import type { Schedule } from 'fhir/r4';
import type { BookabilityBlocker } from './bookabilityReasons';

// BAND 1 of bookability: is this schedule block live at all, independent of what is being booked?
//
// Extracted from PatientBookAppointment.tsx's `bookableSchedules` memo so there is ONE predicate rather than
// an inline copy. Accessors are injected to keep this free of React context and FHIR fetching, matching the
// pattern matchSchedules.ts already uses.
//
// MIRROR, NEVER A GATE - see bookabilityReasons.ts.

export interface UsableAccessors {
  bookingFlags: (s: Schedule) => { allowBooking: boolean; allowPatientSelfBooking: boolean };
  /** The owning PractitionerRole's `active`. `undefined` = no role link (pre-migration) and counts as active. */
  roleActive: (s: Schedule) => boolean | undefined;
  /**
 * Does the owning PractitionerRole hold an ACTIVE clinician seat?
 *
 * The booking funnels already refuse a seatless role (`canBeBookedAsClinician`), but they applied that
 * test THEMSELVES, outside this resolver - so every surface that mirrors bookability from here reported a
 * seatless provider as ready while the picker would not offer them. That is the same two-paths-in-step-by-
 * convention drift this module's own header records paying for once, one axis over.
 *
 * NOT optional, deliberately. A caller that has not been told must not silently mean "seated": the seat
 * defaults to ABSENT everywhere else in this product precisely so it gates rather than suggests.
 */
  roleHoldsClinicianSeat: (s: Schedule) => boolean;
}

export interface BandResult {
  ok: boolean;
  blockers: BookabilityBlocker[];
}

export function evaluateScheduleUsable(schedule: Schedule, accessors: UsableAccessors): BandResult {
  const blockers: BookabilityBlocker[] = [];

  // A schedule with no id cannot be booked against, but that is a data defect rather than a configuration
  // gap - there is nothing a practice could go and fix - so it fails without producing a blocker to report.
  const hasId = Boolean(schedule.id);

  if (accessors.roleActive(schedule) === false) blockers.push('ROLE_INACTIVE');
  if (!accessors.roleHoldsClinicianSeat(schedule)) blockers.push('NO_CLINICIAN_SEAT');

  const flags = accessors.bookingFlags(schedule);
  if (!flags.allowBooking) blockers.push('BLOCK_BOOKING_DISABLED');
  if (!flags.allowPatientSelfBooking) blockers.push('BLOCK_SELF_BOOKING_DISABLED');

  return { ok: hasId && blockers.length === 0, blockers };
}