// 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 <cstddef>

#include <memory>

#include <vector>

#include "lib/jxl/base/common.h"

#include "lib/jxl/base/compiler_specific.h"

#include "lib/jxl/base/status.h"

#include "lib/jxl/coeff_order_fwd.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<std::unique_ptr<BitWriter>>& group_codes,

    const std::vector<coeff_order_t>& permutation,

    BitWriter* JXL_RESTRICT writer, AuxOut* aux_out) {

  return writer->WithMaxBits(

      MaxBits(group_codes.size()), LayerType::Toc, aux_out, [&]() -> Status {

        if (!permutation.empty() && !group_codes.empty()) {

          // Don't write a permutation at all for an empty group_codes.

          writer->Write(1, 1);  // permutation

          JXL_ENSURE(permutation.size() == group_codes.size());

          JXL_RETURN_IF_ERROR(EncodePermutation(permutation.data(), /*skip=*/0,

                                                permutation.size(), writer,

                                                LayerType::Header, aux_out));

        } else {

          writer->Write(1, 0);  // no permutation

        }

        writer->ZeroPadToByte();  // before TOC entries

        for (const auto& bw : group_codes) {

          JXL_ENSURE(bw->BitsWritten() % kBitsPerByte == 0);

          const size_t group_size = bw->BitsWritten() / kBitsPerByte;

          JXL_RETURN_IF_ERROR(U32Coder::Write(kTocDist, group_size, writer));

        }

        writer->ZeroPadToByte();  // before first group

        return true;

      });

}

}  // namespace jxl