/*
 * Copyright ConsenSys AG.
 *
 * 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
 *
 * 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.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
package org.hyperledger.besu.ethereum.p2p.discovery;

import static java.util.Collections.emptyList;
import static org.assertj.core.api.Assertions.assertThat;

import org.hyperledger.besu.ethereum.p2p.discovery.internal.MockPeerDiscoveryAgent;
import org.hyperledger.besu.ethereum.p2p.discovery.internal.MockPeerDiscoveryAgent.IncomingPacket;
import org.hyperledger.besu.ethereum.p2p.discovery.internal.PacketType;
import org.hyperledger.besu.ethereum.p2p.discovery.internal.packet.DaggerPacketPackage;
import org.hyperledger.besu.ethereum.p2p.discovery.internal.packet.Packet;
import org.hyperledger.besu.ethereum.p2p.discovery.internal.packet.PacketPackage;
import org.hyperledger.besu.ethereum.p2p.discovery.internal.packet.findneighbors.FindNeighborsPacketData;
import org.hyperledger.besu.ethereum.p2p.discovery.internal.packet.pong.PongPacketData;

import java.util.Collections;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

public class PeerDiscoveryBondingTest {
  private final PeerDiscoveryTestHelper helper = new PeerDiscoveryTestHelper();
  private PacketPackage packetPackage;

  @BeforeEach
  public void beforeTest() {
    packetPackage = DaggerPacketPackage.create();
  }

  @Test
  public void pongSentUponPing() {
    // Start an agent with no bootstrap peers.
    final MockPeerDiscoveryAgent agent = helper.startDiscoveryAgent(Collections.emptyList());

    // Start a test peer and send a PING packet to the agent under test.
    final MockPeerDiscoveryAgent otherAgent = helper.startDiscoveryAgent();
    assertThat(agent.getAdvertisedPeer().isPresent()).isTrue();
    otherAgent.bond(agent.getAdvertisedPeer().get());

    final List<IncomingPacket> otherAgentIncomingPongs =
        otherAgent.getIncomingPackets().stream()
            .filter(p -> p.packet.getType().equals(PacketType.PONG))
            .toList();
    assertThat(otherAgentIncomingPongs.size()).isEqualTo(1);

    assertThat(
            otherAgentIncomingPongs
                .getFirst()
                .packet
                .getPacketData(PongPacketData.class)
                .isPresent())
        .isTrue();
    final PongPacketData pong =
        otherAgentIncomingPongs.get(0).packet.getPacketData(PongPacketData.class).get();
    assertThat(otherAgent.getAdvertisedPeer().isPresent()).isTrue();
    assertThat(pong.getTo()).isEqualTo(otherAgent.getAdvertisedPeer().get().getEndpoint());

    // The agent considers the test peer BONDED.
    assertThat(agent.streamDiscoveredPeers()).hasSize(1);
    assertThat(agent.streamDiscoveredPeers())
        .allMatch(p -> p.getStatus() == PeerDiscoveryStatus.BONDED);
  }

  @Test
  public void neighborsPacketNotSentUnlessBonded() {
    // Start an agent.
    final MockPeerDiscoveryAgent agent = helper.startDiscoveryAgent(emptyList());

    // Start a test peer that will send a FIND_NEIGHBORS to the agent under test. It should be
    // ignored because
    // we haven't bonded.
    final MockPeerDiscoveryAgent otherNode = helper.startDiscoveryAgent();
    final FindNeighborsPacketData data =
        packetPackage.findNeighborsPacketDataFactory().create(otherNode.getId());
    final Packet packet =
        packetPackage
            .packetFactory()
            .create(PacketType.FIND_NEIGHBORS, data, otherNode.getNodeKey());
    helper.sendMessageBetweenAgents(otherNode, agent, packet);

    // No responses received
    final List<IncomingPacket> incoming = otherNode.getIncomingPackets();
    assertThat(incoming.size()).isEqualTo(0);

    assertThat(agent.getAdvertisedPeer().isPresent()).isTrue();
    otherNode.bond(agent.getAdvertisedPeer().get());

    // Now we received a PONG.
    final List<IncomingPacket> incomingPongs =
        otherNode.getIncomingPackets().stream()
            .filter(p -> p.packet.getType().equals(PacketType.PONG))
            .collect(Collectors.toList());
    assertThat(incomingPongs.size()).isEqualTo(1);
    final Optional<PongPacketData> maybePongData =
        incomingPongs.get(0).packet.getPacketData(PongPacketData.class);
    assertThat(maybePongData).isPresent();
    assertThat(otherNode.getAdvertisedPeer().isPresent()).isTrue();
    assertThat(maybePongData.get().getTo())
        .isEqualTo(otherNode.getAdvertisedPeer().get().getEndpoint());

    // No more packets.
    assertThat(otherNode.getIncomingPackets()).hasSize(0);
  }
}
