import type { Appointment, Encounter } from 'fhir/r4';
import { isArchived } from './archivedResource';

export const DAY_EVENT_TYPES = [
    'com.akashichealthrecords.fhir.appointment.created',
    'com.akashichealthrecords.fhir.appointment.updated',
    'com.akashichealthrecords.fhir.appointment.deleted',
    'com.akashichealthrecords.fhir.encounter.created',
    'com.akashichealthrecords.fhir.encounter.updated',
    'com.akashichealthrecords.fhir.encounter.deleted',
] as const;

export type DayEvent =
    | { kind: 'appointment'; removed: boolean; resource: Appointment }
    | { kind: 'encounter'; removed: boolean; resource: Encounter };

type Resource = { resourceType?: string; id?: string };

/** The payload's resource of this type: sent bare (Encounter) or inside a Bundle with its Slot (Appointment). */
const resourceIn = (data: unknown, resourceType: string): Resource | undefined => {
    const payload = data as (Resource & { entry?: Array<{ resource?: Resource }> }) | undefined;
    if (payload?.resourceType === resourceType) return payload;
    if (payload?.resourceType !== 'Bundle') return undefined;
    return (payload.entry ?? []).find((entry) => entry.resource?.resourceType === resourceType)?.resource;
};

/** Reads a broadcast CloudEvent; undefined for anything the day boards do not show or a payload without an id. */
export const readDayEvent = (cloudEvent: { type?: string; data?: unknown } | undefined): DayEvent | undefined => {
    const match = /^com\.akashichealthrecords\.fhir\.(appointment|encounter)\.(created|updated|deleted)$/.exec(cloudEvent?.type ?? '');
    if (!match) return undefined;
    const resource = resourceIn(cloudEvent?.data, match[1] === 'appointment' ? 'Appointment' : 'Encounter');
    if (!resource?.id) return undefined;
    const removed = match[2] === 'deleted' || isArchived(resource);
    return match[1] === 'appointment'
        ? { kind: 'appointment', removed, resource: resource as Appointment }
        : { kind: 'encounter', removed, resource: resource as Encounter };
};

/** The list with `item` replacing its id, added when `keep` and absent, or dropped when not `keep`. */
export const applyById = <T extends { id?: string }>(list: readonly T[], item: T, keep: boolean): T[] => {
    const rest = list.filter((entry) => entry.id !== item.id);
    if (!keep) return rest.length === list.length ? (list as T[]) : rest;
    return list.some((entry) => entry.id === item.id)
        ? list.map((entry) => (entry.id === item.id ? item : entry))
        : [...list, item];
};

/** Whether an encounter belongs on a board showing these appointments (or is already on it). */
export const encounterBelongsToDay = (
    encounter: Encounter,
    appointmentIds: ReadonlySet<string>,
    shown: readonly Encounter[],
): boolean =>
    shown.some((entry) => entry.id === encounter.id) ||
    (encounter.appointment ?? []).some((ref) => appointmentIds.has(ref.reference?.split('/').pop() ?? ''));

/** A fallback read for a missed event; the socket carries the day between reads. */
export const DAY_FALLBACK_READ_MS = 5 * 60_000;