// Copyright 2017 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_GATT_SERVER_H_
#define SRC_CONNECTIVITY_BLUETOOTH_CORE_BT_HOST_GATT_SERVER_H_

#include "src/connectivity/bluetooth/core/bt-host/att/bearer.h"
#include "src/connectivity/bluetooth/core/bt-host/att/database.h"
#include "src/connectivity/bluetooth/core/bt-host/common/uuid.h"
#include "src/connectivity/bluetooth/core/bt-host/gatt/gatt_defs.h"
#include "src/lib/fxl/memory/ref_ptr.h"
#include "src/lib/fxl/memory/weak_ptr.h"

namespace bt {

namespace att {
class Attribute;
class Database;
class PacketReader;
}  // namespace att

namespace gatt {

// A GATT Server implements the server-role of the ATT protocol over a single
// ATT Bearer. A unique Server instance should exist for each logical link that
// supports GATT.
//
// A Server responds to incoming requests by querying the database that it
// is initialized with. Each Server shares an att::Bearer with a Client.
class Server final {
 public:
  // |peer_id| is the unique system identifier for the peer device.
  // |database| will be queried by the Server to resolve transactions.
  // |bearer| is the ATT data bearer that this Server operates on.
  Server(PeerId peer_id, fxl::RefPtr<att::Database> database, fxl::RefPtr<att::Bearer> bearer);
  ~Server();

  // Sends a Handle-Value notification or indication PDU with the given
  // attribute handle. If |indicate| is true, then an indication will be sent.
  // The underlying att::Bearer will disconnect the link if a confirmation is
  // not received in a timely manner.
  void SendNotification(att::Handle handle, const ByteBuffer& value, bool indicate);

 private:
  // ATT protocol request handlers:
  void OnExchangeMTU(att::Bearer::TransactionId tid, const att::PacketReader& packet);
  void OnFindInformation(att::Bearer::TransactionId tid, const att::PacketReader& packet);
  void OnReadByGroupType(att::Bearer::TransactionId tid, const att::PacketReader& packet);
  void OnReadByType(att::Bearer::TransactionId tid, const att::PacketReader& packet);
  void OnReadRequest(att::Bearer::TransactionId tid, const att::PacketReader& packet);
  void OnWriteRequest(att::Bearer::TransactionId tid, const att::PacketReader& packet);
  void OnWriteCommand(att::Bearer::TransactionId tid, const att::PacketReader& packet);
  void OnReadBlobRequest(att::Bearer::TransactionId tid, const att::PacketReader& packet);
  void OnFindByTypeValueRequest(att::Bearer::TransactionId tid, const att::PacketReader& packet);
  void OnPrepareWriteRequest(att::Bearer::TransactionId tid, const att::PacketReader& packet);
  void OnExecuteWriteRequest(att::Bearer::TransactionId tid, const att::PacketReader& packet);

  // Helper function to serve the Read By Type and Read By Group Type requests.
  // This searches |db| for attributes with the given |type| and adds as many
  // attributes as it can fit within the given |max_data_list_size|. The
  // attribute value that should be included within each attribute data list
  // entry is returned in |out_value_size|.
  //
  // If the result is a dynamic attribute, |out_results| will contain at most
  // one entry. |out_value_size| will point to an undefined value in that case.
  //
  // Returns att::ErrorCode::kNoError on success. On error, returns an error
  // code that can be used in a ATT Error Response.
  att::ErrorCode ReadByTypeHelper(att::Handle start, att::Handle end, const UUID& type,
                                  bool group_type, size_t max_data_list_size, size_t max_value_size,
                                  size_t entry_prefix_size, size_t* out_value_size,
                                  std::list<const att::Attribute*>* out_results);

  PeerId peer_id_;
  fxl::RefPtr<att::Database> db_;
  fxl::RefPtr<att::Bearer> att_;

  // The queue data structure used for queued writes (see Vol 3, Part F, 3.4.6).
  att::PrepareWriteQueue prepare_queue_;

  // ATT protocol request handler IDs
  // TODO(armansito): Storing all these IDs here feels wasteful. Provide a way
  // to unregister GATT server callbacks collectively from an att::Bearer, given
  // that it's server-role functionalities are uniquely handled by this class.
  att::Bearer::HandlerId exchange_mtu_id_;
  att::Bearer::HandlerId find_information_id_;
  att::Bearer::HandlerId read_by_group_type_id_;
  att::Bearer::HandlerId read_by_type_id_;
  att::Bearer::HandlerId read_req_id_;
  att::Bearer::HandlerId write_req_id_;
  att::Bearer::HandlerId write_cmd_id_;
  att::Bearer::HandlerId read_blob_req_id_;
  att::Bearer::HandlerId find_by_type_value_id_;
  att::Bearer::HandlerId prepare_write_id_;
  att::Bearer::HandlerId exec_write_id_;

  fxl::WeakPtrFactory<Server> weak_ptr_factory_;

  DISALLOW_COPY_AND_ASSIGN_ALLOW_MOVE(Server);
};

}  // namespace gatt
}  // namespace bt

#endif  // SRC_CONNECTIVITY_BLUETOOTH_CORE_BT_HOST_GATT_SERVER_H_