import type { TrackReference, TrackReferenceOrPlaceholder } from '@livekit/components-core';
import {
  inject,
  MaybeRef,
  provide,
  computed,
  shallowRef,
  toValue,
  type InjectionKey,
  type ShallowRef,
} from 'vue';

export type TrackRefContext = ShallowRef<TrackReferenceOrPlaceholder | undefined>;

const TrackRefContextKey: InjectionKey<TrackRefContext> = Symbol('livekit-track-ref-context');

function useProvideTrackRefContext(
  ref: TrackReference | TrackReferenceOrPlaceholder,
): TrackRefContext {
  const context = shallowRef<TrackReferenceOrPlaceholder | undefined>(ref);
  provide(TrackRefContextKey, context);
  return context;
}

function useTrackRefContextRaw(): TrackRefContext | undefined {
  return inject(TrackRefContextKey, undefined);
}

export { useProvideTrackRefContext, useTrackRefContextRaw };

export function useMaybeTrackRefContext(): TrackRefContext | undefined {
  try {
    return useTrackRefContextRaw();
  } catch {
    return undefined;
  }
}

export function useTrackRefContext(): TrackRefContext {
  const context = useMaybeTrackRefContext();

  if (!context) {
    throw new Error('Please call `useProvideTrackRefContext` on the appropriate parent component');
  }

  return context;
}

export function useEnsureTrackRef(trackRef?: MaybeRef<TrackReferenceOrPlaceholder>) {
  const ctx = useMaybeTrackRefContext();
  const ref = computed(() => toValue(trackRef) ?? toValue(ctx));
  if (!ref.value) {
    throw new Error(
      'No TrackRef, make sure you are inside a TrackRefContext or pass the TrackRef explicitly',
    );
  }
  return ref as ShallowRef<TrackReferenceOrPlaceholder>;
}