import { execFile } from "node:child_process";
import { chmod, stat } from "node:fs/promises";
import { delimiter } from "node:path";
import { fileURLToPath } from "node:url";

const jar = fileURLToPath(new URL("./android/focus.jar", import.meta.url));
let prepared: Promise<void> | undefined;

/** 0 = unfocused, 3 = focused; anything else is unknown and must stay quiet. */
export async function termuxFocused(
	timeoutMs = 5000,
): Promise<boolean | undefined> {
	try {
		prepared ??= stat(jar).then(async ({ mode }) => {
			// Git restores mode 0644; Android rejects writable DEX/JAR files.
			if (mode & 0o222) await chmod(jar, mode & ~0o222);
		});
		await prepared;
		return await new Promise((resolve) => {
			execFile(
				"app_process",
				["/", "F"],
				{
					env: {
						...process.env,
						PATH: `${process.env["PATH"] ?? ""}${delimiter}/system/bin`,
						CLASSPATH: jar,
						LD_PRELOAD: undefined,
						LD_LIBRARY_PATH: undefined,
					},
					timeout: timeoutMs,
					killSignal: "SIGKILL",
					maxBuffer: 16 * 1024,
				},
				(error) => {
					if (!error) resolve(false);
					else
						resolve(
							error.code === 3 && !error.killed && !error.signal
								? true
								: undefined,
						);
				},
			);
		});
	} catch {
		return undefined;
	}
}