Best_Sellers.php

<?php

add_action( 'widgets_init', create_function( '', 'register_widget("Best_Sellers_Widget");'));

class Best_Sellers_Widget extends WP_Widget {

	static $items = array('first', 'second', 'third');

	public function __construct() {
		$widget_options = array(
			'classname' => 'best_sellers',
			'description' => 'A list of products that are your best sellers'
		);
		parent::__construct("best_sellers", "Best Sellers", $widget_options);
	}

	public function form($instance) {
		$instance = wp_parse_args(
			(array)$instance,
			array(
				'title' => '',
				'first' => '',
				'second' => '',
				'third' => ''
			)
		);

		$form = sprintf(
			'<p>
				<label for="%s">Title</label>
				<input id="%s" name="%s" value="%s" class="widefat" type="text" />
			</p>',
			$this->get_field_id('title'),
			$this->get_field_id('title'),
			$this->get_field_name('title'),
			$instance['title']
		);

		$products = get_posts(array('post_type' => 'product'));

		foreach (self::$items as $item) {
			$form .= sprintf(
				'<div><label for="%s">%s Best Seller</label><select id="%s" name="%s"><option value=""></option>',
				$this->get_field_id($item),
				ucfirst($item),
				$this->get_field_id($item),
				$this->get_field_name($item)
			);

			foreach($products as $product) {
				$form .= sprintf(
					'<option value="%s" %s>%s</option>',
					$product->ID,
					($instance[$item] == $product->ID) ? 'selected' : '',
					$product->post_title
				);

			}

			$form .= sprintf('</select></div>');
		}

		echo $form;

	}

	public function update($new_instance, $old_instance) {
		$instance = $old_instance;

		$instance['title'] = $new_instance['title'];
		foreach (self::$items as $item)
			$instance[$item] = $new_instance[$item];

		return $instance;
	}

	public function widget($args, $instance) {
		global $post;
		extract($args, EXTR_SKIP);

		$title = apply_filters('widget_title', $instance['title'] );

		echo $before_widget;
		echo '<ul>';
			if ($title) echo $before_title . $title . $after_title;

			echo '<ul class="small-block-grid-1 large-block-grid-3">';

				foreach (self::$items as $item) {
					$post = get_post($instance[$item]);
					setup_postdata($post);
					echo sprintf('
						<li>
							<h4><a href="%s">%s</a></h4>
							<a href="%s">%s</a>
						</li>',
						get_permalink(),
						get_the_title(),
						get_permalink(),
						"asdasd"
					);
				}

			echo '</ul>';

		echo '</ul>';
		echo $after_widget;
	}

}