<?php

class MC4WP_API_V3_Client
{
    /**
    * @var string
    */
    private $api_key;

    /**
    * @var string
    */
    private $api_url = 'https://api.mailchimp.com/3.0/';

    /**
    * @var array
    */
    private $last_response;

    /**
    * @var array
    */
    private $last_request;

    /**
    * Constructor
    *
    * @param string $api_key
    */
    public function __construct($api_key)
    {
        $this->api_key = $api_key;

        $dash_position = strpos($api_key, '-');
        if ($dash_position !== false) {
            $this->api_url = str_replace('//api.', '//' . substr($api_key, $dash_position + 1) . '.api.', $this->api_url);
        }
    }


    /**
    * @param string $resource
    * @param array $args
    *
    * @return mixed
    * @throws MC4WP_API_Exception
    */
    public function get($resource, array $args = array())
    {
        return $this->request('GET', $resource, $args);
    }

    /**
    * @param string $resource
    * @param array $data
    *
    * @return mixed
    * @throws MC4WP_API_Exception
    */
    public function post($resource, array $data)
    {
        return $this->request('POST', $resource, $data);
    }

    /**
    * @param string $resource
    * @param array $data
    * @return mixed
    * @throws MC4WP_API_Exception
    */
    public function put($resource, array $data)
    {
        return $this->request('PUT', $resource, $data);
    }

    /**
    * @param string $resource
    * @param array $data
    * @return mixed
    * @throws MC4WP_API_Exception
    */
    public function patch($resource, array $data)
    {
        return $this->request('PATCH', $resource, $data);
    }

    /**
    * @param string $resource
    * @return mixed
    * @throws MC4WP_API_Exception
    */
    public function delete($resource)
    {
        return $this->request('DELETE', $resource);
    }

    /**
    * @param string $method
    * @param string $resource
    * @param array $data
    *
    * @return mixed
    *
    * @throws MC4WP_API_Exception
    */
    private function request($method, $resource, array $data = array())
    {
        $this->reset();

        // don't bother if no API key was given.
        if (empty($this->api_key)) {
            throw new MC4WP_API_Exception('Missing API key', 001);
        }

        $method = strtoupper(trim($method));
        $url    = $this->api_url . ltrim($resource, '/');
        $args   = array(
            'method'    => $method,
            'headers'   => $this->get_headers(),
            'timeout'   => 20,
            'sslverify' => apply_filters('mc4wp_use_sslverify', true),
        );

        if (! empty($data)) {
            if (in_array($method, array( 'GET', 'DELETE' ), true)) {
                $url = add_query_arg($data, $url);
            } else {
                $args['headers']['Content-Type'] = 'application/json';
                $args['body']                    = json_encode($data);
            }
        }

        /**
        * Filter the request arguments for all requests generated by this class
        *
        * @param array $args
        */
        $args = apply_filters('mc4wp_http_request_args', $args, $url);

        // perform request
        $response = wp_remote_request($url, $args);

        // store request & response
        $args['url']         = $url;
        $this->last_request  = $args;
        $this->last_response = $response;

        // parse response
        $data = $this->parse_response($response);

        return $data;
    }

    /**
    * @return array
    */
    private function get_headers()
    {
        global $wp_version;

        $headers = array(
            'Authorization' => sprintf('Basic %s', base64_encode('mc4wp:' . $this->api_key)),
            'User-Agent'    => sprintf('mc4wp/%s; WordPress/%s; %s', MC4WP_VERSION, $wp_version, home_url()),
        );

        // Copy Accept-Language from browser headers
        if (! empty($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {
            $headers['Accept-Language'] = $_SERVER['HTTP_ACCEPT_LANGUAGE'];
        }

        return $headers;
    }

    /**
    * @param array|WP_Error $response
    *
    * @return mixed
    *
    * @throws MC4WP_API_Connection_Exception|MC4WP_API_Resource_Not_Found_Exception|MC4WP_API_Exception
    */
    private function parse_response($response)
    {
        if ($response instanceof WP_Error) {
            throw new MC4WP_API_Connection_Exception($response->get_error_message(), (int) $response->get_error_code(), $this->last_request);
        }

        // decode response body
        $code    = (int) wp_remote_retrieve_response_code($response);
        $message = wp_remote_retrieve_response_message($response);
        $body    = wp_remote_retrieve_body($response);

        // set body to "true" in case Mailchimp returned No Content
        if ($code < 300 && empty($body)) {
            $body = 'true';
        }

        $data = json_decode($body);
        if ($code >= 400) {
            // check for akamai errors
            // {"type":"akamai_error_message","title":"akamai_503","status":503,"ref_no":"Reference Number: 00.950e16c3.1498559813.1450dbe2"}
            if (is_object($data) && isset($data->type) && $data->type === 'akamai_error_message') {
                throw new MC4WP_API_Connection_Exception($message, $code, $this->last_request, $this->last_response, $data);
            }

            if ($code === 404) {
                throw new MC4WP_API_Resource_Not_Found_Exception($message, $code, $this->last_request, $this->last_response, $data);
            }

            // mailchimp returned an error..
            throw new MC4WP_API_Exception($message, $code, $this->last_request, $this->last_response, $data);
        }

        // throw exception if unable to decode response
        if ($data === null) {
            throw new MC4WP_API_Exception($message, $code, $this->last_request, $this->last_response);
        }

        return $data;
    }

    /**
    * Empties all data from previous response
    */
    private function reset()
    {
        $this->last_response = null;
        $this->last_request  = null;
    }

    /**
    * @return string
    */
    public function get_last_response_body()
    {
        return wp_remote_retrieve_body($this->last_response);
    }

    /**
    * @return array
    */
    public function get_last_response_headers()
    {
        return wp_remote_retrieve_headers($this->last_response);
    }

    /**
    * @return array|WP_Error
    */
    public function get_last_response()
    {
        return $this->last_response;
    }
}