// Copyright (c) Google LLC 2020

//

// Use of this source code is governed by an MIT-style

// license that can be found in the LICENSE file or at

// https://opensource.org/licenses/MIT.

#ifndef BRUNSLI_DEC_OUPUT_CHUNK_H_

#define BRUNSLI_DEC_OUPUT_CHUNK_H_

#include <initializer_list>

#include <memory>

#include <vector>

#include <brunsli/types.h>

namespace brunsli {

namespace internal {

namespace dec {

/**

 * A chunk of output data.

 *

 * Data producer creates OutputChunks and adds them to the end output queue.

 * Once control flow leaves the producer code, it is considered that chunk of

 * data is final and can not be changed; to underline this fact |next| is a

 * const-pointer.

 *

 * Data consumer removes OutputChunks from the beginning of the output queue.

 * It is possible to consume OutputChunks partially, by updating |next| and

 * |len|.

 *

 * There are 2 types of output chunks:

 *  - owning: actual data is stored in |buffer| field; producer fills data after

 *    the instance it created; it is legal to reduce |len| to show that not all

 *    the capacity of |buffer| is used

 *  - non-owning: represents the data stored (owned) somewhere else

 */

struct OutputChunk {

  // Non-owning

  template<typename Bytes>

  OutputChunk(Bytes& bytes) : len(bytes.size()) {

    // Deal both with const qualifier and data type.

    const void* src = bytes.data();

    next = reinterpret_cast<const uint8_t*>(src);

  }

  // Non-owning

  OutputChunk(const uint8_t* data, size_t size) : next(data), len(size) {}

  // Owning

  explicit OutputChunk(size_t size = 0) {

    buffer.reset(new std::vector<uint8_t>(size));

    next = buffer->data();

    len = size;

  }

  // Owning

  OutputChunk(std::initializer_list<uint8_t> bytes) {

    buffer.reset(new std::vector<uint8_t>(bytes));

    next = buffer->data();

    len = bytes.size();

  }

  const uint8_t* next;

  size_t len;

  std::unique_ptr<std::vector<uint8_t>> buffer;

};

}  // namespace dec

}  // namespace internal

}  // namespace brunsli

#endif  // BRUNSLI_DEC_OUPUT_CHUNK_H_