// 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/entropy_coder.h"

#include <jxl/memory_manager.h>

#include <cstdint>

#include <vector>

#include "lib/jxl/ac_context.h"

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

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

#include "lib/jxl/coeff_order.h"

#include "lib/jxl/coeff_order_fwd.h"

#include "lib/jxl/dec_bit_reader.h"

#include "lib/jxl/dec_context_map.h"

#include "lib/jxl/fields.h"

#include "lib/jxl/pack_signed.h"

namespace jxl {

Status DecodeBlockCtxMap(JxlMemoryManager* memory_manager, BitReader* br,

                         BlockCtxMap* block_ctx_map) {

  auto& dct = block_ctx_map->dc_thresholds;

  auto& qft = block_ctx_map->qf_thresholds;

  auto& ctx_map = block_ctx_map->ctx_map;

  bool is_default = static_cast<bool>(br->ReadFixedBits<1>());

  if (is_default) {

    *block_ctx_map = BlockCtxMap();

    return true;

  }

  block_ctx_map->num_dc_ctxs = 1;

  for (int j : {0, 1, 2}) {

    dct[j].resize(br->ReadFixedBits<4>());

    block_ctx_map->num_dc_ctxs *= dct[j].size() + 1;

    for (int& i : dct[j]) {

      i = UnpackSigned(U32Coder::Read(kDCThresholdDist, br));

    }

  }

  qft.resize(br->ReadFixedBits<4>());

  for (uint32_t& i : qft) {

    i = U32Coder::Read(kQFThresholdDist, br) + 1;

  }

  if (block_ctx_map->num_dc_ctxs * (qft.size() + 1) > 64) {

    return JXL_FAILURE("Invalid block context map: too big");

  }

  ctx_map.resize(3 * kNumOrders * block_ctx_map->num_dc_ctxs *

                 (qft.size() + 1));

  JXL_RETURN_IF_ERROR(

      DecodeContextMap(memory_manager, &ctx_map, &block_ctx_map->num_ctxs, br));

  if (block_ctx_map->num_ctxs > 16) {

    return JXL_FAILURE("Invalid block context map: too many distinct contexts");

  }

  return true;

}

#if JXL_CXX_LANG < JXL_CXX_17

constexpr uint8_t BlockCtxMap::kDefaultCtxMap[];  // from ac_context.h

#endif

}  // namespace jxl