// Copyright 2017 The Draco Authors.

//

// 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 "draco/metadata/metadata_decoder.h"

#include <string>

#include "draco/core/varint_decoding.h"

namespace draco {

MetadataDecoder::MetadataDecoder() : buffer_(nullptr) {}

bool MetadataDecoder::DecodeMetadata(DecoderBuffer *in_buffer,

                                     Metadata *metadata) {

  if (!metadata) {

    return false;

  }

  buffer_ = in_buffer;

  return DecodeMetadata(metadata);

}

bool MetadataDecoder::DecodeGeometryMetadata(DecoderBuffer *in_buffer,

                                             GeometryMetadata *metadata) {

  if (!metadata) {

    return false;

  }

  buffer_ = in_buffer;

  uint32_t num_att_metadata = 0;

  if (!DecodeVarint(&num_att_metadata, buffer_)) {

    return false;

  }

  // Decode attribute metadata.

  for (uint32_t i = 0; i < num_att_metadata; ++i) {

    uint32_t att_unique_id;

    if (!DecodeVarint(&att_unique_id, buffer_)) {

      return false;

    }

    std::unique_ptr<AttributeMetadata> att_metadata =

        std::unique_ptr<AttributeMetadata>(new AttributeMetadata());

    att_metadata->set_att_unique_id(att_unique_id);

    if (!DecodeMetadata(static_cast<Metadata *>(att_metadata.get()))) {

      return false;

    }

    metadata->AddAttributeMetadata(std::move(att_metadata));

  }

  return DecodeMetadata(static_cast<Metadata *>(metadata));

}

bool MetadataDecoder::DecodeMetadata(Metadata *metadata) {

  // Limit metadata nesting depth to avoid stack overflow in destructor.

  constexpr int kMaxSubmetadataLevel = 1000;

  struct MetadataTuple {

    Metadata *parent_metadata;

    Metadata *decoded_metadata;

    int level;

  };

  std::vector<MetadataTuple> metadata_stack;

  metadata_stack.push_back({nullptr, metadata, 0});

  while (!metadata_stack.empty()) {

    const MetadataTuple mp = metadata_stack.back();

    metadata_stack.pop_back();

    metadata = mp.decoded_metadata;

    if (mp.parent_metadata != nullptr) {

      if (mp.level > kMaxSubmetadataLevel) {

        return false;

      }

      std::string sub_metadata_name;

      if (!DecodeName(&sub_metadata_name)) {

        return false;

      }

      std::unique_ptr<Metadata> sub_metadata =

          std::unique_ptr<Metadata>(new Metadata());

      metadata = sub_metadata.get();

      if (!mp.parent_metadata->AddSubMetadata(sub_metadata_name,

                                              std::move(sub_metadata))) {

        return false;

      }

    }

    if (metadata == nullptr) {

      return false;

    }

    uint32_t num_entries = 0;

    if (!DecodeVarint(&num_entries, buffer_)) {

      return false;

    }

    for (uint32_t i = 0; i < num_entries; ++i) {

      if (!DecodeEntry(metadata)) {

        return false;

      }

    }

    uint32_t num_sub_metadata = 0;

    if (!DecodeVarint(&num_sub_metadata, buffer_)) {

      return false;

    }

    if (num_sub_metadata > buffer_->remaining_size()) {

      // The decoded number of metadata items is unreasonably high.

      return false;

    }

    for (uint32_t i = 0; i < num_sub_metadata; ++i) {

      metadata_stack.push_back(

          {metadata, nullptr, mp.parent_metadata ? mp.level + 1 : mp.level});

    }

  }

  return true;

}

bool MetadataDecoder::DecodeEntry(Metadata *metadata) {

  std::string entry_name;

  if (!DecodeName(&entry_name)) {

    return false;

  }

  uint32_t data_size = 0;

  if (!DecodeVarint(&data_size, buffer_)) {

    return false;

  }

  if (data_size == 0) {

    return false;

  }

  if (data_size > buffer_->remaining_size()) {

    return false;

  }

  std::vector<uint8_t> entry_value(data_size);

  if (!buffer_->Decode(&entry_value[0], data_size)) {

    return false;

  }

  metadata->AddEntryBinary(entry_name, entry_value);

  return true;

}

bool MetadataDecoder::DecodeName(std::string *name) {

  uint8_t name_len = 0;

  if (!buffer_->Decode(&name_len)) {

    return false;

  }

  name->resize(name_len);

  if (name_len == 0) {

    return true;

  }

  if (!buffer_->Decode(&name->at(0), name_len)) {

    return false;

  }

  return true;

}

}  // namespace draco