Automatically apply coupon to cart WooCommerce

auto-coupon-woo.php

add_action( 'woocommerce_before_cart', 'apply_matched_coupons' );

function apply_matched_coupons() {
    global $woocommerce;

    $get1 = 'getonech'; // your coupon code here
    $get2 = 'gettwoch'; // your coupon code here
    $get3 = 'getthreech'; // your coupon code here
    $get4 = 'getfourch'; // your coupon code here
    $get5 = 'getfivech'; // your coupon code here

    if ( $woocommerce->cart->cart_contents_count >= 1 && $woocommerce->cart->cart_contents_count < 2 ) {
        $woocommerce->cart->add_discount( $get1 );
        $woocommerce->show_messages();
    } elseif ( $woocommerce->cart->cart_contents_count >= 2 && $woocommerce->cart->cart_contents_count < 3 ) {
        $woocommerce->cart->add_discount( $get2 );
        $woocommerce->show_messages();
    } elseif ( $woocommerce->cart->cart_contents_count >= 3 && $woocommerce->cart->cart_contents_count < 4 ) {
        $woocommerce->cart->add_discount( $get3 );
        $woocommerce->show_messages();
    } elseif ( $woocommerce->cart->cart_contents_count >= 4 && $woocommerce->cart->cart_contents_count < 5 ) {
        $woocommerce->cart->add_discount( $get4 );
        $woocommerce->show_messages();
    } elseif ( $woocommerce->cart->cart_contents_count >= 5 ) {
        $woocommerce->cart->add_discount( $get5 );
        $woocommerce->show_messages();
    }

}

Can I use this code in REST API? If yes then how? Where should I put this code file in my woocommerce?

I used code similar to this but it looks like customers can get around this by getting to the highest coupon code then just removing items from their cart since all the rules are ">=". Is there code that can be entered which would follow "<=" to automatically remove coupon codes if the rules are no longer met. i.e. items are removed from the cart? Cheers!

Can this be done not with quantity but with the total (Before taxes, and transport)?

Hello, i have a question. i configured a rule on my woocomerce->coupon (for example apply a coupon discount when min spend is 27$). Now when I want to pay the bill, always appear: do you have any coupon? please enter the code....... Then i only want that this message appear only when the bill is >27$.
Thanks