uninstall.php

<?php

/**
 * Fired when the plugin is uninstalled.
 *
 * We are not using an uninstall hook because WordPress performs bad when using it.
 * Even if below issue is "fixed", it did not resolve the performance issue.
 *
 * @see https://core.trac.wordpress.org/ticket/31792
 *
 *
 * When populating this file, consider the following flow
 * of control:
 *
 * - Check if the $_REQUEST['plugin'] content actually is coupon/coupon.php
 * - Check if the $_REQUEST['action'] content actually is delete-plugin
 * - Run a check_ajax_referer check to make sure it goes through authentication
 * - Run a current_user_can check to make sure current user can delete a plugin
 *
 * @todo Consider multisite. Once for a single site in the network, once sitewide.
 *
 * @link       https://github.com/lelinhtinh
 * @since      1.0.0
 * @package    Coupon
 */

/**
 * Perform Uninstall Actions.
 *
 * If uninstall not called from WordPress,
 * If no uninstall action,
 * If not this plugin,
 * If no caps,
 * then exit.
 *
 * @since 1.0.0
 */
function oms_uninstall()
{
	if (
		!defined('WP_UNINSTALL_PLUGIN')
		|| empty($_REQUEST)
		|| !isset($_REQUEST['plugin'])
		|| !isset($_REQUEST['action'])
		|| dirname(plugin_basename(__FILE__)) . '/coupon.php' !== $_REQUEST['plugin']
		|| 'delete-plugin' !== $_REQUEST['action']
		|| !check_ajax_referer('updates', '_ajax_nonce')
		|| !current_user_can('activate_plugins')
	) {
		exit;
	}

	/**
	 * It is now safe to perform your uninstall actions here.
	 *
	 * @see https://developer.wordpress.org/plugins/plugin-basics/uninstall-methods/#method-2-uninstall-php
	 */
	global $wpdb;
	$plugin_name = 'oms_coupons';
	$table_name = $wpdb->prefix . $plugin_name;
	$wpdb->query("DROP TABLE IF EXISTS {$table_name},{$table_name}_user;");
	delete_option($plugin_name . '_version');
}
oms_uninstall();