import type { CodeableConcept } from 'fhir/r4';
import { SNOMED_CT_SYSTEM, getOrgRoleByCode, type StaffRoleOption } from './staffRoleCatalog.ts';

/**
 * Derive the auto-populated `PractitionerRole.specialty` codings from the org roles a staff member holds.
 *
 * Extracted from PractitionerRoleService's save path so the REGRESSION TEST can exercise the
 * real writer rather than a hand-authored fixture. That distinction is the whole point here: the bug this
 * fixes shipped because every test built its own specialty object, so nothing ever asserted on what the
 * writer actually emitted. A fixture would have repeated the mistake.
 *
 * Contract, unchanged from the inline version except for `text`:
 * - only roles that carry a `snomedSpecialty` AND are not `specialtyRequired` auto-derive. A
 * `specialtyRequired` role is generic ("Physician") and the user picks the specialty on the form instead.
 * - deduped on the SNOMED CODE, so a practitioner holding two roles that share a code gets ONE concept.
 * Deliberate and unchanged - the `specialtyKey` helpers in the service key on `system|code` too.
 *
 * `text` carries the ROLE's display, which is both FHIR-correct and the better value - see the long note
 * at the call site in PractitionerRoleService.tsx for why.
 *
 * `coding[0].display` IS DELIBERATELY ABSENT AND IS LOAD-BEARING. 19 of the 40 SNOMED codes in the
 * catalog are wrong - a dentist's resolves to "Transport distance too great" - and the missing display is
 * the only reason none of that reaches a screen. The reason lives in full on `snomedSpecialty` in
 * `staffRoleCatalog.ts`; the tripwire is `__tests__/autoSpecialtyDisplayMask.test.ts`.
 * (This docstring used to send the reader to the call site "for why coding[0].display is left absent".
 * That note is about the blank `text` and says nothing about the display - a pointer to an explanation
 * nobody ever wrote, which reads as an unfinished field rather than a deliberate one.)
 */
export function deriveAutoSpecialtyCodings(
    organizationRoles: Array<Pick<StaffRoleOption, 'code'> | undefined | null>,
): CodeableConcept[] {
    const seenCodes = new Set<string>();
    const codings: CodeableConcept[] = [];

    for (const roleOption of organizationRoles ?? []) {
        const catalogEntry = roleOption?.code ? getOrgRoleByCode(roleOption.code) : undefined;
        if (!catalogEntry?.snomedSpecialty || catalogEntry.specialtyRequired) continue;

        const snomedCode = catalogEntry.snomedSpecialty;
        if (seenCodes.has(snomedCode)) continue;

        seenCodes.add(snomedCode);
        codings.push({
            coding: [{ system: SNOMED_CT_SYSTEM, code: snomedCode }],
            text: catalogEntry.display,
        });
    }

    return codings;
}