import type { MediaPosition } from './specs/types.nitro';

/**
 * Zeroed media position — the default before any playback, and the sentinel
 * value the scoped position hooks return when their item is not the engine's
 * active content. Hooks compare against this by reference identity, so it must
 * stay a single shared instance.
 */
export const IDLE_POSITION: MediaPosition = {
  currentMs: 0,
  durationMs: 0,
  seekableStartMs: 0,
  seekableEndMs: 0,
  isLive: false,
  progress: 0,
  liveEdgeOffsetMs: 0,
  isAtLiveEdge: false,
};

/**
 * Whether two media positions are equal on the fields the position hooks
 * render from. `MediaPosition` arrives from native as a fresh object every
 * tick, so this drives the "reuse previous snapshot" fast path that keeps
 * `useSyncExternalStore` from re-rendering on identical positions.
 */
export function samePosition(a: MediaPosition, b: MediaPosition): boolean {
  return (
    a.currentMs === b.currentMs &&
    a.durationMs === b.durationMs &&
    a.seekableStartMs === b.seekableStartMs &&
    a.seekableEndMs === b.seekableEndMs &&
    a.isLive === b.isLive &&
    a.isAtLiveEdge === b.isAtLiveEdge
  );
}