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

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
   JUCE Privacy Policy: https://juce.com/juce-privacy-policy
   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

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

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

namespace juce
{

struct XFreeDeleter
{
    void operator() (void* ptr) const
    {
        if (ptr != nullptr)
            X11Symbols::getInstance()->xFree (ptr);
    }
};

template <typename Data>
std::unique_ptr<Data, XFreeDeleter> makeXFreePtr (Data* raw) { return std::unique_ptr<Data, XFreeDeleter> (raw); }

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

class PeerListener : private ComponentMovementWatcher
{
public:
    PeerListener (Component& comp, Window embeddedWindow)
        : ComponentMovementWatcher (&comp),
          window (embeddedWindow),
          association (comp.getPeer(), window) {}

private:
    using ComponentMovementWatcher::componentMovedOrResized,
          ComponentMovementWatcher::componentVisibilityChanged;

    void componentMovedOrResized (bool, bool) override {}
    void componentVisibilityChanged() override {}

    void componentPeerChanged() override
    {
        // This should not be rewritten as a ternary expression or similar.
        // The old association must be destroyed before the new one is created.
        association = {};

        if (auto* comp = getComponent())
            association = ScopedWindowAssociation (comp->getPeer(), window);
    }

    Window window{};
    ScopedWindowAssociation association;
};

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

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

        NativeContext& native;
    };

    template <typename Traits>
    class ScopedGLXObject
    {
    public:
        using Type = typename Traits::Type;

        ScopedGLXObject() = default;

        ScopedGLXObject (Type obj, ::Display* d)
            : object (obj), display (d) {}

        ScopedGLXObject (ScopedGLXObject&& other) noexcept
            : object (std::exchange (other.object, Type{})),
              display (std::exchange (other.display, nullptr)) {}

        ScopedGLXObject& operator= (ScopedGLXObject&& other) noexcept
        {
            ScopedGLXObject { std::move (other) }.swap (*this);
            return *this;
        }

        ~ScopedGLXObject() noexcept
        {
            if (object != Type{})
                Traits::destroy (display, object);
        }

        Type get() const { return object; }

        void reset() noexcept
        {
            *this = ScopedGLXObject();
        }

        void swap (ScopedGLXObject& other) noexcept
        {
            std::swap (other.object, object);
            std::swap (other.display, display);
        }

        bool operator== (const ScopedGLXObject& other) const
        {
            const auto tie = [] (const auto& x) { return std::tie (x.object, x.display); };
            return tie (*this) == tie (other);
        }

        bool operator!= (const ScopedGLXObject& other) const
        {
            return ! operator== (other);
        }

    private:
        Type object{};
        ::Display* display{};
    };

    struct TraitsGLXContext
    {
        using Type = GLXContext;

        static void destroy (::Display* display, Type t)
        {
            glXDestroyContext (display, t);
        }
    };

    struct TraitsGLXWindow
    {
        using Type = GLXWindow;

        static void destroy (::Display* display, Type t)
        {
            glXDestroyWindow (display, t);
        }
    };

    using PtrGLXContext = ScopedGLXObject<TraitsGLXContext>;
    using PtrGLXWindow = ScopedGLXObject<TraitsGLXWindow>;

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 visual = glXGetVisualFromFBConfig (display, *bestConfig);
        auto colourMap = X11Symbols::getInstance()->xCreateColormap (display, windowH, visual->visual, AllocNone);

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

        const auto physicalBounds = getPhysicalBounds();

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

        peerListener.emplace (component, embeddedWindow);

        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)
                {
                }
            }
        }
    }

    InitResult initialiseOnRenderThread (OpenGLContext& c)
    {
        XWindowSystemUtilities::ScopedXLock xLock;

        const auto components = [&]() -> Optional<Version>
        {
            switch (c.versionRequired)
            {
                case openGL3_2: return Version { 3, 2 };
                case openGL4_1: return Version { 4, 1 };
                case openGL4_3: return Version { 4, 3 };

                case defaultGLVersion: break;
            }

            return {};
        }();

        if (components.hasValue())
        {
            using GLXCreateContextAttribsARB = GLXContext (*) (Display*, GLXFBConfig, GLXContext, Bool, const int*);

            if (const auto glXCreateContextAttribsARB = (GLXCreateContextAttribsARB) OpenGLHelpers::getExtensionFunction ("glXCreateContextAttribsARB"))
            {
               #if JUCE_DEBUG
                constexpr auto contextFlags = GLX_CONTEXT_DEBUG_BIT_ARB;
               #else
                constexpr auto contextFlags = 0;
               #endif

                const int attribs[]
                {
                    GLX_CONTEXT_MAJOR_VERSION_ARB, components->major,
                    GLX_CONTEXT_MINOR_VERSION_ARB, components->minor,
                    GLX_CONTEXT_PROFILE_MASK_ARB,  GLX_CONTEXT_CORE_PROFILE_BIT_ARB,
                    GLX_CONTEXT_FLAGS_ARB,         contextFlags,
                    None
                };

                renderContext = PtrGLXContext { glXCreateContextAttribsARB (display, *bestConfig, (GLXContext) contextToShareWith, GL_TRUE, attribs),
                                                display };
            }
        }

        if (renderContext == PtrGLXContext{})
            renderContext = PtrGLXContext { glXCreateNewContext (display, *bestConfig, GLX_RGBA_TYPE, (GLXContext) contextToShareWith, GL_TRUE),
                                            display };

        if (renderContext == PtrGLXContext{})
            return InitResult::fatal;

        glxWindow = PtrGLXWindow { glXCreateWindow (display, *bestConfig, embeddedWindow, nullptr),
                                   display };
        c.makeActive();
        context = &c;
        return InitResult::success;
    }

    void shutdownOnRenderThread()
    {
        XWindowSystemUtilities::ScopedXLock xLock;
        context = nullptr;
        deactivateCurrentContext();
        renderContext.reset();
        glxWindow.reset();
    }

    bool makeActive() const noexcept
    {
        XWindowSystemUtilities::ScopedXLock xLock;
        return renderContext != PtrGLXContext{}
                 && glXMakeContextCurrent (display, glxWindow.get(), glxWindow.get(), renderContext.get());
    }

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

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

    void swapBuffers()
    {
        glXSwapBuffers (display, glxWindow.get());
    }

    Rectangle<int> getPhysicalBounds() const
    {
        if (auto* peer = component.getPeer())
        {
            const auto peerBounds = peer->getAreaCoveredBy (component);
            const auto physicalBounds = peerBounds.toDouble() * peer->getPlatformScaleFactor();
            return physicalBounds.toNearestInt();
        }

        return component.getBounds();
    }

    void updateWindowPosition()
    {
        const auto physicalBounds = getPhysicalBounds();

        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 GLXSwapIntervalEXT
              = (PFNGLXSWAPINTERVALEXTPROC) OpenGLHelpers::getExtensionFunction ("glXSwapIntervalEXT"))
        {
            XWindowSystemUtilities::ScopedXLock xLock;
            swapFrames = numFramesPerSwap;
            GLXSwapIntervalEXT (display, glxWindow.get(), numFramesPerSwap);
            return true;
        }

        return false;
    }

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

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

    struct Locker
    {
        explicit Locker (NativeContext& ctx) : lock (ctx.mutex) {}
        const ScopedLock lock;
    };

    void addListener (NativeContextListener&) {}
    void removeListener (NativeContextListener&) {}

private:
    bool tryChooseVisual (const OpenGLPixelFormat& format, const std::vector<GLint>& optionalAttribs)
    {
        std::vector<GLint> allAttribs
        {
            GLX_RENDER_TYPE,      GLX_RGBA_BIT,
            GLX_DOUBLEBUFFER,     True,
            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);

        int nElements = 0;
        bestConfig = makeXFreePtr (glXChooseFBConfig (display, X11Symbols::getInstance()->xDefaultScreen (display), allAttribs.data(), &nElements));

        return nElements != 0 && bestConfig != nullptr;
    }

    static constexpr int embeddedWindowEventMask = ExposureMask | StructureNotifyMask;

    CriticalSection mutex;
    Component& component;
    PtrGLXContext renderContext;
    PtrGLXWindow glxWindow;
    Window embeddedWindow = {};

    std::optional<PeerListener> peerListener;

    int swapFrames = 0;
    std::unique_ptr<GLXFBConfig, XFreeDeleter> bestConfig;
    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
