#include "domain/active_register_repository.h"
#include "domain/project_storage.h"
#include "infrastructure/plc_register_repository.h"
#include "services/offline_simulation_service.h"
#include "services/plc_communication_gateway.h"
#include "services/project_service.h"
#include "services/runtime_mode_service.h"

#include <functional>
#include <iostream>
#include <stdexcept>
#include <utility>

namespace {

class TestProjectStorage final : public ProjectStorage
{
public:
    ProjectSaveResult save(const Project &, const std::string &) override
    {
        return {true, ProjectStorageError::None, {}};
    }

    ProjectLoadResult load(const std::string &) override
    {
        return {false, {}, ProjectStorageError::FileReadFailed, {}};
    }
};

class FakePlcGateway final : public PlcCommunicationGateway
{
public:
    PlcCommunicationResult connectDevice(
        const PlcSerialConfiguration &configuration) override
    {
        last_configuration = configuration;
        connection_state = PlcConnectionState::Connected;
        if (state_changed)
        {
            state_changed();
        }
        return {true, {}};
    }

    void disconnectDevice() override
    {
        connection_state = PlcConnectionState::Disconnected;
        initial_read = false;
        if (initial_read_changed)
        {
            initial_read_changed(false);
        }
        if (state_changed)
        {
            state_changed();
        }
    }

    void setPollAddresses(const std::vector<RegisterAddress> &addresses) override
    {
        poll_addresses = addresses;
    }

    PlcConnectionState state() const override { return connection_state; }
    bool initialReadCompleted() const override { return initial_read; }
    const std::string &lastError() const override { return last_error; }

    void setCallbacks(
        std::function<void()> state_callback,
        std::function<void(bool)> initial_callback,
        std::function<void()> cache_callback,
        std::function<void(const std::string &)> error_callback) override
    {
        state_changed = std::move(state_callback);
        initial_read_changed = std::move(initial_callback);
        cache_updated = std::move(cache_callback);
        error_reported = std::move(error_callback);
    }

    void completeInitialRead()
    {
        initial_read = true;
        if (initial_read_changed)
        {
            initial_read_changed(true);
        }
    }

    PlcConnectionState connection_state = PlcConnectionState::Disconnected;
    bool initial_read = false;
    std::string last_error;
    PlcSerialConfiguration last_configuration;
    std::vector<RegisterAddress> poll_addresses;
    std::function<void()> state_changed;
    std::function<void(bool)> initial_read_changed;
    std::function<void()> cache_updated;
    std::function<void(const std::string &)> error_reported;
};

void require(bool condition, const std::string &message)
{
    if (!condition)
    {
        throw std::runtime_error(message);
    }
}

void testPlcCacheAndWriteForwarding()
{
    PlcRegisterRepository repository;
    const RegisterAddress m0{RegisterArea::M, 0};
    const RegisterAddress d0{RegisterArea::D, 0};
    require(repository.readBit(m0).error == RegisterError::Unavailable,
            "uninitialized PLC bit cache must be unavailable");
    require(repository.readWord(d0).error == RegisterError::Unavailable,
            "uninitialized PLC word cache must be unavailable");

    repository.updateBit(0, true);
    repository.updateWord(0, -123);
    require(repository.readBit(m0).succeeded && repository.readBit(m0).value,
            "valid PLC bit cache must be readable");
    require(repository.readWord(d0).succeeded
                && repository.readWord(d0).value == -123,
            "valid PLC word cache must preserve signed values");

    RegisterAddress written_address{RegisterArea::M, 1};
    bool written_bit = false;
    std::int16_t written_word = 0;
    repository.setWriteHandlers(
        [&](const RegisterAddress &address, bool value)
        {
            written_address = address;
            written_bit = value;
            return RegisterWriteResult{true, RegisterError::None};
        },
        [&](const RegisterAddress &address, std::int16_t value)
        {
            written_address = address;
            written_word = value;
            return RegisterWriteResult{true, RegisterError::None};
        });
    require(repository.writeBit(m0, false).succeeded
                && written_address == m0 && !written_bit,
            "PLC bit writes must be forwarded without changing the cache");
    require(repository.writeWord(d0, 456).succeeded
                && written_address == d0 && written_word == 456,
            "PLC word writes must be forwarded without changing the cache");
    repository.invalidate();
    require(!repository.hasAnyValidValue(),
            "disconnecting must invalidate all PLC cache validity flags");
}

void testRuntimeRepositorySwitchingAndDisconnect()
{
    TestProjectStorage storage;
    ProjectService project_service(storage);
    HmiPage page;
    page.id = "main-page";
    page.name = "Main";
    HmiControl indicator;
    indicator.id = "run-state";
    indicator.type = HmiControlType::Indicator;
    indicator.bounds = {0, 0, 80, 40};
    indicator.text = "Run";
    indicator.binding = RegisterAddress{RegisterArea::M, 5};
    page.controls.push_back(indicator);
    project_service.editProject().hmiPages.push_back(page);
    VirtualRegisterRepository virtual_repository;
    PlcRegisterRepository plc_repository;
    ActiveRegisterRepository active_repository(virtual_repository);
    OfflineSimulationService simulation_service(virtual_repository);
    FakePlcGateway gateway;
    RuntimeModeService service(project_service, simulation_service);
    service.configurePlc(
        gateway, active_repository, virtual_repository, plc_repository);

    const PlcCommunicationResult connected = service.connectPlc(
        {"COM9", 2, 19200, 8, 2, 1, 1000, 2, 200});
    require(connected.succeeded && gateway.poll_addresses.size() == 1U,
            "PLC connection must receive the project address poll set");
    require(service.enterOnlineRunning().error
                == ModeTransitionError::InitialPlcReadRequired,
            "online mode must wait for the first valid PLC read");

    plc_repository.updateBit(5, true);
    gateway.completeInitialRead();
    require(service.enterOnlineRunning().succeeded,
            "online mode must start after the first valid PLC read");
    require(active_repository.readBit({RegisterArea::M, 5}).succeeded
                && active_repository.readBit({RegisterArea::M, 5}).value,
            "online mode must expose the PLC cache through the active repository");

    gateway.disconnectDevice();
    require(service.mode() == ApplicationMode::Editing,
            "an online disconnect must return the application to editing mode");
    require(!service.initialPlcReadCompleted(),
            "an online disconnect must clear the initial read flag");
    require(active_repository.readBit({RegisterArea::M, 5}).succeeded
                && !active_repository.readBit({RegisterArea::M, 5}).value,
            "editing after disconnect must switch back to the virtual repository");
}

} // namespace

int main()
{
    try
    {
        testPlcCacheAndWriteForwarding();
        testRuntimeRepositorySwitchingAndDisconnect();
    }
    catch (const std::exception &error)
    {
        std::cerr << "PLC runtime tests failed: " << error.what() << '\n';
        return 1;
    }
    std::cout << "PLC runtime tests passed\n";
    return 0;
}