import type { Encounter } from 'fhir/r4';

/**
 * One decision about a visit (start it, park it, finish it, room it, link a diagnosis), made on the visit as the
 * server holds it now rather than on the copy a board or workspace was drawn from.
 *
 * It answers the visit with only that change, or says the visit already is what was asked ('unchanged'), or that
 * the decision no longer applies to it ('refused'): Finish on a visit the desk has since cancelled is not a
 * finish, and writing it would undo the cancel.
 */
export type EncounterChange = (current: Encounter) => Encounter | 'unchanged' | 'refused';

export const VISIT_CHANGED_MESSAGE =
    'Someone else changed this visit while you were working on it, so nothing was changed. Look at it as it is now and try again.';

/** Moves a visit from one of `from` to `to`, adding what `shape` says the move also changes. */
export const moveEncounter = (
    from: Encounter['status'][],
    to: Encounter['status'],
    shape?: (current: Encounter) => Partial<Encounter>,
): EncounterChange => (current) => {
    if (current.status === to) return 'unchanged';
    if (!from.includes(current.status)) return 'refused';
    return { ...current, status: to, ...shape?.(current) };
};

/** A visit that has ended takes no further change from the board. */
export const ENDED_ENCOUNTER_STATUSES: Encounter['status'][] = ['finished', 'cancelled', 'entered-in-error'];

/** Before the visit begins, or while it is under way. */
export const OPEN_ENCOUNTER_STATUSES: Encounter['status'][] = ['planned', 'arrived', 'triaged', 'in-progress', 'onleave'];