Install Bower dependencies on WordPress plugin activation

activate_plugin.php

<?php
register_activation_hook(__FILE__, 'activate_my_plugin');

function activate_my_plugin() {
  // Some basic securifying
  if ( ! current_user_can( 'activate_plugins' ) )
    return;
  $plugin = isset( $_REQUEST['plugin'] ) ? $_REQUEST['plugin'] : '';
  check_admin_referer( "activate-plugin_{$plugin}" );

  // Is Node Bower installed on server? Use that if so.
  if (`which bower`) {
    exec('cd ' . dirname(__FILE__) . ' && bower install');
  } else { // Otherwise download and use BowerPHP
    if (!file_exists(dirname(__FILE__) . '/bowerphp')) {
      // include WP_Http to download bowerphp.
      if( !class_exists( 'WP_Http' ) )
        include_once( ABSPATH . WPINC. '/class-http.php' );

      $request = new WP_Http;
      $result = $request->request('http://bowerphp.org/bowerphp.phar');
      file_put_contents(dirname(__FILE__) . '/bowerphp', $result['body']);
      exec('chmod ugo+x ' . dirname(__FILE__) . '/bowerphp');
    }

    //BowerPHP install
    exec('cd ' . dirname(__FILE__) . ' && ' . dirname(__FILE__) . '/bowerphp install');
  }
}