WPUpdates Theme Updater Class (with Envato API verification)

wp-updates-theme.php

<?php
/*
WPUpdates Theme Updater Class (with Envato API verification)
http://wp-updates.com
v1.1

Example Usage:
require_once('wp-updates-theme.php');
new WPUpdatesThemeUpdater( 'http://wp-updates.com/api/1/theme', 1, basename(get_template_directory()) );
*/

if( !class_exists('WPUpdatesThemeUpdater') ) {
    class WPUpdatesThemeUpdater {
    
        var $api_url;
    	var $theme_id;
    	var $theme_slug;
    
        function __construct( $api_url, $theme_id, $theme_slug ) {
    		$this->api_url = $api_url;
    		$this->theme_id = $theme_id;
    		$this->theme_slug = $theme_slug;
    
    		add_filter( 'pre_set_site_transient_update_themes', array(&$this, 'check_for_update') );
    		
    		// This is for testing only!
    		set_site_transient('update_themes', null);
    		
    		// Add notice that theme update is available
    		if( get_option( 'wpu_'. $this->theme_slug .'_update_available' ) ){
        		add_action( 'admin_notices', array(&$this, 'update_notice') );
    		}
    	}
    	
    	function check_for_update( $transient ) {
        	if (empty($transient->checked)) return $transient;
        	
        	/* Envato Verify Purchase */
        	$envato_username = ''; // your envato username
        	$envato_api_key = ''; // your envato API key
        	$envato_purchase_code = get_option('envato_purchase_code'); // the purchase code setting in your theme options
        	
        	$response = wp_remote_get( 'http://marketplace.envato.com/api/v3/'. $envato_username .'/'. $envato_api_key .'/verify-purchase:'. $envato_purchase_code .'.json' );
            if( is_wp_error( $response ) ) {
                return $transient;
            } else {
                $json_data = json_decode($response['body'], true);
                if(!isset($json_data['verify-purchase']['item_name'])){
                    update_option( 'wpu_'. $this->theme_slug .'_update_available', true );
                    return $transient;
                }
            }
            /* End Envato Verify Purchase */
        	
        	$request_args = array(
    		    'id' => $this->theme_id,
    		    'slug' => $this->theme_slug,
    			'version' => $transient->checked[$this->theme_slug]
    		);
    		$request_string = $this->prepare_request( 'theme_update', $request_args );
    		$raw_response = wp_remote_post( $this->api_url, $request_string );
        	
        	$response = null;
    		if( !is_wp_error($raw_response) && ($raw_response['response']['code'] == 200) )
    			$response = unserialize($raw_response['body']);
    		
    		if( !empty($response) ) // Feed the update data into WP updater
    			$transient->response[$this->theme_slug] = $response;
        	
        	return $transient;
        }
        
        function prepare_request( $action, $args ) {
    		global $wp_version;
    		
    		return array(
    			'body' => array(
    				'action' => $action, 
    				'request' => serialize($args),
    				'api-key' => md5(home_url())
    			),
    			'user-agent' => 'WordPress/'. $wp_version .'; '. home_url()
    		);	
    	}
    	
    	function update_notice(){
    	    global $pagenow;
    	    // Change this to a theme setting page URL where users 
    	    // can enter their ThemeForest purchase code
    	    $theme_settings_link = admin_url( 'themes.php' );
    	    
            if ( $pagenow == 'themes.php' || $pagenow == 'update-core.php' ) {
                 $theme_name = 'current';
                 if( function_exists('wp_get_theme') ) $theme_name = '<strong>'. wp_get_theme() .'</strong>';
                 echo '<div class="updated">
                     <p>'. __( 'There is an update availble for the '. $theme_name .' theme, but your ThemeForest purchase code is invalid.' ) .' <a href="'. $theme_settings_link .'">'. __( 'Update settings' ) .'</a></p>
                 </div>';
            }
        }

    }
}

?>