(() => {
  const getSceneById = (scenes, sceneId) => {
    if (!Array.isArray(scenes)) return null;
    return scenes.find((candidate) => candidate.id === sceneId) || null;
  };

  const getSceneIdFromUrl = (scenes) => {
    if (!Array.isArray(scenes)) return null;
    try {
      const params = new URLSearchParams(window.location.search);
      const urlScene = params.get("scene");
      return getSceneById(scenes, urlScene) ? urlScene : null;
    } catch (err) {
      return null;
    }
  };

  const setSceneIdInUrl = (sceneId) => {
    if (!sceneId) return;
    try {
      const url = new URL(window.location.href);
      url.searchParams.set("scene", sceneId);
      history.replaceState({}, "", `${url.pathname}${url.search}${url.hash}`);
    } catch (err) {
      // ignore history failures (blocked or unsupported)
    }
  };

  const getNextSceneId = (scenes, order, currentScene) => {
    if (!Array.isArray(scenes)) return null;
    const ordered = Array.isArray(order) ? order : [];
    const currentId = currentScene?.id;
    const orderedExisting = ordered.filter((id) =>
      scenes.some((s) => s.id === id),
    );
    if (orderedExisting.length > 0 && currentId) {
      const idx = orderedExisting.indexOf(currentId);
      if (idx >= 0 && idx < orderedExisting.length - 1) {
        return orderedExisting[idx + 1];
      }
      if (idx === orderedExisting.length - 1) {
        return orderedExisting[0];
      }
    }
    const fallbackIdx = scenes.findIndex((s) => s.id === currentId);
    if (fallbackIdx >= 0 && fallbackIdx < scenes.length - 1) {
      return scenes[fallbackIdx + 1].id;
    }
    return scenes[0]?.id || null;
  };

  window.PhysilinksSceneRegistry = {
    getSceneById,
    getSceneIdFromUrl,
    setSceneIdInUrl,
    getNextSceneId,
  };
})();