rea/src/process/CurrentEntrypointPath.ts

import { resolve } from "node:path";
import {
  javaScriptRuntime,
  type JavaScriptRuntime,
} from "../domain/runtimeVersion.js";
import { absoluteCallerPath } from "../filesystem/callerPath.js";

/** Runtime-specific absolute argv script selection, or undefined when none was supplied.
 * Native executable paths have different traversal semantics and must not use this.
 */
export const normalizeEntrypointPath = (
  entrypoint: string | undefined,
  runtime: JavaScriptRuntime["id"] = javaScriptRuntime(process.versions).id,
): string | undefined =>
  entrypoint === undefined || entrypoint.length === 0
    ? undefined
    : runtime === "bun"
      ? absoluteCallerPath(entrypoint)
      : resolve(entrypoint);

export const CURRENT_ENTRYPOINT_PATH = normalizeEntrypointPath(process.argv[1]);