// originally on https://example.com
window.location.href = "/\\abc.com"

window.location.href = "/\\abc.com"

function willDomainChangeWhenRedirect(url: string) {
  // Create a link element to easily parse the input URL
  const link = document.createElement("a")
  link.href = url

  // Get the hostname of the input URL and the current window
  const newHostname = link.hostname
  const currentHostname = window.location.hostname

  // Compare the hostnames and return true if they are different
  return newHostname !== currentHostname
}

void KURL::Init(const KURL& base,
                const String& relative,
                const WTF::TextEncoding* query_encoding) {
  // As a performance optimization, we do not use the charset converter
  // if encoding is UTF-8 or other Unicode encodings. Note that this is
  // per HTML5 2.5.3 (resolving URL). The URL canonicalizer will be more
  // efficient with no charset converter object because it can do UTF-8
  // internally with no extra copies.

  StringUTF8Adaptor base_utf8(base.GetString());

  // We feel free to make the charset converter object every time since it's
  // just a wrapper around a reference.
  KURLCharsetConverter charset_converter_object(query_encoding);
  KURLCharsetConverter* charset_converter =
      (!query_encoding || IsUnicodeEncoding(query_encoding))
          ? nullptr
          : &charset_converter_object;

  // Clamp to int max to avoid overflow.
  url::RawCanonOutputT<char> output;
  if (!relative.IsNull() && relative.Is8Bit()) {
    StringUTF8Adaptor relative_utf8(relative);
    is_valid_ = url::ResolveRelative(base_utf8.data(), base_utf8.size(),
                                     base.parsed_, relative_utf8.data(),
                                     ClampTo<int>(relative_utf8.size()),
                                     charset_converter, &output, &parsed_);
  } else {
    is_valid_ = url::ResolveRelative(base_utf8.data(), base_utf8.size(),
                                     base.parsed_, relative.Characters16(),
                                     ClampTo<int>(relative.length()),
                                     charset_converter, &output, &parsed_);
  }

  // url canonicalizes to 7-bit ASCII, using punycode and percent-escapes
  // This makes it safe to call FromUTF8() below and still keep using parsed_
  // which stores byte offsets: Since it's all ASCII, UTF-8 byte offsets
  // map 1-to-1 to UTF-16 codepoint offsets.
  for (size_t i = 0; i < output.length(); ++i) {
    DCHECK(WTF::IsASCII(output.data()[i]));
  }

  // AtomicString::fromUTF8 will re-hash the raw output and check the
  // AtomicStringTable (addWithTranslator) for the string. This can be very
  // expensive for large URLs. However, since many URLs are generated from
  // existing AtomicStrings (which already have their hashes computed), this
  // fast path is used if the input string is already canonicalized.
  //
  // Because this optimization does not apply to non-AtomicStrings, explicitly
  // check that the input is Atomic before moving forward with it. If we mark
  // non-Atomic input as Atomic here, we will render the (const) input string
  // thread unsafe.
  if (!relative.IsNull() && relative.Impl()->IsAtomic() &&
      StringView(output.data(), static_cast<unsigned>(output.length())) ==
          relative) {
    string_ = relative;
  } else {
    string_ = AtomicString::FromUTF8(output.data(), output.length());
  }

  InitProtocolMetadata();
  InitInnerURL();
  DCHECK(!::blink::ProtocolIsJavaScript(string_) || ProtocolIsJavaScript());

  // Check for deviation characters in the string. See
  // https://unicode.org/reports/tr46/#Table_Deviation_Characters
  has_idna2008_deviation_character_ =
      base.has_idna2008_deviation_character_ ||
      relative.Contains(u"\u00DF") ||  // Sharp-s
      relative.Contains(u"\u03C2") ||  // Greek final sigma
      relative.Contains(u"\u200D") ||  // Zero width joiner
      relative.Contains(u"\u200C");    // Zero width non-joiner
}

template<typename CHAR>
bool DoResolveRelative(const char* base_spec,
                       int base_spec_len,
                       const Parsed& base_parsed,
                       const CHAR* in_relative,
                       int in_relative_length,
                       CharsetConverter* charset_converter,
                       CanonOutput* output,
                       Parsed* output_parsed) {
  // Remove any whitespace from the middle of the relative URL, possibly
  // copying to the new buffer.
  STACK_UNINITIALIZED RawCanonOutputT<CHAR> whitespace_buffer;
  int relative_length;
  const CHAR* relative = RemoveURLWhitespace(
      in_relative, in_relative_length, &whitespace_buffer, &relative_length,
      &output_parsed->potentially_dangling_markup);

  bool base_is_authority_based = false;
  bool base_is_hierarchical = false;
  if (base_spec &&
      base_parsed.scheme.is_nonempty()) {
    int after_scheme = base_parsed.scheme.end() + 1;  // Skip past the colon.
    int num_slashes = CountConsecutiveSlashes(base_spec, after_scheme,
                                              base_spec_len);
    base_is_authority_based = num_slashes > 1;
    base_is_hierarchical = num_slashes > 0;
  }

  SchemeType unused_scheme_type = SCHEME_WITH_HOST_PORT_AND_USER_INFORMATION;
  bool standard_base_scheme =
      base_parsed.scheme.is_nonempty() &&
      DoIsStandard(base_spec, base_parsed.scheme, &unused_scheme_type);

  bool is_relative;
  Component relative_component;
  if (!IsRelativeURL(base_spec, base_parsed, relative, relative_length,
                     (base_is_hierarchical || standard_base_scheme),
                     &is_relative, &relative_component)) {
    // Error resolving.
    return false;
  }

  // Don't reserve buffer space here. Instead, reserve in DoCanonicalize and
  // ReserveRelativeURL, to enable more accurate buffer sizes.

  // Pretend for a moment that |base_spec| is a standard URL. Normally
  // non-standard URLs are treated as PathURLs, but if the base has an
  // authority we would like to preserve it.
  if (is_relative && base_is_authority_based && !standard_base_scheme) {
    Parsed base_parsed_authority;
    ParseStandardURL(base_spec, base_spec_len, &base_parsed_authority);
    if (base_parsed_authority.host.is_nonempty()) {
      STACK_UNINITIALIZED RawCanonOutputT<char> temporary_output;
      bool did_resolve_succeed =
          ResolveRelativeURL(base_spec, base_parsed_authority, false, relative,
                             relative_component, charset_converter,
                             &temporary_output, output_parsed);
      // The output_parsed is incorrect at this point (because it was built
      // based on base_parsed_authority instead of base_parsed) and needs to be
      // re-created.
      DoCanonicalize(temporary_output.data(), temporary_output.length(), true,
                     REMOVE_WHITESPACE, charset_converter, output,
                     output_parsed);
      return did_resolve_succeed;
    }
  } else if (is_relative) {
    // Relative, resolve and canonicalize.
    bool file_base_scheme = base_parsed.scheme.is_nonempty() &&
        DoCompareSchemeComponent(base_spec, base_parsed.scheme, kFileScheme);
    return ResolveRelativeURL(base_spec, base_parsed, file_base_scheme, relative,
                              relative_component, charset_converter, output,
                              output_parsed);
  }

  // Not relative, canonicalize the input.
  return DoCanonicalize(relative, relative_length, true,
                        DO_NOT_REMOVE_WHITESPACE, charset_converter, output,
                        output_parsed);
}

// See IsRelativeURL in the header file for usage.
template<typename CHAR>
bool DoIsRelativeURL(const char* base,
                     const Parsed& base_parsed,
                     const CHAR* url,
                     int url_len,
                     bool is_base_hierarchical,
                     bool* is_relative,
                     Component* relative_component) {
  *is_relative = false;  // So we can default later to not relative.

  // Trim whitespace and construct a new range for the substring.
  int begin = 0;
  TrimURL(url, &begin, &url_len);
  if (begin >= url_len) {
    // Empty URLs are relative, but do nothing.
    if (!is_base_hierarchical) {
      // Don't allow relative URLs if the base scheme doesn't support it.
      return false;
    }
    *relative_component = Component(begin, 0);
    *is_relative = true;
    return true;
  }

#ifdef WIN32
  // We special case paths like "C:\foo" so they can link directly to the
  // file on Windows (IE compatibility). The security domain stuff should
  // prevent a link like this from actually being followed if its on a
  // web page.
  //
  // We treat "C:/foo" as an absolute URL. We can go ahead and treat "/c:/"
  // as relative, as this will just replace the path when the base scheme
  // is a file and the answer will still be correct.
  //
  // We require strict backslashes when detecting UNC since two forward
  // slashes should be treated a a relative URL with a hostname.
  if (DoesBeginWindowsDriveSpec(url, begin, url_len) ||
      DoesBeginUNCPath(url, begin, url_len, true))
    return true;
#endif  // WIN32

  // See if we've got a scheme, if not, we know this is a relative URL.
  // BUT, just because we have a scheme, doesn't make it absolute.
  // "http:foo.html" is a relative URL with path "foo.html". If the scheme is
  // empty, we treat it as relative (":foo"), like IE does.
  Component scheme;
  const bool scheme_is_empty =
      !ExtractScheme(url, url_len, &scheme) || scheme.len == 0;
  if (scheme_is_empty) {
    if (url[begin] == '#') {
      // |url| is a bare fragment (e.g. "#foo"). This can be resolved against
      // any base. Fall-through.
    } else if (!is_base_hierarchical) {
      // Don't allow relative URLs if the base scheme doesn't support it.
      return false;
    }

    *relative_component = MakeRange(begin, url_len);
    *is_relative = true;
    return true;
  }

  // If the scheme isn't valid, then it's relative.
  if (!IsValidScheme(url, scheme)) {
    if (url[begin] == '#' &&
        base::FeatureList::IsEnabled(
            kResolveBareFragmentWithColonOnNonHierarchical)) {
      // |url| is a bare fragment (e.g. "#foo:bar"). This can be resolved
      // against any base. Fall-through.
    } else if (!is_base_hierarchical) {
      // Don't allow relative URLs if the base scheme doesn't support it.
      return false;
    }
    *relative_component = MakeRange(begin, url_len);
    *is_relative = true;
    return true;
  }

  // If the scheme is not the same, then we can't count it as relative.
  if (!AreSchemesEqual(base, base_parsed.scheme, url, scheme))
    return true;

  // When the scheme that they both share is not hierarchical, treat the
  // incoming scheme as absolute (this way with the base of "data:foo",
  // "data:bar" will be reported as absolute.
  if (!is_base_hierarchical)
    return true;

  int colon_offset = scheme.end();

  // If it's a filesystem URL, the only valid way to make it relative is not to
  // supply a scheme. There's no equivalent to e.g. http:index.html.
  if (CompareSchemeComponent(url, scheme, kFileSystemScheme))
    return true;

  // ExtractScheme guarantees that the colon immediately follows what it
  // considers to be the scheme. CountConsecutiveSlashes will handle the
  // case where the begin offset is the end of the input.
  int num_slashes = CountConsecutiveSlashes(url, colon_offset + 1, url_len);

  if (num_slashes == 0 || num_slashes == 1) {
    // No slashes means it's a relative path like "http:foo.html". One slash
    // is an absolute path. "http:/home/foo.html"
    *is_relative = true;
    *relative_component = MakeRange(colon_offset + 1, url_len);
    return true;
  }

  // Two or more slashes after the scheme we treat as absolute.
  return true;
}