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#include "platform/image-decoders/ico/ICOImageDecoder.h"

#include "platform/Histogram.h"
#include "platform/image-decoders/png/PNGImageDecoder.h"
#include "wtf/PtrUtil.h"
#include "wtf/Threading.h"
#include <algorithm>

namespace blink {

// Number of bits in .ICO/.CUR used to store the directory and its entries,
// respectively (doesn't match sizeof values for member structs since we omit
// some fields).
static const size_t sizeOfDirectory = 6;
static const size_t sizeOfDirEntry = 16;

ICOImageDecoder::ICOImageDecoder(AlphaOption alphaOption,
                                 GammaAndColorProfileOption colorOptions,
                                 size_t maxDecodedBytes)
    : ImageDecoder(alphaOption, colorOptions, maxDecodedBytes),
      m_fastReader(nullptr),
      m_decodedOffset(0),
      m_dirEntriesCount(0),
      m_gammaAndColorProfileOption(colorOptions) {}

ICOImageDecoder::~ICOImageDecoder() {}

void ICOImageDecoder::onSetData(SegmentReader* data) {
  m_fastReader.setData(data);

  for (BMPReaders::iterator i(m_bmpReaders.begin()); i != m_bmpReaders.end();
       ++i) {
    if (*i)
      (*i)->setData(data);
  }
  for (size_t i = 0; i < m_pngDecoders.size(); ++i)
    setDataForPNGDecoderAtIndex(i);
}

IntSize ICOImageDecoder::size() const {
  return m_frameSize.isEmpty() ? ImageDecoder::size() : m_frameSize;
}

IntSize ICOImageDecoder::frameSizeAtIndex(size_t index) const {
  return (index && (index < m_dirEntries.size())) ? m_dirEntries[index].m_size
                                                  : size();
}

bool ICOImageDecoder::setSize(unsigned width, unsigned height) {
  // The size calculated inside the BMPImageReader had better match the one in
  // the icon directory.
  return m_frameSize.isEmpty()
             ? ImageDecoder::setSize(width, height)
             : ((IntSize(width, height) == m_frameSize) || setFailed());
}

bool ICOImageDecoder::frameIsCompleteAtIndex(size_t index) const {
  if (index >= m_dirEntries.size())
    return false;
  const IconDirectoryEntry& dirEntry = m_dirEntries[index];
  return (dirEntry.m_imageOffset + dirEntry.m_byteSize) <= m_data->size();
}

bool ICOImageDecoder::setFailed() {
  m_bmpReaders.clear();
  m_pngDecoders.clear();
  return ImageDecoder::setFailed();
}

bool ICOImageDecoder::hotSpot(IntPoint& hotSpot) const {
  // When unspecified, the default frame is always frame 0. This is consistent
  // with BitmapImage, where currentFrame() starts at 0 and only increases when
  // animation is requested.
  return hotSpotAtIndex(0, hotSpot);
}

bool ICOImageDecoder::hotSpotAtIndex(size_t index, IntPoint& hotSpot) const {
  if (index >= m_dirEntries.size() || m_fileType != CURSOR)
    return false;

  hotSpot = m_dirEntries[index].m_hotSpot;
  return true;
}

// static
bool ICOImageDecoder::compareEntries(const IconDirectoryEntry& a,
                                     const IconDirectoryEntry& b) {
  // Larger icons are better.  After that, higher bit-depth icons are better.
  const int aEntryArea = a.m_size.width() * a.m_size.height();
  const int bEntryArea = b.m_size.width() * b.m_size.height();
  return (aEntryArea == bEntryArea) ? (a.m_bitCount > b.m_bitCount)
                                    : (aEntryArea > bEntryArea);
}

size_t ICOImageDecoder::decodeFrameCount() {
  decodeSize();

  // If decodeSize() fails, return the existing number of frames.  This way
  // if we get halfway through the image before decoding fails, we won't
  // suddenly start reporting that the image has zero frames.
  if (failed())
    return m_frameBufferCache.size();

  // Length of sequence of completely received frames.
  for (size_t i = 0; i < m_dirEntries.size(); ++i) {
    const IconDirectoryEntry& dirEntry = m_dirEntries[i];
    if ((dirEntry.m_imageOffset + dirEntry.m_byteSize) > m_data->size())
      return i;
  }
  return m_dirEntries.size();
}

void ICOImageDecoder::setDataForPNGDecoderAtIndex(size_t index) {
  if (!m_pngDecoders[index])
    return;

  m_pngDecoders[index]->setData(m_data.get(), isAllDataReceived());
}

void ICOImageDecoder::decode(size_t index, bool onlySize) {
  if (failed())
    return;

  // Defensively clear the FastSharedBufferReader's cache, as another caller
  // may have called SharedBuffer::mergeSegmentsIntoBuffer().
  m_fastReader.clearCache();

  // If we couldn't decode the image but we've received all the data, decoding
  // has failed.
  if ((!decodeDirectory() || (!onlySize && !decodeAtIndex(index))) &&
      isAllDataReceived()) {
    setFailed();
    // If we're done decoding this frame, we don't need the BMPImageReader or
    // PNGImageDecoder anymore.  (If we failed, these have already been
    // cleared.)
  } else if ((m_frameBufferCache.size() > index) &&
             (m_frameBufferCache[index].getStatus() ==
              ImageFrame::FrameComplete)) {
    m_bmpReaders[index].reset();
    m_pngDecoders[index].reset();
  }
}

bool ICOImageDecoder::decodeDirectory() {
  // Read and process directory.
  if ((m_decodedOffset < sizeOfDirectory) && !processDirectory())
    return false;

  // Read and process directory entries.
  return (m_decodedOffset >=
          (sizeOfDirectory + (m_dirEntriesCount * sizeOfDirEntry))) ||
         processDirectoryEntries();
}

bool ICOImageDecoder::decodeAtIndex(size_t index) {
  ASSERT_WITH_SECURITY_IMPLICATION(index < m_dirEntries.size());
  const IconDirectoryEntry& dirEntry = m_dirEntries[index];
  const ImageType imageType = imageTypeAtIndex(index);
  if (imageType == Unknown)
    return false;  // Not enough data to determine image type yet.

  if (imageType == BMP) {
    if (!m_bmpReaders[index]) {
      m_bmpReaders[index] =
          wrapUnique(new BMPImageReader(this, dirEntry.m_imageOffset, 0, true));
      m_bmpReaders[index]->setData(m_data.get());
    }
    // Update the pointer to the buffer as it could change after
    // m_frameBufferCache.resize().
    m_bmpReaders[index]->setBuffer(&m_frameBufferCache[index]);
    m_frameSize = dirEntry.m_size;
    bool result = m_bmpReaders[index]->decodeBMP(false);
    m_frameSize = IntSize();
    return result;
  }

  if (!m_pngDecoders[index]) {
    AlphaOption alphaOption =
        m_premultiplyAlpha ? AlphaPremultiplied : AlphaNotPremultiplied;
    m_pngDecoders[index] = wrapUnique(
        new PNGImageDecoder(alphaOption, m_gammaAndColorProfileOption,
                            m_maxDecodedBytes, dirEntry.m_imageOffset));
    setDataForPNGDecoderAtIndex(index);
  }
  // Fail if the size the PNGImageDecoder calculated does not match the size
  // in the directory.
  if (m_pngDecoders[index]->isSizeAvailable() &&
      (m_pngDecoders[index]->size() != dirEntry.m_size))
    return setFailed();
  m_frameBufferCache[index] = *m_pngDecoders[index]->frameBufferAtIndex(0);
  m_frameBufferCache[index].setPremultiplyAlpha(m_premultiplyAlpha);
  return !m_pngDecoders[index]->failed() || setFailed();
}

bool ICOImageDecoder::processDirectory() {
  // Read directory.
  ASSERT(!m_decodedOffset);
  if (m_data->size() < sizeOfDirectory)
    return false;
  const uint16_t fileType = readUint16(2);
  m_dirEntriesCount = readUint16(4);
  m_decodedOffset = sizeOfDirectory;

  // See if this is an icon filetype we understand, and make sure we have at
  // least one entry in the directory.
  if (((fileType != ICON) && (fileType != CURSOR)) || (!m_dirEntriesCount))
    return setFailed();

  m_fileType = static_cast<FileType>(fileType);
  return true;
}

bool ICOImageDecoder::processDirectoryEntries() {
  // Read directory entries.
  ASSERT(m_decodedOffset == sizeOfDirectory);
  if ((m_decodedOffset > m_data->size()) ||
      ((m_data->size() - m_decodedOffset) <
       (m_dirEntriesCount * sizeOfDirEntry)))
    return false;

  // Enlarge member vectors to hold all the entries.
  m_dirEntries.resize(m_dirEntriesCount);
  m_bmpReaders.resize(m_dirEntriesCount);
  m_pngDecoders.resize(m_dirEntriesCount);

  for (IconDirectoryEntries::iterator i(m_dirEntries.begin());
       i != m_dirEntries.end(); ++i)
    *i = readDirectoryEntry();  // Updates m_decodedOffset.

  // Make sure the specified image offsets are past the end of the directory
  // entries.
  for (IconDirectoryEntries::iterator i(m_dirEntries.begin());
       i != m_dirEntries.end(); ++i) {
    if (i->m_imageOffset < m_decodedOffset)
      return setFailed();
  }

  DEFINE_THREAD_SAFE_STATIC_LOCAL(
      blink::CustomCountHistogram, dimensionsLocationHistogram,
      new blink::CustomCountHistogram(
          "Blink.DecodedImage.EffectiveDimensionsLocation.ICO", 0, 50000, 50));
  dimensionsLocationHistogram.count(m_decodedOffset - 1);

  // Arrange frames in decreasing quality order.
  std::sort(m_dirEntries.begin(), m_dirEntries.end(), compareEntries);

  // The image size is the size of the largest entry.
  const IconDirectoryEntry& dirEntry = m_dirEntries.first();
  // Technically, this next call shouldn't be able to fail, since the width
  // and height here are each <= 256, and |m_frameSize| is empty.
  return setSize(dirEntry.m_size.width(), dirEntry.m_size.height());
}

ICOImageDecoder::IconDirectoryEntry ICOImageDecoder::readDirectoryEntry() {
  // Read icon data.
  // The following calls to readUint8() return a uint8_t, which is appropriate
  // because that's the on-disk type of the width and height values.  Storing
  // them in ints (instead of matching uint8_ts) is so we can record dimensions
  // of size 256 (which is what a zero byte really means).
  int width = readUint8(0);
  if (!width)
    width = 256;
  int height = readUint8(1);
  if (!height)
    height = 256;
  IconDirectoryEntry entry;
  entry.m_size = IntSize(width, height);
  if (m_fileType == CURSOR) {
    entry.m_bitCount = 0;
    entry.m_hotSpot = IntPoint(readUint16(4), readUint16(6));
  } else {
    entry.m_bitCount = readUint16(6);
    entry.m_hotSpot = IntPoint();
  }
  entry.m_byteSize = readUint32(8);
  entry.m_imageOffset = readUint32(12);

  // Some icons don't have a bit depth, only a color count.  Convert the
  // color count to the minimum necessary bit depth.  It doesn't matter if
  // this isn't quite what the bitmap info header says later, as we only use
  // this value to determine which icon entry is best.
  if (!entry.m_bitCount) {
    int colorCount = readUint8(2);
    if (!colorCount)
      colorCount = 256;  // Vague in the spec, needed by real-world icons.
    for (--colorCount; colorCount; colorCount >>= 1)
      ++entry.m_bitCount;
  }

  m_decodedOffset += sizeOfDirEntry;
  return entry;
}

ICOImageDecoder::ImageType ICOImageDecoder::imageTypeAtIndex(size_t index) {
  // Check if this entry is a BMP or a PNG; we need 4 bytes to check the magic
  // number.
  ASSERT_WITH_SECURITY_IMPLICATION(index < m_dirEntries.size());
  const uint32_t imageOffset = m_dirEntries[index].m_imageOffset;
  if ((imageOffset > m_data->size()) || ((m_data->size() - imageOffset) < 4))
    return Unknown;
  char buffer[4];
  const char* data = m_fastReader.getConsecutiveData(imageOffset, 4, buffer);
  return strncmp(data, "\x89PNG", 4) ? BMP : PNG;
}

}  // namespace blink