Merge branch 'develop' into repack-entry-stock-ageing
diff --git a/erpnext/stock/report/stock_ageing/stock_ageing.py b/erpnext/stock/report/stock_ageing/stock_ageing.py
index a89a403..9866e63 100644
--- a/erpnext/stock/report/stock_ageing/stock_ageing.py
+++ b/erpnext/stock/report/stock_ageing/stock_ageing.py
@@ -286,10 +286,11 @@
 	def __compute_incoming_stock(self, row: Dict, fifo_queue: List, transfer_key: Tuple, serial_nos: List):
 		"Update FIFO Queue on inward stock."
 
-		if self.transferred_item_details.get(transfer_key):
-			# inward/outward from same voucher, item & warehouse
-			slot = self.transferred_item_details[transfer_key].pop(0)
-			fifo_queue.append(slot)
+		transfer_data = self.transferred_item_details.get(transfer_key)
+		if transfer_data:
+			# [Repack] inward/outward from same voucher, item & warehouse
+			# consume transfer data and add stock to fifo queue
+			self.__adjust_incoming_transfer_qty(transfer_data, fifo_queue, row)
 		else:
 			if not serial_nos:
 				if fifo_queue and flt(fifo_queue[0][0]) < 0:
@@ -333,6 +334,27 @@
 				self.transferred_item_details[transfer_key].append([qty_to_pop, slot[1]])
 				qty_to_pop = 0
 
+	def __adjust_incoming_transfer_qty(self, transfer_data: Dict, fifo_queue: List, row: Dict):
+		"Add previously removed stock back to FIFO Queue."
+		transfer_qty_to_pop = flt(row.actual_qty)
+		first_bucket_qty = transfer_data[0][0]
+		first_bucket_date = transfer_data[0][1]
+
+		while transfer_qty_to_pop:
+			if transfer_data and 0 > first_bucket_qty <= transfer_qty_to_pop:
+				# bucket qty is not enough, consume whole
+				transfer_qty_to_pop -= first_bucket_qty
+				slot = transfer_data.pop(0)
+				fifo_queue.append(slot)
+			elif not transfer_data:
+				# transfer bucket is empty, extra incoming qty
+				fifo_queue.append([transfer_qty_to_pop, row.posting_date])
+			else:
+				# ample bucket qty to consume
+				first_bucket_qty -= transfer_qty_to_pop
+				fifo_queue.append([transfer_qty_to_pop, first_bucket_date])
+				transfer_qty_to_pop = 0
+
 	def __update_balances(self, row: Dict, key: Union[Tuple, str]):
 		self.item_details[key]["qty_after_transaction"] = row.qty_after_transaction
 
diff --git a/erpnext/stock/report/stock_ageing/stock_ageing_fifo_logic.md b/erpnext/stock/report/stock_ageing/stock_ageing_fifo_logic.md
index 9e9bed4..3d759dd 100644
--- a/erpnext/stock/report/stock_ageing/stock_ageing_fifo_logic.md
+++ b/erpnext/stock/report/stock_ageing/stock_ageing_fifo_logic.md
@@ -71,4 +71,39 @@
 2nd  | -60 | [[-10, 1-12-2021]]
 3rd  | +5  | [[-5, 3-12-2021]]
 4th  | +10 | [[5, 4-12-2021]]
-4th  | +20 | [[5, 4-12-2021], [20, 4-12-2021]]
\ No newline at end of file
+4th  | +20 | [[5, 4-12-2021], [20, 4-12-2021]]
+
+### Concept of Transfer Qty Bucket
+In the case of **Repack**, Quantity that comes in, isn't really incoming. It is just new stock repurposed from old stock, due to incoming-outgoing of the same warehouse.
+
+Here, stock is consumed from the FIFO Queue. It is then re-added back to the queue.
+While adding stock back to the queue we need to know how much to add.
+For this we need to keep track of how much was previously consumed.
+Hence we use **Transfer Qty Bucket**.
+
+While re-adding stock, we try to add buckets that were consumed earlier (date intact), to maintain correctness.
+
+#### Case 1: Same Item-Warehouse in Repack
+Eg:
+-------------------------------------------------------------------------------------
+Date | Qty   | Voucher |             FIFO Queue           	   | Transfer Qty Buckets
+-------------------------------------------------------------------------------------
+1st  | +500  |  PR     | [[500, 1-12-2021]]   				   |
+2nd  | -50   |  Repack | [[450, 1-12-2021]]   				   | [[50, 1-12-2021]]
+2nd  | +50   |  Repack | [[450, 1-12-2021], [50, 1-12-2021]]   | []
+
+- The balance at the end is restored back to 500
+- However, the initial 500 qty bucket is now split into 450 and 50, with the same date
+- The net effect is the same as that before the Repack
+
+#### Case 2: Same Item-Warehouse in Repack with Split Consumption rows
+Eg:
+-------------------------------------------------------------------------------------
+Date | Qty   | Voucher |             FIFO Queue           	   | Transfer Qty Buckets
+-------------------------------------------------------------------------------------
+1st  | +500  |  PR     | [[500, 1-12-2021]]   				   |
+2nd  | -50   |  Repack | [[450, 1-12-2021]]   				   | [[50, 1-12-2021]]
+2nd  | -50   |  Repack | [[400, 1-12-2021]]   				   | [[50, 1-12-2021],
+-	 |		 |		   |									   |[50, 1-12-2021]]
+2nd  | +100  |  Repack | [[400, 1-12-2021], [50, 1-12-2021],   | []
+-	 |		 |		   | [50, 1-12-2021]]					   |
diff --git a/erpnext/stock/report/stock_ageing/test_stock_ageing.py b/erpnext/stock/report/stock_ageing/test_stock_ageing.py
index 66d2f6b..3055332 100644
--- a/erpnext/stock/report/stock_ageing/test_stock_ageing.py
+++ b/erpnext/stock/report/stock_ageing/test_stock_ageing.py
@@ -236,6 +236,159 @@
 		item_wh_balances = [item_wh_wise_slots.get(i).get("qty_after_transaction") for i in item_wh_wise_slots]
 		self.assertEqual(sum(item_wh_balances), item_result["qty_after_transaction"])
 
+	def test_repack_entry_same_item_split_rows(self):
+		"""
+		Split consumption rows and have single repacked item row (same warehouse).
+		Ledger:
+		Item	| Qty | Voucher
+		------------------------
+		Item 1  | 500 | 001
+		Item 1  | -50 | 002 (repack)
+		Item 1  | -50 | 002 (repack)
+		Item 1  | 100 | 002 (repack)
+
+		Case most likely for batch items. Test time bucket computation.
+		"""
+		sle = [
+			frappe._dict( # stock up item
+				name="Flask Item",
+				actual_qty=500, qty_after_transaction=500,
+				warehouse="WH 1",
+				posting_date="2021-12-03", voucher_type="Stock Entry",
+				voucher_no="001",
+				has_serial_no=False, serial_no=None
+			),
+			frappe._dict(
+				name="Flask Item",
+				actual_qty=(-50), qty_after_transaction=450,
+				warehouse="WH 1",
+				posting_date="2021-12-04", voucher_type="Stock Entry",
+				voucher_no="002",
+				has_serial_no=False, serial_no=None
+			),
+			frappe._dict(
+				name="Flask Item",
+				actual_qty=(-50), qty_after_transaction=400,
+				warehouse="WH 1",
+				posting_date="2021-12-04", voucher_type="Stock Entry",
+				voucher_no="002",
+				has_serial_no=False, serial_no=None
+			),
+			frappe._dict(
+				name="Flask Item",
+				actual_qty=100, qty_after_transaction=500,
+				warehouse="WH 1",
+				posting_date="2021-12-04", voucher_type="Stock Entry",
+				voucher_no="002",
+				has_serial_no=False, serial_no=None
+			),
+		]
+		slots = FIFOSlots(self.filters, sle).generate()
+		item_result = slots["Flask Item"]
+		queue = item_result["fifo_queue"]
+
+		self.assertEqual(item_result["total_qty"], 500.0)
+		self.assertEqual(queue[0][0], 400.0)
+		self.assertEqual(queue[1][0], 100.0)
+		# check if time buckets add up to balance qty
+		self.assertEqual(sum([i[0] for i in queue]), 500.0)
+
+	def test_repack_entry_same_item_overconsume(self):
+		"""
+		Over consume item and have less repacked item qty (same warehouse).
+		Ledger:
+		Item	| Qty  | Voucher
+		------------------------
+		Item 1  | 500  | 001
+		Item 1  | -100 | 002 (repack)
+		Item 1  | 50   | 002 (repack)
+
+		Case most likely for batch items. Test time bucket computation.
+		"""
+		sle = [
+			frappe._dict( # stock up item
+				name="Flask Item",
+				actual_qty=500, qty_after_transaction=500,
+				warehouse="WH 1",
+				posting_date="2021-12-03", voucher_type="Stock Entry",
+				voucher_no="001",
+				has_serial_no=False, serial_no=None
+			),
+			frappe._dict(
+				name="Flask Item",
+				actual_qty=(-100), qty_after_transaction=400,
+				warehouse="WH 1",
+				posting_date="2021-12-04", voucher_type="Stock Entry",
+				voucher_no="002",
+				has_serial_no=False, serial_no=None
+			),
+			frappe._dict(
+				name="Flask Item",
+				actual_qty=50, qty_after_transaction=450,
+				warehouse="WH 1",
+				posting_date="2021-12-04", voucher_type="Stock Entry",
+				voucher_no="002",
+				has_serial_no=False, serial_no=None
+			),
+		]
+		slots = FIFOSlots(self.filters, sle).generate()
+		item_result = slots["Flask Item"]
+		queue = item_result["fifo_queue"]
+
+		self.assertEqual(item_result["total_qty"], 450.0)
+		self.assertEqual(queue[0][0], 400.0)
+		self.assertEqual(queue[1][0], 50.0)
+		# check if time buckets add up to balance qty
+		self.assertEqual(sum([i[0] for i in queue]), 450.0)
+
+	def test_repack_entry_same_item_overproduce(self):
+		"""
+		Under consume item and have more repacked item qty (same warehouse).
+		Ledger:
+		Item	| Qty  | Voucher
+		------------------------
+		Item 1  | 500  | 001
+		Item 1  | -50  | 002 (repack)
+		Item 1  | 100  | 002 (repack)
+
+		Case most likely for batch items. Test time bucket computation.
+		"""
+		sle = [
+			frappe._dict( # stock up item
+				name="Flask Item",
+				actual_qty=500, qty_after_transaction=500,
+				warehouse="WH 1",
+				posting_date="2021-12-03", voucher_type="Stock Entry",
+				voucher_no="001",
+				has_serial_no=False, serial_no=None
+			),
+			frappe._dict(
+				name="Flask Item",
+				actual_qty=(-50), qty_after_transaction=450,
+				warehouse="WH 1",
+				posting_date="2021-12-04", voucher_type="Stock Entry",
+				voucher_no="002",
+				has_serial_no=False, serial_no=None
+			),
+			frappe._dict(
+				name="Flask Item",
+				actual_qty=100, qty_after_transaction=550,
+				warehouse="WH 1",
+				posting_date="2021-12-04", voucher_type="Stock Entry",
+				voucher_no="002",
+				has_serial_no=False, serial_no=None
+			),
+		]
+		slots = FIFOSlots(self.filters, sle).generate()
+		item_result = slots["Flask Item"]
+		queue = item_result["fifo_queue"]
+
+		self.assertEqual(item_result["total_qty"], 550.0)
+		self.assertEqual(queue[0][0], 450.0)
+		self.assertEqual(queue[1][0], 100.0)
+		# check if time buckets add up to balance qty
+		self.assertEqual(sum([i[0] for i in queue]), 550.0)
+
 def generate_item_and_item_wh_wise_slots(filters, sle):
 	"Return results with and without 'show_warehouse_wise_stock'"
 	item_wise_slots = FIFOSlots(filters, sle).generate()