[fix] Shipping charges change on qty, item_code and conversion_factor trigger (#12001)

* [wip] shipping rule

* [wip] Shipping Rule tax auto calculate

* [wip] Shipping Rule

* [new] Shipping charges change on different triggers

* [minor] Removed unnecessary comments

* [fix] Minor Changes in function calls
diff --git a/erpnext/public/js/controllers/transaction.js b/erpnext/public/js/controllers/transaction.js
index e86435c..5cb1973 100644
--- a/erpnext/public/js/controllers/transaction.js
+++ b/erpnext/public/js/controllers/transaction.js
@@ -114,7 +114,7 @@
 		}
 
 		if(this.frm.fields_dict["items"]) {
-			this["items_remove"] = this.calculate_taxes_and_totals;
+			this["items_remove"] = this.calculate_net_weight;
 		}
 
 		if(this.frm.fields_dict["recurring_print_format"]) {
@@ -336,18 +336,23 @@
 
 					callback: function(r) {
 						if(!r.exc) {
-							me.frm.script_manager.trigger("price_list_rate", cdt, cdn);
-							me.toggle_conversion_factor(item);
-							if(show_batch_dialog && !frappe.flags.hide_serial_batch_dialog) {
-								var d = locals[cdt][cdn];
-								$.each(r.message, function(k, v) {
-									if(!d[k]) d[k] = v;
-								});
+							frappe.run_serially([
+								() => me.frm.script_manager.trigger("price_list_rate", cdt, cdn),
+								() => me.toggle_conversion_factor(item),
+								() => {
+									if(show_batch_dialog && !frappe.flags.hide_serial_batch_dialog) {
+										var d = locals[cdt][cdn];
+										$.each(r.message, function(k, v) {
+											if(!d[k]) d[k] = v;
+										});
 
-								erpnext.show_serial_batch_selector(me.frm, d, (item) => {
-									me.frm.script_manager.trigger('qty', item.doctype, item.name);
-								});
-							}
+										erpnext.show_serial_batch_selector(me.frm, d, (item) => {
+											me.frm.script_manager.trigger('qty', item.doctype, item.name);
+										});
+									}
+								},
+								() => me.conversion_factor(doc, cdt, cdn, true)
+							]);
 						}
 					}
 				});
@@ -663,8 +668,11 @@
 			var item = frappe.get_doc(cdt, cdn);
 			frappe.model.round_floats_in(item, ["qty", "conversion_factor"]);
 			item.stock_qty = flt(item.qty * item.conversion_factor, precision("stock_qty", item));
+			item.total_weight = flt(item.stock_qty * item.weight_per_unit);
 			refresh_field("stock_qty", item.name, item.parentfield);
+			refresh_field("total_weight", item.name, item.parentfield);
 			this.toggle_conversion_factor(item);
+			this.calculate_net_weight();
 			if (!dont_fetch_price_list_rate &&
 				frappe.meta.has_field(doc.doctype, "price_list_currency")) {
 				this.apply_price_list(item, true);
@@ -678,20 +686,24 @@
 			this.frm.fields_dict.items.grid.toggle_enable("conversion_factor",
 				(item.uom != item.stock_uom)? true: false);
 		}
+
 	},
 
 	qty: function(doc, cdt, cdn) {
 		this.conversion_factor(doc, cdt, cdn, true);
 		this.apply_pricing_rule(frappe.get_doc(cdt, cdn), true);
-		this.calculate_total_weight(doc, cdt, cdn, true);
 	},
 
-	calculate_total_weight: function(doc, cdt, cdn){
-		if(frappe.meta.get_docfield(cdt, "weight_per_unit", cdn)) {
-			var item = frappe.get_doc(cdt, cdn);
-			item.total_weight = flt(item.qty * item.weight_per_unit);
-			refresh_field("total_weight", item.name, item.parentfield);
-		}
+	calculate_net_weight: function(){
+		/* Calculate Total Net Weight then further applied shipping rule to calculate shipping charges.*/
+		var me = this;
+		this.frm.doc.total_net_weight= 0.0;
+
+		$.each(this.frm.doc["items"] || [], function(i, item) {
+			me.frm.doc.total_net_weight += flt(item.total_weight);
+		});
+		refresh_field("total_net_weight");
+		this.shipping_rule();
 	},
 
 	set_dynamic_labels: function() {