/** 主布局内容区：滚动层 + 全屏详情弹窗遮罩层（方案 A，二者为兄弟节点） */

let layoutContentScrollEl: HTMLElement | null = null;
let layoutContentModalMountEl: HTMLElement | null = null;

export const LAYOUT_CONTENT_SCROLL_LOCK_CLASS = "layoutShell__contentScroll_scrollLocked";

let layoutContentScrollLockCount = 0;

export function setLayoutContentScrollRoot(el: HTMLElement | null): void {
  layoutContentScrollEl = el;
}

export function getLayoutContentScrollRoot(): HTMLElement | null {
  return layoutContentScrollEl;
}

export function setLayoutContentModalMount(el: HTMLElement | null): void {
  layoutContentModalMountEl = el;
}

export function getLayoutContentModalMount(): HTMLElement | null {
  return layoutContentModalMountEl;
}

/** 全屏详情弹窗打开时锁住背后滚动层（保留 scrollTop，仅禁止滚动） */
export function lockLayoutContentScroll(): void {
  layoutContentScrollLockCount += 1;
  layoutContentScrollEl?.classList.add(LAYOUT_CONTENT_SCROLL_LOCK_CLASS);
}

export function unlockLayoutContentScroll(): void {
  layoutContentScrollLockCount = Math.max(0, layoutContentScrollLockCount - 1);
  if (layoutContentScrollLockCount === 0) {
    layoutContentScrollEl?.classList.remove(LAYOUT_CONTENT_SCROLL_LOCK_CLASS);
  }
}

export function isLayoutContentScrollLocked(): boolean {
  return layoutContentScrollLockCount > 0;
}

/** 滚动事件是否来自弹窗遮罩层（应忽略，避免误触发 composer 收起） */
export function isScrollEventFromLayoutModalMount(target: EventTarget | null): boolean {
  if (layoutContentModalMountEl == null || target == null) return false;
  return layoutContentModalMountEl.contains(target as Node);
}

/** 滚动是否发生在内容滚动层及其子树内 */
export function isScrollEventInLayoutContentScroll(target: EventTarget | null): boolean {
  if (layoutContentScrollEl == null || !(target instanceof HTMLElement)) return false;
  return target === layoutContentScrollEl || layoutContentScrollEl.contains(target);
}