th-api.php

<?php
/**
 * Plugin Name: Theme Hybrid - API
 * Plugin URI: http://themehybrid.com
 * Description: API for ThemeHybrid.com
 * Version: 0.1.0
 * Author: Justin Tadlock
 * Author URI: http://justintadlock.com
 */

final class TH_API {

	/**
	 * The query variable field to look out for.
	 *
	 * @access public
	 * @since  0.1.0
	 * @var    string
	 */
	public $listener_query_var = 'api';

	/**
	 * The query variable value.
	 *
	 * @since  0.1.0
	 * @access public
	 * @var    string
	 */
	public $listener_query_var_value = '';

	/**
	 * Sets up needed actions and filters.
	 *
	 * @since  0.1.0
	 * @access public
	 * @return void
	 */
	function __construct() {

		/* Parses the request to see if our query vars were called. */
		add_action( 'parse_request', array( $this, 'parse_request' ) );

		/* Adds custom rewrite rules. */
		add_action( 'init', array( $this, 'rewrite' ) );
	}

	/**
	 * Creates custom rewrite rules for the API.  It gives us "/api" (?api) and 
	 * "/api/$var" (?api=$var).
	 *
	 * @since  0.1.0
	 * @access public
	 * @return void
	 */
	public function rewrite() {

		/* Adds the 'api' query var. */
		add_rewrite_tag( '%' . $this->listener_query_var . '%', '([^&]+)' );

		add_rewrite_rule( '^' . $this->listener_query_var . '$',          'index.php?' . $this->listener_query_var,                  'top' );
		add_rewrite_rule( '^' . $this->listener_query_var . '/?([^/]*)$', 'index.php?' . $this->listener_query_var . '=$matches[1]', 'top' );
	}

	/**
	 * Filters 'parse_request' to check for the matching query string for the API.
	 *
	 * @since  0.1.0
	 * @access public
	 * @param  object  $wp
	 */
	public function parse_request( $wp ) {

		//var_dump( $wp->query_vars );

		/* Check if the 'api' query var is set. */
		if ( isset( $wp->query_vars[ $this->listener_query_var ] ) ) {

			/* If so, get the value. */
			$this->listener_query_var_value = sanitize_key( $wp->query_vars[$this->listener_query_var] );

			/* If the value is 'update_theme', check for a theme update. */
			if ( 'update_theme' === $this->listener_query_var_value )
				$this->update_theme();

			/* Else, display the API root/index page. */
			else
				$this->do_api_root();
		}
	}

	/**
	 * Process the data sent.
	 *
	 * @since  0.1.0
	 * @access public
	 * @return void
	 */
	public function update_theme() {

		/* Check if the user agent is WordPress. */
		if ( true == stristr( $_SERVER['HTTP_USER_AGENT'], 'WordPress' ) ) {

			/* Unserialize the data sent. */
			$args = maybe_unserialize( stripslashes( $_POST['request'] ) );

			/* If we don't have a theme slug, bail. */
			if ( empty( $args->slug ) )
				exit;

			/* Get the theme object by name. */
			$theme = get_page_by_path( sanitize_title( $args['slug'] ), 'OBJECT', 'theme' );

			/* If no theme was returned, bail. */
			if ( empty( $theme ) )
				exit;

			/* Get and sanitize the data for the theme. */
			$new_version = strtolower( get_post_meta( $theme->ID, 'version_number', true ) );
			$package     = esc_url( get_post_meta( $theme->ID, 'download_url', true ) );
			$url         = esc_url( $args['theme_uri'] );

			/* If any of the required theme data isn't here, bail. */
			if ( empty( $new_version ) || empty( $package ) || empty( $url ) )
				exit;

			/* Make sure the package (theme download URL) is actually a ZIP file. */
			if ( !preg_match( "/^.*\.(zip)$/i", $package ) )
				exit;

			/* Set up the theme data in an array. */
			$data = array(
				'new_version' => $new_version,
				'package'     => $package,
				'url'         => $url
			);

			/* Print the serialized data. */
			print serialize( $data );
		}

		/* Make sure we don't keep loading the rest of the site. */
		exit;
	}

	/**
	 * Prints data for the API root page or any page with the 'api' query var that doesn't work.
	 *
	 * @todo Turn this into an actual page on the site with info about using the API.
	 *
	 * @since  0.1.0
	 * @access public
	 * @return void
	 */
	public function do_api_root() {

		echo 'API for <a href="http://themehybrid.com">ThemeHybrid.com</a>';
		exit;
	}
}

new TH_API();

?>