updater.php

<?php



class My_Plugin_Updater{
    protected $file;
    protected $plugin;
    protected $basename;
    protected $active;
    private $username;
    private $repository;
    private $authorize_token;
    private $github_response;

    public function __construct( $file ) {
        $this->file = $file;
        add_action( 'admin_init', array( $this, 'set_plugin_properties' ) );
        return $this;
    }

    public function set_plugin_properties() {
        $this->plugin   = get_plugin_data( $this->file );
        $this->basename = plugin_basename( $this->file );
        $this->active   = is_plugin_active( $this->basename );
    }
    

    public function set_username( $username ) {
        $this->username = $username;
    }
    public function set_repository( $repository ) {
        $this->repository = $repository;
    }
    public function authorize( $token ) {
        $this->authorize_token = $token;
    }

    private function get_repository_info() {
          if ( is_null( $this->github_response ) ) { // Do we have a response?
            $request_uri = sprintf( 'https://api.github.com/repos/%s/%s/releases', $this->username, $this->repository ); // Build URI
            if( $this->authorize_token ) { // Is there an access token?
                $request_uri = add_query_arg( 'access_token', $this->authorize_token, $request_uri ); // Append it
            }        
            $response = json_decode( wp_remote_retrieve_body( wp_remote_get( $request_uri ) ), true ); // Get JSON and parse it
            if( is_array( $response ) ) { // If it is an array
                $response = current( $response ); // Get the first item
            }
            //if( $this->authorize_token ) { // Is there an access token?
            //    $response['zipball_url'] = add_query_arg( 'access_token', $this->authorize_token, $response['zipball_url'] ); // Update our zip url with token
            //}
            $this->github_response = $response; // Set it to our property  
          }
    }

    public function initialize() {
      add_filter( 'pre_set_site_transient_update_plugins', array( $this, 'modify_transient' ), 10, 1 );
      add_filter( 'plugins_api', array( $this, 'plugin_popup' ), 10, 3);
      add_filter( 'upgrader_post_install', array( $this, 'after_install' ), 10, 3 );
    }

    public function modify_transient( $transient ) {

          if( property_exists( $transient, 'checked') ) { // Check if transient has a checked property
            if( $checked = $transient->checked ) { // Did WordPress check for updates?
              $this->get_repository_info(); // Get the repo info
              $out_of_date = version_compare( $this->github_response['tag_name'], $checked[$this->basename], 'gt' ); // Check if we're out of date
              if( $out_of_date ) {
                $new_files = $this->github_response['zipball_url']; // Get the ZIP
                $slug = current( explode('/', $this->basename ) ); // Create valid slug
                $plugin = array( // setup our plugin info
                  'url' => $this->plugin["PluginURI"],
                  'slug' => $slug,
                  'package' => $new_files,
                  'new_version' => $this->github_response['tag_name']
                );
                $transient->response[ $this->basename ] = (object) $plugin; // Return it in response
              }
            }
          }
          return $transient; // Return filtered transient
    }


    public function plugin_popup( $result, $action, $args ) {
          if( ! empty( $args->slug ) ) { // If there is a slug
            if( $args->slug == current( explode( '/' , $this->basename ) ) ) { // And it's our slug
              $this->get_repository_info(); // Get our repo info
              // Set it to an array
              $plugin = array(
                'name'              => $this->plugin["Name"],
                'slug'              => $this->basename,
                'version'           => $this->github_response['tag_name'],
                'author'            => $this->plugin["AuthorName"],
                'author_profile'    => $this->plugin["AuthorURI"],
                'last_updated'      => $this->github_response['published_at'],
                'homepage'          => $this->plugin["PluginURI"],
                'short_description' => $this->plugin["Description"],
                'sections'          => array( 
                    'Description'   => $this->plugin["Description"],
                    'Updates'       => $this->github_response['body'],
                ),
                'download_link'     => $this->github_response['zipball_url']
              );
              return (object) $plugin; // Return the data
            }
          }   
          return $result; // Otherwise return default
    }
    public function after_install( $response, $hook_extra, $result ) {
      global $wp_filesystem; // Get global FS object

      $install_directory = plugin_dir_path( $this->file ); // Our plugin directory 
      $wp_filesystem->move( $result['destination'], $install_directory ); // Move files to the plugin dir
      $result['destination'] = $install_directory; // Set the destination for the rest of the stack
       
      if ( $this->active ) { // If it was active
        activate_plugin( $this->basename ); // Reactivate
      }
      return $result;
    }


}