function normalize(path: string): string {
  const absolute = path.startsWith("/");
  const out: string[] = [];
  for (const segment of path.split("/")) {
    if (segment === "" || segment === ".") continue;
    if (segment === "..") {
      if (out.length > 0 && out[out.length - 1] !== "..") out.pop();
      else if (!absolute) out.push("..");
      continue;
    }
    out.push(segment);
  }
  const body = out.join("/");
  if (absolute) return `/${body}`;
  return body === "" ? "." : body;
}

export function joinPath(...parts: string[]): string {
  const joined = parts.filter((part) => part !== "").join("/");
  return joined === "" ? "." : normalize(joined);
}

export function dirnamePath(path: string): string {
  const trimmed = path.length > 1 ? path.replace(/[\\/]+$/, "") : path;
  const cut = Math.max(trimmed.lastIndexOf("/"), trimmed.lastIndexOf("\\"));
  if (cut < 0) return ".";
  if (cut === 0) return trimmed.slice(0, 1);
  return trimmed.slice(0, cut);
}

export function extnamePath(path: string): string {
  const cut = Math.max(path.lastIndexOf("/"), path.lastIndexOf("\\"));
  const base = path.slice(cut + 1);
  const dot = base.lastIndexOf(".");
  return dot <= 0 ? "" : base.slice(dot);
}