/*
    Copyright 2016-2023 melonDS team

    This file is part of melonDS.

    melonDS is free software: you can redistribute it and/or modify it under
    the terms of the GNU General Public License as published by the Free
    Software Foundation, either version 3 of the License, or (at your option)
    any later version.

    melonDS is distributed in the hope that it will be useful, but WITHOUT ANY
    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with melonDS. If not, see http://www.gnu.org/licenses/.
*/

#include <stdlib.h>
#include <time.h>
#include <stdio.h>
#include <string.h>

#include <optional>
#include <vector>
#include <string>
#include <algorithm>

#include <SDL2/SDL.h>

#include "main.h"

#include "types.h"
#include "version.h"

#include "ScreenLayout.h"

#include "Args.h"
#include "NDS.h"
#include "NDSCart.h"
#include "GBACart.h"
#include "GPU.h"
#include "SPU.h"
#include "Wifi.h"
#include "Platform.h"
#include "LocalMP.h"
#include "Config.h"
#include "RTC.h"
#include "DSi.h"
#include "DSi_I2C.h"
#include "GPU3D_Soft.h"
#include "GPU3D_OpenGL.h"
#include "GPU3D_Compute.h"

#include "Savestate.h"

#include "EmuInstance.h"

using namespace melonDS;


EmuThread::EmuThread(EmuInstance* inst, QObject* parent) : QThread(parent)
{
    emuInstance = inst;

    EmuStatus = emuStatus_Exit;
    EmuRunning = emuStatus_Paused;
    EmuPauseStack = EmuPauseStackRunning;
    emuActive = false;
}

void EmuThread::attachWindow(MainWindow* window)
{
    connect(this, SIGNAL(windowUpdate()), window->panel, SLOT(repaint()));
    connect(this, SIGNAL(windowTitleChange(QString)), window, SLOT(onTitleUpdate(QString)));
    connect(this, SIGNAL(windowEmuStart()), window, SLOT(onEmuStart()));
    connect(this, SIGNAL(windowEmuStop()), window, SLOT(onEmuStop()));
    connect(this, SIGNAL(windowEmuPause(bool)), window, SLOT(onEmuPause(bool)));
    connect(this, SIGNAL(windowEmuReset()), window->actReset, SLOT(trigger()));
    connect(this, SIGNAL(windowEmuFrameStep()), window->actFrameStep, SLOT(trigger()));
    connect(this, SIGNAL(windowLimitFPSChange()), window->actLimitFramerate, SLOT(trigger()));
    connect(this, SIGNAL(autoScreenSizingChange(int)), window->panel, SLOT(onAutoScreenSizingChanged(int)));
    connect(this, SIGNAL(windowFullscreenToggle()), window, SLOT(onFullscreenToggled()));
    connect(this, SIGNAL(swapScreensToggle()), window->actScreenSwap, SLOT(trigger()));
    connect(this, SIGNAL(screenEmphasisToggle()), window, SLOT(onScreenEmphasisToggled()));
}

void EmuThread::detachWindow(MainWindow* window)
{
    disconnect(this, SIGNAL(windowUpdate()), window->panel, SLOT(repaint()));
    disconnect(this, SIGNAL(windowTitleChange(QString)), window, SLOT(onTitleUpdate(QString)));
    disconnect(this, SIGNAL(windowEmuStart()), window, SLOT(onEmuStart()));
    disconnect(this, SIGNAL(windowEmuStop()), window, SLOT(onEmuStop()));
    disconnect(this, SIGNAL(windowEmuPause(bool)), window, SLOT(onEmuPause(bool)));
    disconnect(this, SIGNAL(windowEmuReset()), window->actReset, SLOT(trigger()));
    disconnect(this, SIGNAL(windowEmuFrameStep()), window->actFrameStep, SLOT(trigger()));
    disconnect(this, SIGNAL(windowLimitFPSChange()), window->actLimitFramerate, SLOT(trigger()));
    disconnect(this, SIGNAL(autoScreenSizingChange(int)), window->panel, SLOT(onAutoScreenSizingChanged(int)));
    disconnect(this, SIGNAL(windowFullscreenToggle()), window, SLOT(onFullscreenToggled()));
    disconnect(this, SIGNAL(swapScreensToggle()), window->actScreenSwap, SLOT(trigger()));
    disconnect(this, SIGNAL(screenEmphasisToggle()), window, SLOT(onScreenEmphasisToggled()));
}

void EmuThread::run()
{
    Config::Table& globalCfg = emuInstance->getGlobalConfig();
    u32 mainScreenPos[3];
    Platform::FileHandle* file;

    emuInstance->updateConsole(nullptr, nullptr);
    // No carts are inserted when melonDS first boots

    mainScreenPos[0] = 0;
    mainScreenPos[1] = 0;
    mainScreenPos[2] = 0;
    autoScreenSizing = 0;

    videoSettingsDirty = false;

    if (emuInstance->usesOpenGL())
    {
        emuInstance->initOpenGL();

        useOpenGL = true;
        videoRenderer = globalCfg.GetInt("3D.Renderer");
    }
    else
    {
        useOpenGL = false;
        videoRenderer = 0;
    }

    updateRenderer();

    u32 nframes = 0;
    double perfCountsSec = 1.0 / SDL_GetPerformanceFrequency();
    double lastTime = SDL_GetPerformanceCounter() * perfCountsSec;
    double frameLimitError = 0.0;
    double lastMeasureTime = lastTime;

    u32 winUpdateCount = 0, winUpdateFreq = 1;
    u8 dsiVolumeLevel = 0x1F;

    file = Platform::OpenLocalFile("rtc.bin", Platform::FileMode::Read);
    if (file)
    {
        RTC::StateData state;
        Platform::FileRead(&state, sizeof(state), 1, file);
        Platform::CloseFile(file);
        emuInstance->nds->RTC.SetState(state);
    }

    char melontitle[100];

    while (EmuRunning != emuStatus_Exit)
    {
        emuInstance->inputProcess();

        if (emuInstance->hotkeyPressed(HK_FastForwardToggle)) emit windowLimitFPSChange();

        if (emuInstance->hotkeyPressed(HK_Pause)) emuTogglePause();
        if (emuInstance->hotkeyPressed(HK_Reset)) emit windowEmuReset();
        if (emuInstance->hotkeyPressed(HK_FrameStep)) emit windowEmuFrameStep();

        if (emuInstance->hotkeyPressed(HK_FullscreenToggle)) emit windowFullscreenToggle();

        if (emuInstance->hotkeyPressed(HK_SwapScreens)) emit swapScreensToggle();
        if (emuInstance->hotkeyPressed(HK_SwapScreenEmphasis)) emit screenEmphasisToggle();

        if (EmuRunning == emuStatus_Running || EmuRunning == emuStatus_FrameStep)
        {
            EmuStatus = emuStatus_Running;
            if (EmuRunning == emuStatus_FrameStep) EmuRunning = emuStatus_Paused;

            if (emuInstance->hotkeyPressed(HK_SolarSensorDecrease))
            {
                int level = emuInstance->nds->GBACartSlot.SetInput(GBACart::Input_SolarSensorDown, true);
                if (level != -1)
                {
                    emuInstance->osdAddMessage(0, "Solar sensor level: %d", level);
                }
            }
            if (emuInstance->hotkeyPressed(HK_SolarSensorIncrease))
            {
                int level = emuInstance->nds->GBACartSlot.SetInput(GBACart::Input_SolarSensorUp, true);
                if (level != -1)
                {
                    emuInstance->osdAddMessage(0, "Solar sensor level: %d", level);
                }
            }

            if (emuInstance->nds->ConsoleType == 1)
            {
                DSi* dsi = static_cast<DSi*>(emuInstance->nds);
                double currentTime = SDL_GetPerformanceCounter() * perfCountsSec;

                // Handle power button
                if (emuInstance->hotkeyDown(HK_PowerButton))
                {
                    dsi->I2C.GetBPTWL()->SetPowerButtonHeld(currentTime);
                }
                else if (emuInstance->hotkeyReleased(HK_PowerButton))
                {
                    dsi->I2C.GetBPTWL()->SetPowerButtonReleased(currentTime);
                }

                // Handle volume buttons
                if (emuInstance->hotkeyDown(HK_VolumeUp))
                {
                    dsi->I2C.GetBPTWL()->SetVolumeSwitchHeld(DSi_BPTWL::volumeKey_Up);
                }
                else if (emuInstance->hotkeyReleased(HK_VolumeUp))
                {
                    dsi->I2C.GetBPTWL()->SetVolumeSwitchReleased(DSi_BPTWL::volumeKey_Up);
                }

                if (emuInstance->hotkeyDown(HK_VolumeDown))
                {
                    dsi->I2C.GetBPTWL()->SetVolumeSwitchHeld(DSi_BPTWL::volumeKey_Down);
                }
                else if (emuInstance->hotkeyReleased(HK_VolumeDown))
                {
                    dsi->I2C.GetBPTWL()->SetVolumeSwitchReleased(DSi_BPTWL::volumeKey_Down);
                }

                dsi->I2C.GetBPTWL()->ProcessVolumeSwitchInput(currentTime);
            }

            if (useOpenGL)
                emuInstance->makeCurrentGL();

            // update render settings if needed
            if (videoSettingsDirty)
            {
                if (useOpenGL)
                {
                    emuInstance->setVSyncGL(true);
                    videoRenderer = globalCfg.GetInt("3D.Renderer");
                }
#ifdef OGLRENDERER_ENABLED
                else
#endif
                {
                    videoRenderer = 0;
                }

                updateRenderer();

                videoSettingsDirty = false;
            }

            // process input and hotkeys
            emuInstance->nds->SetKeyMask(emuInstance->inputMask);

            if (emuInstance->hotkeyPressed(HK_Lid))
            {
                bool lid = !emuInstance->nds->IsLidClosed();
                emuInstance->nds->SetLidClosed(lid);
                emuInstance->osdAddMessage(0, lid ? "Lid closed" : "Lid opened");
            }

            // microphone input
            emuInstance->micProcess();

            // auto screen layout
            {
                mainScreenPos[2] = mainScreenPos[1];
                mainScreenPos[1] = mainScreenPos[0];
                mainScreenPos[0] = emuInstance->nds->PowerControl9 >> 15;

                int guess;
                if (mainScreenPos[0] == mainScreenPos[2] &&
                    mainScreenPos[0] != mainScreenPos[1])
                {
                    // constant flickering, likely displaying 3D on both screens
                    // TODO: when both screens are used for 2D only...???
                    guess = screenSizing_Even;
                }
                else
                {
                    if (mainScreenPos[0] == 1)
                        guess = screenSizing_EmphTop;
                    else
                        guess = screenSizing_EmphBot;
                }

                if (guess != autoScreenSizing)
                {
                    autoScreenSizing = guess;
                    emit autoScreenSizingChange(autoScreenSizing);
                }
            }


            // emulate
            u32 nlines;
            if (emuInstance->nds->GPU.GetRenderer3D().NeedsShaderCompile())
            {
                compileShaders();
                nlines = 1;
            }
            else
            {
                nlines = emuInstance->nds->RunFrame();
            }

            if (emuInstance->ndsSave)
                emuInstance->ndsSave->CheckFlush();

            if (emuInstance->gbaSave)
                emuInstance->gbaSave->CheckFlush();

            if (emuInstance->firmwareSave)
                emuInstance->firmwareSave->CheckFlush();

            if (!useOpenGL)
            {
                FrontBufferLock.lock();
                FrontBuffer = emuInstance->nds->GPU.FrontBuffer;
                FrontBufferLock.unlock();
            }
            else
            {
                FrontBuffer = emuInstance->nds->GPU.FrontBuffer;
                emuInstance->drawScreenGL();
            }

#ifdef MELONCAP
            MelonCap::Update();
#endif // MELONCAP

            if (EmuRunning == emuStatus_Exit) break;

            winUpdateCount++;
            if (winUpdateCount >= winUpdateFreq && !useOpenGL)
            {
                emit windowUpdate();
                winUpdateCount = 0;
            }

            bool fastforward = emuInstance->hotkeyDown(HK_FastForward);

            if (useOpenGL)
            {
                // when using OpenGL: when toggling fast-forward, change the vsync interval
                if (emuInstance->hotkeyPressed(HK_FastForward))
                {
                    emuInstance->setVSyncGL(false);
                }
                else if (emuInstance->hotkeyReleased(HK_FastForward))
                {
                    emuInstance->setVSyncGL(true);
                }
            }

            if (emuInstance->audioDSiVolumeSync && emuInstance->nds->ConsoleType == 1)
            {
                DSi* dsi = static_cast<DSi*>(emuInstance->nds);
                u8 volumeLevel = dsi->I2C.GetBPTWL()->GetVolumeLevel();
                if (volumeLevel != dsiVolumeLevel)
                {
                    dsiVolumeLevel = volumeLevel;
                    emit syncVolumeLevel();
                }

                emuInstance->audioVolume = volumeLevel * (256.0 / 31.0);
            }

            if (emuInstance->doAudioSync && !fastforward)
                emuInstance->audioSync();

            double frametimeStep = nlines / (60.0 * 263.0);

            {
                bool limitfps = emuInstance->doLimitFPS && !fastforward;

                double practicalFramelimit = limitfps ? frametimeStep : 1.0 / emuInstance->maxFPS;

                double curtime = SDL_GetPerformanceCounter() * perfCountsSec;

                frameLimitError += practicalFramelimit - (curtime - lastTime);
                if (frameLimitError < -practicalFramelimit)
                    frameLimitError = -practicalFramelimit;
                if (frameLimitError > practicalFramelimit)
                    frameLimitError = practicalFramelimit;

                if (round(frameLimitError * 1000.0) > 0.0)
                {
                    SDL_Delay(round(frameLimitError * 1000.0));
                    double timeBeforeSleep = curtime;
                    curtime = SDL_GetPerformanceCounter() * perfCountsSec;
                    frameLimitError -= curtime - timeBeforeSleep;
                }

                lastTime = curtime;
            }

            nframes++;
            if (nframes >= 30)
            {
                double time = SDL_GetPerformanceCounter() * perfCountsSec;
                double dt = time - lastMeasureTime;
                lastMeasureTime = time;

                u32 fps = round(nframes / dt);
                nframes = 0;

                float fpstarget = 1.0/frametimeStep;

                winUpdateFreq = fps / (u32)round(fpstarget);
                if (winUpdateFreq < 1)
                    winUpdateFreq = 1;

                int inst = emuInstance->instanceID;
                if (inst == 0)
                    sprintf(melontitle, "[%d/%.0f] melonDS " MELONDS_VERSION, fps, fpstarget);
                else
                    sprintf(melontitle, "[%d/%.0f] melonDS (%d)", fps, fpstarget, inst+1);
                changeWindowTitle(melontitle);
            }
        }
        else
        {
            // paused
            nframes = 0;
            lastTime = SDL_GetPerformanceCounter() * perfCountsSec;
            lastMeasureTime = lastTime;

            emit windowUpdate();

            EmuStatus = EmuRunning;

            int inst = emuInstance->instanceID;
            if (inst == 0)
                sprintf(melontitle, "melonDS " MELONDS_VERSION);
            else
                sprintf(melontitle, "melonDS (%d)", inst+1);
            changeWindowTitle(melontitle);

            SDL_Delay(75);

            if (useOpenGL)
            {
                emuInstance->drawScreenGL();
            }
        }

        handleMessages();
    }

    file = Platform::OpenLocalFile("rtc.bin", Platform::FileMode::Write);
    if (file)
    {
        RTC::StateData state;
        emuInstance->nds->RTC.GetState(state);
        Platform::FileWrite(&state, sizeof(state), 1, file);
        Platform::CloseFile(file);
    }

    EmuStatus = emuStatus_Exit;

    NDS::Current = nullptr;
}

void EmuThread::sendMessage(Message msg)
{
    msgMutex.lock();
    msgQueue.enqueue(msg);
    msgMutex.unlock();
}

void EmuThread::waitMessage()
{
    if (QThread::currentThread() == this) return;
    msgSemaphore.acquire();
}

void EmuThread::waitAllMessages()
{
    if (QThread::currentThread() == this) return;
    msgSemaphore.acquire(msgSemaphore.available());
}

void EmuThread::handleMessages()
{
    msgMutex.lock();
    while (!msgQueue.empty())
    {
        Message msg = msgQueue.dequeue();
        switch (msg.type)
        {
        case msg_EmuRun:
            EmuRunning = emuStatus_Running;
            EmuPauseStack = EmuPauseStackRunning;
            emuActive = true;

            emuInstance->audioEnable();
            emit windowEmuStart();
            break;

        case msg_EmuPause:
            EmuPauseStack++;
            if (EmuPauseStack > EmuPauseStackPauseThreshold) break;

            PrevEmuStatus = EmuRunning;
            EmuRunning = emuStatus_Paused;

            if (PrevEmuStatus != emuStatus_Paused)
            {
                emuInstance->audioDisable();
                emit windowEmuPause(true);
                emuInstance->osdAddMessage(0, "Paused");
            }
            break;

        case msg_EmuUnpause:
            if (EmuPauseStack < EmuPauseStackPauseThreshold) break;

            EmuPauseStack--;
            if (EmuPauseStack >= EmuPauseStackPauseThreshold) break;

            EmuRunning = PrevEmuStatus;

            if (EmuRunning != emuStatus_Paused)
            {
                emuInstance->audioEnable();
                emit windowEmuPause(false);
                emuInstance->osdAddMessage(0, "Resumed");
            }
            break;

        case msg_EmuStop:
            if (msg.stopExternal) emuInstance->nds->Stop();
            EmuRunning = emuStatus_Paused;
            emuActive = false;

            emuInstance->audioDisable();
            emit windowEmuStop();
            break;

        case msg_InitGL:
            emuInstance->initOpenGL();
            useOpenGL = true;
            break;

        case msg_DeInitGL:
            emuInstance->deinitOpenGL();
            useOpenGL = false;
            break;
        }

        msgSemaphore.release();
    }
    msgMutex.unlock();
}

void EmuThread::changeWindowTitle(char* title)
{
    emit windowTitleChange(QString(title));
}

void EmuThread::initContext()
{
    sendMessage(msg_InitGL);
    waitMessage();
}

void EmuThread::deinitContext()
{
    sendMessage(msg_DeInitGL);
    waitMessage();
}

void EmuThread::emuRun()
{
    sendMessage(msg_EmuRun);
    waitMessage();
}

void EmuThread::emuPause()
{
    sendMessage(msg_EmuPause);
    waitMessage();
}

void EmuThread::emuUnpause()
{
    sendMessage(msg_EmuUnpause);
    waitMessage();
}

void EmuThread::emuTogglePause()
{
    if (EmuRunning == emuStatus_Paused)
        emuUnpause();
    else
        emuPause();
}

void EmuThread::emuStop(bool external)
{
    sendMessage({.type = msg_EmuStop, .stopExternal = external});
    waitMessage();
}

void EmuThread::emuExit()
{
    EmuRunning = emuStatus_Exit;
    EmuPauseStack = EmuPauseStackRunning;

    emuInstance->audioDisable();
}

void EmuThread::emuFrameStep()
{
    //if (EmuPauseStack < EmuPauseStackPauseThreshold) emit windowEmuPause();
    EmuRunning = emuStatus_FrameStep;
}

bool EmuThread::emuIsRunning()
{
    return EmuRunning == emuStatus_Running;
}

bool EmuThread::emuIsActive()
{
    return emuActive;
}

void EmuThread::updateRenderer()
{
    if (videoRenderer != lastVideoRenderer)
    {
        printf("creating renderer %d\n", videoRenderer);
        switch (videoRenderer)
        {
            case renderer3D_Software:
                emuInstance->nds->GPU.SetRenderer3D(std::make_unique<SoftRenderer>());
                break;
            case renderer3D_OpenGL:
                emuInstance->nds->GPU.SetRenderer3D(GLRenderer::New());
                break;
            case renderer3D_OpenGLCompute:
                emuInstance->nds->GPU.SetRenderer3D(ComputeRenderer::New());
                break;
            default: __builtin_unreachable();
        }
    }
    lastVideoRenderer = videoRenderer;

    auto& cfg = emuInstance->getGlobalConfig();
    switch (videoRenderer)
    {
        case renderer3D_Software:
            static_cast<SoftRenderer&>(emuInstance->nds->GPU.GetRenderer3D()).SetThreaded(
                    cfg.GetBool("3D.Soft.Threaded"),
                    emuInstance->nds->GPU);
            break;
        case renderer3D_OpenGL:
            static_cast<GLRenderer&>(emuInstance->nds->GPU.GetRenderer3D()).SetRenderSettings(
                    cfg.GetBool("3D.GL.BetterPolygons"),
                    cfg.GetInt("3D.GL.ScaleFactor"));
            break;
        case renderer3D_OpenGLCompute:
            static_cast<ComputeRenderer&>(emuInstance->nds->GPU.GetRenderer3D()).SetRenderSettings(
                    cfg.GetInt("3D.GL.ScaleFactor"),
                    cfg.GetBool("3D.GL.HiresCoordinates"));
            break;
        default: __builtin_unreachable();
    }
}

void EmuThread::compileShaders()
{
    int currentShader, shadersCount;
    u64 startTime = SDL_GetPerformanceCounter();
    // kind of hacky to look at the wallclock, though it is easier than
    // than disabling vsync
    do
    {
        emuInstance->nds->GPU.GetRenderer3D().ShaderCompileStep(currentShader, shadersCount);
    } while (emuInstance->nds->GPU.GetRenderer3D().NeedsShaderCompile() &&
             (SDL_GetPerformanceCounter() - startTime) * perfCountsSec < 1.0 / 6.0);
    emuInstance->osdAddMessage(0, "Compiling shader %d/%d", currentShader+1, shadersCount);
}