content: /*
   * Copyright © 2017-2023 WireGuard LLC. All Rights Reserved.
   * SPDX-License-Identifier: Apache-2.0
   */
  
  package org.amnezia.awg.backend;
  
  import org.amnezia.awg.config.Config;
  import org.amnezia.awg.util.NonNullForAll;
  
  import java.util.Set;
  
  import androidx.annotation.Nullable;
  
  /**
   * Interface for implementations of the AmneziaWG secure network tunnel.
   */
  
  @NonNullForAll
  public interface Backend {
      /**
       * Enumerate names of currently-running tunnels.
       *
       * @return The set of running tunnel names.
       */
      Set<String> getRunningTunnelNames();
  
      /**
       * Get the state of a tunnel.
       *
       * @param tunnel The tunnel to examine the state of.
       * @return The state of the tunnel.
       * @throws Exception Exception raised when retrieving tunnel's state.
       */
      Tunnel.State getState(Tunnel tunnel) throws Exception;
  
      /**
       * Get statistics about traffic and errors on this tunnel. If the tunnel is not running, the
       * statistics object will be filled with zero values.
       *
       * @param tunnel The tunnel to retrieve statistics for.
       * @return The statistics for the tunnel.
       * @throws Exception Exception raised when retrieving statistics.
       */
      Statistics getStatistics(Tunnel tunnel) throws Exception;
  
      /**
       * Determine version of underlying backend.
       *
       * @return The version of the backend.
       * @throws Exception Exception raised while retrieving version.
       */
      String getVersion() throws Exception;
  
      /**
       * Set the state of a tunnel, updating it's configuration. If the tunnel is already up, config
       * may update the running configuration; config may be null when setting the tunnel down.
       *
       * @param tunnel The tunnel to control the state of.
       * @param state  The new state for this tunnel. Must be {@code UP}, {@code DOWN}, or
       *               {@code TOGGLE}.
       * @param config The configuration for this tunnel, may be null if state is {@code DOWN}.
       * @return The updated state of the tunnel.
       * @throws Exception Exception raised while changing state.
       */
      Tunnel.State setState(Tunnel tunnel, Tunnel.State state, @Nullable Config config) throws Exception;
  }
  