// src/pages/DashboardPage/BillingPage/invoiceLineRow.ts
// Phase B review fix (C1): the InvoiceEditor <-> InvoiceLineDraft conversion, extracted out of
// InvoiceEditor.tsx so it's unit-testable without dragging in the services barrel (InvoiceEditor.tsx
// imports it, no behavior change there).
//
// `fromRow` used to reconstruct the InvoiceLineDraft field-by-field, which silently dropped
// `appointmentId` - a Time line's link back to the Appointment it billed. That broke
// `billedAppointmentIds` (invoiceTransform.ts / unbilledAppointments.ts read `line.appointmentId`),
// silently defeating Phase B's whole double-bill-prevention feature: a saved invoice line looked
// exactly like one with no appointment link, so the same appointment could be billed again on the
// next invoice. Rewritten to destructure out ONLY the three UI-only fields and spread the rest, so
// every current AND future InvoiceLineDraft field (description, unitPriceCents, quantity, taxable,
// sourceType, sourceRef, coding, appointmentId,...) survives the round trip without this file having
// to be touched again when InvoiceLineDraft grows a new field.
import { v4 as uuidv4 } from 'uuid';
import { lineAmountCents, type InvoiceLineDraft } from '../../../utils/invoiceTransform';
import { computeTax, sumCents } from '../../../utils/money';

// Row-local state adds `key` (a stable React key across add/remove - the array index would misattribute
// focus/typed text to the wrong row once a line above it is removed), `amountText` (the raw unit-price
// dollar string as typed), and `quantityText` (the raw quantity string as typed). Both `unitPriceCents`
// and `quantity` are only ever refreshed from *parseable* text, so a half-typed "12." or a momentarily
// empty quantity box is never clobbered back to a canonical value mid-keystroke - canonicalization only
// happens on blur. `taxable` and `sourceRef`/`coding` (Service lines) round-trip untouched - this editor
// only ever writes description/unitPriceCents/quantity.
export type LineRow = InvoiceLineDraft & { key: string; amountText: string; quantityText: string };

export const toRow = (line: InvoiceLineDraft): LineRow => ({
    ...line,
    key: uuidv4(),
    amountText: (line.unitPriceCents / 100).toFixed(2),
    quantityText: String(line.quantity > 0 ? line.quantity : 1),
});

// Destructure out exactly the UI-only fields LineRow adds on top of InvoiceLineDraft (`key`,
// `amountText`, `quantityText`) and spread everything else back out untouched - rather than listing
// InvoiceLineDraft's fields one by one, which is exactly how `appointmentId` got silently dropped
// before. If `toRow` ever adds another UI-only field, it must be destructured here too (the round-trip
// test below would catch a miss: the extra field would leak into the saved draft).
export const fromRow = (row: LineRow): InvoiceLineDraft => {
    const { key, amountText, quantityText, ...draft } = row;
    return draft;
};

export type LineTotals = { subtotalCents: number; taxCents: number; totalCents: number };

// Task 7: the editor's live Subtotal/Tax/Total breakdown for the in-progress draft - mirrors
// invoiceTransform.ts's buildInvoiceResource computation exactly (tax computed ONLY on taxable lines,
// via the same shared computeTax helper - never hand-rolled a second way) so what the biller sees while
// composing a draft always matches what gets frozen onto the invoice on save. Pure/testable independent
// of the InvoiceEditor component; accepts any InvoiceLineDraft[] (LineRow satisfies this) so it works
// directly against the editor's row state without a fromRow conversion first.
export const computeLineTotals = (lines: InvoiceLineDraft[], taxRatePercent: number): LineTotals => {
    const subtotalCents = sumCents(lines.map(lineAmountCents));
    const taxableSubtotalCents = sumCents(lines.filter((line) => line.taxable).map(lineAmountCents));
    const taxCents = computeTax(taxableSubtotalCents, taxRatePercent);
    return { subtotalCents, taxCents, totalCents: subtotalCents + taxCents };
};