// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.clustercontroller.core;

import com.yahoo.vdslib.distribution.ConfiguredNode;
import com.yahoo.vdslib.state.ClusterState;
import com.yahoo.vdslib.state.NodeState;
import com.yahoo.vdslib.state.NodeType;
import com.yahoo.vdslib.state.State;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;

import java.util.ArrayList;
import java.util.List;

import static org.junit.jupiter.api.Assertions.assertEquals;

public class DistributionBitCountTest extends FleetControllerTest {

    DistributionBitCountTest() {
        useRealZooKeeperInTest(false);
    }

    private FleetControllerOptions setUpSystem() throws Exception {
        List<ConfiguredNode> configuredNodes = new ArrayList<>();
        for (int i = 0 ; i < 10; i++) {
            configuredNodes.add(new ConfiguredNode(i, false));
        }
        var builder = defaultOptions(configuredNodes);
        builder.setDistributionBits(17);
        Timer timer = new RealTimer();
        setUpFleetController(timer, builder);
        List<DummyVdsNode> nodes = setUpVdsNodes(timer, true, configuredNodes);
        for (DummyVdsNode node : nodes) {
            node.setNodeState(new NodeState(node.getType(), State.UP).setMinUsedBits(20));
            node.connect();
        }
        waitForState("version:\\d+ bits:17 distributor:10 storage:10");
        return builder.build();
    }

    /**
     * Test that then altering config to increased bit count, that a new system state is sent out if the least split storagenode use more bits.
     * Test that then altering config to increased bit count, that a new system state is not sent out (and not altered) if a storagenode needs it to be no further split.
     */
    @Test
    void testDistributionBitCountConfigIncrease() throws Exception {
        var options = setUpSystem();
        var builder = FleetControllerOptions.Builder.copy(options);
        builder.setDistributionBits(20);
        fleetController().updateOptions(builder.build());
        ClusterState currentState = waitForState("version:\\d+ bits:20 distributor:10 storage:10");

        int version = currentState.getVersion();
        builder.setDistributionBits(23);
        fleetController().updateOptions(builder.build());
        assertEquals(version, currentState.getVersion());
    }

    /**
     * Test that then altering config to decrease bit count, that a new system state is sent out with that bit count.
     */
    @Test
    void testDistributionBitCountConfigDecrease() throws Exception {
        FleetControllerOptions options = setUpSystem();
        var builder = FleetControllerOptions.Builder.copy(options);
        builder.setDistributionBits(12);
        fleetController().updateOptions(builder.build());
        waitForState("version:\\d+ bits:12 distributor:10 storage:10");
    }

    /**
     * Test that when storage node reports higher bit count, but another storage
     * node has equally low bitcount, the fleetcontroller does nothing.
     * <p
     * Test that when storage node reports higher bit count, but another storage
     * node now being lowest, the fleetcontroller adjusts to use that bit in system state.
     */
    @Test
    void testStorageNodeReportingHigherBitCount() throws Exception {
        setUpSystem();

        nodes.get(1).setNodeState(new NodeState(NodeType.STORAGE, State.UP).setMinUsedBits(11));
        nodes.get(3).setNodeState(new NodeState(NodeType.STORAGE, State.UP).setMinUsedBits(11));

        ClusterState startState = waitForState("version:\\d+ bits:11 distributor:10 storage:10");

        nodes.get(1).setNodeState(new NodeState(NodeType.STORAGE, State.UP).setMinUsedBits(12));
        assertEquals(startState.getVersion(), fleetController().getSystemState().getVersion(), startState + "->" + fleetController().getSystemState());

        for (int i = 0; i < 10; ++i) {
            // nodes is array of [distr.0, stor.0, distr.1, stor.1, ...] and we just want the storage nodes
            nodes.get(i * 2 + 1).setNodeState(new NodeState(NodeType.STORAGE, State.UP).setMinUsedBits(17));
        }
        assertEquals(startState.getVersion() + 1, waitForState("version:\\d+ bits:17 distributor:10 storage:10").getVersion());
    }

    /**
     * Test that then storage node report lower bit count, but another storage node with equally low bitcount, the fleetcontroller does nothing.
     * Test that then storage node report lower bit count, and then becomes the smallest, the fleetcontroller adjusts to use that bit in system state.
     */
    @Test
    void testStorageNodeReportingLowerBitCount() throws Exception {
        setUpSystem();

        nodes.get(1).setNodeState(new NodeState(NodeType.STORAGE, State.UP).setMinUsedBits(13));
        ClusterState currentState = waitForState("version:\\d+ bits:13 distributor:10 storage:10");
        int version = currentState.getVersion();

        nodes.get(3).setNodeState(new NodeState(NodeType.STORAGE, State.UP).setMinUsedBits(15));
        assertEquals(version, currentState.getVersion());

        nodes.get(3).setNodeState(new NodeState(NodeType.STORAGE, State.UP).setMinUsedBits(13));
        assertEquals(version, currentState.getVersion());

        nodes.get(3).setNodeState(new NodeState(NodeType.STORAGE, State.UP).setMinUsedBits(12));
        waitForState("version:\\d+ bits:12 distributor:10 storage:10");
    }

}