/*
 *
 * Copyright 2015, Google Inc.
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 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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#include <grpc++/support/byte_buffer.h>
#include <grpc/byte_buffer_reader.h>

namespace grpc {

ByteBuffer::ByteBuffer(const Slice* slices, size_t nslices) {
  // The following assertions check that the representation of a grpc::Slice is
  // identical to that of a gpr_slice:  it has a gpr_slice field, and nothing
  // else.
  static_assert(std::is_same<decltype(slices[0].slice_), gpr_slice>::value,
                "Slice must have same representation as gpr_slice");
  static_assert(sizeof(Slice) == sizeof(gpr_slice),
                "Slice must have same representation as gpr_slice");
  // The const_cast is legal if grpc_raw_byte_buffer_create() does no more
  // than its advertised side effect of increasing the reference count of the
  // slices it processes, and such an increase does not affect the semantics
  // seen by the caller of this constructor.
  buffer_ = grpc_raw_byte_buffer_create(
      reinterpret_cast<gpr_slice*>(const_cast<Slice*>(slices)), nslices);
}

ByteBuffer::~ByteBuffer() {
  if (buffer_) {
    grpc_byte_buffer_destroy(buffer_);
  }
}

void ByteBuffer::Clear() {
  if (buffer_) {
    grpc_byte_buffer_destroy(buffer_);
    buffer_ = nullptr;
  }
}

Status ByteBuffer::Dump(std::vector<Slice>* slices) const {
  slices->clear();
  if (!buffer_) {
    return Status(StatusCode::FAILED_PRECONDITION, "Buffer not initialized");
  }
  grpc_byte_buffer_reader reader;
  if (!grpc_byte_buffer_reader_init(&reader, buffer_)) {
    return Status(StatusCode::INTERNAL,
                  "Couldn't initialize byte buffer reader");
  }
  gpr_slice s;
  while (grpc_byte_buffer_reader_next(&reader, &s)) {
    slices->push_back(Slice(s, Slice::STEAL_REF));
  }
  grpc_byte_buffer_reader_destroy(&reader);
  return Status::OK;
}

size_t ByteBuffer::Length() const {
  if (buffer_) {
    return grpc_byte_buffer_length(buffer_);
  } else {
    return 0;
  }
}

ByteBuffer::ByteBuffer(const ByteBuffer& buf)
    : buffer_(grpc_byte_buffer_copy(buf.buffer_)) {}

ByteBuffer& ByteBuffer::operator=(const ByteBuffer& buf) {
  Clear();  // first remove existing data
  if (buf.buffer_) {
    buffer_ = grpc_byte_buffer_copy(buf.buffer_);  // then copy
  }
  return *this;
}

void ByteBuffer::Swap(ByteBuffer* other) {
  grpc_byte_buffer* tmp = other->buffer_;
  other->buffer_ = buffer_;
  buffer_ = tmp;
}

}  // namespace grpc