import * as fs from "node:fs";

export function preflightLaunchCwd(requestedCwd: string, effectiveCwd: string): string | undefined {
	const resolution = requestedCwd === effectiveCwd ? "" : `\n(resolved from ${JSON.stringify(requestedCwd)})`;
	try {
		if (!fs.statSync(effectiveCwd).isDirectory()) {
			return `Subagent launch aborted: cwd is not a directory: ${effectiveCwd}${resolution}`;
		}
	} catch (error) {
		if ((error as NodeJS.ErrnoException).code === "ENOENT") {
			return `Subagent launch aborted: cwd does not exist: ${effectiveCwd}${resolution}`;
		}
		return `Subagent launch aborted: cwd could not be accessed: ${effectiveCwd}${resolution}\n${error instanceof Error ? error.message : String(error)}`;
	}
	return undefined;
}