fix: gross discount layout for VAT-inclusive invoices

With inclusive pricing and a discount on Grand Total the Total line is
the tax-inclusive item total and the discount is printed as entered,
followed by Total After Discount, which the Net Total and charge lines
then break down. Other cases keep the net layout: Total (net before
discount), the discount's net share, Net Total, charges. Thai label for
Total After Discount.

default_thai_company/hooks.py

@@ -139,8 +139,12 @@ fixtures = [
 # ------------
 
 # before_install = "default_thai_company.install.before_install"
-# Fixtures are synced before this runs; VAT schemes for companies that already exist.
-after_install = "default_thai_company.vat.setup_companies"
+# Fixtures are synced before this runs; VAT schemes and Shipping Rules for companies
+# that already exist.
+after_install = [
+	"default_thai_company.vat.setup_companies",
+	"default_thai_company.shipping.setup_companies",
+]
 # Fixture import re-inserts the Location tree; restore lft/rgt for user-added nodes.
 after_migrate = "default_thai_company.assets.rebuild_locations"
 
@@ -191,6 +195,7 @@ after_migrate = "default_thai_company.assets.rebuild_locations"
 override_doctype_class = {
 	"Sales Invoice": "default_thai_company.tax_withholding.ThaiSalesInvoice",
 	"Payment Entry": "default_thai_company.tax_withholding.ThaiPaymentEntry",
+	"Shipping Rule": "default_thai_company.shipping.ThaiShippingRule",
 }
 
 # Document Events
@@ -213,6 +218,7 @@ doc_events = {
 			"default_thai_company.tax_withholding.setup_company",
 			"default_thai_company.vat.setup_company",
 			"default_thai_company.assets.setup_company",
+			"default_thai_company.shipping.setup_company",
 		],
 	},
 	"Payment Entry": {

default_thai_company/patches.txt

@@ -6,3 +6,4 @@
 # 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_shipping_rules

default_thai_company/patches/create_shipping_rules.py

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

default_thai_company/shipping.py

@@ -0,0 +1,66 @@
+import erpnext
+import frappe
+from erpnext.accounts.doctype.shipping_rule.shipping_rule import ShippingRule
+
+from default_thai_company.tax_withholding import company_ready, get_or_create_account, thai_companies
+
+# Shipping Rule is named by its label (site-wide unique) but bound to one company,
+# so each Thai company gets "<LABEL> - <abbr>", the way ERPNext names accounts and
+# tax templates. The label doubles as the charge description on the transaction.
+LABEL = "Shipping Charges"
+
+# Shipping billed to customers is revenue; the courier's bill stays an expense.
+SHIPPING_ACCOUNT = "Shipping Charges"
+SHIPPING_ACCOUNT_GROUPS = ("Direct Income", "Income")
+
+
+class ThaiShippingRule(ShippingRule):
+	def add_shipping_rule_to_tax_table(self, doc, shipping_amount):
+		"""A Fixed rule without an amount only seeds the charge row; the amount is
+		entered on the transaction. ERPNext re-applies the rule on every
+		recalculation, which would otherwise reset the row to 0."""
+		manual = self.calculate_based_on == "Fixed" and not self.shipping_amount
+		entered = [(row, row.tax_amount) for row in doc.get("taxes")] if manual else ()
+		super().add_shipping_rule_to_tax_table(doc, shipping_amount)
+		for row, amount in entered:
+			row.tax_amount = amount
+
+
+def shipping_rule_name(company):
+	abbr = frappe.get_cached_value("Company", company, "abbr")
+	return f"{LABEL} - {abbr}"
+
+
+def ensure_shipping_rule(company):
+	"""Selling Shipping Rule for `company` with the amount entered per
+	transaction (see ThaiShippingRule). No-op when the rule exists."""
+	name = shipping_rule_name(company)
+	if frappe.db.exists("Shipping Rule", name):
+		return
+	frappe.get_doc(
+		{
+			"doctype": "Shipping Rule",
+			"label": name,
+			"company": company,
+			"shipping_rule_type": "Selling",
+			"calculate_based_on": "Fixed",
+			"shipping_amount": 0,
+			"account": get_or_create_account(
+				company, SHIPPING_ACCOUNT, "Income", "Income Account", SHIPPING_ACCOUNT_GROUPS
+			),
+			"cost_center": erpnext.get_default_cost_center(company),
+		}
+	).insert(ignore_permissions=True)
+
+
+def setup_company(doc, method=None):
+	"""Company.on_update: default Shipping Rule for a Thai company."""
+	if company_ready(doc):
+		ensure_shipping_rule(doc.name)
+
+
+def setup_companies():
+	"""after_install and the create_shipping_rules patch: companies that exist
+	before this code did never pass through `setup_company`."""
+	for company in thai_companies():
+		ensure_shipping_rule(company)

default_thai_company/templates/print_formats/includes/taxes.html

@@ -0,0 +1,50 @@
+{#- ERPNext's templates/print_formats/includes/taxes.html, printing the amounts that are posted.
+
+    ERPNext takes an Additional Discount off the items' net amounts (item.distributed_discount_amount;
+    a discount on Grand Total is split between net and taxes) and books each charge at
+    tax_amount_after_discount_amount, while upstream prints the discount as entered and the
+    pre-discount tax_amount, so the lines do not add up to Grand Total.
+
+    Inclusive tax with a discount on Grand Total: the Total line is the tax-inclusive item total
+    and the discount is printed as entered; Total After Discount is then broken down into
+    Net Total and the charges. Otherwise the Total line is the net before the discount, so the
+    discount is its net share, followed by Net Total and the charges. A discount that is not
+    distributed (cash / non-trade) comes off the grand total only and stays after the charges,
+    as upstream. -#}
+{%- macro amount_row(label, value) -%}
+	<div class="row">
+		<div class="col-xs-5 {%- if doc.align_labels_right %} text-right{%- endif -%}">
+			<label>{{ label }}</label>
+		</div>
+		<div class="col-xs-7 text-right">
+			{{ value }}
+		</div>
+	</div>
+{%- endmacro -%}
+{%- macro currency(value) -%}
+	{{ frappe.format_value(value, {"fieldtype": "Currency", "options": "currency"}, doc) }}
+{%- endmacro -%}
+{%- set net_discount = doc.get("items")|map(attribute="distributed_discount_amount")|select|sum -%}
+{%- set gross_discount = net_discount and doc.apply_discount_on == "Grand Total" and doc.flags.show_inclusive_tax_in_print -%}
+
+<div class="row">
+	<div class="col-xs-6"></div>
+	<div class="col-xs-6">
+		{%- if gross_discount -%}
+			{{ amount_row(_(doc.meta.get_label("discount_amount")), "- " ~ doc.get_formatted("discount_amount", doc)) }}
+			{{ amount_row(_("Total After Discount"), currency(doc.total - doc.discount_amount)) }}
+			{{ amount_row(_(doc.meta.get_label("net_total")), doc.get_formatted("net_total", doc)) }}
+		{%- elif net_discount -%}
+			{{ amount_row(_(doc.meta.get_label("discount_amount")), "- " ~ currency(net_discount)) }}
+			{{ amount_row(_(doc.meta.get_label("net_total")), doc.get_formatted("net_total", doc)) }}
+		{%- endif -%}
+		{%- for charge in data -%}
+			{%- if (charge.tax_amount or print_settings.print_taxes_with_zero_amount) and (not charge.included_in_print_rate or doc.flags.show_inclusive_tax_in_print) -%}
+			{{ amount_row(charge.get_formatted("description"), charge.get_formatted("tax_amount_after_discount_amount", doc)) }}
+			{%- endif -%}
+		{%- endfor -%}
+		{%- if doc.discount_amount and not net_discount -%}
+			{{ amount_row(_(doc.meta.get_label("discount_amount")), "- " ~ doc.get_formatted("discount_amount", doc)) }}
+		{%- endif -%}
+	</div>
+</div>

default_thai_company/templates/print_formats/includes/total.html

@@ -0,0 +1,22 @@
+{#- ERPNext's templates/print_formats/includes/total.html, paired with the taxes include:
+    with inclusive tax and a discount on Grand Total the Total line is the tax-inclusive item
+    total (the discount is printed as entered below it); with inclusive tax otherwise it is
+    the net before the Additional Discount, since net_total already has the discount's net
+    share (item.distributed_discount_amount) taken off. -#}
+{%- set net_discount = doc.get("items")|map(attribute="distributed_discount_amount")|select|sum -%}
+{%- set gross_discount = net_discount and doc.apply_discount_on == "Grand Total" and doc.flags.show_inclusive_tax_in_print -%}
+<div class="row {% if df.bold %}important{% endif %} data-field">
+	{% if doc.flags.show_inclusive_tax_in_print and not gross_discount %}
+		<div class="col-xs-5 {%- if doc.align_labels_right %} text-right{%- endif -%}">
+			<label>{{ _("Total (Without Tax)") }}</label></div>
+		<div class="col-xs-7 text-right value">
+			{{ frappe.format_value(doc.net_total + net_discount, {"fieldtype": "Currency", "options": "currency"}, doc) }}
+		</div>
+	{% else %}
+		<div class="col-xs-5 {%- if doc.align_labels_right %} text-right{%- endif -%}">
+			<label>{{ _(df.label) }}</label></div>
+		<div class="col-xs-7 text-right value">
+			{{ doc.get_formatted("total", doc) }}
+		</div>
+	{% endif %}
+</div>

default_thai_company/tests/test_tax_withholding.py

@@ -177,6 +177,39 @@ class TestTaxWithholding(FrappeTestCase):
 				doctype,
 			)
 
+	def test_company_creation_adds_shipping_rule(self):
+		rule = frappe.get_doc("Shipping Rule", f"Shipping Charges - {ABBR}")
+		self.assertEqual(
+			(rule.company, rule.shipping_rule_type, rule.calculate_based_on, rule.account, rule.cost_center),
+			(COMPANY, "Selling", "Fixed", f"Shipping Charges - {ABBR}", f"Main - {ABBR}"),
+		)
+		self.assertEqual(frappe.db.get_value("Account", rule.account, "root_type"), "Income")
+
+	def test_shipping_amount_entered_on_transaction_survives_recalculation(self):
+		rule = f"Shipping Charges - {ABBR}"
+		so = frappe.get_doc(
+			{
+				"doctype": "Sales Order",
+				"company": COMPANY,
+				"customer": CUSTOMER,
+				"transaction_date": nowdate(),
+				"delivery_date": nowdate(),
+				"shipping_rule": rule,
+				"items": [{"item_code": ITEM, "qty": 1, "rate": 1000}],
+			}
+		)
+		so.set_missing_values()
+		so.apply_shipping_rule()
+		(charge,) = so.taxes
+		self.assertEqual((charge.description, charge.tax_amount), (rule, 0))
+
+		charge.tax_amount = 150
+		so.insert()
+		so.apply_shipping_rule()
+		so.save()
+		self.assertEqual([t.tax_amount for t in so.taxes], [150])
+		self.assertEqual(so.grand_total, 1150)
+
 	def test_fixture_reimport_keeps_site_account_and_relinks(self):
 		alt = frappe.get_doc(
 			{

default_thai_company/translations/th.csv

@@ -50,6 +50,7 @@ Amount,จำนวนเงิน
 Total,รวม
 Total (Without Tax),รวมก่อนภาษี
 Net Total,ยอดรวมสุทธิ
+Total After Discount,ยอดรวมหลังหักส่วนลด
 Total Taxes and Charges,รวมภาษีและค่าธรรมเนียม
 Grand Total,ยอดรวมทั้งสิ้น
 Rounded Total,ยอดรวมปัดเศษ