/*
  ==============================================================================

   This file is part of the JUCE 7 technical preview.
   Copyright (c) 2022 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For the technical preview this file cannot be licensed commercially.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

extern XContext windowHandleXContext;

//==============================================================================
// Defined juce_linux_Windowing.cpp
void juce_LinuxAddRepaintListener (ComponentPeer*, Component* dummy);
void juce_LinuxRemoveRepaintListener (ComponentPeer*, Component* dummy);

//==============================================================================
class OpenGLContext::NativeContext
{
private:
    struct DummyComponent  : public Component
    {
        DummyComponent (OpenGLContext::NativeContext& nativeParentContext)
            : native (nativeParentContext)
        {
        }

        void handleCommandMessage (int commandId) override
        {
            if (commandId == 0)
                native.triggerRepaint();
        }

        OpenGLContext::NativeContext& native;
    };

public:
    NativeContext (Component& comp,
                   const OpenGLPixelFormat& cPixelFormat,
                   void* shareContext,
                   bool useMultisamplingIn,
                   OpenGLVersion)
        : component (comp), contextToShareWith (shareContext), dummy (*this)
    {
        display = XWindowSystem::getInstance()->getDisplay();

        XWindowSystemUtilities::ScopedXLock xLock;

        X11Symbols::getInstance()->xSync (display, False);

        const std::vector<GLint> optionalAttribs
        {
            GLX_SAMPLE_BUFFERS, useMultisamplingIn ? 1 : 0,
            GLX_SAMPLES,        cPixelFormat.multisamplingLevel
        };

        if (! tryChooseVisual (cPixelFormat, optionalAttribs) && ! tryChooseVisual (cPixelFormat, {}))
            return;

        auto* peer = component.getPeer();
        jassert (peer != nullptr);

        auto windowH = (Window) peer->getNativeHandle();
        auto colourMap = X11Symbols::getInstance()->xCreateColormap (display, windowH, bestVisual->visual, AllocNone);

        XSetWindowAttributes swa;
        swa.colormap = colourMap;
        swa.border_pixel = 0;
        swa.event_mask = embeddedWindowEventMask;

        auto glBounds = component.getTopLevelComponent()
                           ->getLocalArea (&component, component.getLocalBounds());

        glBounds = Desktop::getInstance().getDisplays().logicalToPhysical (glBounds);

        embeddedWindow = X11Symbols::getInstance()->xCreateWindow (display, windowH,
                                                                   glBounds.getX(), glBounds.getY(),
                                                                   (unsigned int) jmax (1, glBounds.getWidth()),
                                                                   (unsigned int) jmax (1, glBounds.getHeight()),
                                                                   0, bestVisual->depth,
                                                                   InputOutput,
                                                                   bestVisual->visual,
                                                                   CWBorderPixel | CWColormap | CWEventMask,
                                                                   &swa);

        X11Symbols::getInstance()->xSaveContext (display, (XID) embeddedWindow, windowHandleXContext, (XPointer) peer);

        X11Symbols::getInstance()->xMapWindow (display, embeddedWindow);
        X11Symbols::getInstance()->xFreeColormap (display, colourMap);

        X11Symbols::getInstance()->xSync (display, False);

        juce_LinuxAddRepaintListener (peer, &dummy);
    }

    ~NativeContext()
    {
        if (auto* peer = component.getPeer())
        {
            juce_LinuxRemoveRepaintListener (peer, &dummy);

            if (embeddedWindow != 0)
            {
                XWindowSystemUtilities::ScopedXLock xLock;

                X11Symbols::getInstance()->xUnmapWindow (display, embeddedWindow);
                X11Symbols::getInstance()->xDestroyWindow (display, embeddedWindow);
                X11Symbols::getInstance()->xSync (display, False);

                XEvent event;
                while (X11Symbols::getInstance()->xCheckWindowEvent (display,
                                                                     embeddedWindow,
                                                                     embeddedWindowEventMask,
                                                                     &event) == True)
                {
                }
            }
        }

        if (bestVisual != nullptr)
            X11Symbols::getInstance()->xFree (bestVisual);
    }

    bool initialiseOnRenderThread (OpenGLContext& c)
    {
        XWindowSystemUtilities::ScopedXLock xLock;
        renderContext = glXCreateContext (display, bestVisual, (GLXContext) contextToShareWith, GL_TRUE);
        c.makeActive();
        context = &c;

        return true;
    }

    void shutdownOnRenderThread()
    {
        XWindowSystemUtilities::ScopedXLock xLock;
        context = nullptr;
        deactivateCurrentContext();
        glXDestroyContext (display, renderContext);
        renderContext = nullptr;
    }

    bool makeActive() const noexcept
    {
        XWindowSystemUtilities::ScopedXLock xLock;
        return renderContext != nullptr
                 && glXMakeCurrent (display, embeddedWindow, renderContext);
    }

    bool isActive() const noexcept
    {
        XWindowSystemUtilities::ScopedXLock xLock;
        return glXGetCurrentContext() == renderContext && renderContext != nullptr;
    }

    static void deactivateCurrentContext()
    {
        if (auto* display = XWindowSystem::getInstance()->getDisplay())
        {
            XWindowSystemUtilities::ScopedXLock xLock;
            glXMakeCurrent (display, None, nullptr);
        }
    }

    void swapBuffers()
    {
        XWindowSystemUtilities::ScopedXLock xLock;
        glXSwapBuffers (display, embeddedWindow);
    }

    void updateWindowPosition (Rectangle<int> newBounds)
    {
        bounds = newBounds;
        auto physicalBounds = Desktop::getInstance().getDisplays().logicalToPhysical (bounds);

        XWindowSystemUtilities::ScopedXLock xLock;
        X11Symbols::getInstance()->xMoveResizeWindow (display, embeddedWindow,
                                                      physicalBounds.getX(), physicalBounds.getY(),
                                                      (unsigned int) jmax (1, physicalBounds.getWidth()),
                                                      (unsigned int) jmax (1, physicalBounds.getHeight()));
    }

    bool setSwapInterval (int numFramesPerSwap)
    {
        if (numFramesPerSwap == swapFrames)
            return true;

        if (auto GLXSwapIntervalSGI
              = (PFNGLXSWAPINTERVALSGIPROC) OpenGLHelpers::getExtensionFunction ("glXSwapIntervalSGI"))
        {
            XWindowSystemUtilities::ScopedXLock xLock;
            swapFrames = numFramesPerSwap;
            GLXSwapIntervalSGI (numFramesPerSwap);
            return true;
        }

        return false;
    }

    int getSwapInterval() const                 { return swapFrames; }
    bool createdOk() const noexcept             { return true; }
    void* getRawContext() const noexcept        { return renderContext; }
    GLuint getFrameBufferID() const noexcept    { return 0; }

    void triggerRepaint()
    {
        if (context != nullptr)
            context->triggerRepaint();
    }

    struct Locker { Locker (NativeContext&) {} };

private:
    bool tryChooseVisual (const OpenGLPixelFormat& format, const std::vector<GLint>& optionalAttribs)
    {
        std::vector<GLint> allAttribs
        {
            GLX_RGBA,
            GLX_DOUBLEBUFFER,
            GLX_RED_SIZE,         format.redBits,
            GLX_GREEN_SIZE,       format.greenBits,
            GLX_BLUE_SIZE,        format.blueBits,
            GLX_ALPHA_SIZE,       format.alphaBits,
            GLX_DEPTH_SIZE,       format.depthBufferBits,
            GLX_STENCIL_SIZE,     format.stencilBufferBits,
            GLX_ACCUM_RED_SIZE,   format.accumulationBufferRedBits,
            GLX_ACCUM_GREEN_SIZE, format.accumulationBufferGreenBits,
            GLX_ACCUM_BLUE_SIZE,  format.accumulationBufferBlueBits,
            GLX_ACCUM_ALPHA_SIZE, format.accumulationBufferAlphaBits
        };

        allAttribs.insert (allAttribs.end(), optionalAttribs.begin(), optionalAttribs.end());

        allAttribs.push_back (None);

        bestVisual = glXChooseVisual (display, X11Symbols::getInstance()->xDefaultScreen (display), allAttribs.data());

        return bestVisual != nullptr;
    }

    static constexpr int embeddedWindowEventMask = ExposureMask | StructureNotifyMask;

    Component& component;
    GLXContext renderContext = {};
    Window embeddedWindow = {};

    int swapFrames = 1;
    Rectangle<int> bounds;
    XVisualInfo* bestVisual = nullptr;
    void* contextToShareWith;

    OpenGLContext* context = nullptr;
    DummyComponent dummy;

    ::Display* display = nullptr;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (NativeContext)
};

//==============================================================================
bool OpenGLHelpers::isContextActive()
{
    XWindowSystemUtilities::ScopedXLock xLock;
    return glXGetCurrentContext() != nullptr;
}

} // namespace juce