// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you 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
//
//   http://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.
#pragma once

#include <cstdint>
#include <memory>
#include <string>
#include <vector>

#include "kudu/integration-tests/cluster_itest_util.h"
#include "kudu/integration-tests/ts_itest-base.h"
#include "kudu/util/countdown_latch.h"
#include "kudu/util/status.h"

namespace kudu {

class MonoDelta;

namespace cluster {
class ExternalTabletServer;
}

namespace tserver {

class TabletServerServiceProxy;

// Integration test for the raft consensus implementation.
// Uses the whole tablet server stack with ExternalMiniCluster.
class RaftConsensusITestBase : public TabletServerIntegrationTestBase {
 public:
  // Behavior for the tablet server hosting the fall-behind-WAL-GC replica.
  enum BehindWalGcBehavior {
    STOP_CONTINUE,    // Send SIGSTOP and then SIGCONT to the affected tserver.
    SHUTDOWN_RESTART, // Shutdown and then restart the affected tserver.
    SHUTDOWN,         // Shutdown the affected tserver, don't start it back up.
    DO_NOT_TAMPER,    // Leave the affected tserver alone, running or not.
  };

  RaftConsensusITestBase();

  void SetUp() override;

  void ScanReplica(TabletServerServiceProxy* replica_proxy,
                   std::vector<std::string>* results);

  void InsertTestRowsRemoteThread(
      int first_row, int count, int num_batches,
      const std::vector<std::unique_ptr<CountDownLatch>>& latches = {});
 protected:
  // Retrieve the current term of the first tablet on this tablet server.
  static Status GetTermMetricValue(cluster::ExternalTabletServer* ts,
                                   int64_t* term);

  // Flags needed for CauseFollowerToFallBehindLogGC() to work well.
  static void AddFlagsForLogRolls(std::vector<std::string>* extra_tserver_flags);

  // Pause/shutdown the tserver hosting one of the follower tablet replicas and
  // write enough data to the remaining replicas to cause log GC. Then
  // resume/restart/leave-shutdown the affected tserver. On success,
  // 'leader_uuid' will be set to the UUID of the leader, 'orig_term'
  // will be set to the term of the leader before un-pausing the follower and
  // 'fell_behind_uuid' will be set to the UUID of the follower that was
  // paused/shutdown and caused to fall behind. These can be used for
  // verification purposes. The optional 'tserver_behavior' dictates what
  // whether the affected tserver will be paused/resumed, shutdown/restarted,
  // and so on.
  //
  // Certain flags should be set. You can add the required flags with
  // AddFlagsForLogRolls() before starting the cluster.
  void CauseFollowerToFallBehindLogGC(
      const itest::TabletServerMap& tablet_servers,
      std::string* leader_uuid = nullptr,
      int64_t* orig_term = nullptr,
      std::string* fell_behind_uuid = nullptr,
      BehindWalGcBehavior tserver_behavior = BehindWalGcBehavior::STOP_CONTINUE,
      const MonoDelta& pre_workload_delay = {});

  // Same as above, but the follower to fail is chosen in advance.
  void CauseSpecificFollowerToFallBehindLogGC(
      const itest::TabletServerMap& tablet_servers,
      const std::string& follower_uuid_to_fail,
      std::string* leader_uuid = nullptr,
      int64_t* orig_term = nullptr,
      BehindWalGcBehavior tserver_behavior = BehindWalGcBehavior::STOP_CONTINUE,
      const MonoDelta& pre_workload_delay = {});

  CountDownLatch inserters_;
};

}  // namespace tserver
}  // namespace kudu