Merge pull request #39332 from ruthra-kumar/validate_subscription_billing_currency

refactor: prevent foreign currency subscription for a party
diff --git a/erpnext/accounts/doctype/subscription/subscription.py b/erpnext/accounts/doctype/subscription/subscription.py
index 72e574c..ce56a7b 100644
--- a/erpnext/accounts/doctype/subscription/subscription.py
+++ b/erpnext/accounts/doctype/subscription/subscription.py
@@ -16,6 +16,7 @@
 	date_diff,
 	flt,
 	get_last_day,
+	get_link_to_form,
 	getdate,
 	nowdate,
 )
@@ -317,6 +318,37 @@
 		if self.is_new():
 			self.set_subscription_status()
 
+		self.validate_party_billing_currency()
+
+	def validate_party_billing_currency(self):
+		"""
+		Subscription should be of the same currency as the Party's default billing currency or company default.
+		"""
+		if self.party:
+			party_billing_currency = frappe.get_cached_value(
+				self.party_type, self.party, "default_currency"
+			) or frappe.get_cached_value("Company", self.company, "default_currency")
+
+			plans = [x.plan for x in self.plans]
+			subscription_plan_currencies = frappe.db.get_all(
+				"Subscription Plan", filters={"name": ("in", plans)}, fields=["name", "currency"]
+			)
+			unsupported_plans = []
+			for x in subscription_plan_currencies:
+				if x.currency != party_billing_currency:
+					unsupported_plans.append("{0}".format(get_link_to_form("Subscription Plan", x.name)))
+
+			if unsupported_plans:
+				unsupported_plans = [
+					_(
+						"Below Subscription Plans are of different currency to the party default billing currency/Company currency: {0}"
+					).format(frappe.bold(party_billing_currency))
+				] + unsupported_plans
+
+				frappe.throw(
+					unsupported_plans, frappe.ValidationError, "Unsupported Subscription Plans", as_list=True
+				)
+
 	def validate_trial_period(self) -> None:
 		"""
 		Runs sanity checks on trial period dates for the `Subscription`
diff --git a/erpnext/accounts/doctype/subscription/test_subscription.py b/erpnext/accounts/doctype/subscription/test_subscription.py
index 785fd04..37326fd 100644
--- a/erpnext/accounts/doctype/subscription/test_subscription.py
+++ b/erpnext/accounts/doctype/subscription/test_subscription.py
@@ -463,7 +463,7 @@
 		subscription = create_subscription(
 			start_date="2018-01-01",
 			generate_invoice_at="Beginning of the current subscription period",
-			plans=[{"plan": "_Test Plan Multicurrency", "qty": 1}],
+			plans=[{"plan": "_Test Plan Multicurrency", "qty": 1, "currency": "USD"}],
 			party="_Test Subscription Customer",
 		)
 
@@ -528,13 +528,21 @@
 
 
 def make_plans():
-	create_plan(plan_name="_Test Plan Name", cost=900)
-	create_plan(plan_name="_Test Plan Name 2", cost=1999)
+	create_plan(plan_name="_Test Plan Name", cost=900, currency="INR")
+	create_plan(plan_name="_Test Plan Name 2", cost=1999, currency="INR")
 	create_plan(
-		plan_name="_Test Plan Name 3", cost=1999, billing_interval="Day", billing_interval_count=14
+		plan_name="_Test Plan Name 3",
+		cost=1999,
+		billing_interval="Day",
+		billing_interval_count=14,
+		currency="INR",
 	)
 	create_plan(
-		plan_name="_Test Plan Name 4", cost=20000, billing_interval="Month", billing_interval_count=3
+		plan_name="_Test Plan Name 4",
+		cost=20000,
+		billing_interval="Month",
+		billing_interval_count=3,
+		currency="INR",
 	)
 	create_plan(
 		plan_name="_Test Plan Multicurrency", cost=50, billing_interval="Month", currency="USD"
diff --git a/erpnext/accounts/doctype/subscription_plan/subscription_plan.json b/erpnext/accounts/doctype/subscription_plan/subscription_plan.json
index 563df79..bc1f579 100644
--- a/erpnext/accounts/doctype/subscription_plan/subscription_plan.json
+++ b/erpnext/accounts/doctype/subscription_plan/subscription_plan.json
@@ -41,7 +41,8 @@
    "fieldname": "currency",
    "fieldtype": "Link",
    "label": "Currency",
-   "options": "Currency"
+   "options": "Currency",
+   "reqd": 1
   },
   {
    "fieldname": "column_break_3",
@@ -148,10 +149,11 @@
   }
  ],
  "links": [],
- "modified": "2021-12-10 15:24:15.794477",
+ "modified": "2024-01-14 17:59:34.687977",
  "modified_by": "Administrator",
  "module": "Accounts",
  "name": "Subscription Plan",
+ "naming_rule": "By fieldname",
  "owner": "Administrator",
  "permissions": [
   {
@@ -193,5 +195,6 @@
  ],
  "sort_field": "modified",
  "sort_order": "DESC",
+ "states": [],
  "track_changes": 1
 }
\ No newline at end of file
diff --git a/erpnext/accounts/doctype/subscription_plan/subscription_plan.py b/erpnext/accounts/doctype/subscription_plan/subscription_plan.py
index 118d254..cdfa3e5 100644
--- a/erpnext/accounts/doctype/subscription_plan/subscription_plan.py
+++ b/erpnext/accounts/doctype/subscription_plan/subscription_plan.py
@@ -24,7 +24,7 @@
 		billing_interval_count: DF.Int
 		cost: DF.Currency
 		cost_center: DF.Link | None
-		currency: DF.Link | None
+		currency: DF.Link
 		item: DF.Link
 		payment_gateway: DF.Link | None
 		plan_name: DF.Data