/**
 * Customer invoice numbers for an order, derived from its line items.
 *
 * An order has no invoice column of its own — invoicing happens per
 * `order_items` row, and a partial pickup can put one order across
 * several invoices. The number lives in one of two places depending on
 * which flow raised the invoice:
 *
 *   `order_item_details.invoice.number` — written by the Invoicing page
 *                                        (QuickBooks webhook). Carries the
 *                                        QB link, date and who set it.
 *   `customer_invoice_number`           — written by
 *                                        `reconcileOrderItemInvoicedStatus`.
 *
 * `order_item_details` wins when both are set because it carries the QB
 * metadata. Safe to import from client components.
 *
 * Careful: collection-confirm ALSO writes `order_item_details.invoice`,
 * with the SUPPLIER's invoice number ("Confirmed for invoicing — IN-…"),
 * before the customer is billed. QuickBooks' write-back later replaces
 * it. Only an `invoice` blob carrying QuickBooks fields (`qbInvoiceId`,
 * `qbInvoiceLink` or `billingCompany`) is a customer invoice.
 */

export type InvoiceBearingItem = {
  id?: string;
  customer_invoice_number?: string | null;
  invoiced_date?: string | null;
  order_item_details?: string | Record<string, unknown> | null;
};

export type OrderInvoiceSummary = {
  number: string;
  /** YYYY-MM-DD (or full ISO) when known, else null. */
  date: string | null;
  qbInvoiceLink: string | null;
  billingCompany: string | null;
  setByName: string | null;
  /** How many of the order's lines went out on this invoice. */
  lineCount: number;
};

type InvoiceDetails = {
  number?: unknown;
  date?: unknown;
  qbInvoiceId?: unknown;
  qbInvoiceLink?: unknown;
  billingCompany?: unknown;
  setByName?: unknown;
};

function str(value: unknown): string | null {
  return typeof value === "string" && value.trim() ? value.trim() : null;
}

function readInvoiceDetails(
  details: InvoiceBearingItem["order_item_details"],
): InvoiceDetails | null {
  let parsed: unknown = details;
  if (typeof details === "string") {
    if (!details.trim()) return null;
    try {
      parsed = JSON.parse(details);
    } catch {
      return null;
    }
  }
  if (!parsed || typeof parsed !== "object") return null;
  const invoice = (parsed as { invoice?: unknown }).invoice;
  if (!invoice || typeof invoice !== "object") return null;
  const blob = invoice as InvoiceDetails;
  // Supplier invoice from collection-confirm — not a customer invoice.
  const fromQuickBooks = !!(str(blob.qbInvoiceId) || str(blob.qbInvoiceLink) || str(blob.billingCompany));
  return fromQuickBooks ? blob : null;
}

/** The invoice number a single line went out on, or null. */
export function readItemInvoiceNumber(item: InvoiceBearingItem): string | null {
  return (
    str(readInvoiceDetails(item.order_item_details)?.number) ??
    str(item.customer_invoice_number)
  );
}

/**
 * Distinct invoices across an order's lines, oldest first. Lines with no
 * invoice number are ignored, so an order that isn't invoiced yet returns
 * an empty array.
 */
export function summarizeOrderInvoices(
  items: readonly InvoiceBearingItem[],
): OrderInvoiceSummary[] {
  const byNumber = new Map<string, OrderInvoiceSummary>();
  for (const item of items) {
    const details = readInvoiceDetails(item.order_item_details);
    const number = str(details?.number) ?? str(item.customer_invoice_number);
    if (!number) continue;
    const existing = byNumber.get(number);
    if (existing) {
      existing.lineCount += 1;
      existing.date ??= str(details?.date) ?? str(item.invoiced_date);
      existing.qbInvoiceLink ??= str(details?.qbInvoiceLink);
      existing.billingCompany ??= str(details?.billingCompany);
      existing.setByName ??= str(details?.setByName);
      continue;
    }
    byNumber.set(number, {
      number,
      date: str(details?.date) ?? str(item.invoiced_date),
      qbInvoiceLink: str(details?.qbInvoiceLink),
      billingCompany: str(details?.billingCompany),
      setByName: str(details?.setByName),
      lineCount: 1,
    });
  }
  return [...byNumber.values()].sort((a, b) =>
    (a.date ?? "9999").localeCompare(b.date ?? "9999") ||
    a.number.localeCompare(b.number),
  );
}