// Service-first booking - the funnel rule, in one place.
//
// Spencer, 2026-08-03: "Service shouldn't be optional in the booking flow, it's what determines which
// location and practitioners the appointment can be booked with."
//
// That was already true of PATIENT self-booking, structurally: `bookingFlowSteps.ts` puts `service`
// ahead of `location` and `practitioner` in STEP_ORDER and hides a step until everything before it is
// answered, and `bookablePractitioners` returns [] until a service is chosen. The RECEPTIONIST flow
// disagreed with its own comment - `ReceptionistBookAppointment` says "Service-first: Visit Service is a
// PRIMARY filter (chosen before the practitioner)" while treating it as an optional narrowing that gated
// nothing. This predicate is what makes the receptionist match the stated design and the patient flow.
//
// NOT A SECURITY BOUNDARY, and it must not be mistaken for one. The server refuses a video booking
// that names no eligible service (, `appointment-booking-flags.enforceTelehealthEligibility`).
// This decides only what the staff UI lets you *reach*. Both exist on purpose: the client makes the
// right thing easy, the server makes the wrong thing impossible.
//
// Kept as a shared pure predicate rather than three inline booleans because the receptionist flow gates
// three separate things on it (the practitioner/schedule list, the date-and-time step, the prep step),
// and this file's neighbourhood has already been bitten twice by the same rule living in two hand-kept
// copies that drifted (`getScheduleLocationRefs`, then the picker location gate).

export interface BookingServiceGateInput {
    /** The chosen `HealthcareService` id, or empty/undefined when none has been picked. */
    selectedServiceId: string | undefined;
    /** True when an EXISTING appointment is being edited rather than a new one created. */
    isEditMode: boolean;
}

/**
 * May the booking funnel proceed past the service step?
 *
 * EDIT IS EXEMPT, DELIBERATELY. Creating a booking and changing one are different acts. An
 * appointment may legitimately carry no resolvable service - it predates this rule, or it was created by
 * the staff calendar modal, which has no service field at all (`FhirAppointment` never binds
 * `serviceType`). Gating edits would leave those appointments unmovable and uncancellable from the UI,
 * turning a funnel improvement into stranded real-world data.
 */
export const bookingServiceGateSatisfied = ({
    selectedServiceId,
    isEditMode,
}: BookingServiceGateInput): boolean => Boolean(selectedServiceId) || isEditMode;