WordPress: Countdown, Redirect

countdown-redirect.php

<?php

//Plugin Name: Countdown, Redirect
//Description: Just a demo, thus has limitations


new Countdown_Redirect();

class Countdown_Redirect {

	function __construct() {
		add_action( 'admin_menu', array( &$this, 'menu' ) );
		add_action( 'wp_head', array( &$this, 'countdown_js' ) );
	}
	
	function menu() {
		add_options_page( 'Countdown, Redirect', 'Countdown, Redirect', 'edit_posts', __FILE__, array( &$this, 'page' ) );
	}
	
	function page() {
	?><div class="wrap"><h2><?php _e('Countdown, Redirect'); ?></h2><?php
		if (isset($_POST['countdown_page'])) {
			
			update_option( 'countdown_redirect', array( 
				'onpage' => intval( $_POST['countdown_page'] ),
				'url' => esc_url( $_POST['redirect_url'] ),
				'timeout' => intval( $_POST['timeout'] ),
			) );
			echo '<div class="updated"><p>Updated!</p></div>';
		}
		extract( get_option( 'countdown_redirect', array( 'onpage' => '','url' => '','timeout' => '' ) ) );
		?>
		<form method="post">
		<label>Page ID: <input type="number" name="countdown_page" value="<?php echo $onpage; ?>" /></label><br />
		<label>Redirect URL: <input type="url" name="redirect_url" value="<?php echo $url; ?>" /></label><br />
		<label>Timeout: <input type="number" name="timeout" value="<?php echo $timeout; ?>" /></label><br />
		<input type="submit" />
		</form>
		</form>
		</div><?php
	
	}
	
	function countdown_js() {
	extract ( get_option( 'countdown_redirect', array() ) );
	
	if ( ! isset( $onpage ) || ! is_page( $onpage ) ) return;
	?>
<script type="text/javascript">
var ss = <?php echo $timeout; ?>;
function countdown() {
	ss = ss-1;
	if (ss<0) {
		window.location="<?php echo $url; ?>";
	} else {
		document.getElementById("countdown").innerHTML=ss;
		window.setTimeout("countdown()", 1000);
	}
}
window.onload=countdown;
</script>
	<?php
	}
	
}