import type { Address, Appointment, Location } from "fhir/r4";

/**
 * Where an appointment is, and whether a patient can be given directions to it. R6.
 *
 * THE RULE IS ADDRESS-DERIVED, NEVER TELEHEALTH-FLAG-DERIVED, and that is the whole design. Spencer:
 * *"keep the directions button with a map link action on the card"* - and R6 adds that it must be hidden
 * for a video visit. Asking "is this telehealth?" would answer only that case; asking "does this place
 * have an address?" answers it AND the site nobody has finished configuring, in one rule that cannot
 * drift from the data.
 *
 * A telehealth Location has no address ( - telehealth IS a Location), so it produces no button
 * for free. Offering directions to a video visit is the same class of error as printing the practice's
 * street address on one, which `appointmentLocation.ts` already exists to prevent.
 */

/** The `Location/<id>` an appointment names, if it names one. */
export const appointmentLocationId = (appointment: Appointment | undefined): string | undefined => {
  const reference = (appointment?.participant ?? []).find((participant) =>
    // Anchored on the prefix, matching appointmentLocation.ts. A `.includes("Location")` would let any
    // reference that merely CONTAINS the word win.
    participant.actor?.reference?.startsWith("Location/"),
  )?.actor?.reference;

  return reference?.split("/")[1] || undefined;
};

/**
 * One line of address, or undefined when the place has none worth showing.
 *
 * `line` alone is not an address a map can find, and neither is a lone country. The test is whether
 * there is a STREET and a settlement - anything less produces a map pin in the middle of a state, which
 * is worse than no button because the patient trusts it.
 */
export const formatLocationAddress = (location: Location | undefined): string | undefined => {
  const address: Address | undefined = location?.address;
  if (!address) return undefined;

  const street = (address.line ?? []).map((part) => part?.trim()).filter(Boolean).join(", ");
  const settlement = address.city?.trim();
  if (!street || !settlement) return undefined;

  return [street, settlement, address.state?.trim(), address.postalCode?.trim()]
    .filter(Boolean)
    .join(", ");
};

/**
 * A maps URL for the appointment's location, or undefined when it has no usable address.
 *
 * A LINK, NOT AN INTEGRATION. There is no API, no key and nothing to wrap behind our own endpoint, so
 * is satisfied by there being no third-party call at all -
 * the browser opens whatever handles the URL.
 *
 * The honest tradeoff, stated rather than implied: this is Google's universal maps URL. It resolves in
 * every desktop browser and hands off to the Google Maps app on a phone that has one - but an iPhone
 * user whose map app is Apple Maps gets Google's. The neutral alternative (`geo:`) is not handled by
 * desktop browsers at all, which fails the larger group.
 */
export const directionsUrl = (location: Location | undefined): string | undefined => {
  const address = formatLocationAddress(location);
  if (!address) return undefined;

  return `https://www.google.com/maps/search/?api=1&query=${encodeURIComponent(address)}`;
};