fix: asset monthly WDV and DD schedule and refactor [develop] (#34646)

* fix: monthly wdv and dd schedule

* chore: minor rename

* chore: fix tests

erpnext/assets/doctype/asset/asset.py

@@ -8,16 +8,12 @@ import math
 import frappe
 from frappe import _
 from frappe.utils import (
-	add_months,
 	cint,
-	date_diff,
 	flt,
 	get_datetime,
 	get_last_day,
 	get_link_to_form,
 	getdate,
-	is_last_day_of_the_month,
-	month_diff,
 	nowdate,
 	today,
 )
@@ -239,30 +235,6 @@ class Asset(AccountsController):
 				self.get_depreciation_rate(d, on_validate=True), d.precision("rate_of_depreciation")
 			)
 
-	# if it returns True, depreciation_amount will not be equal for the first and last rows
-	def check_is_pro_rata(self, row):
-		has_pro_rata = False
-
-		# if not existing asset, from_date = available_for_use_date
-		# otherwise, if number_of_depreciations_booked = 2, available_for_use_date = 01/01/2020 and frequency_of_depreciation = 12
-		# from_date = 01/01/2022
-		from_date = self.get_modified_available_for_use_date(row)
-		days = date_diff(row.depreciation_start_date, from_date) + 1
-
-		# if frequency_of_depreciation is 12 months, total_days = 365
-		total_days = get_total_days(row.depreciation_start_date, row.frequency_of_depreciation)
-
-		if days < total_days:
-			has_pro_rata = True
-
-		return has_pro_rata
-
-	def get_modified_available_for_use_date(self, row):
-		return add_months(
-			self.available_for_use_date,
-			(self.number_of_depreciations_booked * row.frequency_of_depreciation),
-		)
-
 	def validate_asset_finance_books(self, row):
 		if flt(row.expected_value_after_useful_life) >= flt(self.gross_purchase_amount):
 			frappe.throw(
@@ -471,29 +443,6 @@ class Asset(AccountsController):
 
 		return records
 
-	@erpnext.allow_regional
-	def get_depreciation_amount(self, depreciable_value, fb_row):
-		if fb_row.depreciation_method in ("Straight Line", "Manual"):
-			# if the Depreciation Schedule is being modified after Asset Repair due to increase in asset life and value
-			if self.flags.increase_in_asset_life:
-				depreciation_amount = (
-					flt(fb_row.value_after_depreciation) - flt(fb_row.expected_value_after_useful_life)
-				) / (date_diff(self.to_date, self.available_for_use_date) / 365)
-			# if the Depreciation Schedule is being modified after Asset Repair due to increase in asset value
-			elif self.flags.increase_in_asset_value_due_to_repair:
-				depreciation_amount = (
-					flt(fb_row.value_after_depreciation) - flt(fb_row.expected_value_after_useful_life)
-				) / flt(fb_row.total_number_of_depreciations)
-			# if the Depreciation Schedule is being prepared for the first time
-			else:
-				depreciation_amount = (
-					flt(self.gross_purchase_amount) - flt(fb_row.expected_value_after_useful_life)
-				) / flt(fb_row.total_number_of_depreciations)
-		else:
-			depreciation_amount = flt(depreciable_value * (flt(fb_row.rate_of_depreciation) / 100))
-
-		return depreciation_amount
-
 	def validate_make_gl_entry(self):
 		purchase_document = self.get_purchase_document()
 		if not purchase_document:
@@ -618,7 +567,12 @@ class Asset(AccountsController):
 		float_precision = cint(frappe.db.get_default("float_precision")) or 2
 
 		if args.get("depreciation_method") == "Double Declining Balance":
-			return 200.0 / args.get("total_number_of_depreciations")
+			return 200.0 / (
+				(
+					flt(args.get("total_number_of_depreciations"), 2) * flt(args.get("frequency_of_depreciation"))
+				)
+				/ 12
+			)
 
 		if args.get("depreciation_method") == "Written Down Value":
 			if (
@@ -635,17 +589,20 @@ class Asset(AccountsController):
 			else:
 				value = flt(args.get("expected_value_after_useful_life")) / flt(self.gross_purchase_amount)
 
-			depreciation_rate = math.pow(value, 1.0 / flt(args.get("total_number_of_depreciations"), 2))
+			depreciation_rate = math.pow(
+				value,
+				1.0
+				/ (
+					(
+						flt(args.get("total_number_of_depreciations"), 2)
+						* flt(args.get("frequency_of_depreciation"))
+					)
+					/ 12
+				),
+			)
 
 			return flt((100 * (1 - depreciation_rate)), float_precision)
 
-	def get_pro_rata_amt(self, row, depreciation_amount, from_date, to_date):
-		days = date_diff(to_date, from_date)
-		months = month_diff(to_date, from_date)
-		total_days = get_total_days(to_date, row.frequency_of_depreciation)
-
-		return (depreciation_amount * flt(days)) / flt(total_days), days, months
-
 
 def update_maintenance_status():
 	assets = frappe.get_all(
@@ -889,15 +846,6 @@ def get_asset_value_after_depreciation(asset_name, finance_book=None):
 	return asset.get_value_after_depreciation(finance_book)
 
 
-def get_total_days(date, frequency):
-	period_start_date = add_months(date, cint(frequency) * -1)
-
-	if is_last_day_of_the_month(date):
-		period_start_date = get_last_day(period_start_date)
-
-	return date_diff(date, period_start_date)
-
-
 @frappe.whitelist()
 def split_asset(asset_name, split_qty):
 	asset = frappe.get_doc("Asset", asset_name)

erpnext/assets/doctype/asset/test_asset.py

@@ -29,8 +29,11 @@ from erpnext.assets.doctype.asset.depreciation import (
 	scrap_asset,
 )
 from erpnext.assets.doctype.asset_depreciation_schedule.asset_depreciation_schedule import (
+	_check_is_pro_rata,
+	_get_pro_rata_amt,
 	get_asset_depr_schedule_doc,
 	get_depr_schedule,
+	get_depreciation_amount,
 )
 from erpnext.stock.doctype.purchase_receipt.purchase_receipt import (
 	make_purchase_invoice as make_invoice,
@@ -234,7 +237,7 @@ class TestAsset(AssetSetup):
 			asset.gross_purchase_amount - asset.finance_books[0].value_after_depreciation,
 			asset.precision("gross_purchase_amount"),
 		)
-		pro_rata_amount, _, _ = asset.get_pro_rata_amt(
+		pro_rata_amount, _, _ = _get_pro_rata_amt(
 			asset.finance_books[0], 9000, get_last_day(add_months(purchase_date, 1)), date
 		)
 		pro_rata_amount = flt(pro_rata_amount, asset.precision("gross_purchase_amount"))
@@ -321,7 +324,7 @@ class TestAsset(AssetSetup):
 		self.assertEquals(second_asset_depr_schedule.status, "Active")
 		self.assertEquals(first_asset_depr_schedule.status, "Cancelled")
 
-		pro_rata_amount, _, _ = asset.get_pro_rata_amt(
+		pro_rata_amount, _, _ = _get_pro_rata_amt(
 			asset.finance_books[0], 9000, get_last_day(add_months(purchase_date, 1)), date
 		)
 		pro_rata_amount = flt(pro_rata_amount, asset.precision("gross_purchase_amount"))
@@ -857,12 +860,12 @@ class TestDepreciationMethods(AssetSetup):
 		)
 
 		expected_schedules = [
-			["2022-02-28", 647.25, 647.25],
+			["2022-02-28", 310.89, 310.89],
-			["2022-03-31", 1210.71, 1857.96],
+			["2022-03-31", 654.45, 965.34],
-			["2022-04-30", 1053.99, 2911.95],
+			["2022-04-30", 654.45, 1619.79],
-			["2022-05-31", 917.55, 3829.5],
+			["2022-05-31", 654.45, 2274.24],
-			["2022-06-30", 798.77, 4628.27],
+			["2022-06-30", 654.45, 2928.69],
-			["2022-07-15", 371.73, 5000.0],
+			["2022-07-15", 2071.31, 5000.0],
 		]
 
 		schedules = [
@@ -938,7 +941,7 @@ class TestDepreciationBasics(AssetSetup):
 			},
 		)
 
-		depreciation_amount = asset.get_depreciation_amount(100000, asset.finance_books[0])
+		depreciation_amount = get_depreciation_amount(asset, 100000, asset.finance_books[0])
 		self.assertEqual(depreciation_amount, 30000)
 
 	def test_make_depr_schedule(self):
@@ -997,7 +1000,7 @@ class TestDepreciationBasics(AssetSetup):
 			},
 		)
 
-		has_pro_rata = asset.check_is_pro_rata(asset.finance_books[0])
+		has_pro_rata = _check_is_pro_rata(asset, asset.finance_books[0])
 		self.assertFalse(has_pro_rata)
 
 		asset.finance_books = []
@@ -1012,7 +1015,7 @@ class TestDepreciationBasics(AssetSetup):
 			},
 		)
 
-		has_pro_rata = asset.check_is_pro_rata(asset.finance_books[0])
+		has_pro_rata = _check_is_pro_rata(asset, asset.finance_books[0])
 		self.assertTrue(has_pro_rata)
 
 	def test_expected_value_after_useful_life_greater_than_purchase_amount(self):

erpnext/assets/doctype/asset_depreciation_schedule/asset_depreciation_schedule.py

@@ -8,12 +8,16 @@ from frappe.utils import (
 	add_days,
 	add_months,
 	cint,
+	date_diff,
 	flt,
 	get_last_day,
 	getdate,
 	is_last_day_of_the_month,
+	month_diff,
 )
 
+import erpnext
+
 
 class AssetDepreciationSchedule(Document):
 	def before_save(self):
@@ -185,7 +189,7 @@ class AssetDepreciationSchedule(Document):
 	):
 		asset_doc.validate_asset_finance_books(row)
 
-		value_after_depreciation = self._get_value_after_depreciation_for_making_schedule(asset_doc, row)
+		value_after_depreciation = _get_value_after_depreciation_for_making_schedule(asset_doc, row)
 		row.value_after_depreciation = value_after_depreciation
 
 		if update_asset_finance_book_row:
@@ -195,21 +199,46 @@ class AssetDepreciationSchedule(Document):
 			self.number_of_depreciations_booked
 		)
 
-		has_pro_rata = asset_doc.check_is_pro_rata(row)
+		has_pro_rata = _check_is_pro_rata(asset_doc, row)
 		if has_pro_rata:
 			number_of_pending_depreciations += 1
 
+		has_wdv_or_dd_non_yearly_pro_rata = False
+		if (
+			row.depreciation_method in ("Written Down Value", "Double Declining Balance")
+			and cint(row.frequency_of_depreciation) != 12
+		):
+			has_wdv_or_dd_non_yearly_pro_rata = _check_is_pro_rata(
+				asset_doc, row, wdv_or_dd_non_yearly=True
+			)
+
 		skip_row = False
 		should_get_last_day = is_last_day_of_the_month(row.depreciation_start_date)
 
+		depreciation_amount = 0
+
 		for n in range(start, number_of_pending_depreciations):
 			# If depreciation is already completed (for double declining balance)
 			if skip_row:
 				continue
 
-			depreciation_amount = asset_doc.get_depreciation_amount(value_after_depreciation, row)
+			if n > 0 and len(self.get("depreciation_schedule")) > n - 1:
+				prev_depreciation_amount = self.get("depreciation_schedule")[n - 1].depreciation_amount
+			else:
+				prev_depreciation_amount = 0
 
-			if not has_pro_rata or n < cint(number_of_pending_depreciations) - 1:
+			depreciation_amount = get_depreciation_amount(
+				asset_doc,
+				value_after_depreciation,
+				row,
+				n,
+				prev_depreciation_amount,
+				has_wdv_or_dd_non_yearly_pro_rata,
+			)
+
+			if not has_pro_rata or (
+				n < (cint(number_of_pending_depreciations) - 1) or number_of_pending_depreciations == 2
+			):
 				schedule_date = add_months(
 					row.depreciation_start_date, n * cint(row.frequency_of_depreciation)
 				)
@@ -227,8 +256,11 @@ class AssetDepreciationSchedule(Document):
 				if self.depreciation_schedule:
 					from_date = self.depreciation_schedule[-1].schedule_date
 
-				depreciation_amount, days, months = asset_doc.get_pro_rata_amt(
+				depreciation_amount, days, months = _get_pro_rata_amt(
-					row, depreciation_amount, from_date, date_of_disposal
+					row,
+					depreciation_amount,
+					from_date,
+					date_of_disposal,
 				)
 
 				if depreciation_amount > 0:
@@ -240,12 +272,20 @@ class AssetDepreciationSchedule(Document):
 				break
 
 			# For first row
-			if has_pro_rata and not self.opening_accumulated_depreciation and n == 0:
+			if (
+				(has_pro_rata or has_wdv_or_dd_non_yearly_pro_rata)
+				and not self.opening_accumulated_depreciation
+				and n == 0
+			):
 				from_date = add_days(
 					asset_doc.available_for_use_date, -1
 				)  # needed to calc depr amount for available_for_use_date too
-				depreciation_amount, days, months = asset_doc.get_pro_rata_amt(
+				depreciation_amount, days, months = _get_pro_rata_amt(
-					row, depreciation_amount, from_date, row.depreciation_start_date
+					row,
+					depreciation_amount,
+					from_date,
+					row.depreciation_start_date,
+					has_wdv_or_dd_non_yearly_pro_rata,
 				)
 
 				# For first depr schedule date will be the start date
@@ -264,8 +304,12 @@ class AssetDepreciationSchedule(Document):
 
 				depreciation_amount_without_pro_rata = depreciation_amount
 
-				depreciation_amount, days, months = asset_doc.get_pro_rata_amt(
+				depreciation_amount, days, months = _get_pro_rata_amt(
-					row, depreciation_amount, schedule_date, asset_doc.to_date
+					row,
+					depreciation_amount,
+					schedule_date,
+					asset_doc.to_date,
+					has_wdv_or_dd_non_yearly_pro_rata,
 				)
 
 				depreciation_amount = self.get_adjusted_depreciation_amount(
@@ -373,15 +417,142 @@ class AssetDepreciationSchedule(Document):
 				accumulated_depreciation, d.precision("accumulated_depreciation_amount")
 			)
 
-	def _get_value_after_depreciation_for_making_schedule(self, asset_doc, fb_row):
-		if asset_doc.docstatus == 1 and fb_row.value_after_depreciation:
-			value_after_depreciation = flt(fb_row.value_after_depreciation)
-		else:
-			value_after_depreciation = flt(self.gross_purchase_amount) - flt(
-				self.opening_accumulated_depreciation
-			)
 
-		return value_after_depreciation
+def _get_value_after_depreciation_for_making_schedule(asset_doc, fb_row):
+	if asset_doc.docstatus == 1 and fb_row.value_after_depreciation:
+		value_after_depreciation = flt(fb_row.value_after_depreciation)
+	else:
+		value_after_depreciation = flt(asset_doc.gross_purchase_amount) - flt(
+			asset_doc.opening_accumulated_depreciation
+		)
+
+	return value_after_depreciation
+
+
+# if it returns True, depreciation_amount will not be equal for the first and last rows
+def _check_is_pro_rata(asset_doc, row, wdv_or_dd_non_yearly=False):
+	has_pro_rata = False
+
+	# if not existing asset, from_date = available_for_use_date
+	# otherwise, if number_of_depreciations_booked = 2, available_for_use_date = 01/01/2020 and frequency_of_depreciation = 12
+	# from_date = 01/01/2022
+	from_date = _get_modified_available_for_use_date(asset_doc, row, wdv_or_dd_non_yearly)
+	days = date_diff(row.depreciation_start_date, from_date) + 1
+
+	if wdv_or_dd_non_yearly:
+		total_days = get_total_days(row.depreciation_start_date, 12)
+	else:
+		# if frequency_of_depreciation is 12 months, total_days = 365
+		total_days = get_total_days(row.depreciation_start_date, row.frequency_of_depreciation)
+
+	if days < total_days:
+		has_pro_rata = True
+
+	return has_pro_rata
+
+
+def _get_modified_available_for_use_date(asset_doc, row, wdv_or_dd_non_yearly=False):
+	if wdv_or_dd_non_yearly:
+		return add_months(
+			asset_doc.available_for_use_date,
+			(asset_doc.number_of_depreciations_booked * 12),
+		)
+	else:
+		return add_months(
+			asset_doc.available_for_use_date,
+			(asset_doc.number_of_depreciations_booked * row.frequency_of_depreciation),
+		)
+
+
+def _get_pro_rata_amt(
+	row, depreciation_amount, from_date, to_date, has_wdv_or_dd_non_yearly_pro_rata=False
+):
+	days = date_diff(to_date, from_date)
+	months = month_diff(to_date, from_date)
+	if has_wdv_or_dd_non_yearly_pro_rata:
+		total_days = get_total_days(to_date, 12)
+	else:
+		total_days = get_total_days(to_date, row.frequency_of_depreciation)
+
+	return (depreciation_amount * flt(days)) / flt(total_days), days, months
+
+
+def get_total_days(date, frequency):
+	period_start_date = add_months(date, cint(frequency) * -1)
+
+	if is_last_day_of_the_month(date):
+		period_start_date = get_last_day(period_start_date)
+
+	return date_diff(date, period_start_date)
+
+
+@erpnext.allow_regional
+def get_depreciation_amount(
+	asset,
+	depreciable_value,
+	row,
+	schedule_idx=0,
+	prev_depreciation_amount=0,
+	has_wdv_or_dd_non_yearly_pro_rata=False,
+):
+	if row.depreciation_method in ("Straight Line", "Manual"):
+		return get_straight_line_or_manual_depr_amount(asset, row)
+	else:
+		return get_wdv_or_dd_depr_amount(
+			depreciable_value,
+			row.rate_of_depreciation,
+			row.frequency_of_depreciation,
+			schedule_idx,
+			prev_depreciation_amount,
+			has_wdv_or_dd_non_yearly_pro_rata,
+		)
+
+
+def get_straight_line_or_manual_depr_amount(asset, row):
+	# if the Depreciation Schedule is being modified after Asset Repair due to increase in asset life and value
+	if asset.flags.increase_in_asset_life:
+		return (flt(row.value_after_depreciation) - flt(row.expected_value_after_useful_life)) / (
+			date_diff(asset.to_date, asset.available_for_use_date) / 365
+		)
+	# if the Depreciation Schedule is being modified after Asset Repair due to increase in asset value
+	elif asset.flags.increase_in_asset_value_due_to_repair:
+		return (flt(row.value_after_depreciation) - flt(row.expected_value_after_useful_life)) / flt(
+			row.total_number_of_depreciations
+		)
+	# if the Depreciation Schedule is being prepared for the first time
+	else:
+		return (flt(asset.gross_purchase_amount) - flt(row.expected_value_after_useful_life)) / flt(
+			row.total_number_of_depreciations
+		)
+
+
+def get_wdv_or_dd_depr_amount(
+	depreciable_value,
+	rate_of_depreciation,
+	frequency_of_depreciation,
+	schedule_idx,
+	prev_depreciation_amount,
+	has_wdv_or_dd_non_yearly_pro_rata,
+):
+	if cint(frequency_of_depreciation) == 12:
+		return flt(depreciable_value) * (flt(rate_of_depreciation) / 100)
+	else:
+		if has_wdv_or_dd_non_yearly_pro_rata:
+			if schedule_idx == 0:
+				return flt(depreciable_value) * (flt(rate_of_depreciation) / 100)
+			elif schedule_idx % (12 / cint(frequency_of_depreciation)) == 1:
+				return (
+					flt(depreciable_value) * flt(frequency_of_depreciation) * (flt(rate_of_depreciation) / 1200)
+				)
+			else:
+				return prev_depreciation_amount
+		else:
+			if schedule_idx % (12 / cint(frequency_of_depreciation)) == 0:
+				return (
+					flt(depreciable_value) * flt(frequency_of_depreciation) * (flt(rate_of_depreciation) / 1200)
+				)
+			else:
+				return prev_depreciation_amount
 
 
 def make_draft_asset_depr_schedules_if_not_present(asset_doc):