[WP][WooCommerce] Calculate sale price dynamically / programmatically based on taxonomy term custom field % (also works for Facebook Catalog feed)

wc_dynamic_saleprice.php

<?php

	// Backend
	function wc_custom_dynamic_sale_price( $sale_price, $product ) {
		$id = $product->get_id();
		$tax = get_the_terms($id,'product_cat');
		$regular_price = wc_format_decimal( $product->get_price() );
		$discount_total = 0;
		foreach ($tax as $term){
			$disc_single = get_field('sale_value', $term->taxonomy . '_' . $term->term_id);
			$discount_total += $disc_single;
		}

		if($discount_total !== 0 || $discount_total !== '')
			return wc_format_decimal($regular_price - ($regular_price / 100 * $discount_total));
		elseif($discount_total == 0 || $discount_total == '')
			return '';
		else
			return $sale_price;
	};
	if(is_admin()) {
		add_filter( 'woocommerce_product_get_sale_price', 'wc_custom_dynamic_sale_price', 10, 2 );
		add_filter( 'woocommerce_product_variation_get_sale_price', 'wc_custom_dynamic_sale_price', 10, 2 );
	}
	function custom_dynamic_sale_price_html( $price_html, $product ) {
		if( $product->is_type('variable') ) return $price_html;

		$price_html = wc_format_sale_price( wc_get_price_to_display( $product, array( 'price' => $product->get_regular_price() ) ), wc_get_price_to_display(  $product, array( 'price' => $product->get_sale_price() ) ) ) . $product->get_price_suffix();

		return $price_html;
	}
	if(is_admin()) {
		add_filter( 'woocommerce_get_price_html', 'custom_dynamic_sale_price_html', 20, 2 );
	}

	// Frontend
	function wc_change_product_price_display( $price ) {
		$id = get_the_ID();
		$tax = get_the_terms($id,'product_cat');
		$discount_total = 0;
		foreach ($tax as $term){
			$disc_single = get_field('sale_value', $term->taxonomy . '_' . $term->term_id);
			$discount_total += $disc_single;
		}
		if ($discount_total !== 0){
			$symbol = get_woocommerce_currency_symbol();
			$new_price = preg_replace("/[^0-9,]/", "",$price);
			$price = '<del>'.$price.'</del> '.wc_format_decimal(($new_price - ($new_price / 100 * $discount_total))).$symbol;
		}

		return $price;
	}
	if(!is_admin()) {
		add_filter( 'woocommerce_get_price_html', 'wc_change_product_price_display', 999 );
	}
	add_filter( 'woocommerce_cart_item_price', 'wc_change_product_price_display', 999 );

	// Discount in cart
	function wc_prefix_add_discount_line( $cart ) {

		$items = $cart->get_cart();
		$disc_cart_total = 0;
		foreach ($items as $item){
			$item_id = $item['product_id'];
			$discount_total = 0;
			$tax = get_the_terms($item_id,'product_cat');
			foreach ($tax as $term){
				$disc_single = get_field('sale_value', $term->taxonomy . '_' . $term->term_id);
				$discount_total += $disc_single;
			}
			if ($discount_total !== 0){
				$current_price = $item['line_total'];
				$discount_price = $current_price / 100 * $discount_total;
				$disc_cart_total +=$discount_price;
			}
		}
		if ($disc_cart_total !== 0){
			$cart->add_fee( __( 'Sale', TEXT_DOMAIN ) , -$disc_cart_total );
		}
	}
	add_action( 'woocommerce_cart_calculate_fees', 'wc_prefix_add_discount_line' );	

?>