node_modules/esrun/tools/findInputFile.js

import { existsSync, statSync, readFileSync } from "fs";
import { posix } from "path";
export default function findInputFile(path) {
    if (!existsSync(path)) {
        if (existsSync(`${path}.ts`))
            path = `${path}.ts`;
        else if (existsSync(`${path}.js`))
            path = `${path}.js`;
        else
            throw `Path '${path}' does not exist`;
    }
    const stat = statSync(path);
    if (stat.isFile())
        return path;
    else if (stat.isDirectory()) {
        // first we check if there is a package.json file with a `main` key
        const packageFile = posix.resolve(path, "package.json");
        if (existsSync(packageFile) && statSync(packageFile).isFile()) {
            const { main } = JSON.parse(readFileSync(packageFile, "utf8"));
            if (main)
                return findInputFile(posix.resolve(path, main));
        }
        // otherwise we look for a default entry point
        const name = posix.basename(path);
        for (const subpath of [
            posix.resolve(path, "index.ts"),
            posix.resolve(path, name),
            posix.resolve(path, `${name}.ts`),
            posix.resolve(path, "main.ts"),
            posix.resolve(path, "index.js"),
            posix.resolve(path, `${name}.js`),
            posix.resolve(path, "main.js"),
        ])
            if (existsSync(subpath) && statSync(subpath).isFile())
                return subpath;
        throw `Could not resolve an entry point in folder '${path}`;
    }
    else
        throw `Path '${path}' should be a file or a directory`;
}