feat: Thai VAT schemes as Sales/Purchase Taxes and Charges Templates

Per Thai company: Thailand VAT 7%, Thailand VAT 7% (Included) for
VAT-inclusive pricing, Thailand VAT 0% for zero-rated supplies. Sales
schemes post to Output VAT, purchase schemes to Input VAT (category
Total, so recoverable VAT stays out of valuation). The 7% scheme is the
default when the company has none. Created on Company save, after
install, and by a patch for existing companies.

default_thai_company/hooks.py

@@ -103,7 +103,8 @@ fixtures = [
 # ------------
 
 # before_install = "default_thai_company.install.before_install"
-# after_install = "default_thai_company.install.after_install"
+# Fixtures are synced before this runs; VAT schemes for companies that already exist.
+after_install = "default_thai_company.vat.setup_companies"
 
 # Uninstallation
 # ------------
@@ -167,7 +168,10 @@ doc_events = {
 		"before_import": "default_thai_company.tax_withholding.prepare_fixture_accounts",
 	},
 	"Company": {
-		"on_update": "default_thai_company.tax_withholding.setup_company",
+		"on_update": [
+			"default_thai_company.tax_withholding.setup_company",
+			"default_thai_company.vat.setup_company",
+		],
 	},
 	"Payment Entry": {
 		"validate": "default_thai_company.tax_withholding.set_customer_withholding",

default_thai_company/patches.txt

@@ -5,3 +5,4 @@
 [post_model_sync]
 # Patches added in this section will be executed after doctypes are migrated
 default_thai_company.patches.create_vat_accounts
+default_thai_company.patches.create_vat_templates

default_thai_company/patches/create_vat_templates.py

@@ -0,0 +1,5 @@
+from default_thai_company.vat import setup_companies
+
+
+def execute():
+	setup_companies()

default_thai_company/tax_withholding.py

@@ -118,9 +118,14 @@ def prepare_fixture_accounts(doc, method=None):
 			link_company(doc, company, ensure_company_accounts(company))
 
 
+def company_ready(doc):
+	"""A Thai company whose chart of accounts exists."""
+	return doc.country == "Thailand" and frappe.db.exists("Account", {"company": doc.name})
+
+
 def setup_company(doc, method=None):
 	"""Company.on_update: create the tax accounts and link every WHT category."""
-	if doc.country != "Thailand" or not frappe.db.exists("Account", {"company": doc.name}):
+	if not company_ready(doc):
 		return
 
 	account = ensure_company_accounts(doc.name)

default_thai_company/tests/test_tax_withholding.py

@@ -149,6 +149,34 @@ class TestTaxWithholding(FrappeTestCase):
 		for name in categories:
 			self.assertEqual(self.category_account(name), self.payable, name)
 
+	def test_company_creation_adds_vat_schemes(self):
+		for doctype, account in (
+			("Sales Taxes and Charges Template", f"{OUTPUT_VAT_ACCOUNT} - {ABBR}"),
+			("Purchase Taxes and Charges Template", f"{INPUT_VAT_ACCOUNT} - {ABBR}"),
+		):
+			schemes = {}
+			for name in frappe.get_all(
+				doctype, filters={"company": COMPANY, "title": ("like", "Thailand VAT%")}, pluck="name"
+			):
+				doc = frappe.get_doc(doctype, name)
+				(row,) = doc.taxes
+				schemes[doc.title] = (
+					doc.is_default,
+					row.account_head,
+					row.charge_type,
+					row.rate,
+					row.included_in_print_rate,
+				)
+			self.assertEqual(
+				schemes,
+				{
+					"Thailand VAT 7%": (1, account, "On Net Total", 7.0, 0),
+					"Thailand VAT 7% (Included)": (0, account, "On Net Total", 7.0, 1),
+					"Thailand VAT 0%": (0, account, "On Net Total", 0.0, 0),
+				},
+				doctype,
+			)
+
 	def test_fixture_reimport_keeps_site_account_and_relinks(self):
 		alt = frappe.get_doc(
 			{

default_thai_company/vat.py

@@ -0,0 +1,78 @@
+import erpnext
+import frappe
+
+from default_thai_company.tax_withholding import (
+	INPUT_VAT_ACCOUNT,
+	OUTPUT_VAT_ACCOUNT,
+	company_ready,
+	get_or_create_account,
+	thai_companies,
+)
+
+RATE = 7.0
+
+# title, rate, included_in_print_rate. Exempt supplies take no template.
+SCHEMES = (
+	("Thailand VAT 7%", RATE, 0),
+	("Thailand VAT 7% (Included)", RATE, 1),  # VAT-inclusive prices, the retail norm
+	("Thailand VAT 0%", 0.0, 0),  # zero-rated: exports, international transport
+)
+DEFAULT_SCHEME = "Thailand VAT 7%"
+
+# doctype, account, root type, extra row fields. Input VAT is recoverable, so on
+# purchases it is "Total" (added to the bill, kept out of item valuation).
+TEMPLATES = (
+	("Sales Taxes and Charges Template", OUTPUT_VAT_ACCOUNT, "Liability", {}),
+	(
+		"Purchase Taxes and Charges Template",
+		INPUT_VAT_ACCOUNT,
+		"Asset",
+		{"category": "Total", "add_deduct_tax": "Add"},
+	),
+)
+
+
+def ensure_vat_templates(company):
+	"""Create the VAT schemes for `company`, skipping titles that exist. The 7%
+	scheme becomes the default when the company has no default template."""
+	cost_center = erpnext.get_default_cost_center(company)
+	for doctype, account_name, root_type, extra in TEMPLATES:
+		account = get_or_create_account(company, account_name, root_type)
+		has_default = frappe.db.exists(doctype, {"company": company, "is_default": 1})
+		for title, rate, included in SCHEMES:
+			if frappe.db.exists(doctype, {"company": company, "title": title}):
+				continue
+			is_default = title == DEFAULT_SCHEME and not has_default
+			frappe.get_doc(
+				{
+					"doctype": doctype,
+					"title": title,
+					"company": company,
+					"is_default": int(is_default),
+					"taxes": [
+						{
+							"charge_type": "On Net Total",
+							"account_head": account,
+							"rate": rate,
+							"description": f"VAT {rate:g}%",
+							"included_in_print_rate": included,
+							"cost_center": cost_center,
+							**extra,
+						}
+					],
+				}
+			).insert(ignore_permissions=True)
+			has_default = has_default or is_default
+
+
+def setup_company(doc, method=None):
+	"""Company.on_update: VAT schemes for a Thai company."""
+	if company_ready(doc):
+		ensure_vat_templates(doc.name)
+
+
+def setup_companies():
+	"""after_install and the create_vat_templates patch: companies that exist
+	before this code did never pass through `setup_company`."""
+	for company in thai_companies():
+		ensure_vat_templates(company)