Apply discount on the cheapest item in WooCommerce

/**

* Snippet Name:	Apply discount on the cheapest item

*/

add_action( 'woocommerce_before_calculate_totals', 'apply_discount_on_cheapest_item', 999 );

function apply_discount_on_cheapest_item( $cart ) {

    if ( is_admin() && ! defined( 'DOING_AJAX' ) ) return;

    if ( did_action( 'woocommerce_before_calculate_totals' ) >= 2 ) return;

    if ( count( $cart->get_cart() ) < 2 ) return; // Return if less than 2 products

    $min = PHP_FLOAT_MAX;

    // Find the cheapest item

    foreach ( $cart->get_cart() as $cart_item_key => $cart_item ) {

      if ( $cart_item['data']->get_price() <= $min ) {

         $min = $cart_item['data']->get_price();

         $cheapest = $cart_item_key;

      }

    }

    // Reduce the cheapest item price by 50%

    foreach ( $cart->get_cart() as $cart_item_key => $cart_item ) {

      if ( $cheapest == $cart_item_key ) {

         $price = $cart_item['data']->get_price() / 2;

         $cart_item['data']->set_price( $price );

         $cart_item['data']->set_sale_price( $price );

      }

    }

}