// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

#include "lib/jxl/enc_toc.h"

#include <stdint.h>

#include "lib/jxl/base/common.h"
#include "lib/jxl/coeff_order.h"
#include "lib/jxl/enc_aux_out.h"
#include "lib/jxl/enc_coeff_order.h"
#include "lib/jxl/field_encodings.h"
#include "lib/jxl/fields.h"
#include "lib/jxl/toc.h"

namespace jxl {
Status WriteGroupOffsets(const std::vector<BitWriter>& group_codes,
                         const std::vector<coeff_order_t>& permutation,
                         BitWriter* JXL_RESTRICT writer, AuxOut* aux_out) {
  BitWriter::Allotment allotment(writer, MaxBits(group_codes.size()));
  if (!permutation.empty() && !group_codes.empty()) {
    // Don't write a permutation at all for an empty group_codes.
    writer->Write(1, 1);  // permutation
    JXL_DASSERT(permutation.size() == group_codes.size());
    EncodePermutation(permutation.data(), /*skip=*/0, permutation.size(),
                      writer, /* layer= */ 0, aux_out);

  } else {
    writer->Write(1, 0);  // no permutation
  }
  writer->ZeroPadToByte();  // before TOC entries

  for (size_t i = 0; i < group_codes.size(); i++) {
    JXL_ASSERT(group_codes[i].BitsWritten() % kBitsPerByte == 0);
    const size_t group_size = group_codes[i].BitsWritten() / kBitsPerByte;
    JXL_RETURN_IF_ERROR(U32Coder::Write(kTocDist, group_size, writer));
  }
  writer->ZeroPadToByte();  // before first group
  allotment.ReclaimAndCharge(writer, kLayerTOC, aux_out);
  return true;
}

}  // namespace jxl
