// Copyright 2022 Google LLC
//
// 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
//
//     https://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 THIRD_PARTY_NEARBY_SHARING_INCOMING_SHARE_SESSION_H_
#define THIRD_PARTY_NEARBY_SHARING_INCOMING_SHARE_SESSION_H_

#include <functional>
#include <memory>
#include <optional>
#include <string>
#include <vector>

#include "absl/functional/any_invocable.h"
#include "internal/base/file_path.h"
#include "internal/platform/clock.h"
#include "internal/platform/task_runner.h"
#include "sharing/analytics/analytics_recorder.h"
#include "sharing/nearby_connection.h"
#include "sharing/nearby_connections_manager.h"
#include "sharing/nearby_connections_types.h"
#include "sharing/proto/wire_format.pb.h"
#include "sharing/share_session.h"
#include "sharing/share_target.h"
#include "sharing/thread_timer.h"
#include "sharing/transfer_metadata.h"

namespace nearby::sharing {

// Class that represents a single incoming share session.
// This class is thread-compatible.
class IncomingShareSession : public ShareSession {
 public:
  IncomingShareSession(
      Clock* clock, TaskRunner& service_thread,
      NearbyConnectionsManager* connections_manager,
      analytics::AnalyticsRecorder& analytics_recorder, std::string endpoint_id,
      const ShareTarget& share_target,
      std::function<void(const IncomingShareSession&, const TransferMetadata&)>
          transfer_update_callback);
  IncomingShareSession(IncomingShareSession&&);
  ~IncomingShareSession() override;

  bool IsIncoming() const override { return true; }

  // Returns nullopt on success.
  // On failure, returns the status that should be used to terminate the
  // connection.
  std::optional<TransferMetadata::Status> ProcessIntroduction(
      const nearby::sharing::service::proto::IntroductionFrame&
          introduction_frame);

  // Returns true if the transfer can begin and AcceptTransfer should be called
  // immediately.
  // Returns false if user needs to accept the transfer.
  bool ReadyForTransfer(
      std::function<void()> accept_timeout_callback,
      std::function<
          void(bool is_timeout,
               std::optional<nearby::sharing::service::proto::V1Frame> frame)>
          frame_read_callback);

  // Accept the transfer and begin listening for payload transfer updates.
  // Returns false if session is not in a state to accept the transfer.
  bool AcceptTransfer(
      absl::AnyInvocable<void()> payload_transfer_updates_callback);

  // Returns the file paths of all file payloads.
  std::vector<FilePath> GetPayloadFilePaths() const;

  // Upgrade bandwidth if it is needed.
  // Returns true if bandwidth upgrade was requested.
  bool TryUpgradeBandwidth();

  // Send TransferMetadataUpdate with the final |status|.
  // Map |status| to corresponding ConnectionResponseFrame::Status and send
  // response to remote device.
  void SendFailureResponse(TransferMetadata::Status status);

  // Process payload transfer updates.
  // The `update_file_paths_in_progress` flag determines if the payload paths
  // should be updated in the attachments on each update notification.
  // If queued PayloadTransferUpdates results in a change in the transfer
  // metadata, the latest TransferMetadata is returned. Otherwise, nullopt is
  // returned.
  std::optional<TransferMetadata> ProcessPayloadTransferUpdates(
      bool update_file_paths_in_progress);

  // Pushes a payload transfer update to the queue.  For testing only.
  void PushPayloadTransferUpdateForTest(
      std::unique_ptr<PayloadTransferUpdate> update);

  // Called when an incoming connection is established.
  void OnConnected(NearbyConnection* connection);

 protected:
  void InvokeTransferUpdateCallback(const TransferMetadata& metadata) override;

 private:
  enum class SessionPhase {
    kUninitialized,
    kTransfer,
    kSync,
  };

  // Update file attachment paths with payload paths.
  bool UpdateFilePayloadPaths();

  // Copy payload contents from the NearbyConnection to the Attachment.
  bool UpdatePayloadContents();

  // Once transfer has completed, make payload content available in the
  // corresponding Attachment.
  // Returns true if all payloads were successfully finalized.
  bool FinalizePayloads();

  std::function<void(const IncomingShareSession&, const TransferMetadata&)>
      transfer_update_callback_;

  bool bandwidth_upgrade_requested_ = false;
  bool ready_for_accept_ = false;
  // This alarm is used to disconnect the sharing connection if both sides do
  // not press accept within the timeout.
  std::unique_ptr<ThreadTimer> mutual_acceptance_timeout_;

  SessionPhase session_phase_ = SessionPhase::kUninitialized;
};

}  // namespace nearby::sharing

#endif  // THIRD_PARTY_NEARBY_SHARING_INCOMING_SHARE_SESSION_H_