<?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;
	}
}