import type { Practitioner, PractitionerRole, Reference } from 'fhir/r4';
import { isClinicianEnabled } from './clinicianEnabled';
import { practitionerIdOfRole, seatCapacityAdmits, type SeatStanding } from './seatStanding';
import { holdsClinicalRole } from './staffRoleCatalog';

/**
 * WHO MAY BE RECORDED AS HAVING ORDERED SOMETHING CLINICAL.
 *
 * MEASURED 2026-08-30 at Great River: the requester picker on a medication order offered all thirteen
 * staff members - HR, Marketing, Billing, the Receptionist and the Platform Manager among them. Five of
 * those hold no clinical role at all, and any of them could be recorded as having prescribed a drug.
 *
 * NOTHING DOWNSTREAM ACTS ON THE FIELD, so this is not an unsafe dispense - it is an inaccurate clinical
 * record. But it is the field a pharmacy, an audit or a malpractice review reads to answer "who ordered
 * this", and the product was willing to answer "the marketing coordinator".
 *
 * TWO CONDITIONS, BOTH REQUIRED, AND THIS IS THE PRODUCT'S EXISTING ANSWER RATHER THAN A NEW RULE.
 * The clinician SEAT is what makes somebody able to act clinically at all - without it the Practitioner
 * workspace is dropped at token mint - and the Practitioner WORKSPACE is what the seat is supposed to sit
 * on. Requiring both matters because the two have come apart in real data: a seat sat on a RECEPTIONIST
 * role at our own practice, and the booking picker honoured it until somebody noticed a receptionist was
 * bookable for a consultation.
 *
 * READ PER PERSON, NEVER PER ROLE. One human holds several roles in one organization and the seat is
 * granted across all of them at once, so a `find` on the first role answers about the wrong one.
 *
 * NOT FOR THE `recorder`, AND THAT DISTINCTION IS THE POINT. A prescription has two people on it: who
 * ORDERED it and who TYPED it. A receptionist transcribing a phone order is ordinary practice, so the
 * recorder stays open to whoever is entering it. Only the requester narrows.
 */
export const mayPrescribe = (roles: readonly PractitionerRole[], seat: SeatStanding | null): boolean =>
    holdsClinicalRole(roles) && roles.some(
        (role) => role.active !== false && isClinicianEnabled(role) && seatCapacityAdmits(practitionerIdOfRole(role), seat),
    );

/**
 * The staff a clinical ORDER may name, with whoever is already on the record kept in the list.
 *
 * THE SECOND ARGUMENT IS THE CONTROL AND IT IS NOT OPTIONAL IN SPIRIT. An order signed months ago may
 * name somebody who has since lost their seat, changed roles or left. Filtering them out would blank the
 * field on a record that already answers the question - and a name that VANISHES from a signed order is
 * worse than a name that should not have been offered in the first place. They stay, and they stay
 * selected; they simply stop being offered to anybody else.
 */
export const prescriberOptions = (
    staff: ReadonlyArray<{ practitioner: Practitioner; roles: PractitionerRole[] }>,
    alreadyNamed: Reference | ReadonlyArray<Reference | undefined> | undefined,
    seat: SeatStanding | null,
): Practitioner[] => {
    const named = new Set(
        (Array.isArray(alreadyNamed) ? alreadyNamed : [alreadyNamed])
            .map((reference) => reference?.reference)
            .filter((reference): reference is string => Boolean(reference))
            .map((reference) => reference.split('/')[1])
            .filter(Boolean),
    );

    return staff
        .filter((entry) => mayPrescribe(entry.roles, seat)
            || (entry.practitioner.id !== undefined && named.has(entry.practitioner.id)))
        .map((entry) => entry.practitioner);
};