import type { Observation } from 'fhir/r4';
import { ORGANIZATION_TAG_SYSTEM } from './carePlanAuthorship';
import { createdAtOrganization } from './createdAtOrganization';

export interface ObservationPractice {
    /** Recorded at a practice other than the reader's, so it is shown and not editable here. */
    fromAnotherPractice: boolean;
    /** That practice's name, when the record carries one. */
    practiceName?: string;
    /** Why it cannot be changed here, ready to render. */
    readOnlyReason?: string;
}

/**
 * Mirrors the server's `evaluateObservationPracticeAuthorship`, so a surface never hides an edit the server allows. When
 * either practice cannot be told, nothing is claimed.
 */
export const observationPractice = (
    observation: Observation | undefined,
    currentOrganizationId: string | undefined,
): ObservationPractice => {
    const origin = createdAtOrganization(observation);
    const tags = (observation?.meta?.tag ?? []).filter((tag) => tag.system === ORGANIZATION_TAG_SYSTEM && tag.code);
    const owner = origin.id ?? (tags.length === 1 ? tags[0].code : undefined);
    // The server writes `Organization/<id>` as the display when it could not read the name.
    const practiceName = origin.name && !origin.name.startsWith('Organization/') ? origin.name : undefined;
    const patientRecordedIt = (observation?.performer ?? []).some((performer) =>
        performer.reference?.startsWith('Patient/') || performer.reference?.startsWith('RelatedPerson/'));

    const fromAnotherPractice = !patientRecordedIt
        && Boolean(owner && currentOrganizationId && owner !== currentOrganizationId);

    return {
        fromAnotherPractice,
        ...(practiceName ? { practiceName } : {}),
        ...(fromAnotherPractice ? {
            readOnlyReason: practiceName
                ? `This reading was recorded at ${practiceName}. Only that practice can change it - you can still read it.`
                : 'This reading was recorded at another practice. Only the practice that recorded it can change it - you can still read it.',
        } : {}),
    };
};