import * as path from "path";
import * as fs from "fs";

export function findNearest(
  filename: string,
  start: string | undefined
): string {
  let pathSegments: string[] = [];
  if (typeof start === "string") {
    if (start[start.length - 1] !== path.sep) {
      start += path.sep;
    }
    start = path.normalize(start);
    pathSegments = start.split(path.sep);
  } else if (require.main?.path) {
    pathSegments = require.main?.path.split(path.sep);
  }
  if (!pathSegments.length) {
    throw new Error(filename + " not found in path");
  }
  // remove trailing '' element
  pathSegments.pop();
  let dir = pathSegments.join(path.sep);
  let fullPath = path.join(dir, filename);
  if (fs.existsSync(fullPath)) {
    return path.normalize(fullPath);
  } else {
    // pop current dir, recurse one dir closer to root
    pathSegments.pop();
    return findNearest(filename, pathSegments.join(path.sep));
  }
}