content: /*
   * 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.
   */
  package org.apache.kafka.raft;
  
  import org.apache.kafka.common.Uuid;
  import org.apache.kafka.common.utils.LogContext;
  import org.apache.kafka.common.utils.MockTime;
  
  import org.junit.jupiter.api.Test;
  import org.junit.jupiter.params.ParameterizedTest;
  import org.junit.jupiter.params.provider.CsvSource;
  import org.junit.jupiter.params.provider.ValueSource;
  
  import java.util.Optional;
  import java.util.Set;
  import java.util.stream.IntStream;
  import java.util.stream.Stream;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  public class CandidateStateTest {
      private final ReplicaKey localReplicaKey = ReplicaKey.of(0, Uuid.randomUuid());
      private final int epoch = 5;
      private final MockTime time = new MockTime();
      private final int electionTimeoutMs = 5000;
      private final LogContext logContext = new LogContext();
  
      private CandidateState newCandidateState(VoterSet voters) {
          return new CandidateState(
              time,
              localReplicaKey.id(),
              localReplicaKey.directoryId().get(),
              epoch,
              voters,
              Optional.empty(),
              electionTimeoutMs,
              logContext
          );
      }
  
      @ParameterizedTest
      @ValueSource(booleans = { true, false })
      public void testSingleNodeQuorum(boolean withDirectoryId) {
          CandidateState state = newCandidateState(voterSetWithLocal(IntStream.empty(), withDirectoryId));
          assertTrue(state.epochElection().isVoteGranted());
          assertFalse(state.epochElection().isVoteRejected());
          assertEquals(Set.of(), state.epochElection().unrecordedVoters());
      }
  
      @ParameterizedTest
      @ValueSource(booleans = { true, false })
      public void testTwoNodeQuorumVoteRejected(boolean withDirectoryId) {
          ReplicaKey otherNode = replicaKey(1, withDirectoryId);
          CandidateState state = newCandidateState(
              voterSetWithLocal(Stream.of(otherNode), withDirectoryId)
          );
          assertFalse(state.epochElection().isVoteGranted());
          assertFalse(state.epochElection().isVoteRejected());
          assertEquals(Set.of(otherNode), state.epochElection().unrecordedVoters());
          assertTrue(state.recordRejectedVote(otherNode.id()));
          assertFalse(state.epochElection().isVoteGranted());
          assertTrue(state.epochElection().isVoteRejected());
      }
  
      @ParameterizedTest
      @ValueSource(booleans = { true, false })
      public void testTwoNodeQuorumVoteGranted(boolean withDirectoryId) {
          ReplicaKey otherNode = replicaKey(1, withDirectoryId);
          CandidateState state = newCandidateState(
              voterSetWithLocal(Stream.of(otherNode), withDirectoryId)
          );
          assertFalse(state.epochElection().isVoteGranted());
          assertFalse(state.epochElection().isVoteRejected());
          assertEquals(Set.of(otherNode), state.epochElection().unrecordedVoters());
          assertTrue(state.recordGrantedVote(otherNode.id()));
          assertEquals(Set.of(), state.epochElection().unrecordedVoters());
          assertFalse(state.epochElection().isVoteRejected());
          assertTrue(state.epochElection().isVoteGranted());
      }
  
      @ParameterizedTest
      @ValueSource(booleans = { true, false })
      public void testThreeNodeQuorumVoteGranted(boolean withDirectoryId) {
          ReplicaKey node1 = replicaKey(1, withDirectoryId);
          ReplicaKey node2 = replicaKey(2, withDirectoryId);
          CandidateState state = newCandidateState(
              voterSetWithLocal(Stream.of(node1, node2), withDirectoryId)
          );
          assertFalse(state.epochElection().isVoteGranted());
          assertFalse(state.epochElection().isVoteRejected());
          assertEquals(Set.of(node1, node2), state.epochElection().unrecordedVoters());
          assertTrue(state.recordGrantedVote(node1.id()));
          assertEquals(Set.of(node2), state.epochElection().unrecordedVoters());
          assertTrue(state.epochElection().isVoteGranted());
          assertFalse(state.epochElection().isVoteRejected());
          assertTrue(state.recordRejectedVote(node2.id()));
          assertEquals(Set.of(), state.epochElection().unrecordedVoters());
          assertTrue(state.epochElection().isVoteGranted());
          assertFalse(state.epochElection().isVoteRejected());
      }
  
      @ParameterizedTest
      @ValueSource(booleans = { true, false })
      public void testThreeNodeQuorumVoteRejected(boolean withDirectoryId) {
          ReplicaKey node1 = replicaKey(1, withDirectoryId);
          ReplicaKey node2 = replicaKey(2, withDirectoryId);
          CandidateState state = newCandidateState(
              voterSetWithLocal(Stream.of(node1, node2), withDirectoryId)
          );
          assertFalse(state.epochElection().isVoteGranted());
          assertFalse(state.epochElection().isVoteRejected());
          assertEquals(Set.of(node1, node2), state.epochElection().unrecordedVoters());
          assertTrue(state.recordRejectedVote(node1.id()));
          assertEquals(Set.of(node2), state.epochElection().unrecordedVoters());
          assertFalse(state.epochElection().isVoteGranted());
          assertFalse(state.epochElection().isVoteRejected());
          assertTrue(state.recordRejectedVote(node2.id()));
          assertEquals(Set.of(), state.epochElection().unrecordedVoters());
          assertFalse(state.epochElection().isVoteGranted());
          assertTrue(state.epochElection().isVoteRejected());
      }
  
      @ParameterizedTest
      @ValueSource(booleans = { true, false })
      public void testCannotRejectVoteFromLocalId(boolean withDirectoryId) {
          int otherNodeId = 1;
          CandidateState state = newCandidateState(
              voterSetWithLocal(IntStream.of(otherNodeId), withDirectoryId)
          );
          assertThrows(
              IllegalArgumentException.class,
              () -> state.recordRejectedVote(localReplicaKey.id())
          );
      }
  
      @ParameterizedTest
      @ValueSource(booleans = { true, false })
      public void testCannotChangeVoteGrantedToRejected(boolean withDirectoryId) {
          int otherNodeId = 1;
          CandidateState state = newCandidateState(
              voterSetWithLocal(IntStream.of(otherNodeId), withDirectoryId)
          );
          assertTrue(state.recordGrantedVote(otherNodeId));
          assertThrows(IllegalArgumentException.class, () -> state.recordRejectedVote(otherNodeId));
          assertTrue(state.epochElection().isVoteGranted());
      }
  
      @ParameterizedTest
      @ValueSource(booleans = { true, false })
      public void testCannotChangeVoteRejectedToGranted(boolean withDirectoryId) {
          int otherNodeId = 1;
          CandidateState state = newCandidateState(
              voterSetWithLocal(IntStream.of(otherNodeId), withDirectoryId)
          );
          assertTrue(state.recordRejectedVote(otherNodeId));
          assertThrows(IllegalArgumentException.class, () -> state.recordGrantedVote(otherNodeId));
          assertTrue(state.epochElection().isVoteRejected());
      }
  
      @ParameterizedTest
      @ValueSource(booleans = { true, false })
      public void testCannotGrantOrRejectNonVoters(boolean withDirectoryId) {
          int nonVoterId = 1;
          CandidateState state = newCandidateState(voterSetWithLocal(IntStream.empty(), withDirectoryId));
          assertThrows(IllegalArgumentException.class, () -> state.recordGrantedVote(nonVoterId));
          assertThrows(IllegalArgumentException.class, () -> state.recordRejectedVote(nonVoterId));
      }
  
      @ParameterizedTest
      @ValueSource(booleans = { true, false })
      public void testIdempotentGrant(boolean withDirectoryId) {
          int otherNodeId = 1;
          CandidateState state = newCandidateState(
              voterSetWithLocal(IntStream.of(otherNodeId), withDirectoryId)
          );
          assertTrue(state.recordGrantedVote(otherNodeId));
          assertFalse(state.recordGrantedVote(otherNodeId));
      }
  
      @ParameterizedTest
      @ValueSource(booleans = {true, false})
      public void testIdempotentReject(boolean withDirectoryId) {
          int otherNodeId = 1;
          CandidateState state = newCandidateState(
              voterSetWithLocal(IntStream.of(otherNodeId), withDirectoryId)
          );
          assertTrue(state.recordRejectedVote(otherNodeId));
          assertFalse(state.recordRejectedVote(otherNodeId));
      }
  
      @ParameterizedTest
      @CsvSource({ "true,true", "true,false", "false,true", "false,false" })
      public void testGrantVote(boolean isLogUpToDate, boolean withDirectoryId) {
          ReplicaKey node0 = replicaKey(0, withDirectoryId);
          ReplicaKey node1 = replicaKey(1, withDirectoryId);
          ReplicaKey node2 = replicaKey(2, withDirectoryId);
          ReplicaKey node3 = replicaKey(3, withDirectoryId);
  
          CandidateState state = newCandidateState(
              voterSetWithLocal(Stream.of(node1, node2, node3), withDirectoryId)
          );
  
          assertEquals(isLogUpToDate, state.canGrantVote(node0, isLogUpToDate, true));
          assertEquals(isLogUpToDate, state.canGrantVote(node1, isLogUpToDate, true));
          assertEquals(isLogUpToDate, state.canGrantVote(node2, isLogUpToDate, true));
          assertEquals(isLogUpToDate, state.canGrantVote(node3, isLogUpToDate, true));
  
          assertFalse(state.canGrantVote(node0, isLogUpToDate, false));
          assertFalse(state.canGrantVote(node1, isLogUpToDate, false));
          assertFalse(state.canGrantVote(node2, isLogUpToDate, false));
          assertFalse(state.canGrantVote(node3, isLogUpToDate, false));
      }
  
      @ParameterizedTest
      @ValueSource(booleans = {true, false})
      public void testElectionState(boolean withDirectoryId) {
          VoterSet voters = voterSetWithLocal(IntStream.of(1, 2, 3), withDirectoryId);
          CandidateState state = newCandidateState(voters);
          assertEquals(
              ElectionState.withVotedCandidate(
                  epoch,
                  localReplicaKey,
                  voters.voterIds()
              ),
              state.election()
          );
      }
  
      @ParameterizedTest
      @ValueSource(booleans = {true, false})
      public void testInvalidVoterSet(boolean withDirectoryId) {
          assertThrows(
              IllegalArgumentException.class,
              () -> newCandidateState(
                  VoterSetTest.voterSet(VoterSetTest.voterMap(IntStream.of(1, 2, 3), withDirectoryId))
              )
          );
      }
  
      @Test
      void testLeaderEndpoints() {
          CandidateState state = newCandidateState(
              voterSetWithLocal(IntStream.of(1, 2, 3), true)
          );
  
          assertEquals(Endpoints.empty(), state.leaderEndpoints());
      }
  
      private ReplicaKey replicaKey(int id, boolean withDirectoryId) {
          Uuid directoryId = withDirectoryId ? Uuid.randomUuid() : ReplicaKey.NO_DIRECTORY_ID;
          return ReplicaKey.of(id, directoryId);
      }
  
      private VoterSet voterSetWithLocal(IntStream remoteVoterIds, boolean withDirectoryId) {
          Stream<ReplicaKey> remoteVoterKeys = remoteVoterIds
              .boxed()
              .map(id -> replicaKey(id, withDirectoryId));
  
          return voterSetWithLocal(remoteVoterKeys, withDirectoryId);
      }
  
      private VoterSet voterSetWithLocal(Stream<ReplicaKey> remoteVoterKeys, boolean withDirectoryId) {
          ReplicaKey actualLocalVoter = withDirectoryId ?
              localReplicaKey :
              ReplicaKey.of(localReplicaKey.id(), ReplicaKey.NO_DIRECTORY_ID);
  
          return VoterSetTest.voterSet(
              Stream.concat(Stream.of(actualLocalVoter), remoteVoterKeys)
          );
      }
  }
  