From c8e7674d63efbbafc1de09f35acfcdd264009dd8 Mon Sep 17 00:00:00 2001
From: diptanilsaha <diptanil@frappe.io>
Date: Thu, 16 Jul 2026 23:07:40 +0530
Subject: [PATCH] fix: added missing validations for `Dunning Type`

---
 .../doctype/dunning_type/dunning_type.py      | 134 ++++++++++++++++++
 1 file changed, 134 insertions(+)

diff --git a/erpnext/accounts/doctype/dunning_type/dunning_type.py b/erpnext/accounts/doctype/dunning_type/dunning_type.py
index 77f2e004e3d..f267ee5b9a1 100644
--- a/erpnext/accounts/doctype/dunning_type/dunning_type.py
+++ b/erpnext/accounts/doctype/dunning_type/dunning_type.py
@@ -3,7 +3,10 @@
 
 
 import frappe
+from frappe import _
 from frappe.model.document import Document
+from frappe.utils import comma_and
+from frappe.utils.jinja import validate_template
 
 
 class DunningType(Document):
@@ -30,3 +33,134 @@ class DunningType(Document):
 	def autoname(self):
 		company_abbr = frappe.get_value("Company", self.company, "abbr")
 		self.name = f"{self.dunning_type} - {company_abbr}"
+
+	def validate(self):
+		self.validate_dunning_letter_text()
+		self.validate_income_account()
+		self.validate_cost_center()
+		self.set_default_dunning_type()
+
+	def validate_dunning_letter_text(self):
+		self.validate_languages()
+		self.validate_is_default_language()
+		self.validate_dunning_letter_text_templates()
+
+	def validate_income_account(self):
+		if not self.income_account:
+			return
+
+		account = frappe.get_cached_doc("Account", self.income_account)
+
+		msg = []
+		if account.company != self.company:
+			msg.append(
+				_(
+					"{0} doesn't belong to Company {1}. Please select an Income Account that belongs to Company {1}."
+				).format(frappe.bold(self.income_account), frappe.bold(self.company))
+			)
+
+		if account.disabled:
+			msg.append(
+				_("{0} is disabled. Please select a valid Income Account.").format(
+					frappe.bold(self.income_account)
+				)
+			)
+
+		if account.root_type != "Income":
+			msg.append(
+				_("{0} is not an Income Account. Please select a valid Income Account.").format(
+					frappe.bold(self.income_account)
+				)
+			)
+
+		if account.is_group:
+			msg.append(
+				_("{0} is a group account. Please select a non-group Income Account.").format(
+					frappe.bold(self.income_account)
+				)
+			)
+
+		if msg:
+			frappe.msgprint(
+				msg,
+				title=_("Income Account Validation Error"),
+				as_list=True,
+				raise_exception=frappe.ValidationError,
+			)
+
+	def validate_cost_center(self):
+		if not self.cost_center:
+			return
+
+		cost_center = frappe.get_cached_doc("Cost Center", self.cost_center)
+
+		msg = []
+		if cost_center.company != self.company:
+			msg.append(
+				_(
+					"{0} doesn't belong to Company {1}. Please select a Cost Center that belongs to Company {1}."
+				).format(frappe.bold(self.cost_center), frappe.bold(self.company))
+			)
+
+		if cost_center.disabled:
+			msg.append(
+				_("{0} is disabled. Please select an enabled Cost Center.").format(
+					frappe.bold(self.cost_center)
+				)
+			)
+
+		if cost_center.is_group:
+			msg.append(
+				_("{0} is a group Cost Center. Please select a non-group Cost Center.").format(
+					frappe.bold(self.cost_center)
+				)
+			)
+
+		if msg:
+			frappe.msgprint(
+				msg,
+				title=_("Cost Center Validation Error"),
+				as_list=True,
+				raise_exception=frappe.ValidationError,
+			)
+
+	def validate_languages(self):
+		languages = [d.language for d in self.dunning_letter_text]
+
+		if len(languages) == len(set(languages)):
+			return
+
+		frappe.throw(_("Duplicate languages found on Dunning Letter Text. Keep only one of them."))
+
+	def validate_is_default_language(self):
+		is_default_language_list = [
+			d.language for d in self.dunning_letter_text if d.is_default_language == 1
+		]
+
+		if len(is_default_language_list) <= 1:
+			return
+
+		frappe.throw(
+			_("{0} languages are marked as default languages. Please select only one of them.").format(
+				comma_and(is_default_language_list, add_quotes=True)
+			)
+		)
+
+	def validate_dunning_letter_text_templates(self):
+		for d in self.dunning_letter_text:
+			if d.body_text:
+				validate_template(d.body_text, restrict_globals=True)
+
+			if d.closing_text:
+				validate_template(d.closing_text, restrict_globals=True)
+
+	def set_default_dunning_type(self):
+		if self.is_default != 1:
+			return
+
+		frappe.db.set_value(
+			"Dunning Type",
+			{"company": self.company, "is_default": 1, "name": ["!=", self.name]},
+			"is_default",
+			0,
+		)