import { detectWideners } from './bookabilityWideners';
import { widenerCopy } from './bookabilityCopy';

// What the "Services offered here" picker is actually choosing FROM, said out loud.
//
// The fallback this narrates is DELIBERATE and stays. In ManageScheduleModal the block's candidate services
// are scoped to the practitioner's offered-service set - and when that set is EMPTY it falls back to the whole
// org catalog, so pre-migration schedules keep working and a one-provider practice never has to fill it in.
// That is not a bug. It is just invisible, which IS the bug. We narrate; we do not remove.

export interface BlockServiceScopeInput {
  /** Size of the practitioner's offered-service set (PractitionerRole.healthcareService). */
  offeredCount: number;
  /** How many services survive the location filter and are therefore actually pickable right now. */
  eligibleCount: number;
  orgCatalogSize: number;
  /** How many services this BLOCK currently lists. 0 no patient can self-book it, for anything. */
  selectedCount: number;
}

export function describeBlockServiceScope(input: BlockServiceScopeInput): {
  /** Draw the operator's attention - amber + an icon. NOT "the config is broader than intended": the
 * sharpest case is the opposite, a block that offers nothing. It has only ever driven styling. */
  warn: boolean;
  message: string;
} {
  // What the picker is choosing FROM, said once, so the consequence sentence below can borrow it.
  const widened = detectWideners({
    practitionerOfferedServiceCount: input.offeredCount,
    orgCatalogSize: input.orgCatalogSize,
    // Not the location or self-bookable axis - this line is only about the SERVICE scope of the picker.
    serviceLocationCount: 1,
    orgLocationCount: 1,
    selfBookableSetExplicitly: true,
  }).includes('WIDENED_ALL_SERVICES');

  const choicesSentence = widened
    ? widenerCopy('WIDENED_ALL_SERVICES', { orgCatalogSize: input.orgCatalogSize, orgLocationCount: 1 })
    : `Choosing from the ${input.offeredCount} service${
        input.offeredCount === 1 ? '' : 's'
      } this provider offers.`;

  // Checked FIRST: telling someone they are "choosing from 3 services" while the picker is empty would be
  // actively misleading, so the dead-end message wins over everything below.
  if (input.eligibleCount === 0) {
    return {
      warn: true,
      message:
        'This provider offers none of their services at the selected location. Patients cannot book this block here.',
    };
  }

  // THE CONSEQUENCE OF LEAVING THIS EMPTY, which nothing on this screen used to say.
  // Patient booking asks a block "do you offer service X?" and a block listing nothing answers no to every
  // service - so the provider is not offered at all, with no error anywhere. The practice's only clue was a
  // dismissible save warning naming a single service. Staff are unaffected: the receptionist picker falls
  // back to the whole catalog rather than blocking (ReceptionistBookAppointment.tsx:740), which is why the
  // reassurance is TRUE here and must not be dropped - without it this reads as breakage rather than a step.
  if (input.selectedCount === 0) {
    return {
      warn: true,
      message: `No services are listed for this block. Add a service so patients can book it. Staff can still book it. ${choicesSentence}`,
    };
  }

  return { warn: widened, message: choicesSentence };
}