// The encounter page's finish, reachable from inside its call. On a phone the call covers the page, so
// the host finishes from the call (practitioner#s-video-visit board 15); it must be the page's own finish
// - end the call, then flip the encounter - never a second implementation of that order.
import { useSyncExternalStore } from 'react';
import type { FinishRefusal } from '../../services/scribe/recordingDisposition';

/** Resolves with a refusal when the visit cannot finish yet; existing void finishers stay valid. */
export type EncounterFinisher = () => void | Promise<void | FinishRefusal>;

const finishers = new Map<string, EncounterFinisher>();
const listeners = new Set<() => void>();
const notify = () => listeners.forEach((listener) => listener());
const subscribe = (listener: () => void) => {
    listeners.add(listener);
    return () => { listeners.delete(listener); };
};

/** Registers the finish for a call context (`encounter#<id>`); the returned function withdraws it. */
export const registerEncounterFinisher = (context: string, finisher: EncounterFinisher): (() => void) => {
    finishers.set(context, finisher);
    notify();
    return () => {
        if (finishers.get(context) === finisher) finishers.delete(context);
        notify();
    };
};

/** The finish registered for this call's context, if its encounter page is mounted. */
export const useEncounterFinisher = (context: string | undefined): EncounterFinisher | undefined =>
    useSyncExternalStore(subscribe, () => (context ? finishers.get(context) : undefined));