/*
    RawSpeed - RAW file decoder.

    Copyright (C) 2017 Axel Waggershauser
    Copyright (C) 2017 Roman Lebedev

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/

#include "decompressors/LJpegDecompressor.h"
#include "common/Common.h"                // for unroll_loop, roundUpDivision
#include "common/Point.h"                 // for iPoint2D
#include "common/RawImage.h"              // for RawImage, RawImageData
#include "decoders/RawDecoderException.h" // for ThrowRDE
#include "io/BitPumpJPEG.h"               // for BitPumpJPEG, BitStream<>::...
#include <algorithm>                      // for copy_n
#include <array>                          // for array
#include <cassert>                        // for assert

using std::copy_n;

namespace rawspeed {

LJpegDecompressor::LJpegDecompressor(const ByteStream& bs, const RawImage& img)
    : AbstractLJpegDecompressor(bs, img) {
  if (mRaw->getDataType() != RawImageType::UINT16)
    ThrowRDE("Unexpected data type (%u)",
             static_cast<unsigned>(mRaw->getDataType()));

  if (!((mRaw->getCpp() == 1 && mRaw->getBpp() == sizeof(uint16_t)) ||
        (mRaw->getCpp() == 2 && mRaw->getBpp() == 2 * sizeof(uint16_t)) ||
        (mRaw->getCpp() == 3 && mRaw->getBpp() == 3 * sizeof(uint16_t))))
    ThrowRDE("Unexpected component count (%u)", mRaw->getCpp());

  if (mRaw->dim.x == 0 || mRaw->dim.y == 0)
    ThrowRDE("Image has zero size");

#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
  // Yeah, sure, here it would be just dumb to leave this for production :)
  if (mRaw->dim.x > 7424 || mRaw->dim.y > 5552) {
    ThrowRDE("Unexpected image dimensions found: (%u; %u)", mRaw->dim.x,
             mRaw->dim.y);
  }
#endif
}

void LJpegDecompressor::decode(uint32_t offsetX, uint32_t offsetY,
                               uint32_t width, uint32_t height,
                               bool fixDng16Bug_) {
  if (offsetX >= static_cast<unsigned>(mRaw->dim.x))
    ThrowRDE("X offset outside of image");
  if (offsetY >= static_cast<unsigned>(mRaw->dim.y))
    ThrowRDE("Y offset outside of image");

  if (width > static_cast<unsigned>(mRaw->dim.x))
    ThrowRDE("Tile wider than image");
  if (height > static_cast<unsigned>(mRaw->dim.y))
    ThrowRDE("Tile taller than image");

  if (offsetX + width > static_cast<unsigned>(mRaw->dim.x))
    ThrowRDE("Tile overflows image horizontally");
  if (offsetY + height > static_cast<unsigned>(mRaw->dim.y))
    ThrowRDE("Tile overflows image vertically");

  if (width == 0 || height == 0)
    return; // We do not need anything from this tile.

  offX = offsetX;
  offY = offsetY;
  w = width;
  h = height;

  fixDng16Bug = fixDng16Bug_;

  AbstractLJpegDecompressor::decode();
}

void LJpegDecompressor::decodeScan()
{
  assert(frame.cps > 0);

  if (predictorMode != 1)
    ThrowRDE("Unsupported predictor mode: %u", predictorMode);

  for (uint32_t i = 0; i < frame.cps; i++)
    if (frame.compInfo[i].superH != 1 || frame.compInfo[i].superV != 1)
      ThrowRDE("Unsupported subsampling");

  assert(static_cast<unsigned>(mRaw->dim.x) > offX);
  if ((mRaw->getCpp() * (mRaw->dim.x - offX)) < frame.cps)
    ThrowRDE("Got less pixels than the components per sample");

  // How many output pixels are we expected to produce, as per DNG tiling?
  const auto tileRequiredWidth = mRaw->getCpp() * w;

  // How many full pixel blocks do we need to consume for that?
  if (const auto blocksToConsume =
          roundUpDivision(tileRequiredWidth, frame.cps);
      frame.w < blocksToConsume || frame.h < h) {
    ThrowRDE("LJpeg frame (%u, %u) is smaller than expected (%u, %u)",
             frame.cps * frame.w, frame.h, tileRequiredWidth, h);
  }

  // How many full pixel blocks will we produce?
  fullBlocks = tileRequiredWidth / frame.cps; // Truncating division!
  // Do we need to also produce part of a block?
  trailingPixels = tileRequiredWidth % frame.cps;

  if (trailingPixels == 0) {
    switch (frame.cps) {
    case 1:
      decodeN<1>();
      break;
    case 2:
      decodeN<2>();
      break;
    case 3:
      decodeN<3>();
      break;
    case 4:
      decodeN<4>();
      break;
    default:
      ThrowRDE("Unsupported number of components: %u", frame.cps);
    }
  } else /* trailingPixels != 0 */ {
    // FIXME: using different function just for one tile likely causes
    // i-cache misses and whatnot. Need to check how not splitting it into
    // two different functions affects performance of the normal case.
    switch (frame.cps) {
    // Naturally can't happen for CPS=1.
    case 2:
      decodeN<2, /*WeirdWidth=*/true>();
      break;
    case 3:
      decodeN<3, /*WeirdWidth=*/true>();
      break;
    case 4:
      decodeN<4, /*WeirdWidth=*/true>();
      break;
    default:
      ThrowRDE("Unsupported number of components: %u", frame.cps);
    }
  }
}

// N_COMP == number of components (2, 3 or 4)

template <int N_COMP, bool WeirdWidth> void LJpegDecompressor::decodeN() {
  assert(mRaw->getCpp() > 0);
  assert(N_COMP > 0);
  assert(N_COMP >= mRaw->getCpp());
  assert((N_COMP / mRaw->getCpp()) > 0);

  assert(mRaw->dim.x >= N_COMP);
  assert((mRaw->getCpp() * (mRaw->dim.x - offX)) >= N_COMP);

  const CroppedArray2DRef img(mRaw->getU16DataAsUncroppedArray2DRef(),
                              mRaw->getCpp() * offX, offY, mRaw->getCpp() * w,
                              h);

  auto ht = getHuffmanTables<N_COMP>();
  auto pred = getInitialPredictors<N_COMP>();
  uint16_t* predNext = pred.data();

  BitPumpJPEG bitStream(input);

  // A recoded DNG might be split up into tiles of self contained LJpeg blobs.
  // The tiles at the bottom and the right may extend beyond the dimension of
  // the raw image buffer. The excessive content has to be ignored.

  assert(frame.h >= h);
  assert(frame.cps * frame.w >= mRaw->getCpp() * w);

  assert(offY + h <= static_cast<unsigned>(mRaw->dim.y));
  assert(offX + w <= static_cast<unsigned>(mRaw->dim.x));

  // For y, we can simply stop decoding when we reached the border.
  for (unsigned row = 0; row < h; ++row) {
    unsigned col = 0;

    copy_n(predNext, N_COMP, pred.data());
    // the predictor for the next line is the start of this line
    predNext = &img(row, col);

    // FIXME: predictor may have value outside of the uint16_t.
    // https://github.com/darktable-org/rawspeed/issues/175

    // For x, we first process all full pixel blocks within the image buffer ...
    for (; col < N_COMP * fullBlocks; col += N_COMP) {
      for (int i = 0; i != N_COMP; ++i) {
        pred[i] = uint16_t(pred[i] + ht[i]->decodeDifference(bitStream));
        img(row, col + i) = pred[i];
      }
    }

    // Sometimes we also need to consume one more block, and produce part of it.
    if /*constexpr*/ (WeirdWidth) {
      // FIXME: evaluate i-cache implications due to this being compile-time.
      static_assert(N_COMP > 1 || !WeirdWidth,
                    "can't want part of 1-pixel-wide block");
      // Some rather esoteric DNG's have odd dimensions, e.g. width % 2 = 1.
      // We may end up needing just part of last N_COMP pixels.
      assert(trailingPixels > 0);
      assert(trailingPixels < N_COMP);
      unsigned c = 0;
      for (; c < trailingPixels; ++c) {
        pred[c] = uint16_t(pred[c] + ht[c]->decodeDifference(bitStream));
        img(row, col + c) = pred[c];
      }
      // Discard the rest of the block.
      assert(c < N_COMP);
      for (; c < N_COMP; ++c) {
        ht[c]->decodeDifference(bitStream);
      }
      col += N_COMP; // We did just process one more block.
    }

    // ... and discard the rest.
    for (; col < N_COMP * frame.w; col += N_COMP) {
      for (int i = 0; i != N_COMP; ++i) ht[i]->decodeDifference(bitStream);
    }
  }
}

} // namespace rawspeed
