import lockfile from "proper-lockfile";

/**
 * Internal lock acquisition helper.
 * Returns release function, or null if lock couldn't be acquired within timeout.
 */
async function acquireLock(
	targetPath: string,
	timeoutMs: number,
): Promise<(() => Promise<void>) | null> {
	try {
		const release = await lockfile.lock(targetPath, {
			retries: { retries: Math.ceil(timeoutMs / 200), factor: 1, minTimeout: 200 },
			stale: 30000,
		});
		return release;
	} catch {
		return null;
	}
}

/**
 * Acquire exclusive lock for restore operations.
 * Returns release function, or null if lock couldn't be acquired within timeout.
 */
export async function acquireRestoreLock(
	targetPath: string,
	timeoutMs = 5000,
): Promise<(() => Promise<void>) | null> {
	return acquireLock(targetPath, timeoutMs);
}

/**
 * Acquire exclusive lock for sync operations.
 * Targets the same file as acquireRestoreLock to ensure mutual exclusion.
 * Returns release function, or null if lock couldn't be acquired within timeout.
 */
export async function acquireSyncLock(
	targetPath: string,
	timeoutMs = 5000,
): Promise<(() => Promise<void>) | null> {
	return acquireLock(targetPath, timeoutMs);
}

export async function isLocked(targetPath: string): Promise<boolean> {
	return lockfile.check(targetPath, { stale: 30000 });
}