Merge pull request #29701 from nextchamp-saqib/consolidation-round-off-err

fix(pos): incorrect grand_total in case of inclusive taxes on item
diff --git a/erpnext/accounts/doctype/pos_invoice/test_pos_invoice.py b/erpnext/accounts/doctype/pos_invoice/test_pos_invoice.py
index ba751c0..cf8affd 100644
--- a/erpnext/accounts/doctype/pos_invoice/test_pos_invoice.py
+++ b/erpnext/accounts/doctype/pos_invoice/test_pos_invoice.py
@@ -586,23 +586,29 @@
 		item_price.insert()
 		pr = make_pricing_rule(selling=1, priority=5, discount_percentage=10)
 		pr.save()
-		pos_inv = create_pos_invoice(qty=1, do_not_submit=1)
-		pos_inv.items[0].rate = 300
-		pos_inv.save()
-		self.assertEquals(pos_inv.items[0].discount_percentage, 10)
-		# rate shouldn't change
-		self.assertEquals(pos_inv.items[0].rate, 405)
 
-		pos_inv.ignore_pricing_rule = 1
-		pos_inv.items[0].rate = 300
-		pos_inv.save()
-		self.assertEquals(pos_inv.ignore_pricing_rule, 1)
-		# rate should change since pricing rules are ignored
-		self.assertEquals(pos_inv.items[0].rate, 300)
+		try:
+			pos_inv = create_pos_invoice(qty=1, do_not_submit=1)
+			pos_inv.items[0].rate = 300
+			pos_inv.save()
+			self.assertEquals(pos_inv.items[0].discount_percentage, 10)
+			# rate shouldn't change
+			self.assertEquals(pos_inv.items[0].rate, 405)
 
-		item_price.delete()
-		pos_inv.delete()
-		pr.delete()
+			pos_inv.ignore_pricing_rule = 1
+			pos_inv.save()
+			self.assertEquals(pos_inv.ignore_pricing_rule, 1)
+			# rate should reset since pricing rules are ignored
+			self.assertEquals(pos_inv.items[0].rate, 450)
+
+			pos_inv.items[0].rate = 300
+			pos_inv.save()
+			self.assertEquals(pos_inv.items[0].rate, 300)
+
+		finally:
+			item_price.delete()
+			pos_inv.delete()
+			pr.delete()
 
 
 def create_pos_invoice(**args):
diff --git a/erpnext/accounts/doctype/pricing_rule/pricing_rule.py b/erpnext/accounts/doctype/pricing_rule/pricing_rule.py
index ac96b04..933fda8 100644
--- a/erpnext/accounts/doctype/pricing_rule/pricing_rule.py
+++ b/erpnext/accounts/doctype/pricing_rule/pricing_rule.py
@@ -249,13 +249,17 @@
 		"free_item_data": [],
 		"parent": args.parent,
 		"parenttype": args.parenttype,
-		"child_docname": args.get('child_docname')
+		"child_docname": args.get('child_docname'),
 	})
 
 	if args.ignore_pricing_rule or not args.item_code:
 		if frappe.db.exists(args.doctype, args.name) and args.get("pricing_rules"):
-			item_details = remove_pricing_rule_for_item(args.get("pricing_rules"),
-				item_details, args.get('item_code'))
+			item_details = remove_pricing_rule_for_item(
+				args.get("pricing_rules"),
+				item_details,
+				item_code=args.get("item_code"),
+				rate=args.get("price_list_rate"),
+			)
 		return item_details
 
 	update_args_for_pricing_rule(args)
@@ -308,8 +312,12 @@
 		if not doc: return item_details
 
 	elif args.get("pricing_rules"):
-		item_details = remove_pricing_rule_for_item(args.get("pricing_rules"),
-			item_details, args.get('item_code'))
+		item_details = remove_pricing_rule_for_item(
+			args.get("pricing_rules"),
+			item_details,
+			item_code=args.get("item_code"),
+			rate=args.get("price_list_rate"),
+		)
 
 	return item_details
 
@@ -390,7 +398,7 @@
 			item_details[field] += (pricing_rule.get(field, 0)
 				if pricing_rule else args.get(field, 0))
 
-def remove_pricing_rule_for_item(pricing_rules, item_details, item_code=None):
+def remove_pricing_rule_for_item(pricing_rules, item_details, item_code=None, rate=None):
 	from erpnext.accounts.doctype.pricing_rule.utils import (
 		get_applied_pricing_rules,
 		get_pricing_rule_items,
@@ -403,6 +411,7 @@
 			if pricing_rule.rate_or_discount == 'Discount Percentage':
 				item_details.discount_percentage = 0.0
 				item_details.discount_amount = 0.0
+				item_details.rate = rate or 0.0
 
 			if pricing_rule.rate_or_discount == 'Discount Amount':
 				item_details.discount_amount = 0.0
@@ -421,6 +430,7 @@
 			item_details.applied_on_items = ','.join(items)
 
 	item_details.pricing_rules = ''
+	item_details.pricing_rule_removed = True
 
 	return item_details
 
@@ -432,9 +442,12 @@
 	out = []
 	for item in item_list:
 		item = frappe._dict(item)
-		if item.get('pricing_rules'):
-			out.append(remove_pricing_rule_for_item(item.get("pricing_rules"),
-				item, item.item_code))
+		if item.get("pricing_rules"):
+			out.append(
+				remove_pricing_rule_for_item(
+					item.get("pricing_rules"), item, item.item_code, item.get("price_list_rate")
+				)
+			)
 
 	return out
 
diff --git a/erpnext/accounts/doctype/pricing_rule/test_pricing_rule.py b/erpnext/accounts/doctype/pricing_rule/test_pricing_rule.py
index 968137e..8338a5b0 100644
--- a/erpnext/accounts/doctype/pricing_rule/test_pricing_rule.py
+++ b/erpnext/accounts/doctype/pricing_rule/test_pricing_rule.py
@@ -628,6 +628,46 @@
 		for doc in [si, si1]:
 			doc.delete()
 
+	def test_remove_pricing_rule(self):
+		item = make_item("Water Flask")
+		make_item_price("Water Flask", "_Test Price List", 100)
+
+		pricing_rule_record = {
+			"doctype": "Pricing Rule",
+			"title": "_Test Water Flask Rule",
+			"apply_on": "Item Code",
+			"price_or_product_discount": "Price",
+			"items": [{
+				"item_code": "Water Flask",
+			}],
+			"selling": 1,
+			"currency": "INR",
+			"rate_or_discount": "Discount Percentage",
+			"discount_percentage": 20,
+			"company": "_Test Company"
+		}
+		rule = frappe.get_doc(pricing_rule_record)
+		rule.insert()
+
+		si = create_sales_invoice(do_not_save=True, item_code="Water Flask")
+		si.selling_price_list = "_Test Price List"
+		si.save()
+
+		self.assertEqual(si.items[0].price_list_rate, 100)
+		self.assertEqual(si.items[0].discount_percentage, 20)
+		self.assertEqual(si.items[0].rate, 80)
+
+		si.ignore_pricing_rule = 1
+		si.save()
+
+		self.assertEqual(si.items[0].discount_percentage, 0)
+		self.assertEqual(si.items[0].rate, 100)
+
+		si.delete()
+		rule.delete()
+		frappe.get_doc("Item Price", {"item_code": "Water Flask"}).delete()
+		item.delete()
+
 	def test_multiple_pricing_rules_with_min_qty(self):
 		make_pricing_rule(discount_percentage=20, selling=1, priority=1, min_qty=4,
 			apply_multiple_pricing_rules=1, title="_Test Pricing Rule with Min Qty - 1")
@@ -648,6 +688,7 @@
 		frappe.delete_doc_if_exists("Pricing Rule", "_Test Pricing Rule with Min Qty - 1")
 		frappe.delete_doc_if_exists("Pricing Rule", "_Test Pricing Rule with Min Qty - 2")
 
+
 test_dependencies = ["Campaign"]
 
 def make_pricing_rule(**args):
diff --git a/erpnext/controllers/accounts_controller.py b/erpnext/controllers/accounts_controller.py
index 8be88b8..994b903 100644
--- a/erpnext/controllers/accounts_controller.py
+++ b/erpnext/controllers/accounts_controller.py
@@ -407,6 +407,22 @@
 								if item_qty != len(get_serial_nos(item.get('serial_no'))):
 									item.set(fieldname, value)
 
+							elif (
+								ret.get("pricing_rule_removed")
+								and value is not None
+								and fieldname
+								in [
+									"discount_percentage",
+									"discount_amount",
+									"rate",
+									"margin_rate_or_amount",
+									"margin_type",
+									"remove_free_item",
+								]
+							):
+								# reset pricing rule fields if pricing_rule_removed
+								item.set(fieldname, value)
+
 					if self.doctype in ["Purchase Invoice", "Sales Invoice"] and item.meta.get_field('is_fixed_asset'):
 						item.set('is_fixed_asset', ret.get('is_fixed_asset', 0))
 
diff --git a/erpnext/manufacturing/doctype/work_order/test_work_order.py b/erpnext/manufacturing/doctype/work_order/test_work_order.py
index 7697801..67c47ef 100644
--- a/erpnext/manufacturing/doctype/work_order/test_work_order.py
+++ b/erpnext/manufacturing/doctype/work_order/test_work_order.py
@@ -201,6 +201,21 @@
 		self.assertEqual(cint(bin1_on_end_production.reserved_qty_for_production),
 			cint(bin1_on_start_production.reserved_qty_for_production))
 
+	def test_reserved_qty_for_production_closed(self):
+
+		wo1 = make_wo_order_test_record(item="_Test FG Item", qty=2,
+			source_warehouse=self.warehouse)
+		item = wo1.required_items[0].item_code
+		bin_before = get_bin(item, self.warehouse)
+		bin_before.update_reserved_qty_for_production()
+
+		make_wo_order_test_record(item="_Test FG Item", qty=2,
+			source_warehouse=self.warehouse)
+		close_work_order(wo1.name, "Closed")
+
+		bin_after = get_bin(item, self.warehouse)
+		self.assertEqual(bin_before.reserved_qty_for_production, bin_after.reserved_qty_for_production)
+
 	def test_backflush_qty_for_overpduction_manufacture(self):
 		cancel_stock_entry = []
 		allow_overproduction("overproduction_percentage_for_work_order", 30)
diff --git a/erpnext/manufacturing/doctype/work_order/work_order.py b/erpnext/manufacturing/doctype/work_order/work_order.py
index a86edfa..7315249 100644
--- a/erpnext/manufacturing/doctype/work_order/work_order.py
+++ b/erpnext/manufacturing/doctype/work_order/work_order.py
@@ -8,6 +8,8 @@
 from frappe import _
 from frappe.model.document import Document
 from frappe.model.mapper import get_mapped_doc
+from frappe.query_builder import Case
+from frappe.query_builder.functions import Sum
 from frappe.utils import (
 	cint,
 	date_diff,
@@ -1175,3 +1177,27 @@
 	doc.set_item_locations()
 
 	return doc
+
+def get_reserved_qty_for_production(item_code: str, warehouse: str) -> float:
+	"""Get total reserved quantity for any item in specified warehouse"""
+	wo = frappe.qb.DocType("Work Order")
+	wo_item = frappe.qb.DocType("Work Order Item")
+
+	return (
+	frappe.qb
+		.from_(wo)
+		.from_(wo_item)
+		.select(Sum(Case()
+				.when(wo.skip_transfer == 0, wo_item.required_qty - wo_item.transferred_qty)
+				.else_(wo_item.required_qty - wo_item.consumed_qty))
+			)
+		.where(
+			(wo_item.item_code == item_code)
+			& (wo_item.parent == wo.name)
+			& (wo.docstatus == 1)
+			& (wo_item.source_warehouse == warehouse)
+			& (wo.status.notin(["Stopped", "Completed", "Closed"]))
+			& ((wo_item.required_qty > wo_item.transferred_qty)
+				| (wo_item.required_qty > wo_item.consumed_qty))
+		)
+	).run()[0][0] or 0.0
diff --git a/erpnext/patches.txt b/erpnext/patches.txt
index feafecb..d300340 100644
--- a/erpnext/patches.txt
+++ b/erpnext/patches.txt
@@ -350,3 +350,4 @@
 erpnext.patches.v13_0.convert_to_website_item_in_item_card_group_template
 erpnext.patches.v13_0.shopping_cart_to_ecommerce
 erpnext.patches.v13_0.update_disbursement_account
+erpnext.patches.v13_0.update_reserved_qty_closed_wo
diff --git a/erpnext/patches/v13_0/update_reserved_qty_closed_wo.py b/erpnext/patches/v13_0/update_reserved_qty_closed_wo.py
new file mode 100644
index 0000000..00926b0
--- /dev/null
+++ b/erpnext/patches/v13_0/update_reserved_qty_closed_wo.py
@@ -0,0 +1,28 @@
+import frappe
+
+from erpnext.stock.utils import get_bin
+
+
+def execute():
+
+	wo = frappe.qb.DocType("Work Order")
+	wo_item = frappe.qb.DocType("Work Order Item")
+
+	incorrect_item_wh = (
+		frappe.qb
+			.from_(wo)
+			.join(wo_item).on(wo.name == wo_item.parent)
+			.select(wo_item.item_code, wo.source_warehouse).distinct()
+			.where(
+				(wo.status == "Closed")
+				& (wo.docstatus == 1)
+				& (wo.source_warehouse.notnull())
+			)
+	).run()
+
+	for item_code, warehouse in incorrect_item_wh:
+		if not (item_code and warehouse):
+			continue
+
+		bin = get_bin(item_code, warehouse)
+		bin.update_reserved_qty_for_production()
diff --git a/erpnext/public/js/controllers/transaction.js b/erpnext/public/js/controllers/transaction.js
index ab3e802..aa3e2f3 100644
--- a/erpnext/public/js/controllers/transaction.js
+++ b/erpnext/public/js/controllers/transaction.js
@@ -1463,7 +1463,8 @@
 						"item_code": d.item_code,
 						"pricing_rules": d.pricing_rules,
 						"parenttype": d.parenttype,
-						"parent": d.parent
+						"parent": d.parent,
+						"price_list_rate": d.price_list_rate
 					})
 				}
 			});
diff --git a/erpnext/stock/doctype/bin/bin.py b/erpnext/stock/doctype/bin/bin.py
index c34e9d0..d2bae65 100644
--- a/erpnext/stock/doctype/bin/bin.py
+++ b/erpnext/stock/doctype/bin/bin.py
@@ -35,28 +35,9 @@
 	def update_reserved_qty_for_production(self):
 		'''Update qty reserved for production from Production Item tables
 			in open work orders'''
+		from erpnext.manufacturing.doctype.work_order.work_order import get_reserved_qty_for_production
 
-		wo = frappe.qb.DocType("Work Order")
-		wo_item = frappe.qb.DocType("Work Order Item")
-
-		self.reserved_qty_for_production = (
-				frappe.qb
-					.from_(wo)
-					.from_(wo_item)
-					.select(Sum(Case()
-							.when(wo.skip_transfer == 0, wo_item.required_qty - wo_item.transferred_qty)
-							.else_(wo_item.required_qty - wo_item.consumed_qty))
-						)
-					.where(
-						(wo_item.item_code == self.item_code)
-						& (wo_item.parent == wo.name)
-						& (wo.docstatus == 1)
-						& (wo_item.source_warehouse == self.warehouse)
-						& (wo.status.notin(["Stopped", "Completed"]))
-						& ((wo_item.required_qty > wo_item.transferred_qty)
-							| (wo_item.required_qty > wo_item.consumed_qty))
-					)
-		).run()[0][0] or 0.0
+		self.reserved_qty_for_production = get_reserved_qty_for_production(self.item_code, self.warehouse)
 
 		self.set_projected_qty()
 
diff --git a/erpnext/stock/doctype/item/item.json b/erpnext/stock/doctype/item/item.json
index e71cdb3..b05f58a 100644
--- a/erpnext/stock/doctype/item/item.json
+++ b/erpnext/stock/doctype/item/item.json
@@ -346,7 +346,7 @@
    "fieldname": "valuation_method",
    "fieldtype": "Select",
    "label": "Valuation Method",
-   "options": "\nFIFO\nMoving Average"
+   "options": "\nFIFO\nMoving Average\nLIFO"
   },
   {
    "depends_on": "is_stock_item",
@@ -987,4 +987,4 @@
  "states": [],
  "title_field": "item_name",
  "track_changes": 1
-}
\ No newline at end of file
+}
diff --git a/erpnext/stock/doctype/stock_settings/stock_settings.json b/erpnext/stock/doctype/stock_settings/stock_settings.json
index 438ec16..ec7fb0f 100644
--- a/erpnext/stock/doctype/stock_settings/stock_settings.json
+++ b/erpnext/stock/doctype/stock_settings/stock_settings.json
@@ -99,7 +99,7 @@
    "fieldname": "valuation_method",
    "fieldtype": "Select",
    "label": "Default Valuation Method",
-   "options": "FIFO\nMoving Average"
+   "options": "FIFO\nMoving Average\nLIFO"
   },
   {
    "description": "The percentage you are allowed to receive or deliver more against the quantity ordered. For example, if you have ordered 100 units, and your Allowance is 10%, then you are allowed to receive 110 units.",
@@ -346,7 +346,7 @@
  "index_web_pages_for_search": 1,
  "issingle": 1,
  "links": [],
- "modified": "2022-02-04 15:33:43.692736",
+ "modified": "2022-02-05 15:33:43.692736",
  "modified_by": "Administrator",
  "module": "Stock",
  "name": "Stock Settings",
diff --git a/erpnext/stock/report/stock_ledger_invariant_check/stock_ledger_invariant_check.py b/erpnext/stock/report/stock_ledger_invariant_check/stock_ledger_invariant_check.py
index 48753b0..cb35bf7 100644
--- a/erpnext/stock/report/stock_ledger_invariant_check/stock_ledger_invariant_check.py
+++ b/erpnext/stock/report/stock_ledger_invariant_check/stock_ledger_invariant_check.py
@@ -167,7 +167,7 @@
 		{
 			"fieldname": "stock_queue",
 			"fieldtype": "Data",
-			"label": "FIFO Queue",
+			"label": "FIFO/LIFO Queue",
 		},
 
 		{
diff --git a/erpnext/stock/stock_ledger.py b/erpnext/stock/stock_ledger.py
index 0a7ab40..41c4002 100644
--- a/erpnext/stock/stock_ledger.py
+++ b/erpnext/stock/stock_ledger.py
@@ -16,7 +16,7 @@
 	get_or_make_bin,
 	get_valuation_method,
 )
-from erpnext.stock.valuation import FIFOValuation
+from erpnext.stock.valuation import FIFOValuation, LIFOValuation
 
 
 class NegativeStockError(frappe.ValidationError): pass
@@ -461,7 +461,7 @@
 					self.wh_data.qty_after_transaction += flt(sle.actual_qty)
 					self.wh_data.stock_value = flt(self.wh_data.qty_after_transaction) * flt(self.wh_data.valuation_rate)
 				else:
-					self.update_fifo_values(sle)
+					self.update_queue_values(sle)
 					self.wh_data.qty_after_transaction += flt(sle.actual_qty)
 
 		# rounding as per precision
@@ -701,14 +701,18 @@
 						sle.voucher_type, sle.voucher_no, self.allow_zero_rate,
 						currency=erpnext.get_company_currency(sle.company), company=sle.company)
 
-	def update_fifo_values(self, sle):
+	def update_queue_values(self, sle):
 		incoming_rate = flt(sle.incoming_rate)
 		actual_qty = flt(sle.actual_qty)
 		outgoing_rate = flt(sle.outgoing_rate)
 
-		fifo_queue = FIFOValuation(self.wh_data.stock_queue)
+		if self.valuation_method == "LIFO":
+			stock_queue = LIFOValuation(self.wh_data.stock_queue)
+		else:
+			stock_queue = FIFOValuation(self.wh_data.stock_queue)
+
 		if actual_qty > 0:
-			fifo_queue.add_stock(qty=actual_qty, rate=incoming_rate)
+			stock_queue.add_stock(qty=actual_qty, rate=incoming_rate)
 		else:
 			def rate_generator() -> float:
 				allow_zero_valuation_rate = self.check_if_allow_zero_valuation_rate(sle.voucher_type, sle.voucher_detail_no)
@@ -719,11 +723,11 @@
 				else:
 					return 0.0
 
-			fifo_queue.remove_stock(qty=abs(actual_qty), outgoing_rate=outgoing_rate, rate_generator=rate_generator)
+			stock_queue.remove_stock(qty=abs(actual_qty), outgoing_rate=outgoing_rate, rate_generator=rate_generator)
 
-		stock_qty, stock_value = fifo_queue.get_total_stock_and_value()
+		stock_qty, stock_value = stock_queue.get_total_stock_and_value()
 
-		self.wh_data.stock_queue = fifo_queue.get_state()
+		self.wh_data.stock_queue = stock_queue.state
 		self.wh_data.stock_value = stock_value
 		if stock_qty:
 			self.wh_data.valuation_rate = stock_value / stock_qty
diff --git a/erpnext/stock/tests/test_valuation.py b/erpnext/stock/tests/test_valuation.py
index 85788ba..648d440 100644
--- a/erpnext/stock/tests/test_valuation.py
+++ b/erpnext/stock/tests/test_valuation.py
@@ -1,16 +1,21 @@
+import json
 import unittest
 
+import frappe
 from hypothesis import given
 from hypothesis import strategies as st
 
-from erpnext.stock.valuation import FIFOValuation, _round_off_if_near_zero
+from erpnext.stock.doctype.item.test_item import make_item
+from erpnext.stock.doctype.stock_entry.stock_entry_utils import make_stock_entry
+from erpnext.stock.valuation import FIFOValuation, LIFOValuation, _round_off_if_near_zero
+from erpnext.tests.utils import ERPNextTestCase
 
 qty_gen = st.floats(min_value=-1e6, max_value=1e6)
 value_gen = st.floats(min_value=1, max_value=1e6)
 stock_queue_generator = st.lists(st.tuples(qty_gen, value_gen), min_size=10)
 
 
-class TestFifoValuation(unittest.TestCase):
+class TestFIFOValuation(unittest.TestCase):
 
 	def setUp(self):
 		self.queue = FIFOValuation([])
@@ -164,3 +169,184 @@
 				total_value -= sum(q * r for q, r in consumed)
 			self.assertTotalQty(total_qty)
 			self.assertTotalValue(total_value)
+
+
+class TestLIFOValuation(unittest.TestCase):
+
+	def setUp(self):
+		self.stack = LIFOValuation([])
+
+	def tearDown(self):
+		qty, value = self.stack.get_total_stock_and_value()
+		self.assertTotalQty(qty)
+		self.assertTotalValue(value)
+
+	def assertTotalQty(self, qty):
+		self.assertAlmostEqual(sum(q for q, _ in self.stack), qty, msg=f"stack: {self.stack}", places=4)
+
+	def assertTotalValue(self, value):
+		self.assertAlmostEqual(sum(q * r for q, r in self.stack), value, msg=f"stack: {self.stack}", places=2)
+
+	def test_simple_addition(self):
+		self.stack.add_stock(1, 10)
+		self.assertTotalQty(1)
+
+	def test_merge_new_stock(self):
+		self.stack.add_stock(1, 10)
+		self.stack.add_stock(1, 10)
+		self.assertEqual(self.stack, [[2, 10]])
+
+	def test_simple_removal(self):
+		self.stack.add_stock(1, 10)
+		self.stack.remove_stock(1)
+		self.assertTotalQty(0)
+
+	def test_adding_negative_stock_keeps_rate(self):
+		self.stack = LIFOValuation([[-5.0, 100]])
+		self.stack.add_stock(1, 10)
+		self.assertEqual(self.stack, [[-4, 100]])
+
+	def test_adding_negative_stock_updates_rate(self):
+		self.stack = LIFOValuation([[-5.0, 100]])
+		self.stack.add_stock(6, 10)
+		self.assertEqual(self.stack, [[1, 10]])
+
+	def test_rounding_off(self):
+		self.stack.add_stock(1.0, 1.0)
+		self.stack.remove_stock(1.0 - 1e-9)
+		self.assertTotalQty(0)
+
+	def test_lifo_consumption(self):
+		self.stack.add_stock(10, 10)
+		self.stack.add_stock(10, 20)
+		consumed = self.stack.remove_stock(15)
+		self.assertEqual(consumed, [[10, 20], [5, 10]])
+		self.assertTotalQty(5)
+
+	def test_lifo_consumption_going_negative(self):
+		self.stack.add_stock(10, 10)
+		self.stack.add_stock(10, 20)
+		consumed = self.stack.remove_stock(25)
+		self.assertEqual(consumed, [[10, 20], [10, 10], [5, 10]])
+		self.assertTotalQty(-5)
+
+	def test_lifo_consumption_multiple(self):
+		self.stack.add_stock(1, 1)
+		self.stack.add_stock(2, 2)
+		consumed = self.stack.remove_stock(1)
+		self.assertEqual(consumed, [[1, 2]])
+
+		self.stack.add_stock(3, 3)
+		consumed = self.stack.remove_stock(4)
+		self.assertEqual(consumed, [[3, 3], [1, 2]])
+
+		self.stack.add_stock(4, 4)
+		consumed = self.stack.remove_stock(5)
+		self.assertEqual(consumed, [[4, 4], [1, 1]])
+
+		self.stack.add_stock(5, 5)
+		consumed = self.stack.remove_stock(5)
+		self.assertEqual(consumed, [[5, 5]])
+
+
+	@given(stock_queue_generator)
+	def test_lifo_qty_hypothesis(self, stock_stack):
+		self.stack = LIFOValuation([])
+		total_qty = 0
+
+		for qty, rate in stock_stack:
+			if qty == 0:
+				continue
+			if qty > 0:
+				self.stack.add_stock(qty, rate)
+				total_qty += qty
+			else:
+				qty = abs(qty)
+				consumed = self.stack.remove_stock(qty)
+				self.assertAlmostEqual(qty, sum(q for q, _ in consumed), msg=f"incorrect consumption {consumed}")
+				total_qty -= qty
+			self.assertTotalQty(total_qty)
+
+	@given(stock_queue_generator)
+	def test_lifo_qty_value_nonneg_hypothesis(self, stock_stack):
+		self.stack = LIFOValuation([])
+		total_qty = 0.0
+		total_value = 0.0
+
+		for qty, rate in stock_stack:
+			# don't allow negative stock
+			if qty == 0 or total_qty + qty < 0 or abs(qty) < 0.1:
+				continue
+			if qty > 0:
+				self.stack.add_stock(qty, rate)
+				total_qty += qty
+				total_value += qty * rate
+			else:
+				qty = abs(qty)
+				consumed = self.stack.remove_stock(qty)
+				self.assertAlmostEqual(qty, sum(q for q, _ in consumed), msg=f"incorrect consumption {consumed}")
+				total_qty -= qty
+				total_value -= sum(q * r for q, r in consumed)
+			self.assertTotalQty(total_qty)
+			self.assertTotalValue(total_value)
+
+class TestLIFOValuationSLE(ERPNextTestCase):
+	ITEM_CODE = "_Test LIFO item"
+	WAREHOUSE = "_Test Warehouse - _TC"
+
+	@classmethod
+	def setUpClass(cls) -> None:
+		super().setUpClass()
+		make_item(cls.ITEM_CODE, {"valuation_method": "LIFO"})
+
+	def _make_stock_entry(self, qty, rate=None):
+		kwargs = {
+			"item_code": self.ITEM_CODE,
+			"from_warehouse" if qty < 0 else "to_warehouse": self.WAREHOUSE,
+			"rate": rate,
+			"qty": abs(qty),
+		}
+		return make_stock_entry(**kwargs)
+
+	def assertStockQueue(self, se, expected_queue):
+		sle_name = frappe.db.get_value("Stock Ledger Entry", {"voucher_no": se.name, "is_cancelled": 0, "voucher_type": "Stock Entry"})
+		sle = frappe.get_doc("Stock Ledger Entry", sle_name)
+
+		stock_queue = json.loads(sle.stock_queue)
+
+		total_qty, total_value = LIFOValuation(stock_queue).get_total_stock_and_value()
+		self.assertEqual(sle.qty_after_transaction, total_qty)
+		self.assertEqual(sle.stock_value, total_value)
+
+		if total_qty > 0:
+			self.assertEqual(stock_queue, expected_queue)
+
+
+	def test_lifo_values(self):
+
+		in1 = self._make_stock_entry(1, 1)
+		self.assertStockQueue(in1, [[1, 1]])
+
+		in2 = self._make_stock_entry(2, 2)
+		self.assertStockQueue(in2, [[1, 1], [2, 2]])
+
+		out1 = self._make_stock_entry(-1)
+		self.assertStockQueue(out1, [[1, 1], [1, 2]])
+
+		in3 = self._make_stock_entry(3, 3)
+		self.assertStockQueue(in3, [[1, 1], [1, 2], [3, 3]])
+
+		out2 = self._make_stock_entry(-4)
+		self.assertStockQueue(out2, [[1, 1]])
+
+		in4 = self._make_stock_entry(4, 4)
+		self.assertStockQueue(in4, [[1, 1], [4,4]])
+
+		out3 = self._make_stock_entry(-5)
+		self.assertStockQueue(out3, [])
+
+		in5 = self._make_stock_entry(5, 5)
+		self.assertStockQueue(in5, [[5, 5]])
+
+		out5 = self._make_stock_entry(-5)
+		self.assertStockQueue(out5, [])
diff --git a/erpnext/stock/utils.py b/erpnext/stock/utils.py
index 7c63c17..c75c737 100644
--- a/erpnext/stock/utils.py
+++ b/erpnext/stock/utils.py
@@ -9,6 +9,7 @@
 from frappe.utils import cstr, flt, get_link_to_form, nowdate, nowtime
 
 import erpnext
+from erpnext.stock.valuation import FIFOValuation, LIFOValuation
 
 
 class InvalidWarehouseCompany(frappe.ValidationError): pass
@@ -228,10 +229,10 @@
 	else:
 		valuation_method = get_valuation_method(args.get("item_code"))
 		previous_sle = get_previous_sle(args)
-		if valuation_method == 'FIFO':
+		if valuation_method in ('FIFO', 'LIFO'):
 			if previous_sle:
 				previous_stock_queue = json.loads(previous_sle.get('stock_queue', '[]') or '[]')
-				in_rate = get_fifo_rate(previous_stock_queue, args.get("qty") or 0) if previous_stock_queue else 0
+				in_rate = _get_fifo_lifo_rate(previous_stock_queue, args.get("qty") or 0, valuation_method) if previous_stock_queue else 0
 		elif valuation_method == 'Moving Average':
 			in_rate = previous_sle.get('valuation_rate') or 0
 
@@ -261,29 +262,25 @@
 
 def get_fifo_rate(previous_stock_queue, qty):
 	"""get FIFO (average) Rate from Queue"""
-	if flt(qty) >= 0:
-		total = sum(f[0] for f in previous_stock_queue)
-		return sum(flt(f[0]) * flt(f[1]) for f in previous_stock_queue) / flt(total) if total else 0.0
-	else:
-		available_qty_for_outgoing, outgoing_cost = 0, 0
-		qty_to_pop = abs(flt(qty))
-		while qty_to_pop and previous_stock_queue:
-			batch = previous_stock_queue[0]
-			if 0 < batch[0] <= qty_to_pop:
-				# if batch qty > 0
-				# not enough or exactly same qty in current batch, clear batch
-				available_qty_for_outgoing += flt(batch[0])
-				outgoing_cost += flt(batch[0]) * flt(batch[1])
-				qty_to_pop -= batch[0]
-				previous_stock_queue.pop(0)
-			else:
-				# all from current batch
-				available_qty_for_outgoing += flt(qty_to_pop)
-				outgoing_cost += flt(qty_to_pop) * flt(batch[1])
-				batch[0] -= qty_to_pop
-				qty_to_pop = 0
+	return _get_fifo_lifo_rate(previous_stock_queue, qty, "FIFO")
 
-		return outgoing_cost / available_qty_for_outgoing
+def get_lifo_rate(previous_stock_queue, qty):
+	"""get LIFO (average) Rate from Queue"""
+	return _get_fifo_lifo_rate(previous_stock_queue, qty, "LIFO")
+
+
+def _get_fifo_lifo_rate(previous_stock_queue, qty, method):
+	ValuationKlass = LIFOValuation if method == "LIFO" else FIFOValuation
+
+	stock_queue = ValuationKlass(previous_stock_queue)
+	if flt(qty) >= 0:
+		total_qty, total_value = stock_queue.get_total_stock_and_value()
+		return total_value / total_qty if total_qty else 0.0
+	else:
+		popped_bins = stock_queue.remove_stock(abs(flt(qty)))
+
+		total_qty, total_value = ValuationKlass(popped_bins).get_total_stock_and_value()
+		return total_value / total_qty if total_qty else 0.0
 
 def get_valid_serial_nos(sr_nos, qty=0, item_code=''):
 	"""split serial nos, validate and return list of valid serial nos"""
diff --git a/erpnext/stock/valuation.py b/erpnext/stock/valuation.py
index 45c5083..ee9477e 100644
--- a/erpnext/stock/valuation.py
+++ b/erpnext/stock/valuation.py
@@ -1,15 +1,54 @@
+from abc import ABC, abstractmethod, abstractproperty
 from typing import Callable, List, NewType, Optional, Tuple
 
 from frappe.utils import flt
 
-FifoBin = NewType("FifoBin", List[float])
+StockBin = NewType("StockBin", List[float])  # [[qty, rate], ...]
 
 # Indexes of values inside FIFO bin 2-tuple
 QTY = 0
 RATE = 1
 
 
-class FIFOValuation:
+class BinWiseValuation(ABC):
+
+	@abstractmethod
+	def add_stock(self, qty: float, rate: float) -> None:
+		pass
+
+	@abstractmethod
+	def remove_stock(
+		self, qty: float, outgoing_rate: float = 0.0, rate_generator: Callable[[], float] = None
+	) -> List[StockBin]:
+		pass
+
+	@abstractproperty
+	def state(self) -> List[StockBin]:
+		pass
+
+	def get_total_stock_and_value(self) -> Tuple[float, float]:
+		total_qty = 0.0
+		total_value = 0.0
+
+		for qty, rate in self.state:
+			total_qty += flt(qty)
+			total_value += flt(qty) * flt(rate)
+
+		return _round_off_if_near_zero(total_qty), _round_off_if_near_zero(total_value)
+
+	def __repr__(self):
+		return str(self.state)
+
+	def __iter__(self):
+		return iter(self.state)
+
+	def __eq__(self, other):
+		if isinstance(other, list):
+			return self.state == other
+		return type(self) == type(other) and self.state == other.state
+
+
+class FIFOValuation(BinWiseValuation):
 	"""Valuation method where a queue of all the incoming stock is maintained.
 
 	New stock is added at end of the queue.
@@ -24,34 +63,14 @@
 	# ref: https://docs.python.org/3/reference/datamodel.html#slots
 	__slots__ = ["queue",]
 
-	def __init__(self, state: Optional[List[FifoBin]]):
-		self.queue: List[FifoBin] = state if state is not None else []
+	def __init__(self, state: Optional[List[StockBin]]):
+		self.queue: List[StockBin] = state if state is not None else []
 
-	def __repr__(self):
-		return str(self.queue)
-
-	def __iter__(self):
-		return iter(self.queue)
-
-	def __eq__(self, other):
-		if isinstance(other, list):
-			return self.queue == other
-		return self.queue == other.queue
-
-	def get_state(self) -> List[FifoBin]:
+	@property
+	def state(self) -> List[StockBin]:
 		"""Get current state of queue."""
 		return self.queue
 
-	def get_total_stock_and_value(self) -> Tuple[float, float]:
-		total_qty = 0.0
-		total_value = 0.0
-
-		for qty, rate in self.queue:
-			total_qty += flt(qty)
-			total_value += flt(qty) * flt(rate)
-
-		return _round_off_if_near_zero(total_qty), _round_off_if_near_zero(total_value)
-
 	def add_stock(self, qty: float, rate: float) -> None:
 		"""Update fifo queue with new stock.
 
@@ -78,7 +97,7 @@
 
 	def remove_stock(
 		self, qty: float, outgoing_rate: float = 0.0, rate_generator: Callable[[], float] = None
-	) -> List[FifoBin]:
+	) -> List[StockBin]:
 		"""Remove stock from the queue and return popped bins.
 
 		args:
@@ -136,6 +155,101 @@
 		return consumed_bins
 
 
+class LIFOValuation(BinWiseValuation):
+	"""Valuation method where a *stack* of all the incoming stock is maintained.
+
+	New stock is added at top of the stack.
+	Qty consumption happens on Last In First Out basis.
+
+	Stack is implemented using "bins" of [qty, rate].
+
+	ref: https://en.wikipedia.org/wiki/FIFO_and_LIFO_accounting
+	Implementation detail: appends and pops both at end of list.
+	"""
+
+	# specifying the attributes to save resources
+	# ref: https://docs.python.org/3/reference/datamodel.html#slots
+	__slots__ = ["stack",]
+
+	def __init__(self, state: Optional[List[StockBin]]):
+		self.stack: List[StockBin] = state if state is not None else []
+
+	@property
+	def state(self) -> List[StockBin]:
+		"""Get current state of stack."""
+		return self.stack
+
+	def add_stock(self, qty: float, rate: float) -> None:
+		"""Update lifo stack with new stock.
+
+			args:
+				qty: new quantity to add
+				rate: incoming rate of new quantity.
+
+			Behaviour of this is same as FIFO valuation.
+		"""
+		if not len(self.stack):
+			self.stack.append([0, 0])
+
+		# last row has the same rate, merge new bin.
+		if self.stack[-1][RATE] == rate:
+			self.stack[-1][QTY] += qty
+		else:
+			# Item has a positive balance qty, add new entry
+			if self.stack[-1][QTY] > 0:
+				self.stack.append([qty, rate])
+			else:  # negative balance qty
+				qty = self.stack[-1][QTY] + qty
+				if qty > 0:  # new balance qty is positive
+					self.stack[-1] = [qty, rate]
+				else:  # new balance qty is still negative, maintain same rate
+					self.stack[-1][QTY] = qty
+
+
+	def remove_stock(
+		self, qty: float, outgoing_rate: float = 0.0, rate_generator: Callable[[], float] = None
+	) -> List[StockBin]:
+		"""Remove stock from the stack and return popped bins.
+
+		args:
+			qty: quantity to remove
+			rate: outgoing rate - ignored. Kept for backwards compatibility.
+			rate_generator: function to be called if stack is not found and rate is required.
+		"""
+		if not rate_generator:
+			rate_generator = lambda : 0.0  # noqa
+
+		consumed_bins = []
+		while qty:
+			if not len(self.stack):
+				# rely on rate generator.
+				self.stack.append([0, rate_generator()])
+
+			# start at the end.
+			index = -1
+
+			stock_bin = self.stack[index]
+			if qty >= stock_bin[QTY]:
+				# consume current bin
+				qty = _round_off_if_near_zero(qty - stock_bin[QTY])
+				to_consume = self.stack.pop(index)
+				consumed_bins.append(list(to_consume))
+
+				if not self.stack and qty:
+					# stock finished, qty still remains to be withdrawn
+					# negative stock, keep in as a negative bin
+					self.stack.append([-qty, outgoing_rate or stock_bin[RATE]])
+					consumed_bins.append([qty, outgoing_rate or stock_bin[RATE]])
+					break
+			else:
+				# qty found in current bin consume it and exit
+				stock_bin[QTY] = _round_off_if_near_zero(stock_bin[QTY] - qty)
+				consumed_bins.append([qty, stock_bin[RATE]])
+				qty = 0
+
+		return consumed_bins
+
+
 def _round_off_if_near_zero(number: float, precision: int = 7) -> float:
 	"""Rounds off the number to zero only if number is close to zero for decimal
 	specified in precision. Precision defaults to 7.