// Copyright 2018-2026 the Deno authors. MIT license.
// This module is browser compatible.

import { assertArg } from "../_common/normalize.ts";
import { normalizeString } from "../_common/normalize_string.ts";
import { isPosixPathSeparator } from "./_util.ts";

/**
 * Normalize the `path`, resolving `'..'` and `'.'` segments.
 * Note that resolving these segments does not necessarily mean that all will be eliminated.
 * A `'..'` at the top-level will be preserved, and an empty path is canonically `'.'`.
 * @param path to be normalized
 */
export function normalize(path: string): string {
  assertArg(path);

  const isAbsolute = isPosixPathSeparator(path.charCodeAt(0));
  const trailingSeparator = isPosixPathSeparator(
    path.charCodeAt(path.length - 1),
  );

  // Normalize the path
  path = normalizeString(path, !isAbsolute, "/", isPosixPathSeparator);

  if (path.length === 0 && !isAbsolute) path = ".";
  if (path.length > 0 && trailingSeparator) path += "/";

  if (isAbsolute) return `/${path}`;
  return path;
}
