From a630db1b2163ed4ca1a94c8387733deef9dc4e87 Mon Sep 17 00:00:00 2001
From: Anand Baburajan <anandbaburajan@gmail.com>
Date: Thu, 8 Jun 2023 23:16:28 +0530
Subject: [PATCH] fix: calculate wdv depr schedule properly for existing assets
 [v14] (#35613)

* fix: calculate wdv depr schedule properly for existing assets

* fix: calculate wdv depr schedule properly for existing assets properly

(cherry picked from commit feb5d0089b48ed48748c8383a7c4f324ef822bb9)
---
 erpnext/assets/doctype/asset/asset.py        | 27 +++++++++++++++-----
 erpnext/assets/doctype/asset/depreciation.py | 17 +++++++++++-
 erpnext/assets/doctype/asset/test_asset.py   |  4 +--
 3 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/erpnext/assets/doctype/asset/asset.py b/erpnext/assets/doctype/asset/asset.py
index ae77b9b94ce..02260c6da3a 100644
--- a/erpnext/assets/doctype/asset/asset.py
+++ b/erpnext/assets/doctype/asset/asset.py
@@ -26,6 +26,7 @@ from erpnext.accounts.general_ledger import make_reverse_gl_entries
 from erpnext.assets.doctype.asset.depreciation import (
 	get_depreciation_accounts,
 	get_disposal_account_and_cost_center,
+	is_first_day_of_the_month,
 	is_last_day_of_the_month,
 )
 from erpnext.assets.doctype.asset_category.asset_category import get_asset_category_account
@@ -359,8 +360,14 @@ class Asset(AccountsController):
 				break
 
 			# For first row
-			if n == 0 and has_pro_rata and not self.opening_accumulated_depreciation:
-				from_date = add_days(self.available_for_use_date, -1)
+			if (
+				n == 0
+				and (has_pro_rata or has_wdv_or_dd_non_yearly_pro_rata)
+				and not self.opening_accumulated_depreciation
+			):
+				from_date = add_days(
+					self.available_for_use_date, -1
+				)  # needed to calc depr amount for available_for_use_date too
 				depreciation_amount, days, months = self.get_pro_rata_amt(
 					finance_book,
 					depreciation_amount,
@@ -369,10 +376,18 @@ class Asset(AccountsController):
 					has_wdv_or_dd_non_yearly_pro_rata,
 				)
 			elif n == 0 and has_wdv_or_dd_non_yearly_pro_rata and self.opening_accumulated_depreciation:
-				from_date = add_months(
-					getdate(self.available_for_use_date),
-					(self.number_of_depreciations_booked * finance_book.frequency_of_depreciation),
-				)
+				if not is_first_day_of_the_month(getdate(self.available_for_use_date)):
+					from_date = get_last_day(
+						add_months(
+							getdate(self.available_for_use_date),
+							((self.number_of_depreciations_booked - 1) * finance_book.frequency_of_depreciation),
+						)
+					)
+				else:
+					from_date = add_months(
+						getdate(add_days(self.available_for_use_date, -1)),
+						(self.number_of_depreciations_booked * finance_book.frequency_of_depreciation),
+					)
 				depreciation_amount, days, months = self.get_pro_rata_amt(
 					finance_book,
 					depreciation_amount,
diff --git a/erpnext/assets/doctype/asset/depreciation.py b/erpnext/assets/doctype/asset/depreciation.py
index 163752b65eb..0c8d5f527fd 100644
--- a/erpnext/assets/doctype/asset/depreciation.py
+++ b/erpnext/assets/doctype/asset/depreciation.py
@@ -4,7 +4,16 @@
 
 import frappe
 from frappe import _
-from frappe.utils import add_months, cint, flt, get_last_day, getdate, nowdate, today
+from frappe.utils import (
+	add_months,
+	cint,
+	flt,
+	get_first_day,
+	get_last_day,
+	getdate,
+	nowdate,
+	today,
+)
 from frappe.utils.data import get_link_to_form
 from frappe.utils.user import get_users_with_role
 
@@ -591,3 +600,9 @@ def is_last_day_of_the_month(date):
 	last_day_of_the_month = get_last_day(date)
 
 	return getdate(last_day_of_the_month) == getdate(date)
+
+
+def is_first_day_of_the_month(date):
+	first_day_of_the_month = get_first_day(date)
+
+	return getdate(first_day_of_the_month) == getdate(date)
diff --git a/erpnext/assets/doctype/asset/test_asset.py b/erpnext/assets/doctype/asset/test_asset.py
index 1c0972f2374..fea6ed3d2bd 100644
--- a/erpnext/assets/doctype/asset/test_asset.py
+++ b/erpnext/assets/doctype/asset/test_asset.py
@@ -766,14 +766,14 @@ class TestDepreciationMethods(AssetSetup):
 			number_of_depreciations_booked=1,
 			opening_accumulated_depreciation=50000,
 			expected_value_after_useful_life=10000,
-			depreciation_start_date="2030-12-31",
+			depreciation_start_date="2031-12-31",
 			total_number_of_depreciations=3,
 			frequency_of_depreciation=12,
 		)
 
 		self.assertEqual(asset.status, "Draft")
 
-		expected_schedules = [["2030-12-31", 33333.50, 83333.50], ["2031-12-31", 6666.50, 90000.0]]
+		expected_schedules = [["2031-12-31", 33333.50, 83333.50], ["2032-12-31", 6666.50, 90000.0]]
 
 		schedules = [
 			[cstr(d.schedule_date), d.depreciation_amount, d.accumulated_depreciation_amount]