// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.

import { normalizeString } from "./../_common/normalize_string.ts";
import { assertPath } from "./../_common/assert_path.ts";
import { isPosixPathSeparator } from "./_util.ts";

/**
 * Resolves path segments into a `path`
 * @param pathSegments to process to path
 */
export function resolve(...pathSegments: string[]): string {
  let resolvedPath = "";
  let resolvedAbsolute = false;

  for (let i = pathSegments.length - 1; i >= -1 && !resolvedAbsolute; i--) {
    let path: string;

    if (i >= 0) path = pathSegments[i];
    else {
      // deno-lint-ignore no-explicit-any
      const { Deno } = globalThis as any;
      if (typeof Deno?.cwd !== "function") {
        throw new TypeError("Resolved a relative path without a CWD.");
      }
      path = Deno.cwd();
    }

    assertPath(path);

    // Skip empty entries
    if (path.length === 0) {
      continue;
    }

    resolvedPath = `${path}/${resolvedPath}`;
    resolvedAbsolute = isPosixPathSeparator(path.charCodeAt(0));
  }

  // At this point the path should be resolved to a full absolute path, but
  // handle relative paths to be safe (might happen when Deno.cwd() fails)

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

  if (resolvedAbsolute) {
    if (resolvedPath.length > 0) return `/${resolvedPath}`;
    else return "/";
  } else if (resolvedPath.length > 0) return resolvedPath;
  else return ".";
}