<?php

namespace Smush\Core\Background;

/**
 * Abstract WP_Async_Request class.
 *
 * @abstract
 */
abstract class Async_Request {
	/**
	 * Identifier
	 *
	 * @var mixed
	 * @access protected
	 */
	protected $identifier;

	/**
	 * Data
	 *
	 * (default value: array())
	 *
	 * @var array
	 * @access protected
	 */
	protected $data = array();

	/**
	 * Initiate new async request
	 */
	public function __construct( $identifier ) {
		$this->identifier = $identifier;

		add_action( 'wp_ajax_' . $this->identifier, array( $this, 'maybe_handle' ) );
		add_action( 'wp_ajax_nopriv_' . $this->identifier, array( $this, 'maybe_handle' ) );
	}

	/**
	 * Set data used during the request
	 *
	 * @param array $data Data.
	 *
	 * @return $this
	 */
	public function data( $data ) {
		$this->data = $data;

		return $this;
	}

	/**
	 * Dispatch the async request
	 *
	 * @param int $instance_id
	 *
	 * @return array|\WP_Error
	 */
	public function dispatch( $instance_id ) {
		$query_args = $this->get_query_args( $instance_id );
		$url        = add_query_arg( $query_args, $this->get_query_url() );
		$args       = $this->get_post_args();

		return wp_remote_post( esc_url_raw( $url ), $args );
	}

	/**
	 * Get query args
	 *
	 * @return array
	 */
	protected function get_query_args( $instance_id ) {
		if ( property_exists( $this, 'query_args' ) ) {
			return $this->query_args;
		}

		return array(
			'action'      => $this->identifier,
			'nonce'       => wp_create_nonce( $this->identifier ),
			'instance_id' => $instance_id,
		);
	}

	/**
	 * Get query URL
	 *
	 * @return string
	 */
	protected function get_query_url() {
		if ( property_exists( $this, 'query_url' ) ) {
			return $this->query_url;
		}

		return admin_url( 'admin-ajax.php' );
	}

	/**
	 * Get process headers.
	 *
	 * @return array
	 */
	protected function get_process_headers() {
		$headers = array();
		if ( isset( $_SERVER['PHP_AUTH_USER'] ) && isset( $_SERVER['PHP_AUTH_PW'] ) ) {
			$headers['Authorization'] = 'Basic ' . base64_encode( wp_unslash( $_SERVER['PHP_AUTH_USER'] ) . ':' . wp_unslash( $_SERVER['PHP_AUTH_PW'] ) );
		}

		return apply_filters( $this->identifier . '_process_headers', $headers );
	}

	/**
	 * Get post args
	 *
	 * @return array
	 */
	protected function get_post_args() {
		if ( property_exists( $this, 'post_args' ) ) {
			return $this->post_args;
		}

		$post_args = array(
			'timeout'   => 0.01,
			'blocking'  => false,
			'body'      => $this->data,
			'cookies'   => $_COOKIE,
			'sslverify' => apply_filters( 'https_local_ssl_verify', false ),
		);

		$headers = $this->get_process_headers();
		if ( ! empty( $headers ) ) {
			$post_args['headers'] = $headers;
		}

		return $post_args;
	}

	/**
	 * Maybe handle
	 *
	 * Check for correct nonce and pass to handler.
	 */
	public function maybe_handle() {
		// Don't lock up other requests while processing
		session_write_close();

		check_ajax_referer( $this->identifier, 'nonce' );

		$instance_id = empty( $_GET['instance_id'] )
			? false
			: sanitize_key( $_GET['instance_id'] );
		$this->handle( $instance_id );

		wp_die();
	}

	/**
	 * Handle
	 *
	 * Override this method to perform any actions required
	 * during the async request.
	 */
	abstract protected function handle( $instance_id );

}