#include <iostream>
#include <csignal>
#include <QtCore>
#include <thread>
#include <QJsonDocument>
#include <QCoreApplication>
#include <unistd.h>
#include <filesystem>

#include "Application.hpp"
#include "src/Logger/Logger.hpp"
#include "SignalHandler/SignalHandler.hpp"
#include "Exceptions/InvalidConfig.hpp"

using namespace Bloom;
using namespace Bloom::Events;
using namespace Bloom::Exceptions;

int Application::run(const std::vector<std::string>& arguments) {
    try {
        this->setName("Bloom");

        if (!arguments.empty()) {
            auto firstArg = arguments.front();
            auto commandsToCallbackMapping = this->getCommandToHandlerMapping();

            if (commandsToCallbackMapping.contains(firstArg)) {
                // User has passed an argument that maps to a command callback - invoke the callback and shutdown
                auto returnValue = commandsToCallbackMapping.at(firstArg)();

                this->shutdown();
                return returnValue;

            } else {
                // If the first argument didn't map to a command, we assume it's an environment name
                this->selectedEnvironmentName = firstArg;
            }
        }

#ifdef BLOOM_DEBUG_BUILD
        Logger::warning("This is a debug build - some functions may not work as expected.");
#endif

        this->startup();

        if (this->insightConfig.insightEnabled) {
            this->insight.setApplicationConfig(this->applicationConfig);
            this->insight.setEnvironmentConfig(this->environmentConfig);
            this->insight.setInsightConfig(this->insightConfig);
            this->insight.run();
            Logger::debug("Insight closed");
            this->shutdown();
            return EXIT_SUCCESS;
        }

        // Main event loop
        while (Thread::getThreadState() == ThreadState::READY) {
            this->applicationEventListener->waitAndDispatch();
        }

    } catch (const InvalidConfig& exception) {
        Logger::error(exception.getMessage());

    } catch (const Exception& exception) {
        Logger::error(exception.getMessage());
    }

    this->shutdown();
    return EXIT_SUCCESS;
}

void Application::startup() {
    auto applicationEventListener = this->applicationEventListener;
    this->eventManager.registerListener(applicationEventListener);
    applicationEventListener->registerCallbackForEventType<Events::ShutdownApplication>(
        std::bind(&Application::onShutdownApplicationRequest, this, std::placeholders::_1)
    );

    this->applicationConfig = this->extractConfig();
    Logger::configure(this->applicationConfig);

    // Start signal handler
    this->blockAllSignalsOnCurrentThread();
    this->signalHandlerThread = std::thread(&SignalHandler::run, std::ref(this->signalHandler));

    Logger::info("Selected environment: " + this->selectedEnvironmentName);
    Logger::debug("Number of environments extracted from config: "
        + std::to_string(this->applicationConfig.environments.size()));

    // Validate the selected environment
    if (!applicationConfig.environments.contains(this->selectedEnvironmentName)) {
        throw InvalidConfig("Environment (\"" + this->selectedEnvironmentName + "\") not found in configuration.");
    }

    this->environmentConfig = applicationConfig.environments.at(this->selectedEnvironmentName);
    this->insightConfig = this->environmentConfig.insightConfig.value_or(this->applicationConfig.insightConfig);

    if (this->environmentConfig.debugServerConfig.has_value()) {
        this->debugServerConfig = this->environmentConfig.debugServerConfig.value();

    } else if (this->applicationConfig.debugServerConfig.has_value()) {
        this->debugServerConfig = this->applicationConfig.debugServerConfig.value();

    } else {
        throw InvalidConfig("Debug server configuration missing.");
    }

    applicationEventListener->registerCallbackForEventType<Events::TargetControllerThreadStateChanged>(
        std::bind(&Application::onTargetControllerThreadStateChanged, this, std::placeholders::_1)
    );

    applicationEventListener->registerCallbackForEventType<Events::DebugServerThreadStateChanged>(
        std::bind(&Application::onDebugServerThreadStateChanged, this, std::placeholders::_1)
    );

    this->startTargetController();
    this->startDebugServer();

    Thread::setThreadState(ThreadState::READY);
}

ApplicationConfig Application::extractConfig() {
    auto appConfig = ApplicationConfig();
    auto currentPath = std::filesystem::current_path().string();
    auto jsonConfigFile = QFile(QString::fromStdString(currentPath + "/bloom.json"));

    if (!jsonConfigFile.exists()) {
        throw InvalidConfig("Bloom configuration file (bloom.json) not found. Working directory: "
            + currentPath);
    }

    if (!jsonConfigFile.open(QIODevice::ReadOnly)) {
        throw InvalidConfig("Failed to load Bloom configuration file (bloom.json) Working directory: "
            + currentPath);
    }

    auto jsonObject = QJsonDocument::fromJson(jsonConfigFile.readAll()).object();
    appConfig.init(jsonObject);

    jsonConfigFile.close();
    return appConfig;
}

int Application::presentHelpText() {
    /*
     * Silence all logging here, as we're just to display the help text and then exit the application. Any
     * further logging will just be noise.
     */
    Logger::silence();

    // The file help.txt is included in the binary image as a resource. See src/resource.qrc
    auto helpFile = QFile(":/compiled/resources/help.txt");

    if (!helpFile.open(QIODevice::ReadOnly)) {
        // This should never happen - if it does, something has gone very wrong
        throw Exception("Failed to open help file - please report this issue at https://bloom.oscillate.io/report-issue");
    }

    std::cout << "Bloom v" << Application::VERSION_STR << "\n";
    std::cout << QTextStream(&helpFile).readAll().toUtf8().constData() << "\n";
    return EXIT_SUCCESS;
}

int Application::presentVersionText() {
    Logger::silence();

    std::cout << "Bloom v" << Application::VERSION_STR << "\n";

#ifdef BLOOM_DEBUG_BUILD
    std::cout << "DEBUG BUILD - Compilation timestamp: " << __DATE__ << " " << __TIME__ << "\n";
#endif

    std::cout << "https://bloom.oscillate.io/\n";
    std::cout << "Nav Mohammed\n";
    return EXIT_SUCCESS;
}

int Application::initProject() {
    auto configFile = QFile(QString::fromStdString(std::filesystem::current_path().string() + "/bloom.json"));

    if (configFile.exists()) {
        throw Exception("Bloom configuration file (bloom.json) already exists in working directory.");
    }

    /*
     * The file bloom.template.json is just a template Bloom config file that is included in the binary image as
     * a resource. See src/resource.qrc
     *
     * We simply copy the template file into the user's working directory.
     */
    auto templateConfigFile = QFile(":/compiled/resources/bloom.template.json");

    if (!templateConfigFile.open(QIODevice::ReadOnly)) {
        throw Exception("Failed to open template configuration file - please report this issue at https://bloom.oscillate.io/report-issue");
    }

    if (!configFile.open(QIODevice::ReadWrite)) {
        throw Exception("Failed to create Bloom configuration file (bloom.json)");
    }

    configFile.write(templateConfigFile.readAll());

    configFile.close();
    templateConfigFile.close();

    Logger::info("Bloom configuration file (bloom.json) created in working directory.");
    return EXIT_SUCCESS;
}

void Application::shutdown() {
    auto appState = Thread::getThreadState();
    if (appState == ThreadState::STOPPED || appState == ThreadState::SHUTDOWN_INITIATED) {
        return;
    }

    Thread::setThreadState(ThreadState::SHUTDOWN_INITIATED);
    Logger::info("Shutting down Bloom");

    this->stopDebugServer();
    this->stopTargetController();

    if (this->signalHandler.getThreadState() != ThreadState::STOPPED) {
        // Signal handler is still running
        this->signalHandler.triggerShutdown();

        // Send meaningless signal to the SignalHandler thread to have it shutdown.
        pthread_kill(this->signalHandlerThread.native_handle(), SIGUSR1);
    }

    if (this->signalHandlerThread.joinable()) {
        Logger::debug("Joining SignalHandler thread");
        this->signalHandlerThread.join();
        Logger::debug("SignalHandler thread joined");
    }

    Thread::setThreadState(ThreadState::STOPPED);
}

void Application::startTargetController() {
    this->targetController.setApplicationConfig(this->applicationConfig);
    this->targetController.setEnvironmentConfig(this->environmentConfig);

    this->targetControllerThread = std::thread(
        &TargetController::run,
        std::ref(this->targetController)
    );

    auto tcStateChangeEvent = this->applicationEventListener->waitForEvent<Events::TargetControllerThreadStateChanged>();

    if (!tcStateChangeEvent.has_value() || tcStateChangeEvent->get()->getState() != ThreadState::READY) {
        throw Exception("TargetController failed to startup.");
    }
}

void Application::stopTargetController() {
    auto targetControllerState = this->targetController.getThreadState();
    if (targetControllerState == ThreadState::STARTING || targetControllerState == ThreadState::READY) {
        this->eventManager.triggerEvent(std::make_shared<Events::ShutdownTargetController>());
        this->applicationEventListener->waitForEvent<Events::TargetControllerThreadStateChanged>(
            std::chrono::milliseconds(10000)
        );
    }

    if (this->targetControllerThread.joinable()) {
        Logger::debug("Joining TargetController thread");
        this->targetControllerThread.join();
        Logger::debug("TargetController thread joined");
    }
}

void Application::startDebugServer() {
    auto supportedDebugServers = this->getSupportedDebugServers();
    if (!supportedDebugServers.contains(this->debugServerConfig.name)) {
        throw Exceptions::InvalidConfig("DebugServer \"" + this->debugServerConfig.name + "\" not found.");
    }

    this->debugServer = supportedDebugServers.at(this->debugServerConfig.name)();
    this->debugServer->setApplicationConfig(this->applicationConfig);
    this->debugServer->setEnvironmentConfig(this->environmentConfig);
    this->debugServer->setDebugServerConfig(this->debugServerConfig);

    Logger::info("Selected DebugServer: " + this->debugServer->getName());

    this->debugServerThread = std::thread(
        &DebugServers::DebugServer::run,
        this->debugServer.get()
    );

    auto dsStateChangeEvent = this->applicationEventListener->waitForEvent<Events::DebugServerThreadStateChanged>();

    if (!dsStateChangeEvent.has_value() || dsStateChangeEvent->get()->getState() != ThreadState::READY) {
        throw Exception("DebugServer failed to startup.");
    }
}

void Application::stopDebugServer() {
    if (this->debugServer == nullptr) {
        // DebugServer hasn't been resolved yet.
        return;
    }

    auto debugServerState = this->debugServer->getThreadState();
    if (debugServerState == ThreadState::STARTING || debugServerState == ThreadState::READY) {
        this->eventManager.triggerEvent(std::make_shared<Events::ShutdownDebugServer>());
        this->applicationEventListener->waitForEvent<Events::DebugServerThreadStateChanged>(
            std::chrono::milliseconds(5000)
        );
    }

    if (this->debugServerThread.joinable()) {
        Logger::debug("Joining DebugServer thread");
        this->debugServerThread.join();
        Logger::debug("DebugServer thread joined");
    }
}

void Application::onTargetControllerThreadStateChanged(EventPointer<Events::TargetControllerThreadStateChanged> event) {
    if (event->getState() == ThreadState::STOPPED || event->getState() == ThreadState::SHUTDOWN_INITIATED) {
        // TargetController has unexpectedly shutdown - it must have encountered a fatal error.
        this->shutdown();
    }
}

void Application::onShutdownApplicationRequest(EventPointer<Events::ShutdownApplication>) {
    Logger::debug("ShutdownApplication event received.");
    this->shutdown();
}

void Application::onDebugServerThreadStateChanged(EventPointer<Events::DebugServerThreadStateChanged> event) {
    if (event->getState() == ThreadState::STOPPED || event->getState() == ThreadState::SHUTDOWN_INITIATED) {
        // DebugServer has unexpectedly shutdown - it must have encountered a fatal error.
        this->shutdown();
    }
}

std::string Application::getApplicationDirPath() {
    auto pathCharArray = std::array<char, PATH_MAX>();

    if (readlink("/proc/self/exe", pathCharArray.data(), PATH_MAX) < 0) {
        throw Exception("Failed to obtain application directory path.");
    }

    return std::filesystem::path(std::string(pathCharArray.begin(), pathCharArray.end())).parent_path();
}

std::string Application::getResourcesDirPath() {
    return Application::getApplicationDirPath() + "/../resources/";
}

bool Application::isRunningAsRoot() {
    return geteuid() == 0;
}