// Copyright 2023 Google Inc.

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//      http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

//

////////////////////////////////////////////////////////////////////////////////

#include <cstddef>

#include <cstdint>

#include <cstring>

#include <string_view>

#include "./fuzz_utils.h"

#include "src/dec/vp8li_dec.h"

#include "src/utils/bit_reader_utils.h"

#include "src/utils/huffman_utils.h"

#include "src/utils/utils.h"

#include "src/webp/format_constants.h"

namespace {

void HuffmanTest(std::string_view blob) {

  const uint8_t* const data = reinterpret_cast<const uint8_t*>(blob.data());

  const size_t size = blob.size();

  // Number of bits to initialize data.

  static const int kColorCacheBitsBits = 4;

  // 'num_htree_groups' is contained in the RG channel, hence 16 bits.

  static const int kNumHtreeGroupsBits = 16;

  if (size * sizeof(*data) < kColorCacheBitsBits + kNumHtreeGroupsBits) {

    return;

  }

  // A non-NULL mapping brings minor changes that are tested by the normal

  // fuzzer.

  int* const mapping = NULL;

  HuffmanTables huffman_tables;

  memset(&huffman_tables, 0, sizeof(huffman_tables));

  HTreeGroup* htree_groups = NULL;

  int num_htree_groups, num_htree_groups_max, color_cache_bits;

  VP8LBitReader* br;

  VP8LDecoder* dec = VP8LNew();

  if (dec == NULL) goto Error;

  br = &dec->br;

  VP8LInitBitReader(br, data, size);

  color_cache_bits = VP8LReadBits(br, kColorCacheBitsBits);

  if (color_cache_bits < 1 || color_cache_bits > MAX_CACHE_BITS) goto Error;

  num_htree_groups = VP8LReadBits(br, kNumHtreeGroupsBits);

  // 'num_htree_groups' cannot be 0 as it is built from a non-empty image.

  if (num_htree_groups == 0) goto Error;

  // This variable is only useful when mapping is not NULL.

  num_htree_groups_max = num_htree_groups;

  (void)ReadHuffmanCodesHelper(color_cache_bits, num_htree_groups,

                               num_htree_groups_max, mapping, dec,

                               &huffman_tables, &htree_groups);

Error:

  WebPSafeFree(mapping);

  VP8LHtreeGroupsFree(htree_groups);

  VP8LHuffmanTablesDeallocate(&huffman_tables);

  VP8LDelete(dec);

}

}  // namespace

FUZZ_TEST(Huffman, HuffmanTest).WithDomains(fuzztest::String());