export type InstallCommandBlock = {
	label: string;
	commands: string[];
};

export type NonExecutableBinaryMessageOptions = {
	binPath: string;
	trustPackages: string;
	bunInstallBlocks: InstallCommandBlock[];
	genericInstallCommands?: string[];
	binaryName?: string;
};

export type FsSubset = {
	accessSync: (path: string, mode?: number) => void;
	chmodSync: (path: string, mode: number) => void;
	constants: { X_OK: number };
};

export function isBunRuntime(): boolean {
	if (typeof process?.versions?.bun === "string") return true;
	const userAgent = process?.env?.npm_config_user_agent || "";
	return userAgent.includes("bun/");
}

const PERMISSION_ERRORS = new Set(["EACCES", "EPERM", "ENOEXEC"]);

function isPermissionError(error: unknown): boolean {
	if (!error || typeof error !== "object") return false;
	const code = (error as { code?: unknown }).code;
	return typeof code === "string" && PERMISSION_ERRORS.has(code);
}

/**
 * Checks if a binary is executable and attempts to make it executable if not.
 * Returns true if the binary is (or was made) executable, false if it couldn't
 * be made executable due to permission errors. Throws for other errors.
 *
 * Requires fs to be passed in to avoid static imports that break browser builds.
 */
export function assertExecutable(binPath: string, fs: FsSubset): boolean {
	if (process.platform === "win32") {
		return true;
	}

	try {
		fs.accessSync(binPath, fs.constants.X_OK);
		return true;
	} catch {
		// Not executable, try to fix
	}

	try {
		fs.chmodSync(binPath, 0o755);
		return true;
	} catch (error) {
		if (isPermissionError(error)) {
			return false;
		}
		throw error;
	}
}

export function formatNonExecutableBinaryMessage(
	options: NonExecutableBinaryMessageOptions,
): string {
	const {
		binPath,
		trustPackages,
		bunInstallBlocks,
		genericInstallCommands,
		binaryName,
	} = options;

	const label = binaryName ?? "sandbox-agent";
	const lines = [`${label} binary is not executable: ${binPath}`];

	if (isBunRuntime()) {
		lines.push(
			"Allow Bun to run postinstall scripts for native binaries and reinstall:",
		);
		for (const block of bunInstallBlocks) {
			lines.push(`${block.label}:`);
			for (const command of block.commands) {
				lines.push(`  ${command}`);
			}
		}
		lines.push(`Or run: chmod +x "${binPath}"`);
		return lines.join("\n");
	}

	lines.push(
		"Postinstall scripts for native packages did not run, so the binary was left non-executable.",
	);
	if (genericInstallCommands && genericInstallCommands.length > 0) {
		lines.push("Reinstall with scripts enabled:");
		for (const command of genericInstallCommands) {
			lines.push(`  ${command}`);
		}
	} else {
		lines.push("Reinstall with scripts enabled for:");
		lines.push(`  ${trustPackages}`);
	}
	lines.push(`Or run: chmod +x "${binPath}"`);
	return lines.join("\n");
}