#include "cluster/ClioNode.hpp"
#include "cluster/ClusterCommunicationService.hpp"
#include "data/BackendInterface.hpp"
#include "etl/SystemState.hpp"
#include "util/MockBackendTestFixture.hpp"
#include "util/MockLedgerCacheLoadingState.hpp"
#include "util/MockPrometheus.hpp"
#include "util/MockWriterState.hpp"
#include "util/NameGenerator.hpp"
#include "util/config/ConfigDefinition.hpp"
#include "util/config/ConfigValue.hpp"
#include "util/config/Types.hpp"
#include "util/prometheus/Prometheus.hpp"

#include <boost/json/object.hpp>
#include <boost/json/serialize.hpp>
#include <boost/json/value_from.hpp>
#include <boost/uuid/uuid.hpp>
#include <gmock/gmock.h>
#include <gtest/gtest.h>

#include <algorithm>
#include <atomic>
#include <chrono>
#include <cstdint>
#include <memory>
#include <semaphore>
#include <string>
#include <thread>
#include <utility>
#include <vector>

using namespace cluster;

struct ClusterCommunicationServiceTest : util::prometheus::WithPrometheus, MockBackendTest {
    std::unique_ptr<NiceMockWriterState> writerState = std::make_unique<NiceMockWriterState>();
    NiceMockWriterState& writerStateRef = *writerState;
    std::unique_ptr<NiceMockLedgerCacheLoadingState> cacheLoadingState =
        std::make_unique<NiceMockLedgerCacheLoadingState>();

    static constexpr std::chrono::milliseconds kSHORT_INTERVAL{1};

    static boost::uuids::uuid
    makeUuid(uint8_t value)
    {
        boost::uuids::uuid uuid{};
        std::ranges::fill(uuid, value);
        return uuid;
    }

    static ClioNode
    makeNode(boost::uuids::uuid const& uuid, ClioNode::DbRole role)
    {
        return ClioNode{
            .uuid = std::make_shared<boost::uuids::uuid>(uuid),
            .updateTime = std::chrono::system_clock::now(),
            .dbRole = role,
            .etlStarted = true,
            .cacheIsFull = true,
            .cacheIsCurrentlyLoading = false,
        };
    }

    static std::string
    nodeToJson(ClioNode const& node)
    {
        boost::json::value const v = boost::json::value_from(node);
        return boost::json::serialize(v);
    }

    ClusterCommunicationServiceTest()
    {
        ON_CALL(writerStateRef, clone()).WillByDefault(testing::Invoke([]() {
            auto state = std::make_unique<NiceMockWriterState>();
            ON_CALL(*state, isReadOnly()).WillByDefault(testing::Return(false));
            ON_CALL(*state, isWriting()).WillByDefault(testing::Return(true));
            return state;
        }));
        ON_CALL(writerStateRef, isReadOnly()).WillByDefault(testing::Return(false));
        ON_CALL(writerStateRef, isWriting()).WillByDefault(testing::Return(true));
        ON_CALL(*cacheLoadingState, clone()).WillByDefault(testing::Invoke([]() {
            return std::make_unique<NiceMockLedgerCacheLoadingState>();
        }));
    }

    static bool
    waitForSignal(
        std::binary_semaphore& sem,
        std::chrono::milliseconds timeout = std::chrono::milliseconds{1000}
    )
    {
        return sem.try_acquire_for(timeout);
    }
};

TEST_F(ClusterCommunicationServiceTest, BackendReadsAndWritesData)
{
    auto const otherUuid = makeUuid(0x02);
    std::binary_semaphore fetchSemaphore{0};
    std::binary_semaphore writeSemaphore{0};

    BackendInterface::ClioNodesDataFetchResult fetchResult{
        std::vector<std::pair<boost::uuids::uuid, std::string>>{
            {otherUuid, nodeToJson(makeNode(otherUuid, ClioNode::DbRole::Writer))}
        }
    };

    ON_CALL(*backend_, fetchClioNodesData).WillByDefault(testing::Invoke([&](auto) {
        fetchSemaphore.release();
        return fetchResult;
    }));

    ON_CALL(*backend_, writeNodeMessage).WillByDefault(testing::Invoke([&](auto, auto) {
        writeSemaphore.release();
    }));

    ClusterCommunicationService service{
        backend_,
        std::move(writerState),
        std::move(cacheLoadingState),
        kSHORT_INTERVAL,
        kSHORT_INTERVAL
    };

    service.run();

    EXPECT_TRUE(waitForSignal(fetchSemaphore));
    EXPECT_TRUE(waitForSignal(writeSemaphore));

    service.stop();
}

TEST_F(ClusterCommunicationServiceTest, MetricsGetsNewStateFromBackend)
{
    auto const otherUuid = makeUuid(0x02);
    std::binary_semaphore writerActionSemaphore{0};

    BackendInterface::ClioNodesDataFetchResult fetchResult{
        std::vector<std::pair<boost::uuids::uuid, std::string>>{
            {otherUuid, nodeToJson(makeNode(otherUuid, ClioNode::DbRole::Writer))}
        }
    };

    ON_CALL(*backend_, fetchClioNodesData).WillByDefault(testing::Invoke([&](auto) {
        return fetchResult;
    }));

    ON_CALL(writerStateRef, clone()).WillByDefault(testing::Invoke([&]() mutable {
        auto state = std::make_unique<NiceMockWriterState>();
        ON_CALL(*state, startWriting()).WillByDefault(testing::Invoke([&]() {
            writerActionSemaphore.release();
        }));
        ON_CALL(*state, giveUpWriting()).WillByDefault(testing::Invoke([&]() {
            writerActionSemaphore.release();
        }));
        return state;
    }));

    auto& nodesInClusterMetric = PrometheusService::gaugeInt("cluster_nodes_total_number", {});
    auto isHealthyMetric = PrometheusService::boolMetric("cluster_communication_is_healthy", {});

    ClusterCommunicationService service{
        backend_,
        std::move(writerState),
        std::move(cacheLoadingState),
        kSHORT_INTERVAL,
        kSHORT_INTERVAL
    };

    service.run();

    // WriterDecider is called after metrics are updated so we could use it as a signal to stop
    EXPECT_TRUE(waitForSignal(writerActionSemaphore));

    service.stop();

    EXPECT_EQ(nodesInClusterMetric.value(), 2);
    EXPECT_TRUE(static_cast<bool>(isHealthyMetric));
}

TEST_F(ClusterCommunicationServiceTest, WriterDeciderCallsWriterStateMethodsAccordingly)
{
    auto const smallerUuid = makeUuid(0x00);
    std::binary_semaphore fetchSemaphore{0};
    std::binary_semaphore writerActionSemaphore{0};

    BackendInterface::ClioNodesDataFetchResult fetchResult{
        std::vector<std::pair<boost::uuids::uuid, std::string>>{
            {smallerUuid, nodeToJson(makeNode(smallerUuid, ClioNode::DbRole::Writer))}
        }
    };

    ON_CALL(*backend_, fetchClioNodesData).WillByDefault(testing::Invoke([&](auto) {
        fetchSemaphore.release();
        return fetchResult;
    }));

    ON_CALL(*backend_, writeNodeMessage).WillByDefault(testing::Return());

    ON_CALL(writerStateRef, clone()).WillByDefault(testing::Invoke([&]() mutable {
        auto state = std::make_unique<NiceMockWriterState>();
        ON_CALL(*state, startWriting()).WillByDefault(testing::Invoke([&]() {
            writerActionSemaphore.release();
        }));
        ON_CALL(*state, giveUpWriting()).WillByDefault(testing::Invoke([&]() {
            writerActionSemaphore.release();
        }));
        return state;
    }));

    ClusterCommunicationService service{
        backend_,
        std::move(writerState),
        std::move(cacheLoadingState),
        kSHORT_INTERVAL,
        kSHORT_INTERVAL
    };

    service.run();

    EXPECT_TRUE(waitForSignal(fetchSemaphore));
    EXPECT_TRUE(waitForSignal(writerActionSemaphore));

    service.stop();
}

TEST_F(ClusterCommunicationServiceTest, StopHaltsBackendOperations)
{
    std::atomic<int> backendOperationsCount{0};
    std::binary_semaphore fetchSemaphore{0};

    BackendInterface::ClioNodesDataFetchResult fetchResult{
        std::vector<std::pair<boost::uuids::uuid, std::string>>{}
    };

    ON_CALL(*backend_, fetchClioNodesData).WillByDefault(testing::Invoke([&](auto) {
        backendOperationsCount++;
        fetchSemaphore.release();
        return fetchResult;
    }));
    ON_CALL(*backend_, writeNodeMessage).WillByDefault(testing::Invoke([&](auto&&, auto&&) {
        backendOperationsCount++;
    }));

    ClusterCommunicationService service{
        backend_,
        std::move(writerState),
        std::move(cacheLoadingState),
        kSHORT_INTERVAL,
        kSHORT_INTERVAL
    };

    service.run();
    EXPECT_TRUE(waitForSignal(fetchSemaphore));
    service.stop();

    auto const countAfterStop = backendOperationsCount.load();
    std::this_thread::sleep_for(std::chrono::milliseconds{50});
    EXPECT_EQ(backendOperationsCount.load(), countAfterStop);
}

struct ClusterCommunicationServiceMakeTestBundle {
    std::string testName;
    bool limitLoadInCluster;
};

struct ClusterCommunicationServiceMakeTest
    : util::prometheus::WithPrometheus,
      MockBackendTest,
      testing::WithParamInterface<ClusterCommunicationServiceMakeTestBundle> {
    std::shared_ptr<etl::SystemState> systemState = std::make_shared<etl::SystemState>();
};

INSTANTIATE_TEST_SUITE_P(
    LimitLoadInCluster,
    ClusterCommunicationServiceMakeTest,
    testing::Values(
        ClusterCommunicationServiceMakeTestBundle{
            .testName = "AllowsLoadingWhenTrue",
            .limitLoadInCluster = true
        },
        ClusterCommunicationServiceMakeTestBundle{
            .testName = "DoesNotAllowLoadingWhenFalse",
            .limitLoadInCluster = false
        }
    ),
    tests::util::kNAME_GENERATOR
);

TEST_P(ClusterCommunicationServiceMakeTest, LoadingAllowedMatchesConfig)
{
    auto const& param = GetParam();
    util::config::ClioConfigDefinition const config{
        {{"cache.limit_load_in_cluster",
          util::config::ConfigValue{util::config::ConfigType::Boolean}.defaultValue(
              param.limitLoadInCluster
          )}}
    };

    auto result = ClusterCommunicationService::make(config, backend_, systemState);

    ASSERT_NE(result.cacheLoadingState, nullptr);
    EXPECT_EQ(result.cacheLoadingState->isLoadingAllowed(), not param.limitLoadInCluster);
}