From f9f10ed743aa6dd64b97e286c25b9dfe47248466 Mon Sep 17 00:00:00 2001
From: Ankush <ankush@iwebnotes.com>
Date: Mon, 15 Mar 2021 17:58:17 +0530
Subject: [PATCH] fix: Add warning for invalid GST invoice numbers (#24837)

* fix: Add warning for invalid GST invoice numbers

GST Invoice numbers should be 16 characters alphanumeric with dash(/) or
slash(-) only. Add check for doc.name before saving and warn about
naming series.

* refactor: move regex patterns to global variables

Co-authored-by: Deepesh Garg <42651287+deepeshgarg007@users.noreply.github.com>
---
 erpnext/hooks.py                |  3 +++
 erpnext/regional/india/utils.py | 29 ++++++++++++++++++++++++-----
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/erpnext/hooks.py b/erpnext/hooks.py
index 219e426d782..2d995ed0e67 100644
--- a/erpnext/hooks.py
+++ b/erpnext/hooks.py
@@ -261,6 +261,9 @@ doc_events = {
 	('Sales Invoice', 'Sales Order', 'Delivery Note', 'Purchase Invoice', 'Purchase Order', 'Purchase Receipt'): {
 		'validate': ['erpnext.regional.india.utils.set_place_of_supply']
 	},
+	('Sales Invoice', 'Purchase Invoice'): {
+		'validate': ['erpnext.regional.india.utils.validate_document_name']
+	},
 	"Contact": {
 		"on_trash": "erpnext.support.doctype.issue.issue.update_issue",
 		"after_insert": "erpnext.communication.doctype.call_log.call_log.set_caller_information",
diff --git a/erpnext/regional/india/utils.py b/erpnext/regional/india/utils.py
index 89677433392..99b37818a0a 100644
--- a/erpnext/regional/india/utils.py
+++ b/erpnext/regional/india/utils.py
@@ -2,7 +2,7 @@ from __future__ import unicode_literals
 import frappe, re, json
 from frappe import _
 import erpnext
-from frappe.utils import cstr, flt, date_diff, nowdate, round_based_on_smallest_currency_fraction, money_in_words
+from frappe.utils import cstr, flt, date_diff, nowdate, round_based_on_smallest_currency_fraction, money_in_words, getdate
 from erpnext.regional.india import states, state_numbers
 from erpnext.controllers.taxes_and_totals import get_itemised_tax, get_itemised_taxable_amount, calculate_outstanding_amount
 from erpnext.controllers.accounts_controller import get_taxes_and_charges
@@ -15,6 +15,13 @@ from erpnext.accounts.utils import get_account_currency
 from frappe.contacts.doctype.address.address import get_address_display
 from frappe.model.utils import get_fetch_values
 
+
+GST_INVOICE_NUMBER_FORMAT = re.compile(r"^[a-zA-Z0-9\-/]+$")   #alphanumeric and - /
+GSTIN_FORMAT = re.compile("^[0-9]{2}[A-Z]{4}[0-9A-Z]{1}[0-9]{4}[A-Z]{1}[1-9A-Z]{1}[1-9A-Z]{1}[0-9A-Z]{1}$")
+GSTIN_UIN_FORMAT = re.compile("^[0-9]{4}[A-Z]{3}[0-9]{5}[0-9A-Z]{3}")
+PAN_NUMBER_FORMAT = re.compile("[A-Z]{5}[0-9]{4}[A-Z]{1}")
+
+
 def validate_gstin_for_india(doc, method):
 	if hasattr(doc, 'gst_state') and doc.gst_state:
 		doc.gst_state_number = state_numbers[doc.gst_state]
@@ -38,12 +45,10 @@ def validate_gstin_for_india(doc, method):
 		frappe.throw(_("Invalid GSTIN! A GSTIN must have 15 characters."))
 
 	if gst_category and gst_category == 'UIN Holders':
-		p = re.compile("^[0-9]{4}[A-Z]{3}[0-9]{5}[0-9A-Z]{3}")
-		if not p.match(doc.gstin):
+		if not GSTIN_UIN_FORMAT.match(doc.gstin):
 			frappe.throw(_("Invalid GSTIN! The input you've entered doesn't match the GSTIN format for UIN Holders or Non-Resident OIDAR Service Providers"))
 	else:
-		p = re.compile("^[0-9]{2}[A-Z]{4}[0-9A-Z]{1}[0-9]{4}[A-Z]{1}[1-9A-Z]{1}[1-9A-Z]{1}[0-9A-Z]{1}$")
-		if not p.match(doc.gstin):
+		if not GSTIN_FORMAT.match(doc.gstin):
 			frappe.throw(_("Invalid GSTIN! The input you've entered doesn't match the format of GSTIN."))
 
 		validate_gstin_check_digit(doc.gstin)
@@ -162,6 +167,20 @@ def set_transporter_address(doc, method=None):
 	doc.transporter_address = transporter_address
 	doc.transporter_address_display = get_address_display(transporter_address)
 
+def validate_document_name(doc, method=None):
+	"""Validate GST invoice number requirements."""
+	country = frappe.get_cached_value("Company", doc.company, "country")
+
+	# Date was chosen as start of next FY to avoid irritating current users.
+	if country != "India" or getdate(doc.posting_date) < getdate("2021-04-01"):
+		return
+
+	if len(doc.name) > 16:
+		frappe.throw(_("Maximum length of document number should be 16 characters as per GST rules. Please change the naming series."))
+
+	if not GST_INVOICE_NUMBER_FORMAT.match(doc.name):
+		frappe.throw(_("Document name should only contain alphanumeric values, dash(-) and slash(/) characters as per GST rules. Please change the naming series."))
+
 # don't remove this function it is used in tests
 def test_method():
 	'''test function'''