// Fare model tuned to the Lebanese market:
// - Distance-based with a base fare (like CTaxi/local taxis), not time-only.
// - Typical Beirut rides land in the $3–8 range riders expect.
// - Prices are quoted in USD (the de facto ride-hailing currency) with an
//   L.B.P. equivalent shown for cash settlement.

import { DEFAULT_SERVICE, SERVICES, type ServiceId } from "@/constants/services";

export const FARE = {
  base: 1.5, // USD, flag drop
  perKm: 0.55, // USD per kilometer of the trip
  perMin: 0.15, // USD per minute of the trip
  minimum: 3.0, // USD minimum fare
} as const;

// Parallel market rate used for the L.B.P. cash equivalent shown in-app.
export const LBP_RATE = 89500;

export const calculateFare = (
  {
    distanceMeters,
    durationSeconds,
  }: {
    distanceMeters: number;
    durationSeconds: number;
  },
  service: ServiceId = DEFAULT_SERVICE,
): string => {
  const km = distanceMeters / 1000;
  const minutes = durationSeconds / 60;

  const multiplier =
    SERVICES.find((s) => s.id === service)?.fareMultiplier ?? 1;
  const fare = (FARE.base + km * FARE.perKm + minutes * FARE.perMin) * multiplier;

  // The minimum fare is a floor on the final amount.
  return Math.max(fare, FARE.minimum).toFixed(2);
};

// Rounds to the nearest 1,000 L.B.P. — the smallest practical cash note.
export const formatLBP = (usd: number): string =>
  `${(Math.round((usd * LBP_RATE) / 1000) * 1000).toLocaleString("en-US")} L.B.P.`;