/** Supplier list rules: folding names into one key, payment terms and due dates. Pure — client-safe. */

export type Terms = "" | "cash" | "30" | "60";
export const TERMS: { id: Terms; label: string }[] = [
  { id: "cash", label: "Cash" },
  { id: "30", label: "30 days" },
  { id: "60", label: "60 days" },
];
export const termsLabel = (t: string) => TERMS.find((x) => x.id === t)?.label ?? "Not set";
export const parseTerms = (v: unknown): Terms => (v === "cash" || v === "30" || v === "60" ? v : "");
export const isAccount = (t: string) => t === "30" || t === "60";

// Company-form words that change between a PO and a till slip but never name a different supplier.
const NOISE = new Set(["PTY", "LTD", "LIMITED", "CC", "INC", "THE", "AND"]);

/**
 * "Lube Force Traders cc" → "LUBEFORCETRADERS". Upper-case, punctuation gone, company-form words
 * dropped. This is the same name typed two ways — it is NOT a fuzzy match: "Your Tyre Shop" and
 * "Tyre Shop" stay different suppliers.
 */
export function supplierKey(name: string): string {
  return (name || "")
    .toUpperCase()
    .replace(/&/g, " AND ")
    .replace(/[^A-Z0-9]+/g, " ")
    .split(" ")
    .filter((w) => w && !NOISE.has(w))
    .join("");
}

/** The day an account purchase falls due: PO date + terms. "" when there are no account terms or no valid date. */
export function dueDate(poDate: string, terms: string): string {
  if (!isAccount(terms)) return "";
  const d = new Date(`${(poDate || "").slice(0, 10)}T00:00:00Z`);
  if (Number.isNaN(d.getTime())) return "";
  d.setUTCDate(d.getUTCDate() + Number(terms));
  return d.toISOString().slice(0, 10);
}