/*

 * Copyright 2021 Google Inc. All rights reserved.

 *

 * 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.

 */

#ifndef FLATBUFFERS_DETACHED_BUFFER_H_

#define FLATBUFFERS_DETACHED_BUFFER_H_

#include "flatbuffers/allocator.h"

#include "flatbuffers/base.h"

#include "flatbuffers/default_allocator.h"

namespace mapserver {

namespace flatbuffers {

// DetachedBuffer is a finished flatbuffer memory region, detached from its

// builder. The original memory region and allocator are also stored so that

// the DetachedBuffer can manage the memory lifetime.

class DetachedBuffer {

 public:

  DetachedBuffer()

      : allocator_(nullptr),

        own_allocator_(false),

        buf_(nullptr),

        reserved_(0),

        cur_(nullptr),

        size_(0) {}

  DetachedBuffer(Allocator *allocator, bool own_allocator, uint8_t *buf,

                 size_t reserved, uint8_t *cur, size_t sz)

      : allocator_(allocator),

        own_allocator_(own_allocator),

        buf_(buf),

        reserved_(reserved),

        cur_(cur),

        size_(sz) {}

  DetachedBuffer(DetachedBuffer &&other)

      : allocator_(other.allocator_),

        own_allocator_(other.own_allocator_),

        buf_(other.buf_),

        reserved_(other.reserved_),

        cur_(other.cur_),

        size_(other.size_) {

    other.reset();

  }

  DetachedBuffer &operator=(DetachedBuffer &&other) {

    if (this == &other) return *this;

    destroy();

    allocator_ = other.allocator_;

    own_allocator_ = other.own_allocator_;

    buf_ = other.buf_;

    reserved_ = other.reserved_;

    cur_ = other.cur_;

    size_ = other.size_;

    other.reset();

    return *this;

  }

  ~DetachedBuffer() { destroy(); }

  const uint8_t *data() const { return cur_; }

  uint8_t *data() { return cur_; }

  size_t size() const { return size_; }

  // These may change access mode, leave these at end of public section

  FLATBUFFERS_DELETE_FUNC(DetachedBuffer(const DetachedBuffer &other));

  FLATBUFFERS_DELETE_FUNC(

      DetachedBuffer &operator=(const DetachedBuffer &other));

 protected:

  Allocator *allocator_;

  bool own_allocator_;

  uint8_t *buf_;

  size_t reserved_;

  uint8_t *cur_;

  size_t size_;

  inline void destroy() {

    if (buf_) Deallocate(allocator_, buf_, reserved_);

    if (own_allocator_ && allocator_) { delete allocator_; }

    reset();

  }

  inline void reset() {

    allocator_ = nullptr;

    own_allocator_ = false;

    buf_ = nullptr;

    reserved_ = 0;

    cur_ = nullptr;

    size_ = 0;

  }

};

}  // namespace flatbuffers

}  // namespace mapserver

#endif  // FLATBUFFERS_DETACHED_BUFFER_H_