import policy from "./invoice-party-policy.json";
import type { Invoice } from "./data";

// Which half of the register an invoice belongs to. Both pages are the SAME PocketBase
// collection split by this module — see ./invoice-party-policy.json for why it is one
// collection and not two.
//
// Deliberately pure and import-safe from client components: no server-only, no PB. The
// pages filter on the server before handing plain data to the client list, and this
// module is the only thing that decides which side a row lands on.

export type PartyScope = "internal" | "external";

const norm = (v: unknown) => String(v ?? "").trim().toLowerCase();

// The group entities that count as internal. Matched on name OR debtor number, so an
// invoice that prints "Mega Infrastructure" and one that prints only "09MIS001" both
// land on the internal page.
const INTERNAL = policy.internalDebtors.map((d) => ({
  name: norm(d.name),
  debtorNo: norm(d.debtorNo),
}));

type PartyBearing = Pick<Invoice, "debtor" | "debtor_no">;

// True when the debtor is a known group entity.
export function isInternalParty(inv: PartyBearing): boolean {
  const name = norm(inv.debtor);
  const no = norm(inv.debtor_no);
  if (!name && !no) return false;
  return INTERNAL.some((d) => (name && name === d.name) || (no && no === d.debtorNo));
}

// An invoice naming no debtor cannot be placed by evidence, so it is reported as
// unclassified rather than assumed internal. It still appears on the external page —
// nothing may be invisible on both screens.
export function isClassified(inv: PartyBearing): boolean {
  return Boolean(norm(inv.debtor) || norm(inv.debtor_no));
}

export function partyOf(inv: PartyBearing): PartyScope {
  return isInternalParty(inv) ? "internal" : "external";
}

export function filterByParty<T extends PartyBearing>(invoices: T[], scope: PartyScope): T[] {
  return invoices.filter((i) => partyOf(i) === scope);
}

// Shown on the external page when a row landed there only because it named no debtor.
// Keeps an unclassifiable invoice visible as a question rather than a silent filing.
export function unclassifiedCount(invoices: Invoice[]): number {
  return invoices.filter((i) => partyOf(i) === "external" && !isClassified(i)).length;
}