Auto-update invoice due date when invoice date changes

Port of master's 241ec092 (Feat: Automatically set due date when invoice date is changed). The original commit was a JavaScript Options-API watcher in the deleted v1 InvoiceCreate.vue; v3.0's equivalent is a Composition-API TypeScript view at resources/scripts/features/company/invoices/views/InvoiceCreateView.vue, so this is a re-implementation rather than a cherry-pick.

Behaviour: if the company setting invoice_set_due_date_automatically is 'YES', a watcher on invoiceStore.newInvoice.invoice_date recomputes the due date as invoice_date + invoice_due_date_days whenever the invoice date changes. A second watcher on due_date tracks whether the user has manually edited it; if the manual value is still valid (>= the new invoice date) it is left alone, otherwise the auto value takes over. An isAutoUpdatingDueDate guard avoids a feedback loop when the watcher writes back to the store.

Uses moment for the date math, matching the original master commit and several other v3.0 features (reports, CreateCustomFields) that already import moment. companyStore is newly imported in this view to read selectedCompanySettings.

resources/scripts/features/company/invoices/views/InvoiceCreateView.vue

@@ -109,6 +109,7 @@ import { computed, ref, watch } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 import { useI18n } from 'vue-i18n'
 import cloneDeep from 'lodash/cloneDeep'
+import moment from 'moment'
 import {
   required,
   maxLength,
@@ -119,6 +120,7 @@ import {
 import useVuelidate from '@vuelidate/core'
 import { useInvoiceStore } from '../store'
 import { useRecurringInvoiceStore } from '@/scripts/features/company/recurring-invoices/store'
+import { useCompanyStore } from '@/scripts/stores/company.store'
 import InvoiceBasicFields from '../components/InvoiceBasicFields.vue'
 import {
   DocumentItemsTable,
@@ -130,6 +132,7 @@ import {
 
 const invoiceStore = useInvoiceStore()
 const recurringInvoiceStore = useRecurringInvoiceStore()
+const companyStore = useCompanyStore()
 const { t } = useI18n()
 const route = useRoute()
 const router = useRouter()
@@ -139,6 +142,12 @@ const isSaving = ref<boolean>(false)
 const isMarkAsDefault = ref<boolean>(false)
 const isRecurring = ref<boolean>(false)
 
+// Auto-due-date bookkeeping: tracks whether the user has manually edited the
+// due date, so the invoice_date watcher can avoid clobbering a manual value.
+const dueDateManuallyChanged = ref<boolean>(false)
+let isAutoUpdatingDueDate = false
+const expectedAutoDueDate = ref<string | null>(null)
+
 const invoiceNoteFieldList = ref<string[]>(['customer', 'company', 'invoice'])
 
 const isLoadingContent = computed<boolean>(
@@ -262,6 +271,71 @@ watch(
   },
 )
 
+// Detect manual edits to the due date so we know not to overwrite them
+// when the invoice date changes afterwards.
+watch(
+  () => invoiceStore.newInvoice.due_date,
+  (newDueDate, oldDueDate) => {
+    if (
+      !isAutoUpdatingDueDate
+      && newDueDate !== oldDueDate
+      && oldDueDate !== undefined
+      && newDueDate !== expectedAutoDueDate.value
+    ) {
+      dueDateManuallyChanged.value = true
+    }
+  },
+)
+
+// Auto-compute due_date = invoice_date + invoice_due_date_days whenever the
+// invoice date changes, if the company setting opts into automatic dates
+// and the user hasn't locked a manual due date in the future.
+watch(
+  () => invoiceStore.newInvoice.invoice_date,
+  (newInvoiceDate, oldInvoiceDate) => {
+    if (
+      companyStore.selectedCompanySettings?.invoice_set_due_date_automatically !== 'YES'
+      || !newInvoiceDate
+      || newInvoiceDate === oldInvoiceDate
+      || oldInvoiceDate === undefined
+    ) {
+      return
+    }
+
+    const dueDateDays = parseInt(
+      companyStore.selectedCompanySettings?.invoice_due_date_days ?? '0',
+      10,
+    )
+    const invoiceDate = moment(newInvoiceDate as string)
+    if (!invoiceDate.isValid()) {
+      return
+    }
+
+    const calculatedDueDate = invoiceDate
+      .clone()
+      .add(dueDateDays, 'days')
+      .format('YYYY-MM-DD')
+    expectedAutoDueDate.value = calculatedDueDate
+
+    if (dueDateManuallyChanged.value) {
+      const currentDueDate = invoiceStore.newInvoice.due_date
+      if (currentDueDate) {
+        const currentMoment = moment(currentDueDate as string)
+        if (currentMoment.isValid() && currentMoment.isSameOrAfter(invoiceDate, 'day')) {
+          // Manual due date still valid — leave it alone
+          return
+        }
+      }
+      // Manual due date is in the past / invalid — take back control
+      dueDateManuallyChanged.value = false
+    }
+
+    isAutoUpdatingDueDate = true
+    invoiceStore.newInvoice.due_date = calculatedDueDate
+    isAutoUpdatingDueDate = false
+  },
+)
+
 async function submitForm(): Promise<void> {
   v$.value.$touch()