/**
 * Cheque status lookup.
 *
 * There is no CBS endpoint for this yet — `endpoints.ts` has cheque book
 * requests and stop payments but nothing that answers "what happened to leaf
 * 123456". Until there is, the answer is resolved locally, in the same way the
 * dashboard, cards and loans resolve from fixtures today.
 *
 * The result is derived from the cheque number rather than drawn at random, so
 * the same number always gives the same answer. A demo that changes its mind
 * between two taps of the same button reads as a bug, and it makes the screen
 * impossible to write a test against.
 *
 * To go live, replace the body of `lookupChequeFate` with the API call. The
 * `ChequeFate` shape is what the screen renders, so it is the contract to map
 * the response onto.
 */

export type ChequeFateStatus = 'paid' | 'in_clearing' | 'returned' | 'stopped' | 'not_found';

export type ChequeFate = {
  chequeNumber: string;
  status: ChequeFateStatus;
  /** Short human label for the status, shown as the result headline. */
  label: string;
  amount?: number;
  presentedOn?: string;
  clearedOn?: string;
  payee?: string;
  /** Why a cheque was returned or stopped. Absent for a clean outcome. */
  reason?: string;
  /** The caveat under the result — what the customer should do next. */
  note: string;
};

const formatDay = (daysAgo: number) => {
  const date = new Date();

  date.setDate(date.getDate() - daysAgo);

  return new Intl.DateTimeFormat('en-IN', {
    day: '2-digit',
    month: 'short',
    year: 'numeric',
  }).format(date);
};

export type ChequeFateQuery = {
  accountNumber: string;
  chequeNumber: string;
};

export const lookupChequeFate = async ({
  accountNumber,
  chequeNumber,
}: ChequeFateQuery): Promise<ChequeFate> => {
  // Stands in for the round trip, so the button's loading state is visible and
  // the screen is exercised the way it will behave against the real API.
  await new Promise((resolve) => setTimeout(resolve, 600));

  const digits = Number.parseInt(chequeNumber, 10);
  // Mixing the account in means the same leaf number on two accounts gives two
  // answers, which is the behaviour the real ledger has.
  const seed = (Number.isNaN(digits) ? 0 : digits) + Number(accountNumber.slice(-2) || 0);
  const amount = 1500 + (seed % 220) * 125;

  switch (seed % 5) {
    case 0:
      return {
        chequeNumber,
        status: 'paid',
        label: 'Paid',
        amount,
        presentedOn: formatDay(6),
        clearedOn: formatDay(4),
        payee: 'Meghana Rao',
        note: 'Funds have left your account. The clearing house record is final.',
      };
    case 1:
      return {
        chequeNumber,
        status: 'in_clearing',
        label: 'In clearing',
        amount,
        presentedOn: formatDay(1),
        payee: 'Sunrise Traders',
        note: 'Presented and awaiting settlement. Cheques normally clear within two working days.',
      };
    case 2:
      return {
        chequeNumber,
        status: 'returned',
        label: 'Returned unpaid',
        amount,
        presentedOn: formatDay(3),
        payee: 'Vasan Electricals',
        reason: 'Insufficient funds',
        note: 'A return charge may apply. Contact your branch before re-presenting the cheque.',
      };
    case 3:
      return {
        chequeNumber,
        status: 'stopped',
        label: 'Stop payment in force',
        amount,
        presentedOn: formatDay(2),
        reason: 'Stop payment requested by you',
        note: 'This cheque will not be paid while the stop instruction stands.',
      };
    default:
      return {
        chequeNumber,
        status: 'not_found',
        label: 'No record found',
        note: 'This cheque has not been presented on the selected account. Check the number and the account, then try again.',
      };
  }
};