freezmo/lib/use-wake-lock.ts

"use client";

import { useEffect } from "react";

type WakeLockSentinelLike = {
  release: () => Promise<void>;
  addEventListener: (type: string, listener: () => void) => void;
};

type NavigatorWithWakeLock = Navigator & {
  wakeLock?: { request: (type: "screen") => Promise<WakeLockSentinelLike> };
};

/**
 * Keeps the screen awake while a study session or guide is open
 * (feature-detected; silently does nothing where unsupported or denied).
 * Re-acquires when the tab becomes visible again, releases on leave.
 */
export function useWakeLock(active = true): void {
  useEffect(() => {
    if (!active || typeof navigator === "undefined") return;
    const wakeLock = (navigator as NavigatorWithWakeLock).wakeLock;
    if (!wakeLock) return;

    let sentinel: WakeLockSentinelLike | null = null;
    let disposed = false;

    const acquire = async () => {
      try {
        sentinel = await wakeLock.request("screen");
        sentinel.addEventListener("release", () => {
          sentinel = null;
        });
      } catch {
        /* denied or not allowed without a gesture — fine */
      }
    };

    const onVisibility = () => {
      if (document.visibilityState === "visible" && !sentinel && !disposed) void acquire();
    };

    void acquire();
    document.addEventListener("visibilitychange", onVisibility);
    return () => {
      disposed = true;
      document.removeEventListener("visibilitychange", onVisibility);
      void sentinel?.release().catch(() => {});
    };
  }, [active]);
}