//------------------------------------------------------------------------------
/*
    This file is part of clio: https://github.com/XRPLF/clio
    Copyright (c) 2022, the clio developers.

    Permission to use, copy, modify, and distribute this software for any
    purpose with or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================

#pragma once

#include "data/BackendInterface.hpp"
#include "util/MockBackend.hpp"
#include "util/MockCounters.hpp"
#include "util/MockETLService.hpp"
#include "util/MockLoadBalancer.hpp"
#include "util/MockPrometheus.hpp"
#include "util/MockSubscriptionManager.hpp"
#include "util/log/Logger.hpp"

#include <boost/asio/executor_work_guard.hpp>
#include <boost/asio/io_context.hpp>
#include <boost/asio/io_service.hpp>
#include <boost/asio/spawn.hpp>
#include <boost/log/core/core.hpp>
#include <boost/log/expressions/predicates/channel_severity_filter.hpp>
#include <boost/log/keywords/format.hpp>
#include <boost/log/utility/setup/common_attributes.hpp>
#include <boost/log/utility/setup/console.hpp>
#include <boost/log/utility/setup/formatter_parser.hpp>
#include <gmock/gmock.h>
#include <gtest/gtest.h>

#include <memory>
#include <mutex>
#include <optional>
#include <ostream>
#include <sstream>
#include <string>
#include <thread>

/**
 * @brief Fixture with util::Logger support.
 */
class LoggerFixture : virtual public ::testing::Test {
    /**
     * @brief A simple string buffer that can be used to mock std::cout for
     * console logging.
     */
    class FakeBuffer final : public std::stringbuf {
    public:
        std::string
        getStrAndReset()
        {
            auto value = str();
            str("");
            return value;
        }
    };

    FakeBuffer buffer_;
    std::ostream stream_ = std::ostream{&buffer_};

public:
    // Simulates the `util::Logger::init(config)` call
    LoggerFixture()
    {
        static std::once_flag once_;
        std::call_once(once_, [] {
            boost::log::add_common_attributes();
            boost::log::register_simple_formatter_factory<util::Severity, char>("Severity");
        });

        namespace keywords = boost::log::keywords;
        namespace expr = boost::log::expressions;
        auto core = boost::log::core::get();

        core->remove_all_sinks();
        boost::log::add_console_log(stream_, keywords::format = "%Channel%:%Severity% %Message%");
        auto min_severity = expr::channel_severity_filter(util::log_channel, util::log_severity);
        min_severity["General"] = util::Severity::DBG;
        min_severity["Trace"] = util::Severity::TRC;
        core->set_filter(min_severity);
        core->set_logging_enabled(true);
    }

protected:
    void
    checkEqual(std::string expected)
    {
        auto value = buffer_.getStrAndReset();
        ASSERT_EQ(value, expected + '\n');
    }

    void
    checkEmpty()
    {
        ASSERT_TRUE(buffer_.getStrAndReset().empty());
    }
};

/**
 * @brief Fixture with util::Logger support but completely disabled logging.
 *
 * This is meant to be used as a base for other fixtures.
 */
struct NoLoggerFixture : virtual LoggerFixture {
    NoLoggerFixture()
    {
        boost::log::core::get()->set_logging_enabled(false);
    }
};

/**
 * @brief Fixture with an embedded boost::asio context running on a thread
 *
 * This is meant to be used as a base for other fixtures.
 */
struct AsyncAsioContextTest : virtual public NoLoggerFixture {
    AsyncAsioContextTest()
    {
        work.emplace(ctx);  // make sure ctx does not stop on its own
        runner.emplace([&] { ctx.run(); });
    }

    ~AsyncAsioContextTest() override
    {
        work.reset();
        if (runner->joinable())
            runner->join();
        ctx.stop();
    }

    void
    stop()
    {
        work.reset();
        if (runner->joinable())
            runner->join();
        ctx.stop();
    }

protected:
    boost::asio::io_context ctx;

private:
    std::optional<boost::asio::io_service::work> work;
    std::optional<std::thread> runner;
};

/**
 * @brief Fixture with an embedded boost::asio context that is not running by
 * default but can be progressed on the calling thread
 *
 * Use `run_for(duration)` etc. directly on `ctx`.
 * This is meant to be used as a base for other fixtures.
 */
struct SyncAsioContextTest : virtual public NoLoggerFixture {
    template <typename F>
    void
    runSpawn(F&& f)
    {
        using namespace boost::asio;

        testing::MockFunction<void()> call;
        spawn(ctx, [&, _ = make_work_guard(ctx)](yield_context yield) {
            f(yield);
            call.Call();
        });

        EXPECT_CALL(call, Call());
        runContext();
    }

    void
    runContext()
    {
        ctx.run();
        ctx.reset();
    }

protected:
    boost::asio::io_context ctx;
};

template <template <typename> typename MockType = ::testing::NiceMock>
struct MockBackendTestBase : virtual public NoLoggerFixture {
    void
    SetUp() override
    {
        backend.reset();
    }

    class BackendProxy {
        std::shared_ptr<BackendInterface> backend;

    private:
        void
        reset()
        {
            backend = std::make_shared<MockType<MockBackend>>(util::Config{});
        }

        friend MockBackendTestBase;

    public:
        auto
        operator->()
        {
            return backend.get();
        }

        operator std::shared_ptr<BackendInterface>()
        {
            return backend;
        }

        operator std::shared_ptr<BackendInterface const>() const
        {
            return backend;
        }

        operator MockBackend*()
        {
            MockBackend* ret = dynamic_cast<MockBackend*>(backend.get());
            [&] { ASSERT_NE(ret, nullptr); }();
            return ret;
        }
    };

protected:
    BackendProxy backend;
};

/**
 * @brief Fixture with a "nice" mock backend.
 *
 * Use @see MockBackendTestNaggy during development to get unset call expectation warnings.
 * Once the test is ready and you are happy you can switch to this fixture to mute the warnings.
 *
 * A fixture that is based off of this MockBackendTest or MockBackendTestNaggy get a `backend` member
 * that is a `BackendProxy` that can be used to access the mock backend. It can be used wherever a
 * `std::shared_ptr<BackendInterface>` is expected as well as `*backend` can be used with EXPECT_CALL and ON_CALL.
 */
using MockBackendTest = MockBackendTestBase<::testing::NiceMock>;

/**
 * @brief Fixture with a "naggy" mock backend.
 *
 * Use this during development to get unset call expectation warnings.
 */
using MockBackendTestNaggy = MockBackendTestBase<::testing::NaggyMock>;

/**
 * @brief Fixture with a "strict" mock backend.
 */
using MockBackendTestStrict = MockBackendTestBase<::testing::StrictMock>;

/**
 * @brief Fixture with a mock subscription manager
 */
struct MockSubscriptionManagerTest : virtual public NoLoggerFixture {
    void
    SetUp() override
    {
        mockSubscriptionManagerPtr = std::make_shared<MockSubscriptionManager>();
    }
    void
    TearDown() override
    {
        mockSubscriptionManagerPtr.reset();
    }

protected:
    std::shared_ptr<MockSubscriptionManager> mockSubscriptionManagerPtr;
};

/**
 * @brief Fixture with a mock etl balancer
 */
struct MockLoadBalancerTest : virtual public NoLoggerFixture {
    void
    SetUp() override
    {
        mockLoadBalancerPtr = std::make_shared<MockLoadBalancer>();
    }
    void
    TearDown() override
    {
        mockLoadBalancerPtr.reset();
    }

protected:
    std::shared_ptr<MockLoadBalancer> mockLoadBalancerPtr;
};

/**
 * @brief Fixture with a mock subscription manager
 */
struct MockETLServiceTest : virtual public NoLoggerFixture {
    void
    SetUp() override
    {
        mockETLServicePtr = std::make_shared<MockETLService>();
    }
    void
    TearDown() override
    {
        mockETLServicePtr.reset();
    }

protected:
    std::shared_ptr<MockETLService> mockETLServicePtr;
};

/**
 * @brief Fixture with mock counters
 */
struct MockCountersTest : virtual public NoLoggerFixture {
    void
    SetUp() override
    {
        mockCountersPtr = std::make_shared<MockCounters>();
    }
    void
    TearDown() override
    {
        mockCountersPtr.reset();
    }

protected:
    std::shared_ptr<MockCounters> mockCountersPtr;
};

/**
 * @brief Fixture with an mock backend and an embedded boost::asio context.
 *
 * Use as a handler unittest base fixture thru either @see HandlerBaseTest, @see HandlerBaseTestNaggy or @see
 * HandlerBaseTestStrict.
 */
template <template <typename> typename MockType = ::testing::NiceMock>
struct HandlerBaseTestBase : public MockBackendTestBase<MockType>,
                             public util::prometheus::WithPrometheus,
                             public SyncAsioContextTest,
                             public MockETLServiceTest {
protected:
    void
    SetUp() override
    {
        MockBackendTestBase<MockType>::SetUp();
        SyncAsioContextTest::SetUp();
        MockETLServiceTest::SetUp();
    }

    void
    TearDown() override
    {
        MockETLServiceTest::TearDown();
        SyncAsioContextTest::TearDown();
        MockBackendTestBase<MockType>::TearDown();
    }
};

/**
 * @brief Fixture with a "nice" backend mock and an embedded boost::asio context.
 *
 * Use @see HandlerBaseTest during development to get unset call expectation warnings from the backend mock.
 * Once the test is ready and you are happy you can switch to this fixture to mute the warnings.
 *
 * @see BackendBaseTest for more details on the injected backend mock.
 */
using HandlerBaseTest = HandlerBaseTestBase<::testing::NiceMock>;

/**
 * @brief Fixture with a "naggy" backend mock and an embedded boost::asio context.
 *
 * Use this during development to get unset call expectation warnings from the backend mock.
 */
using HandlerBaseTestNaggy = HandlerBaseTestBase<::testing::NaggyMock>;

/**
 * @brief Fixture with a "strict" backend mock and an embedded boost::asio context.
 */
using HandlerBaseTestStrict = HandlerBaseTestBase<::testing::StrictMock>;