// 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/modular/encoding/dec_ma.h"

#include <jxl/memory_manager.h>

#include <limits>

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

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

#include "lib/jxl/dec_ans.h"

#include "lib/jxl/modular/encoding/ma_common.h"

#include "lib/jxl/modular/modular_image.h"

#include "lib/jxl/pack_signed.h"

namespace jxl {

namespace {

Status ValidateTree(

    const Tree &tree,

    const std::vector<std::pair<pixel_type, pixel_type>> &prop_bounds,

    size_t root) {

  if (tree[root].property == -1) return true;

  size_t p = tree[root].property;

  int val = tree[root].splitval;

  if (prop_bounds[p].first > val) return JXL_FAILURE("Invalid tree");

  // Splitting at max value makes no sense: left range will be exactly same

  // as parent, right range will be invalid (min > max).

  if (prop_bounds[p].second <= val) return JXL_FAILURE("Invalid tree");

  auto new_bounds = prop_bounds;

  new_bounds[p].first = val + 1;

  JXL_RETURN_IF_ERROR(ValidateTree(tree, new_bounds, tree[root].lchild));

  new_bounds[p] = prop_bounds[p];

  new_bounds[p].second = val;

  return ValidateTree(tree, new_bounds, tree[root].rchild);

}

Status DecodeTree(BitReader *br, ANSSymbolReader *reader,

                  const std::vector<uint8_t> &context_map, Tree *tree,

                  size_t tree_size_limit) {

  size_t leaf_id = 0;

  size_t to_decode = 1;

  tree->clear();

  while (to_decode > 0) {

    JXL_RETURN_IF_ERROR(br->AllReadsWithinBounds());

    if (tree->size() > tree_size_limit) {

      return JXL_FAILURE("Tree is too large: %" PRIuS " nodes vs %" PRIuS

                         " max nodes",

                         tree->size(), tree_size_limit);

    }

    to_decode--;

    uint32_t prop1 = reader->ReadHybridUint(kPropertyContext, br, context_map);

    if (prop1 > 256) return JXL_FAILURE("Invalid tree property value");

    int property = prop1 - 1;

    if (property == -1) {

      size_t predictor =

          reader->ReadHybridUint(kPredictorContext, br, context_map);

      if (predictor >= kNumModularPredictors) {

        return JXL_FAILURE("Invalid predictor");

      }

      int64_t predictor_offset =

          UnpackSigned(reader->ReadHybridUint(kOffsetContext, br, context_map));

      uint32_t mul_log =

          reader->ReadHybridUint(kMultiplierLogContext, br, context_map);

      if (mul_log >= 31) {

        return JXL_FAILURE("Invalid multiplier logarithm");

      }

      uint32_t mul_bits =

          reader->ReadHybridUint(kMultiplierBitsContext, br, context_map);

      if (mul_bits >= (1u << (31u - mul_log)) - 1u) {

        return JXL_FAILURE("Invalid multiplier");

      }

      uint32_t multiplier = (mul_bits + 1U) << mul_log;

      tree->emplace_back(-1, 0, leaf_id++, 0, static_cast<Predictor>(predictor),

                         predictor_offset, multiplier);

      continue;

    }

    int splitval =

        UnpackSigned(reader->ReadHybridUint(kSplitValContext, br, context_map));

    tree->emplace_back(property, splitval, tree->size() + to_decode + 1,

                       tree->size() + to_decode + 2, Predictor::Zero, 0, 1);

    to_decode += 2;

  }

  std::vector<std::pair<pixel_type, pixel_type>> prop_bounds;

  prop_bounds.resize(256, {std::numeric_limits<pixel_type>::min(),

                           std::numeric_limits<pixel_type>::max()});

  return ValidateTree(*tree, prop_bounds, 0);

}

}  // namespace

Status DecodeTree(JxlMemoryManager *memory_manager, BitReader *br, Tree *tree,

                  size_t tree_size_limit) {

  std::vector<uint8_t> tree_context_map;

  ANSCode tree_code;

  JXL_RETURN_IF_ERROR(DecodeHistograms(memory_manager, br, kNumTreeContexts,

                                       &tree_code, &tree_context_map));

  // TODO(eustas): investigate more infinite tree cases.

  if (tree_code.degenerate_symbols[tree_context_map[kPropertyContext]] > 0) {

    return JXL_FAILURE("Infinite tree");

  }

  JXL_ASSIGN_OR_RETURN(ANSSymbolReader reader,

                       ANSSymbolReader::Create(&tree_code, br));

  JXL_RETURN_IF_ERROR(DecodeTree(br, &reader, tree_context_map, tree,

                                 std::min(tree_size_limit, kMaxTreeSize)));

  if (!reader.CheckANSFinalState()) {

    return JXL_FAILURE("ANS decode final state failed");

  }

  return true;

}

}  // namespace jxl