<?php

namespace PR\DHL\REST_API;

use PR\DHL\REST_API\Interfaces\API_Auth_Interface;
use PR\DHL\REST_API\Interfaces\API_Driver_Interface;

/**
 * A generic REST API client implementation.
 *
 * This class does not expose any public methods. It is intended to be extended to create real client classes,
 * alleviating most of the work involved in using drivers, auth handlers, creating request and response objects as
 * well as ensuring proper request URL integrity.
 *
 * This class provides the following functionality:
 * - protected methods for sending GET, POST and DELETE requests
 * - a base URL property that is prepended to routes before creating and sending requests
 * - implements usage of a REST API driver for sending requests
 * - implements optional usage of an auth handler to authorize requests before sending them via the driver
 *
 * Example usage:
 *  ```
 *  class My_API_Client extends API_Client {
 *
 *      public function do_foo_bar( ) {
 *          $response = $this->post( 'foo/bar, array('some' => 'data') );
 *
 *          if ($response->status === 200) {
 *              return $response->body;
 *          }
 *
 *          throw new Exception($response->body->error_msg);
 *      }
 *
 *  }
 *  ```
 *
 * @since [*next-version*]
 */
class API_Client
{
    /**
     * The base URL for the REST API.
     *
     * @since [*next-version*]
     *
     * @var string
     */
    protected $base_url;

    /**
     * The REST API driver to use.
     *
     * @since [*next-version*]
     *
     * @var API_Driver_Interface
     */
    protected $driver;

    /**
     * The authorization driver to use.
     *
     * @since [*next-version*]
     *
     * @var API_Auth_Interface|null
     */
    protected $auth;

    /**
     * Constructor.
     *
     * @since [*next-version*]
     *
     * @param  string  $base_url  The base URL for the REST API.
     * @param  API_Driver_Interface  $driver  The REST API driver to use.
     * @param  API_Auth_Interface|null  $auth  Optional authorization driver to use.
     */
    public function __construct(string $base_url, API_Driver_Interface $driver, ?API_Auth_Interface $auth = null)
    {
        $this->base_url = $base_url;
        $this->driver = $driver;
        $this->auth = $auth;
    }

    /**
     * @since [*next-version*]
     */
    protected function get($route, array $params = [], array $headers = [], array $cookies = [])
    {
        return $this->send_request(Request::TYPE_GET, $route, $params, '', $headers, $cookies);
    }

    /**
     * @since [*next-version*]
     */
    protected function post($route, $body = '', array $headers = [], array $cookies = [])
    {
        return $this->send_request(Request::TYPE_POST, $route, [], $body, $headers, $cookies);
    }

    /**
     * @since [*next-version*]
     */
    protected function delete($route, $body = '', array $headers = [], array $cookies = [])
    {
        return $this->send_request(Request::TYPE_DELETE, $route, [], $body, $headers, $cookies);
    }

    /**
     * Sends a request using the internal driver.
     *
     * @since [*next-version*]
     *
     * @param  int  $type  The request type, either {@link TYPE_GET} or {@link TYPE_POST}.
     * @param  string  $route  The request route, relative to the REST API's base URL.
     * @param  array  $params  The GET params for this request.
     * @param  mixed|null  $body  The body of the request.
     * @param  array  $headers  The request headers to send.
     * @param  array  $cookies  The request cookies to send.
     * @return Response The response.
     */
    protected function send_request(
        $type,
        $route,
        array $params = [],
        $body = '',
        array $headers = [],
        array $cookies = []
    ) {
        // Generate the full URL and the request object
        $full_url = URL_Utils::merge_url_and_route($this->base_url, $route);
        $request = new Request($type, $full_url, $params, $body, $headers, $cookies);

        // If we have an authorization driver, authorize the request
        if ($this->auth !== null) {
            $request = $this->auth->authorize($request);
        }

        // Send the request using the driver and obtain the response
        $response = $this->driver->send($request);

        return $response;
    }
}