#include "asio.hpp"
#include "Global.h"
#include "Plot_p.h"
#include <QApplication>
#include <algorithm>
namespace YSG {
    struct RenderSchedulerPrivate {
        asio::io_context mIoContext;
        std::unique_ptr<asio::executor_work_guard<asio::io_context::executor_type>> mWorkGuard;
        std::unique_ptr<asio::thread_pool> mCpuPool;
        std::thread mSchedulerThread;
        std::thread::id mSchedulerThreadId;
        QList<Plot*> mPlots;
        std::atomic_bool mRunning{false};
        std::atomic_bool mCpuJoined{true};
    };
    RenderScheduler::RenderScheduler() : d(std::make_unique<RenderSchedulerPrivate>()) {
        QObject::connect(QApplication::instance(), &QApplication::aboutToQuit, [this]() {
            shutdown();
        });
    }
    RenderScheduler::~RenderScheduler() {
        shutdown();
    }
    void RenderScheduler::start() {
        if(d->mRunning.exchange(true, std::memory_order_acq_rel)) return;
        d->mIoContext.restart();
        d->mWorkGuard = std::make_unique<asio::executor_work_guard<asio::io_context::executor_type>>(d->mIoContext.get_executor());
        unsigned cpuCount = std::max(1u, std::thread::hardware_concurrency() > 1 ? std::thread::hardware_concurrency() - 1 : 1u);
        d->mCpuPool = std::make_unique<asio::thread_pool>(cpuCount);
        d->mCpuJoined.store(false, std::memory_order_release);
        d->mSchedulerThread = std::thread([this]() {
            d->mSchedulerThreadId = std::this_thread::get_id();
            for(Plot* plot : d->mPlots) {
                initializePlotOnScheduler(plot);
            }
            d->mIoContext.run();
            d->mRunning.store(false, std::memory_order_release);
        });
    }
    void RenderScheduler::shutdown() {
        if(!d->mRunning.load(std::memory_order_acquire)) {
            joinCpuPool();
            if(d->mSchedulerThread.joinable() && d->mSchedulerThread.get_id() != std::this_thread::get_id()) d->mSchedulerThread.join();
            d->mCpuPool.reset();
            d->mWorkGuard.reset();
            return;
        }
        if(isSchedulerThread()) {
            shutdownOnScheduler();
            d->mWorkGuard.reset();
            joinCpuPool();
            return;
        }
        postAndWait([this]() {
            shutdownOnScheduler();
        });
        joinCpuPool();
        post([this]() {
            d->mWorkGuard.reset();
        });
        if(d->mSchedulerThread.joinable()) d->mSchedulerThread.join();
        d->mCpuPool.reset();
    }
    void RenderScheduler::post(std::function<void()> task) {
        asio::post(d->mIoContext, std::move(task));
    }
    void RenderScheduler::postCpu(std::function<void()> task) {
        if(d->mCpuPool) {
            asio::post(*d->mCpuPool, std::move(task));
        } else {
            post(std::move(task));
        }
    }
    void RenderScheduler::registerPlot(Plot* plot) {
        if(d->mRunning.load(std::memory_order_acquire) && !isSchedulerThread()) {
            postAndWait([this, plot]() {
                registerPlotOnScheduler(plot);
            });
            return;
        }
        registerPlotOnScheduler(plot);
    }
    void RenderScheduler::removePlot(Plot* plot) {
        if(d->mRunning.load(std::memory_order_acquire) && !isSchedulerThread()) {
            postAndWait([this, plot]() {
                removePlotOnScheduler(plot);
            });
            return;
        }
        removePlotOnScheduler(plot);
    }
    bool RenderScheduler::isSchedulerThread() const {
        return std::this_thread::get_id() == d->mSchedulerThreadId;
    }
    bool RenderScheduler::isRunning() const {
        return d->mRunning.load(std::memory_order_acquire);
    }
    asio::io_context& RenderScheduler::ioContext() {
        return d->mIoContext;
    }
    void RenderScheduler::joinCpuPool() {
        if(d->mCpuPool && !d->mCpuJoined.exchange(true, std::memory_order_acq_rel)) d->mCpuPool->join();
    }
    void RenderScheduler::postAndWait(std::function<void()> task) {
        if(isSchedulerThread() || !d->mRunning.load(std::memory_order_acquire)) {
            task();
            return;
        }
        std::mutex mutex;
        std::condition_variable cv;
        bool done = false;
        post([&task, &mutex, &cv, &done]() {
            task();
            {
                std::lock_guard<std::mutex> lock(mutex);
                done = true;
            }
            cv.notify_one();
        });
        std::unique_lock<std::mutex> lock(mutex);
        cv.wait(lock, [&done]() {
            return done;
        });
    }
    void RenderScheduler::registerPlotOnScheduler(Plot* plot) {
        if(!d->mPlots.contains(plot)) d->mPlots.append(plot);
        if(d->mRunning.load(std::memory_order_acquire)) initializePlotOnScheduler(plot);
    }
    void RenderScheduler::removePlotOnScheduler(Plot* plot) {
        d->mPlots.removeAll(plot);
        PlotPrivate* data = plot->d;
        data->mRenderEnabled.store(false, std::memory_order_release);
        if(data->mRenderTimer) {
            data->mRenderTimer->cancel();
            data->mRenderTimer.reset();
        }
    }
    void RenderScheduler::shutdownOnScheduler() {
        for(Plot* plot : d->mPlots) {
            PlotPrivate* data = plot->d;
            data->mDestroying.store(true, std::memory_order_release);
            data->mRenderEnabled.store(false, std::memory_order_release);
            if(data->mRenderTimer) {
                data->mRenderTimer->cancel();
                data->mRenderTimer.reset();
            }
        }
        d->mPlots.clear();
    }
    void RenderScheduler::initializePlotOnScheduler(Plot* plot) {
        PlotPrivate* data = plot->d;
        if(!data->mRenderTimer) data->mRenderTimer = std::make_unique<asio::steady_timer>(d->mIoContext);
        data->mRenderSize = QSize(data->mPendingRenderWidth.load(std::memory_order_acquire), data->mPendingRenderHeight.load(std::memory_order_acquire));
        if(plot->isVisible()) data->mRenderEnabled.store(true, std::memory_order_release);
        if(data->mRenderEnabled.load(std::memory_order_acquire)) plot->scheduleRenderTimer();
        plot->submitRender();
    }
    RenderScheduler& Global::renderScheduler() {
        return mRenderScheduler;
    }
    void Global::startRenderScheduler() {
        mRenderScheduler.start();
    }
}