import { useSyncExternalStore, useRef } from 'react';
import { useAviationPlayer } from '../AviationContext';
import type { CastState, CastDevice } from '../specs/types.nitro';
import type { AviationPlayer } from '../Aviation';

export interface CastStateInfo {
  /** Current cast connection state. */
  state: CastState;
  /** Connected device info, if any. */
  device: CastDevice | undefined;
  /** Whether audio/video is being sent to an external device. */
  isConnected: boolean;
}

const IDLE_CAST_STATE: CastStateInfo = {
  state: 'disconnected',
  device: undefined,
  isConnected: false,
};

/**
 * Subscribe to AirPlay/cast connection state changes.
 *
 * Reflects whichever playback output currently owns the session: AirPlay
 * presence on iOS, a Cast session on either platform (Chromecast requires
 * @react-native-aviation/cast).
 *
 * Uses a ref-memoized snapshot so identical state does not trigger re-renders.
 *
 * @example
 * ```tsx
 * const { isConnected, device } = useCastState();
 * if (isConnected) {
 *   console.log(`Playing on ${device?.name}`);
 * }
 * ```
 */
export function useCastState(playerArg?: AviationPlayer): CastStateInfo {
  const player = useAviationPlayer(playerArg);
  const store = player.store;
  const ref = useRef<CastStateInfo>(IDLE_CAST_STATE);

  const getSnapshot = () => {
    const snapshot = store.getCastStateSnapshot();
    const prev = ref.current;

    if (
      prev.state === snapshot.state &&
      prev.device === snapshot.device &&
      prev.isConnected === snapshot.isConnected
    ) {
      return prev;
    }

    ref.current = {
      state: snapshot.state,
      device: snapshot.device,
      isConnected: snapshot.isConnected,
    };
    return ref.current;
  };

  return useSyncExternalStore(store.subscribeCastState, getSnapshot);
}