/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "third_party/blink/renderer/core/loader/text_resource_decoder_builder.h"

#include <memory>

#include "base/stl_util.h"
#include "third_party/blink/renderer/core/dom/document.h"
#include "third_party/blink/renderer/core/dom/dom_implementation.h"
#include "third_party/blink/renderer/core/frame/local_frame.h"
#include "third_party/blink/renderer/core/frame/settings.h"
#include "third_party/blink/renderer/platform/network/mime/mime_type_registry.h"
#include "third_party/blink/renderer/platform/weborigin/security_origin.h"

namespace blink {

static inline bool CanReferToParentFrameEncoding(
    const LocalFrame* frame,
    const LocalFrame* parent_frame) {
  return parent_frame &&
         parent_frame->GetDocument()->GetSecurityOrigin()->CanAccess(
             frame->GetDocument()->GetSecurityOrigin());
}

namespace {

struct LegacyEncoding {
  const char* domain;
  const char* encoding;
};

static const LegacyEncoding kEncodings[] = {
    {"au", "windows-1252"}, {"az", "ISO-8859-9"},   {"bd", "windows-1252"},
    {"bg", "windows-1251"}, {"br", "windows-1252"}, {"ca", "windows-1252"},
    {"ch", "windows-1252"}, {"cn", "GBK"},          {"cz", "windows-1250"},
    {"de", "windows-1252"}, {"dk", "windows-1252"}, {"ee", "windows-1256"},
    {"eg", "windows-1257"}, {"et", "windows-1252"}, {"fi", "windows-1252"},
    {"fr", "windows-1252"}, {"gb", "windows-1252"}, {"gr", "ISO-8859-7"},
    {"hk", "Big5"},         {"hr", "windows-1250"}, {"hu", "ISO-8859-2"},
    {"il", "windows-1255"}, {"ir", "windows-1257"}, {"is", "windows-1252"},
    {"it", "windows-1252"}, {"jp", "Shift_JIS"},    {"kr", "windows-949"},
    {"lt", "windows-1256"}, {"lv", "windows-1256"}, {"mk", "windows-1251"},
    {"nl", "windows-1252"}, {"no", "windows-1252"}, {"pl", "ISO-8859-2"},
    {"pt", "windows-1252"}, {"ro", "ISO-8859-2"},   {"rs", "windows-1251"},
    {"ru", "windows-1251"}, {"se", "windows-1252"}, {"si", "ISO-8859-2"},
    {"sk", "windows-1250"}, {"th", "windows-874"},  {"tr", "ISO-8859-9"},
    {"tw", "Big5"},         {"tz", "windows-1252"}, {"ua", "windows-1251"},
    {"us", "windows-1252"}, {"vn", "windows-1258"}, {"xa", "windows-1252"},
    {"xb", "windows-1257"}};

static const WTF::TextEncoding GetEncodingFromDomain(const KURL& url) {
  Vector<String> tokens;
  url.Host().Split(".", tokens);
  if (!tokens.IsEmpty()) {
    auto tld = tokens.back();
    for (size_t i = 0; i < base::size(kEncodings); i++) {
      if (tld == kEncodings[i].domain)
        return WTF::TextEncoding(kEncodings[i].encoding);
    }
  }
  return WTF::TextEncoding();
}

TextResourceDecoderOptions::ContentType DetermineContentType(
    const String& mime_type) {
  if (DeprecatedEqualIgnoringCase(mime_type, "text/css"))
    return TextResourceDecoderOptions::kCSSContent;
  if (DeprecatedEqualIgnoringCase(mime_type, "text/html"))
    return TextResourceDecoderOptions::kHTMLContent;
  if (DOMImplementation::IsXMLMIMEType(mime_type))
    return TextResourceDecoderOptions::kXMLContent;
  return TextResourceDecoderOptions::kPlainTextContent;
}

}  // namespace

std::unique_ptr<TextResourceDecoder> BuildTextResourceDecoderFor(
    Document* document,
    const AtomicString& mime_type,
    const AtomicString& encoding) {
  const WTF::TextEncoding encoding_from_domain =
      GetEncodingFromDomain(document->Url());

  LocalFrame* frame = document->GetFrame();
  LocalFrame* parent_frame = nullptr;
  if (frame)
    parent_frame = DynamicTo<LocalFrame>(frame->Tree().Parent());

  // Set the hint encoding to the parent frame encoding only if the parent and
  // the current frames share the security origin. We impose this condition
  // because somebody can make a child frameg63 containing a carefully crafted
  // html/javascript in one encoding that can be mistaken for hintEncoding (or
  // related encoding) by an auto detector. When interpreted in the latter, it
  // could be an attack vector.
  // FIXME: This might be too cautious for non-7bit-encodings and we may
  // consider relaxing this later after testing.
  bool use_hint_encoding =
      frame && CanReferToParentFrameEncoding(frame, parent_frame);

  std::unique_ptr<TextResourceDecoder> decoder;
  if (frame && frame->GetSettings()) {
    const WTF::TextEncoding default_encoding =
        encoding_from_domain.IsValid()
            ? encoding_from_domain
            : WTF::TextEncoding(
                  frame->GetSettings()->GetDefaultTextEncodingName());
    // Disable autodetection for XML/JSON to honor the default encoding (UTF-8)
    // for unlabelled documents.
    if (DOMImplementation::IsXMLMIMEType(mime_type)) {
      decoder =
          std::make_unique<TextResourceDecoder>(TextResourceDecoderOptions(
              TextResourceDecoderOptions::kXMLContent, default_encoding));
      use_hint_encoding = false;
    } else if (MIMETypeRegistry::IsJSONMimeType(mime_type)) {
      decoder =
          std::make_unique<TextResourceDecoder>(TextResourceDecoderOptions(
              TextResourceDecoderOptions::kJSONContent, default_encoding));
      use_hint_encoding = false;
    } else {
      WTF::TextEncoding hint_encoding;
      if (use_hint_encoding &&
          parent_frame->GetDocument()->EncodingWasDetectedHeuristically())
        hint_encoding = parent_frame->GetDocument()->Encoding();
      decoder = std::make_unique<TextResourceDecoder>(
          TextResourceDecoderOptions::CreateWithAutoDetection(
              DetermineContentType(mime_type), default_encoding, hint_encoding,
              document->Url()));
    }
  } else {
    decoder = std::make_unique<TextResourceDecoder>(TextResourceDecoderOptions(
        DetermineContentType(mime_type), encoding_from_domain));
  }
  DCHECK(decoder);

  if (!encoding.IsEmpty()) {
    decoder->SetEncoding(WTF::TextEncoding(encoding.GetString()),
                         TextResourceDecoder::kEncodingFromHTTPHeader);
  } else if (use_hint_encoding) {
    decoder->SetEncoding(parent_frame->GetDocument()->Encoding(),
                         TextResourceDecoder::kEncodingFromParentFrame);
  }

  return decoder;
}

}  // namespace blink