[FIX] point_of_sale: correctly add Global Discount with fiscal position

Previously, it was not possible to apply the Global Discount in cases
where there was a fiscal position with tax included in the price. This
was because of using in the `get_taxes` function, which do not return
taxes after fiscal position.

opw-3267243

closes odoo/odoo#123612

X-original-commit: cb5a1eae7502c140fed09a9471f4d5a97429df74
Signed-off-by: Joseph Caburnay (jcb) <jcb@odoo.com>
Signed-off-by: Pedram Bi Ria (pebr) <pebr@odoo.com>

addons/point_of_sale/static/src/js/models.js

@@ -2392,9 +2392,13 @@ export class Orderline extends PosModel {
      * @returns {Number} the total amount of price included taxes
      */
     get_total_taxes_included_in_price() {
-        return this.get_taxes()
-            .filter((tax) => tax.price_include)
-            .reduce((sum, tax) => sum + this.get_tax_details()[tax.id], 0);
+        const productTaxes = this._getProductTaxesAfterFiscalPosition();
+        const taxDetails = this.get_tax_details();
+        return productTaxes
+            .filter(tax => tax.price_include)
+            .reduce((sum, tax) => sum + taxDetails[tax.id],
+            0
+        );
     }
     _map_tax_fiscal_position(tax, order = false) {
         return this.pos._map_tax_fiscal_position(tax, order);
@@ -2421,6 +2425,17 @@ export class Orderline extends PosModel {
             handle_price_include
         );
     }
+    /**
+     * Calculates the taxes for a product, and converts the taxes based on the fiscal position of the order.
+     *
+     * @returns {Object} The calculated product taxes after filtering and fiscal position conversion.
+     */
+    _getProductTaxesAfterFiscalPosition() {
+        const product = this.get_product();
+        let taxesIds = this.tax_ids || product.taxes_id;
+        taxesIds = _.filter(taxesIds, t => t in this.pos.taxes_by_id);
+        return this.pos.get_taxes_after_fp(taxesIds, this.order.fiscal_position);
+    }
     get_all_prices(qty = this.get_quantity()) {
         var price_unit = this.get_unit_price() * (1.0 - this.get_discount() / 100.0);
         var taxtotal = 0;
@@ -3291,7 +3306,7 @@ export class Order extends PosModel {
     }
     _get_tax_group_key(line) {
         return line
-            .get_taxes()
+            ._getProductTaxesAfterFiscalPosition()
             .map((tax) => tax.id)
             .join(",");
     }