fix: check future negative stock for batches

batch's ledger is only maintained in form of `actual_qty` on batch's
SLEs. To validate if batch has any negative qty in future, cumulative
total of `actual_qty` is required to ensure it never goes negative.

erpnext/stock/stock_ledger.py

@@ -1089,17 +1089,36 @@ def validate_negative_qty_in_future_sle(args, allow_negative_stock=False):
 	allow_negative_stock = cint(allow_negative_stock) \
 		or cint(frappe.db.get_single_value("Stock Settings", "allow_negative_stock"))
 
-	if (args.actual_qty < 0 or args.voucher_type == "Stock Reconciliation") and not allow_negative_stock:
-		sle = get_future_sle_with_negative_qty(args)
-		if sle:
-			message = _("{0} units of {1} needed in {2} on {3} {4} for {5} to complete this transaction.").format(
-				abs(sle[0]["qty_after_transaction"]),
-				frappe.get_desk_link('Item', args.item_code),
-				frappe.get_desk_link('Warehouse', args.warehouse),
-				sle[0]["posting_date"], sle[0]["posting_time"],
-				frappe.get_desk_link(sle[0]["voucher_type"], sle[0]["voucher_no"]))
-
-			frappe.throw(message, NegativeStockError, title='Insufficient Stock')
+	if allow_negative_stock:
+		return
+	if not (args.actual_qty < 0 or args.voucher_type == "Stock Reconciliation"):
+		return
+
+	neg_sle = get_future_sle_with_negative_qty(args)
+	if neg_sle:
+		message = _("{0} units of {1} needed in {2} on {3} {4} for {5} to complete this transaction.").format(
+			abs(neg_sle[0]["qty_after_transaction"]),
+			frappe.get_desk_link('Item', args.item_code),
+			frappe.get_desk_link('Warehouse', args.warehouse),
+			neg_sle[0]["posting_date"], neg_sle[0]["posting_time"],
+			frappe.get_desk_link(neg_sle[0]["voucher_type"], neg_sle[0]["voucher_no"]))
+
+		frappe.throw(message, NegativeStockError, title='Insufficient Stock')
+
+
+	if not args.batch_no:
+		return
+
+	neg_batch_sle = get_future_sle_with_negative_batch_qty(args)
+	if neg_batch_sle:
+		message = _("{0} units of {1} needed in {2} on {3} {4} for {5} to complete this transaction.").format(
+			abs(neg_batch_sle[0]["cumulative_total"]),
+			frappe.get_desk_link('Batch', args.batch_no),
+			frappe.get_desk_link('Warehouse', args.warehouse),
+			neg_batch_sle[0]["posting_date"], neg_batch_sle[0]["posting_time"],
+			frappe.get_desk_link(neg_batch_sle[0]["voucher_type"], neg_batch_sle[0]["voucher_no"]))
+		frappe.throw(message, NegativeStockError, title="Insufficient Stock for Batch")
+
 
 def get_future_sle_with_negative_qty(args):
 	return frappe.db.sql("""
@@ -1118,6 +1137,29 @@ def get_future_sle_with_negative_qty(args):
 		limit 1
 	""", args, as_dict=1)
 
+
+def get_future_sle_with_negative_batch_qty(args):
+	return frappe.db.sql("""
+		with batch_ledger as (
+			select
+				posting_date, posting_time, voucher_type, voucher_no,
+				sum(actual_qty) over (order by posting_date, posting_time, creation) as cumulative_total
+			from `tabStock Ledger Entry`
+			where
+				item_code = %(item_code)s
+				and warehouse = %(warehouse)s
+				and batch_no=%(batch_no)s
+				and is_cancelled = 0
+			order by posting_date, posting_time, creation
+		)
+		select * from batch_ledger
+		where
+			cumulative_total < 0.0
+			and timestamp(posting_date, posting_time) >= timestamp(%(posting_date)s, %(posting_time)s)
+		limit 1
+	""", args, as_dict=1)
+
+
 def _round_off_if_near_zero(number: float, precision: int = 6) -> float:
 	""" Rounds off the number to zero only if number is close to zero for decimal
 		specified in precision. Precision defaults to 6.