Multi backend plugin

• Add backend class.
• Add php docstrings.
• Hide multipart from public API.

includes/class-http-backend.php

+<?php
+
+namespace WPCT_HTTP;
+
+use Exception;
+
+/**
+ * HTTP Backend
+ *
+ * @since 3.0.0
+ */
+class Http_Backend
+{
+    /**
+     * Handle backend data.
+     *
+     * @since 3.0.0
+     */
+    private $data = null;
+
+    /**
+     * Store backend data
+     *
+     * @since 3.0.0
+     */
+    public function __construct($name)
+    {
+        $this->data = $this->get_backend($name);
+        if (!$this->data) {
+            throw new Exception("Http backend error: Unkown backend with name {$name}");
+        }
+    }
+
+    /**
+     * Backend data getter.
+     *
+     * @since 3.0.0
+     */
+    private function get_backend($name)
+    {
+        $backends = Settings::get_setting('wpct-http-bridge', 'general', 'backends');
+        foreach ($backends as $backend) {
+            if ($backend['name'] === $name) {
+                return $backend;
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Intercept class gets and lookup on backend data.
+     *
+     * @since 3.0.0
+     */
+    public function __get($attr)
+    {
+        if (isset($this->data[$attr])) {
+            return $this->data[$attr];
+        }
+
+        return null;
+    }
+
+    /**
+     * Get backend absolute URL.
+     *
+     * @since 3.0.0
+     *
+     * @param string $path URL relative path.
+     * @return string $url Absolute URL.
+     */
+    public function get_endpoint_url($path)
+    {
+        $url_data = parse_url($path);
+        if (isset($url_data['scheme'])) {
+            return $path;
+        }
+
+        $base_url = $this->base_url;
+        return preg_replace('/\/$/', '', $base_url) . '/' . preg_replace('/^\//', '', $path);
+    }
+
+    /**
+     * Get backend default headers.
+     *
+     * @since 3.0.0
+     *
+     * @return array $headers Backend headers.
+     */
+    public function get_headers()
+    {
+        $headers = [];
+        foreach ($this->headers as $header) {
+            $headers[strtolower(trim($header['name']))] = trim($header['value']);
+        }
+
+        return $headers;
+    }
+}
+
+// Get new backend instance.
+add_filter('wpct_http_backend', function ($null, $name) {
+    return new Http_Backend($name);
+}, 10, 2);