updater.php

<?php

class wp_auto_update
{
    /**
     * The plugin current version
     * @var string
     */
    public $current_version;

    /**
     * The plugin remote update path
     * @var string
     */
    public $update_path;

    /**
     * Plugin Slug (plugin_directory/plugin_file.php)
     * @var string
     */
    public $plugin_slug;

    /**
     * Plugin name (plugin_file)
     * @var string
     */
    public $slug;

    /**
     * Initialize a new instance of the WordPress Auto-Update class
     * @param string $current_version
     * @param string $update_path
     * @param string $plugin_slug
     */
    function __construct($current_version, $update_path, $plugin_slug)
    {
        // Set the class public variables
        $this->current_version = $current_version;
        $this->update_path = $update_path;
        $this->plugin_slug = $plugin_slug;
        list ($t1, $t2) = explode('/', $plugin_slug);
        $this->slug = str_replace('.php', '', $t2);

        // define the alternative API for updating checking
        add_filter('pre_set_site_transient_update_plugins', array(&$this, 'check_update'));

        // Define the alternative response for information checking
        add_filter('plugins_api', array(&$this, 'check_info'), 10, 3);
    }

    /**
     * Add our self-hosted autoupdate plugin to the filter transient
     *
     * @param $transient
     * @return object $ transient
     */
    public function check_update($transient)
    {
        if (empty($transient->checked)) {
            return $transient;
        }

        // Get the remote version
        $remote_version = $this->getRemote_version();

        // If a newer version is available, add the update
        if (version_compare($this->current_version, $remote_version, '<')) {
            $obj = new stdClass();
            $obj->slug = $this->slug;
            $obj->new_version = $remote_version;
            $obj->url = $this->update_path;
            $obj->package = $this->update_path;
            $transient->response[$this->plugin_slug] = $obj;
        }
        var_dump($transient);
        return $transient;
    }

    /**
     * Add our self-hosted description to the filter
     *
     * @param boolean $false
     * @param array $action
     * @param object $arg
     * @return bool|object
     */
    public function check_info($false, $action, $arg)
    {
        if ($arg->slug === $this->slug) {
            $information = $this->getRemote_information();
            return $information;
        }
        return false;
    }

    /**
     * Return the remote version
     * @return string $remote_version
     */
    public function getRemote_version()
    {
        logEvent("Getting Remote Version.");
        $request = wp_remote_post($this->update_path, array('body' => array('action' => 'version')));
        if (!is_wp_error($request) || wp_remote_retrieve_response_code($request) === 200) {
            return $request['body'];
        }
        return false;
    }

    /**
     * Get information about the remote version
     * @return bool|object
     */
    public function getRemote_information()
    {
        $request = wp_remote_post($this->update_path, array('body' => array('action' => 'info')));
        if (!is_wp_error($request) || wp_remote_retrieve_response_code($request) === 200) {
            return unserialize($request['body']);
        }
        return false;
    }

    /**
     * Return the status of the plugin licensing
     * @return boolean $remote_license
     */
    public function getRemote_license()
    {
        $request = wp_remote_post($this->update_path, array('body' => array('action' => 'license')));
        if (!is_wp_error($request) || wp_remote_retrieve_response_code($request) === 200) {
            return $request['body'];
        }
        return false;
    }
}