import { accessSync, constants, statSync } from "node:fs";
import { delimiter, resolve } from "node:path";

export interface ExecutableLookupOptions {
	path?: string;
	platform?: string;
}

function pathValue(
	platform: string,
	path: string | undefined,
): string | undefined {
	if (path !== undefined) return path;
	if (platform !== "win32") return process.env.PATH;
	return Object.entries(process.env).find(
		([key]) => key.toLowerCase() === "path",
	)?.[1];
}

export function findExecutableFile(
	path: string,
	options: Pick<ExecutableLookupOptions, "platform"> = {},
): string | undefined {
	try {
		if (!statSync(path).isFile()) return undefined;
		if ((options.platform ?? process.platform) !== "win32")
			accessSync(path, constants.X_OK);
		return path;
	} catch {
		return undefined;
	}
}

export function findExecutable(
	names: readonly string[],
	options: ExecutableLookupOptions = {},
): string | undefined {
	const platform = options.platform ?? process.platform;
	const windows = platform === "win32";
	const path = pathValue(platform, options.path);
	if (!path) return undefined;
	for (const rawDirectory of path.split(windows ? ";" : delimiter)) {
		const directory =
			windows && rawDirectory.startsWith('"') && rawDirectory.endsWith('"')
				? rawDirectory.slice(1, -1)
				: rawDirectory;
		if (!directory) continue;
		for (const name of names) {
			if (name.includes("/") || name.includes("\\")) continue;
			const candidate = resolve(directory, name);
			if (findExecutableFile(candidate, { platform })) return candidate;
		}
	}
	return undefined;
}