/**
 * Module dependencies.
 */

var sep = require('path').sep || '/';

/**
 * Module exports.
 */

module.exports = fileUriToPath;

/**
 * File URI to Path function.
 *
 * @param {String} uri
 * @return {String} path
 * @api public
 */

function fileUriToPath (uri) {
  if ('string' != typeof uri ||
      uri.length <= 7 ||
      'file://' != uri.substring(0, 7)) {
    throw new TypeError('must pass in a file:// URI to convert to a file path');
  }

  var rest = decodeURI(uri.substring(7));
  var firstSlash = rest.indexOf('/');
  var host = rest.substring(0, firstSlash);
  var path = rest.substring(firstSlash + 1);

  // 2.  Scheme Definition
  // As a special case, <host> can be the string "localhost" or the empty
  // string; this is interpreted as "the machine from which the URL is
  // being interpreted".
  if ('localhost' == host) host = '';

  if (host) {
    host = sep + sep + host;
  }

  // 3.2  Drives, drive letters, mount points, file system root
  // Drive letters are mapped into the top of a file URI in various ways,
  // depending on the implementation; some applications substitute
  // vertical bar ("|") for the colon after the drive letter, yielding
  // "file:///c|/tmp/test.txt".  In some cases, the colon is left
  // unchanged, as in "file:///c:/tmp/test.txt".  In other cases, the
  // colon is simply omitted, as in "file:///c/tmp/test.txt".
  path = path.replace(/^(.+)\|/, '$1:');

  // for Windows, we need to invert the path separators from what a URI uses
  if (sep == '\\') {
    path = path.replace(/\//g, '\\');
  }

  if (/^.+\:/.test(path)) {
    // has Windows drive at beginning of path
  } else {
    // unix path…
    path = sep + path;
  }

  return host + path;
}