feat: company wise valuation method

erpnext/setup/doctype/company/company.json

@@ -117,6 +117,7 @@
   "enable_item_wise_inventory_account",
   "enable_provisional_accounting_for_non_stock_items",
   "default_inventory_account",
+  "valuation_method",
   "column_break_32",
   "stock_adjustment_account",
   "stock_received_but_not_billed",
@@ -890,6 +891,14 @@
    "fieldtype": "Check",
    "label": "Enable Item-wise Inventory Account"
   },
+  {
+   "default": "FIFO",
+   "fieldname": "valuation_method",
+   "fieldtype": "Select",
+   "label": "Default Stock Valuation Method",
+   "options": "FIFO\nMoving Average\nLIFO",
+   "reqd": 1
+  },
   {
    "fieldname": "default_wip_warehouse",
    "fieldtype": "Link",

erpnext/setup/doctype/company/company.py

@@ -116,6 +116,7 @@ class Company(NestedSet):
 		transactions_annual_history: DF.Code | None
 		unrealized_exchange_gain_loss_account: DF.Link | None
 		unrealized_profit_loss_account: DF.Link | None
+		valuation_method: DF.Literal["FIFO", "Moving Average", "LIFO"]
 		website: DF.Data | None
 		write_off_account: DF.Link | None
 	# end: auto-generated types
@@ -166,6 +167,32 @@ class Company(NestedSet):
 		self.validate_parent_company()
 		self.set_reporting_currency()
 		self.validate_inventory_account_settings()
+		self.cant_change_valuation_method()
+
+	def cant_change_valuation_method(self):
+		doc_before_save = self.get_doc_before_save()
+		if not doc_before_save:
+			return
+
+		previous_valuation_method = doc_before_save.get("valuation_method")
+
+		if previous_valuation_method and previous_valuation_method != self.valuation_method:
+			# check if there are any stock ledger entries against items
+			# which does not have it's own valuation method
+			sle = frappe.db.sql(
+				"""select name from `tabStock Ledger Entry` sle
+				where exists(select name from tabItem
+					where name=sle.item_code and (valuation_method is null or valuation_method='')) and sle.company=%s limit 1
+			""",
+				self.name,
+			)
+
+			if sle:
+				frappe.throw(
+					_(
+						"Can't change the valuation method, as there are transactions against some items which do not have its own valuation method"
+					)
+				)
 
 	def validate_inventory_account_settings(self):
 		doc_before_save = self.get_doc_before_save()