Correct GST state selection for walk-in and named customers

api/src/helpers/bill-payload.js

@@ -254,15 +254,7 @@ function taxRows(sale, branch, allocation = null) {
     const taxMinor = money.toMinor(tax, policy);
     const firstHalf = Math.ceil(taxMinor / 2);
     const rate = gstRate(sale);
-    const stateKey = (value) => {
-      const key = String(value || '')
-        .trim()
-        .toLowerCase();
-      const match = require('../json/gst_state_code.json').gststate.find(
-        (row) => row.id === key.padStart(2, '0') || row.value.toLowerCase() === key
-      );
-      return match ? match.id : key;
-    };
+    const { stateKey } = require('./gst-place');
     const supplierState = stateKey(sale.branch_state || branch.state);
     const supplyState = stateKey(sale.place_of_supply || sale.customer_state);
     if (supplierState && supplyState && supplierState !== supplyState) {

api/src/helpers/gst-place.js

@@ -0,0 +1,29 @@
+const { gststate } = require('../json/gst_state_code.json');
+
+function stateKey(value) {
+  const key = String(value || '')
+    .trim()
+    .toLowerCase()
+    .replace(/\s+/g, ' ');
+  const state = gststate.find(
+    (row) => row.id === key.padStart(2, '0') || row.value.toLowerCase() === key
+  );
+  return state ? state.id : key;
+}
+
+function isInterState(supplierState, customerState) {
+  const supplier = stateKey(supplierState);
+  const customer = stateKey(customerState);
+  return Boolean(supplier && customer && supplier !== customer);
+}
+
+function customerState(data, branch, customer) {
+  const supplier = String(branch.state || '').trim();
+  const isDefault =
+    !data.customer_id ||
+    (branch.default_customer && String(data.customer_id) === String(branch.default_customer));
+  if (isDefault) return supplier;
+  return String(data.customer_state || customer?.state || '').trim() || supplier;
+}
+
+module.exports = { stateKey, isInterState, customerState };

api/src/repositories/sale.repository.js

@@ -949,10 +949,10 @@ class SalesRepository {
                 const customerState = (doc.customer_state || '').toString().trim();
                 const branchState = (branchDoc?.state || '').toString().trim();
 
-                const isInterState =
-                  customerState &&
-                  branchState &&
-                  customerState.toLowerCase() !== branchState.toLowerCase();
+                const isInterState = require('../helpers/gst-place').isInterState(
+                  branchState,
+                  customerState
+                );
 
                 if (isInterState) {
                   cloned.igst_tax = perLineGstAmount;

api/src/services/sale.service.js

@@ -426,6 +426,13 @@ const processSale = async (
     const pricingCustomer = data.customer_id
       ? await customerRepository.findById(data.customer_id)
       : null;
+    const gstPlace = require('../helpers/gst-place');
+    const supplierState = context.branchState || pricingBranch.state || '';
+    const saleCustomerState = gstPlace.customerState(
+      data,
+      { ...pricingBranch, state: supplierState },
+      pricingCustomer
+    );
     let priceList;
     if (pricingCustomer?.category_id) {
       const pricingDb = await BaseModel.getDb();
@@ -662,7 +669,7 @@ const processSale = async (
 
       const indianGstSetting = context.branchSettings?.indian_gst || 'gst_off';
 
-      const interPlace = (data.customer_state || '').trim() !== (context.branchState || '').trim();
+      const interPlace = gstPlace.isInterState(supplierState, saleCustomerState);
       if (indianGstSetting === 'gst_on' && gstValue > 0) {
         if (interPlace) {
           igst_value = gstValue;
@@ -1274,7 +1281,7 @@ const processSale = async (
           }
         : {}),
       customer_email: (data.customer_email || '').trim(),
-      customer_state: (data.customer_state || '').trim(),
+      customer_state: saleCustomerState,
       customer_country: (data.customer_country || '').trim(),
       country_sort: finalCountrySort,
       customer_gst_type: (data.customer_gst_type || '').trim(),

api/tests/unit/helpers/gst-place.test.js

@@ -0,0 +1,23 @@
+const { stateKey, isInterState, customerState } = require('../../../src/helpers/gst-place');
+
+test.each([
+  ['Tamil Nadu', '33', false],
+  ['33', ' tamil   nadu ', false],
+  ['Tamil Nadu', 'Karnataka', true],
+  ['33', '29', true],
+  ['33', '', false],
+  ['', '29', false],
+])('GST state comparison %s / %s is interstate: %s', (supplier, customer, expected) => {
+  expect(isInterState(supplier, customer)).toBe(expected);
+});
+
+test('walk-in and configured default customers use the branch state', () => {
+  const branch = { state: 'Tamil Nadu', default_customer: 'walkin-id' };
+  expect(customerState({}, branch)).toBe('Tamil Nadu');
+  expect(customerState({ customer_id: 'walkin-id', customer_state: '29' }, branch)).toBe(
+    'Tamil Nadu'
+  );
+  expect(customerState({ customer_id: 'named-id' }, branch, { state: '29' })).toBe('29');
+  expect(customerState({ customer_id: 'named-id' }, branch)).toBe('Tamil Nadu');
+  expect(stateKey(' 33 ')).toBe('33');
+});

api/tests/unit/services/sale.service.test.js

@@ -187,6 +187,46 @@ describe('SalesService', () => {
     mockRegisterRepositoryInstance.validateSessionOwner.mockResolvedValue({ status: true });
   });
 
+  test.each([
+    ['', undefined, '', false],
+    ['64f8f2f4c2b9c0a1e4b22222', '', '', false],
+    ['64f8f2f4c2b9c0a1e4b22222', '33', '', false],
+    ['64f8f2f4c2b9c0a1e4b22222', ' tamil nadu ', '', false],
+    ['64f8f2f4c2b9c0a1e4b22222', 'Karnataka', '', true],
+    ['64f8f2f4c2b9c0a1e4b22222', '29', '', true],
+    ['64f8f2f4c2b9c0a1e4b22222', '29', '64f8f2f4c2b9c0a1e4b22222', false],
+  ])(
+    'saves GST by customer state (%s, %s, default %s)',
+    async (customer_id, customer_state, default_customer, inter) => {
+      mockItemRepositoryInstance.findItemById.mockResolvedValue(
+        makeItemDoc({ selling_price: 100, tax: 18, tax_type: 'exclusive' })
+      );
+      const result = await salesService.processSale(
+        makeSaleData({
+          customer_id,
+          customer_state,
+          sales_total: '236',
+          multi_payment: { Cash: 236 },
+        }),
+        '',
+        'Add',
+        makeContext({
+          branchState: 'Tamil Nadu',
+          branchSettings: { sortname: 'IN', indian_gst: 'gst_on', default_customer },
+        })
+      );
+      expect(result.status).toBe(true);
+      const saved = salesRepository.create.mock.calls[0][0];
+      expect(saved.items[0].igst_tax).toBe(inter ? 36 : 0);
+      expect(saved.items[0].cgst_tax).toBe(inter ? 0 : 18);
+      expect(saved.items[0].sgst_tax).toBe(inter ? 0 : 18);
+      expect(saved.items[0].tax_components.map((component) => component.name)).toEqual(
+        inter ? ['IGST'] : ['CGST', 'SGST']
+      );
+      if (!customer_state || default_customer) expect(saved.customer_state).toBe('Tamil Nadu');
+    }
+  );
+
   afterEach(() => {
     process.removeListener(KOT_EVENT, onKotReady);
     consoleErrorSpy.mockRestore();