// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SRC_CONNECTIVITY_BLUETOOTH_CORE_BT_HOST_SM_PACKET_H_
#define SRC_CONNECTIVITY_BLUETOOTH_CORE_BT_HOST_SM_PACKET_H_

#include "lib/fpromise/result.h"
#include "src/connectivity/bluetooth/core/bt-host/common/byte_buffer.h"
#include "src/connectivity/bluetooth/core/bt-host/common/packet_view.h"
#include "src/connectivity/bluetooth/core/bt-host/sm/smp.h"

namespace bt::sm {

// Utilities for processing SMP packets.
// TODO(fxbug.dev/48978): Merge PacketReader & ValidPacketReader types into one type for validating
// & accessing SM packets once PacketReader is no longer used.
class PacketReader : public PacketView<Header> {
 public:
  explicit PacketReader(const ByteBuffer* buffer);
  inline Code code() const { return header().code; }
};

// A type which has been verified to satisfy all the preconditions of a valid SMP packet. Namely,
// 1.) The packet's length is at least that of an SMP header.
// 2.) The packet's header code is a valid SMP code that our stack supports.
// 3.) The length of the packet's payload matches the payload associated with its header code.
class ValidPacketReader : public PacketReader {
 public:
  // Convert a ByteBufferPtr to a ValidPacketReader if possible to allow unchecked access to
  // its payload, or an error explaining why we could not.
  static fpromise::result<ValidPacketReader, ErrorCode> ParseSdu(const ByteBufferPtr& sdu);

 private:
  // Private constructor because a valid PacketReader must be parsed from a ByteBufferPtr
  explicit ValidPacketReader(const ByteBuffer* buffer);
};

class PacketWriter : public MutablePacketView<Header> {
 public:
  // Constructor writes |code| into |buffer|.
  PacketWriter(Code code, MutableByteBuffer* buffer);
};

}  // namespace bt::sm

#endif  // SRC_CONNECTIVITY_BLUETOOTH_CORE_BT_HOST_SM_PACKET_H_