAMESCAPE = '\MailPoet\API\Endpoints\\';
+
+  function __construct() {
+    $this->api_request = isset($_GET[self::API_NAME]) ? true : false;
+    $this->endpoint = isset($_GET['endpoint']) ?
+      Helpers::underscoreToCamelCase($_GET['endpoint']) :
+      false;
+    $this->endpoint = self::ENDPOINT_NAMESCAPE . ucfirst($this->endpoint);
+    $this->action = isset($_GET['action']) ?
+      Helpers::underscoreToCamelCase($_GET['action']) :
+      false;
+    $this->data = $this->validateRequestData();
+  }
+
+  function init() {
+    if(!$this->api_request) return;
+    if(!$this->endpoint) {
+      $this->terminateRequest(404, __('Invalid API endpoint.'));
+    }
+    $this->callEndpoint($this->endpoint, $this->action, $this->data);
+  }
+
+  function callEndpoint($endpoint, $action, $data) {
+    if(!method_exists($endpoint, $action)) {
+      $this->terminateRequest(404, __('Invalid API action.'));
+    }
+    call_user_func(
+      array(
+        $endpoint,
+        $action
+      ),
+      $data
+    );
+  }
+
+  function validateRequestData() {
+    if(!isset($_GET['data'])) return false;
+    $data = base64_decode($_GET['data']);
+    return (is_serialized($data)) ?
+      unserialize($data) :
+      $this->terminateRequest(404, __('Invalid API data format.'));
+  }
+
+  static function buildRequest($endpoint, $action, $data) {
+    $params = array(
+      self::API_NAME => '',
+      'endpoint' => $endpoint,
+      'action' => $action,
+      'data' => $data
+    );
+    return add_query_arg($params, home_url());
+  }
+
+  function terminateRequest($code, $message) {
+    status_header($code, $message);
+    exit;
+  }
+}