feat(banking): add cost centres and VAT to account allocations

frontend/utils/bankAllocationTax.ts

@@ -0,0 +1,43 @@
+export const BANK_ALLOCATION_TAX_ITEMS = [
+    { value: "9", label: "19 % Vorsteuer", rate: 19, kind: "input" },
+    { value: "8", label: "7 % Vorsteuer", rate: 7, kind: "input" },
+    { value: "3", label: "19 % Umsatzsteuer", rate: 19, kind: "output" },
+    { value: "2", label: "7 % Umsatzsteuer", rate: 7, kind: "output" },
+    { value: "40", label: "Ohne Umsatzsteuer", rate: 0, kind: "none" },
+]
+
+export const isDirectBankAllocation = (allocation: any) => Boolean(
+    allocation?.bankstatement && (allocation.account || allocation.ownaccount)
+    && !allocation.createddocument && !allocation.incominginvoice
+    && !allocation.customer && !allocation.vendor && !allocation.archived
+)
+
+// The signed bank amount always remains gross. Refunds retain their sign.
+export function getBankAllocationAmounts(allocation: any) {
+    const amountGross = Number(allocation?.amount || 0)
+    const tax = isDirectBankAllocation(allocation)
+        ? BANK_ALLOCATION_TAX_ITEMS.find(item => item.value === String(allocation.datevTaxKey))
+        : undefined
+    const rate = tax?.rate || 0
+    const amountNet = Number((amountGross / (1 + rate / 100)).toFixed(2))
+    const amountTax = Number((amountGross - amountNet).toFixed(2))
+    return { amountGross, amountNet, amountTax, rate, kind: tax?.kind || "none" }
+}
+
+export function getBankAllocationTaxBreakdown(allocation: any) {
+    const output = { net19: 0, tax19: 0, net7: 0, tax7: 0, net0: 0 }
+    const input = { ...output }
+    if (!isDirectBankAllocation(allocation)) return { output, input }
+    const { amountNet, amountTax, rate, kind } = getBankAllocationAmounts(allocation)
+    if (kind === "none") return { output, input }
+    const target = kind === "input" ? input : output
+    const sign = kind === "input" ? -1 : 1
+    if (rate === 19) {
+        target.net19 = amountNet * sign
+        target.tax19 = amountTax * sign
+    } else if (rate === 7) {
+        target.net7 = amountNet * sign
+        target.tax7 = amountTax * sign
+    }
+    return { output, input }
+}