set after_insert methods:

- if subscription is not in trial period, generate sales invoice

erpnext/accounts/doctype/subscriptions/subscriptions.py

@@ -42,6 +42,17 @@ class Subscriptions(Document):
 			self.status = 'Active'
 			# todo: then generate new invoice
 
+	def is_trialling(self):
+		return not self.period_has_passed(self.trial_period_end) and self.is_new_subscription()
+
+	def period_has_passed(self, end_date):
+		# todo: test for illegal time
+		if not end_date:
+			return True
+
+		end_date = getdate(end_date)
+		return nowdate() > end_date
+
 	def is_past_grace_period(self):
 		current_invoice = self.get_current_invoice()
 		if self.current_invoice_is_past_due(current_invoice):
@@ -58,6 +69,12 @@ class Subscriptions(Document):
 		else:
 			return nowdate() > current_invoice.due_date
 
+	def get_current_invoice(self):
+		if len(self.invoices):
+			current = self.invoices[-1]
+			doc = frappe.get_doc('Sales Invoice', current)
+			return doc
+
 	def is_new_subscription(self):
 		return len(self.invoices) == 0
 
@@ -72,3 +89,67 @@ class Subscriptions(Document):
 		elif self.trial_period_start or self.trial_period_end:
 			frappe.throw(_('Both Trial Period Start Date and Trial Period End Date must be set'))
 
+	def after_insert(self):
+		if not self.is_trialling():
+			self.generate_invoice()
+
+	def generate_invoice(self):
+		invoice = self.create_invoice()
+		invoice.save()
+		invoice.submit()
+		self.append('invoices', {'invoice': invoice.name})
+		self.subscription_updated(invoice)
+
+		return invoice
+
+	def create_invoice(self):
+		invoice = frappe.new_doc('Sales Invoice')
+		invoice.customer = self.get_customer(self.subscriber)
+
+		# Subscription is better suited for service items. I won't update `update_stock`
+		# for that reason
+		items_list = self.get_items_from_plans(self.plans)
+		for item in items_list:
+			item['qty'] = self.quantity
+			invoice.append('items',	item)
+
+		# Taxes
+		# todo: tax template does not populate tax table
+		if self.tax_template:
+			invoice.taxes_and_charges = self.tax_template
+
+		# Due date
+		if cint(self.days_until_due):
+			invoice.append(
+				'payment_schedule', 
+				{
+					'due_date': add_days(nowdate(), cint(self.days_until_due)),
+					'invoice_portion': 100
+				}
+			)
+
+		# Discounts
+		if self.apply_additional_discount:
+			invoice.apply_discount_on = self.apply_additional_discount
+
+		if self.additional_discount_percentage:
+			invoice.additional_discount_percentage = self.additional_discount_percentage
+
+		if self.additional_discount_amount:
+			invoice.additional_discount_amount = self.additional_discount_amount
+
+		return invoice
+
+	def get_customer(self, subscriber_name):
+		return frappe.get_value('Subscriber', subscriber_name)
+
+	def get_items_from_plans(self, plans):
+		plan_items = [plan.plan for plan in plans]
+
+		if plan_items:
+			item_names = frappe.db.sql(
+				'select item as item_code, cost as rate from `tabSubscription Plan` where name=%s',
+				plan_items, as_dict=1
+			)
+			return item_names
+