refactor: POS workflow (#20789)

* refactor: add pos invoice doctype replacing sales invoice in POS

* refactor: move pos.py to pos invoice

* feat: add pos invoice merge log doctype

* feat: ability to merge pos invoices into a sales invoice

* feat: [wip] new ui for point of sale

* fix: pos.py moved to pos_invoice

* feat: loyalty points for POS Invoice

* fix: loyalty points on merging

* feat: return against pos invoices

* Merge 'fork/serial-no-selector' into refactor-pos-invoice

* chore: status fix and set warehouse from pos profile

* fix: naming series

* feat: merge pos returns into credit notes

* feat: add pos list action for merging into sales invoices

* feat[UX]: add shortcuts & focus on search after customer selection

* feat: stock validation from previous pos transactions

* Merge 'fork/serial-no-selector' into refactor-pos-invoice

* chore: fix df not found for base_amount precision

* feat: serial no validation from previous pos transactions

* chore: move pos.py into pos page

* feat: pos opening voucher

* feat: link pos closing voucher with opening voucher

* chore: use map_doc instead of get_mapped_doc for better perf

* feat: enforce opening voucher on pos page

* feat: [ui] [wip] point of sale beta ui refactor

* fix: auto fetching serial nos with batch no

* feat: [ui] item details section for new pos ui

* feat: remove item from cart

* refactor: [ui] [wip] split point_of_sale into components
* new payment component
* new numberpad
* fix pos opening status
* move from flex to grids

* fix: search from item selector

* feat: loyalty points as payment method

* feat: pos invoice status
* fix a bug with invalid JSON

* fix: loyalty program ui fixes

* feat: past order list and past order summary

* feat: (minor) setting discount from item details

* fix: adding item before customer selection

* feat: post order submission summary
* save and open draft orders
* fix: item group filter

* fix:  item_det not defined while submitting sle

* fix: minor bugs

* fix: minor ux fixes

* feat: show opening time in pos ui

* feat: item and customer images

* feat: emailing and printing an invoice

* fix: item details field edit shows empty alert

* fix: (minor) ux fixes

* chore: rename pos opening voucher to pos opening entry

* chore: (minor) rename pos closing voucher and sub doctypes

* chore: add patch for renaming pos closing doctypes

* fix: negative stock not allowed in pos invoices* default is_pos in pos invoices* fix: transalation

* fix: invoices not getting fetched on pos closing

* fix: indentation

* feat: view / edit customer info

* fix: minor bugs

* fix: minor bug

* fix: patch

* fix: minor ux issues

* fix: remove uppercase status

* refactor: pos closing payment reconciliation

* fix: move pos invoice print formats to pos invoice doctype

* fix: ui issues

* feat: new child doctype to store pos payment mode details

* fix: add to patches.txt

* feat: search by serial no

* chore: [wip] code cleanup

* fix: item not selectable from cart

* chore: [wip] code cleanup

* fix: minor issues
* loyalty points transactions
* default payment mode

* fix: minor fixes
* set correct mop amount with loaylty points
* editing draft invoices from UI

* chore: pos invoice merge log tests

* fix: batch / serial validation in pos ui and on submission

* feat: use onscan js for barcode scan events

* fix: cart header with amount column

* fix: validate batch no and qty in pos transactions

* chore: do not fetch closing balances as opening balance

* feat: show available qty in item selector

* feat: shortcuts

* fix: onscan.js not found

* fix: onscan.js not found

* fix: cannot return partial items

* fix: neagtive stock indicator

* feat: invoice discount

* fix: change available stock on warehouse change

* chore: cleanup code

* fix: pos profile payment method table

* feat: adding same item with different uom

* fix: loyalty points deleted after consolidation

* fix: enter loyalty amount instead of loyalty points

* chore: return print format

* feat: custom fields in pos view

* chore: pos invoice test

* chore: remove offline pos

* fix: cyclic dependency

* fix: cyclic dependency

* patch: remove pos page and order fixes

* chore: little fixes

* fix: patch perf and plural naming

* chore: tidy up pos invoice validation

* chore: move pos closing to accounts

* fix: move pos doctypes to accounts

* fix: move pos doctypes to accounts

* fix: item description in cart

* fix: item description in cart

* chore: loyalty tests
* minor fixes

* chore: rename point of sale beta to point of sale

* chore: reset past order summary on filter change

* chore: add point of sale to accounting desk

* fix: payment reconciliation table in pos closing

* fix: travis

* Update accounting.json

* fix: test cases

* fix: tests
* patch loyalty point entries

* fix: remove test
* default mode of payment is mandatory for pos transaction

* chore: remove unused checks from pos profile

* fix: loyalty point entry patch

* fix: numpad reset and patches

* fix: minor bugs

* fix: travis

* fix: travis

* fix: travis

* fix: travis

Co-authored-by: Nabin Hait <nabinhait@gmail.com>
diff --git a/erpnext/public/js/controllers/taxes_and_totals.js b/erpnext/public/js/controllers/taxes_and_totals.js
index b72ceb2..405a33c 100644
--- a/erpnext/public/js/controllers/taxes_and_totals.js
+++ b/erpnext/public/js/controllers/taxes_and_totals.js
@@ -34,12 +34,12 @@
 		this.calculate_discount_amount();
 
 		// Advance calculation applicable to Sales /Purchase Invoice
-		if(in_list(["Sales Invoice", "Purchase Invoice"], this.frm.doc.doctype)
+		if(in_list(["Sales Invoice", "POS Invoice", "Purchase Invoice"], this.frm.doc.doctype)
 			&& this.frm.doc.docstatus < 2 && !this.frm.doc.is_return) {
 			this.calculate_total_advance(update_paid_amount);
 		}
 
-		if (this.frm.doc.doctype == "Sales Invoice" && this.frm.doc.is_pos &&
+		if (in_list(["Sales Invoice", "POS Invoice"], this.frm.doc.doctype) && this.frm.doc.is_pos &&
 			this.frm.doc.is_return) {
 			this.update_paid_amount_for_return();
 		}
@@ -425,7 +425,7 @@
 			? this.frm.doc["taxes"][tax_count - 1].total + flt(this.frm.doc.rounding_adjustment)
 			: this.frm.doc.net_total);
 
-		if(in_list(["Quotation", "Sales Order", "Delivery Note", "Sales Invoice"], this.frm.doc.doctype)) {
+		if(in_list(["Quotation", "Sales Order", "Delivery Note", "Sales Invoice", "POS Invoice"], this.frm.doc.doctype)) {
 			this.frm.doc.base_grand_total = (this.frm.doc.total_taxes_and_charges) ?
 				flt(this.frm.doc.grand_total * this.frm.doc.conversion_rate) : this.frm.doc.base_net_total;
 		} else {
@@ -604,7 +604,7 @@
 		// NOTE:
 		// paid_amount and write_off_amount is only for POS/Loyalty Point Redemption Invoice
 		// total_advance is only for non POS Invoice
-		if(this.frm.doc.doctype == "Sales Invoice" && this.frm.doc.is_return){
+		if(in_list(["Sales Invoice", "POS Invoice"], this.frm.doc.doctype) && this.frm.doc.is_return){
 			this.calculate_paid_amount();
 		}
 
@@ -612,7 +612,7 @@
 
 		frappe.model.round_floats_in(this.frm.doc, ["grand_total", "total_advance", "write_off_amount"]);
 
-		if(in_list(["Sales Invoice", "Purchase Invoice"], this.frm.doc.doctype)) {
+		if(in_list(["Sales Invoice", "POS Invoice", "Purchase Invoice"], this.frm.doc.doctype)) {
 			var grand_total = this.frm.doc.rounded_total || this.frm.doc.grand_total;
 
 			if(this.frm.doc.party_account_currency == this.frm.doc.currency) {
@@ -634,7 +634,7 @@
 				this.frm.refresh_field("base_paid_amount");
 			}
 
-			if(this.frm.doc.doctype == "Sales Invoice") {
+			if(in_list(["Sales Invoice", "POS Invoice"], this.frm.doc.doctype)) {
 				let total_amount_for_payment = (this.frm.doc.redeem_loyalty_points && this.frm.doc.loyalty_amount)
 					? flt(total_amount_to_pay - this.frm.doc.loyalty_amount, precision("base_grand_total"))
 					: total_amount_to_pay;
@@ -691,11 +691,13 @@
 		if(this.frm.doc.is_pos && (update_paid_amount===undefined || update_paid_amount)) {
 			$.each(this.frm.doc['payments'] || [], function(index, data) {
 				if(data.default && payment_status && total_amount_to_pay > 0) {
-					data.base_amount = flt(total_amount_to_pay, precision("base_amount"));
-					data.amount = flt(total_amount_to_pay / me.frm.doc.conversion_rate, precision("amount"));
+					let base_amount = flt(total_amount_to_pay, precision("base_amount", data));
+					frappe.model.set_value(data.doctype, data.name, "base_amount", base_amount);
+					let amount = flt(total_amount_to_pay / me.frm.doc.conversion_rate, precision("amount", data));
+					frappe.model.set_value(data.doctype, data.name, "amount", amount);
 					payment_status = false;
 				} else if(me.frm.doc.paid_amount) {
-					data.amount = 0.0;
+					frappe.model.set_value(data.doctype, data.name, "amount", 0.0);
 				}
 			});
 		}
@@ -707,7 +709,7 @@
 		var base_paid_amount = 0.0;
 		if(this.frm.doc.is_pos) {
 			$.each(this.frm.doc['payments'] || [], function(index, data){
-				data.base_amount = flt(data.amount * me.frm.doc.conversion_rate, precision("base_amount"));
+				data.base_amount = flt(data.amount * me.frm.doc.conversion_rate, precision("base_amount", data));
 				paid_amount += data.amount;
 				base_paid_amount += data.base_amount;
 			});
@@ -719,14 +721,14 @@
 			paid_amount += flt(this.frm.doc.loyalty_amount / me.frm.doc.conversion_rate, precision("paid_amount"));
 		}
 
-		this.frm.doc.paid_amount = flt(paid_amount, precision("paid_amount"));
-		this.frm.doc.base_paid_amount = flt(base_paid_amount, precision("base_paid_amount"));
+		this.frm.set_value('paid_amount', flt(paid_amount, precision("paid_amount")));
+		this.frm.set_value('base_paid_amount', flt(base_paid_amount, precision("base_paid_amount")));
 	},
 
 	calculate_change_amount: function(){
 		this.frm.doc.change_amount = 0.0;
 		this.frm.doc.base_change_amount = 0.0;
-		if(this.frm.doc.doctype == "Sales Invoice"
+		if(in_list(["Sales Invoice", "POS Invoice"], this.frm.doc.doctype)
 			&& this.frm.doc.paid_amount > this.frm.doc.grand_total && !this.frm.doc.is_return) {
 
 			var payment_types = $.map(this.frm.doc.payments, function(d) { return d.type; });
diff --git a/erpnext/public/js/controllers/transaction.js b/erpnext/public/js/controllers/transaction.js
index 3c56a63..4e50f3d 100644
--- a/erpnext/public/js/controllers/transaction.js
+++ b/erpnext/public/js/controllers/transaction.js
@@ -651,7 +651,7 @@
 					let child = frappe.model.add_child(me.frm.doc, "taxes");
 					child.charge_type = "On Net Total";
 					child.account_head = tax;
-					child.rate = 0;
+					child.rate = rate;
 				}
 			});
 		}
diff --git a/erpnext/public/js/utils/serial_no_batch_selector.js b/erpnext/public/js/utils/serial_no_batch_selector.js
index d75633e..42f9cabc 100644
--- a/erpnext/public/js/utils/serial_no_batch_selector.js
+++ b/erpnext/public/js/utils/serial_no_batch_selector.js
@@ -43,6 +43,7 @@
 				label: __(me.warehouse_details.type),
 				default: typeof me.warehouse_details.name == "string" ? me.warehouse_details.name : '',
 				onchange: function(e) {
+					me.warehouse_details.name = this.get_value();
 
 					if(me.has_batch && !me.has_serial_no) {
 						fields = fields.concat(me.get_batch_fields());
@@ -50,7 +51,6 @@
 						fields = fields.concat(me.get_serial_no_fields());
 					}
 
-					me.warehouse_details.name = this.get_value();
 					var batches = this.layout.fields_dict.batches;
 					if(batches) {
 						batches.grid.df.data = [];
@@ -98,8 +98,13 @@
 					numbers.then((data) => {
 						let auto_fetched_serial_numbers = data.message;
 						let records_length = auto_fetched_serial_numbers.length;
+						if (!records_length) {
+							const warehouse = me.dialog.fields_dict.warehouse.get_value().bold();
+							frappe.msgprint(__(`Serial numbers unavailable for Item ${me.item.item_code.bold()} 
+								under warehouse ${warehouse}. Please try changing warehouse.`));
+						}
 						if (records_length < qty) {
-							frappe.msgprint(`Fetched only ${records_length} serial numbers.`);
+							frappe.msgprint(__(`Fetched only ${records_length} available serial numbers.`));
 						}
 						let serial_no_list_field = this.dialog.fields_dict.serial_no;
 						numbers = auto_fetched_serial_numbers.join('\n');
@@ -445,6 +450,28 @@
 			serial_no_filters['warehouse'] = me.warehouse_details.name;
 		}
 
+		if (me.frm.doc.doctype === 'POS Invoice' && !this.showing_reserved_serial_nos_error) {
+			frappe.call({
+				method: "erpnext.stock.doctype.serial_no.serial_no.get_pos_reserved_serial_nos",
+				args: {
+					item_code: me.item_code,
+					warehouse: typeof me.warehouse_details.name == "string" ? me.warehouse_details.name : ''
+				}
+			}).then((data) => {
+				if (!data.message[1].length) {
+					this.showing_reserved_serial_nos_error = true;
+					const warehouse = me.dialog.fields_dict.warehouse.get_value().bold();
+					const d = frappe.msgprint(__(`Serial numbers unavailable for Item ${me.item.item_code.bold()} 
+						under warehouse ${warehouse}. Please try changing warehouse.`));
+					d.get_close_btn().on('click', () => {
+						this.showing_reserved_serial_nos_error = false;
+						d.hide();
+					});
+				}
+				serial_no_filters['name'] = ["not in", data.message[0]]
+			})
+		}
+
 		return [
 			{fieldtype: 'Section Break', label: __('Serial Numbers')},
 			{