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

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

   JUCE is an open source library subject to commercial or open-source
   licensing.

   By using JUCE, you agree to the terms of both the JUCE 7 End-User License
   Agreement and JUCE Privacy Policy.

   End User License Agreement: www.juce.com/juce-7-licence
   Privacy Policy: www.juce.com/juce-privacy-policy

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

   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 ComponentPeer* createNonRepaintingEmbeddedWindowsPeer (Component&, void* parent);

//==============================================================================
class OpenGLContext::NativeContext  : private ComponentPeer::ScaleFactorListener
{
public:
    NativeContext (Component& component,
                   const OpenGLPixelFormat& pixelFormat,
                   void* contextToShareWithIn,
                   bool /*useMultisampling*/,
                   OpenGLVersion version)
    {
        dummyComponent.reset (new DummyComponent (*this));
        createNativeWindow (component);

        PIXELFORMATDESCRIPTOR pfd;
        initialisePixelFormatDescriptor (pfd, pixelFormat);

        auto pixFormat = ChoosePixelFormat (dc.get(), &pfd);

        if (pixFormat != 0)
            SetPixelFormat (dc.get(), pixFormat, &pfd);

        initialiseWGLExtensions (dc.get());
        renderContext.reset (createRenderContext (version, dc.get()));

        if (renderContext != nullptr)
        {
            makeActive();

            auto wglFormat = wglChoosePixelFormatExtension (pixelFormat);
            deactivateCurrentContext();

            if (wglFormat != pixFormat && wglFormat != 0)
            {
                // can't change the pixel format of a window, so need to delete the
                // old one and create a new one.
                dc.reset();
                nativeWindow = nullptr;
                createNativeWindow (component);

                if (SetPixelFormat (dc.get(), wglFormat, &pfd))
                {
                    renderContext.reset();
                    renderContext.reset (createRenderContext (version, dc.get()));
                }
            }

            if (contextToShareWithIn != nullptr)
                wglShareLists ((HGLRC) contextToShareWithIn, renderContext.get());

            component.getTopLevelComponent()->repaint();
            component.repaint();
        }
    }

    ~NativeContext() override
    {
        renderContext.reset();
        dc.reset();

        if (safeComponent != nullptr)
            if (auto* peer = safeComponent->getTopLevelComponent()->getPeer())
                peer->removeScaleFactorListener (this);
    }

    bool initialiseOnRenderThread (OpenGLContext& c)
    {
        threadAwarenessSetter = std::make_unique<ScopedThreadDPIAwarenessSetter> (nativeWindow->getNativeHandle());
        context = &c;
        return true;
    }

    void shutdownOnRenderThread()
    {
        deactivateCurrentContext();
        context = nullptr;
        threadAwarenessSetter = nullptr;
    }

    static void deactivateCurrentContext()  { wglMakeCurrent (nullptr, nullptr); }
    bool makeActive() const noexcept        { return isActive() || wglMakeCurrent (dc.get(), renderContext.get()) != FALSE; }
    bool isActive() const noexcept          { return wglGetCurrentContext() == renderContext.get(); }
    void swapBuffers() const noexcept       { SwapBuffers (dc.get()); }

    bool setSwapInterval (int numFramesPerSwap)
    {
        jassert (isActive()); // this can only be called when the context is active..
        return wglSwapIntervalEXT != nullptr && wglSwapIntervalEXT (numFramesPerSwap) != FALSE;
    }

    int getSwapInterval() const
    {
        jassert (isActive()); // this can only be called when the context is active..
        return wglGetSwapIntervalEXT != nullptr ? wglGetSwapIntervalEXT() : 0;
    }

    void updateWindowPosition (Rectangle<int> bounds)
    {
        if (nativeWindow != nullptr)
        {
            if (! approximatelyEqual (nativeScaleFactor, 1.0))
                bounds = (bounds.toDouble() * nativeScaleFactor).toNearestInt();

            SetWindowPos ((HWND) nativeWindow->getNativeHandle(), nullptr,
                          bounds.getX(), bounds.getY(), bounds.getWidth(), bounds.getHeight(),
                          SWP_NOACTIVATE | SWP_NOZORDER | SWP_NOOWNERZORDER);
        }
    }

    bool createdOk() const noexcept                 { return getRawContext() != nullptr; }
    void* getRawContext() const noexcept            { return renderContext.get(); }
    unsigned int getFrameBufferID() const noexcept  { return 0; }

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

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

    HWND getNativeHandle()
    {
        if (nativeWindow != nullptr)
            return (HWND) nativeWindow->getNativeHandle();

        return nullptr;
    }

private:
    //==============================================================================
    static void initialiseWGLExtensions (HDC dcIn)
    {
        static bool initialised = false;

        if (initialised)
            return;

        initialised = true;

        const auto dummyContext = wglCreateContext (dcIn);
        wglMakeCurrent (dcIn, dummyContext);

        #define JUCE_INIT_WGL_FUNCTION(name)    name = (type_ ## name) OpenGLHelpers::getExtensionFunction (#name);
        JUCE_INIT_WGL_FUNCTION (wglChoosePixelFormatARB)
        JUCE_INIT_WGL_FUNCTION (wglSwapIntervalEXT)
        JUCE_INIT_WGL_FUNCTION (wglGetSwapIntervalEXT)
        JUCE_INIT_WGL_FUNCTION (wglCreateContextAttribsARB)
        #undef JUCE_INIT_WGL_FUNCTION

        wglMakeCurrent (nullptr, nullptr);
        wglDeleteContext (dummyContext);
    }

    static void initialisePixelFormatDescriptor (PIXELFORMATDESCRIPTOR& pfd, const OpenGLPixelFormat& pixelFormat)
    {
        zerostruct (pfd);
        pfd.nSize           = sizeof (pfd);
        pfd.nVersion        = 1;
        pfd.dwFlags         = PFD_SUPPORT_OPENGL | PFD_DRAW_TO_WINDOW | PFD_DOUBLEBUFFER;
        pfd.iPixelType      = PFD_TYPE_RGBA;
        pfd.iLayerType      = PFD_MAIN_PLANE;
        pfd.cColorBits      = (BYTE) (pixelFormat.redBits + pixelFormat.greenBits + pixelFormat.blueBits);
        pfd.cRedBits        = (BYTE) pixelFormat.redBits;
        pfd.cGreenBits      = (BYTE) pixelFormat.greenBits;
        pfd.cBlueBits       = (BYTE) pixelFormat.blueBits;
        pfd.cAlphaBits      = (BYTE) pixelFormat.alphaBits;
        pfd.cDepthBits      = (BYTE) pixelFormat.depthBufferBits;
        pfd.cStencilBits    = (BYTE) pixelFormat.stencilBufferBits;
        pfd.cAccumBits      = (BYTE) (pixelFormat.accumulationBufferRedBits + pixelFormat.accumulationBufferGreenBits
                                        + pixelFormat.accumulationBufferBlueBits + pixelFormat.accumulationBufferAlphaBits);
        pfd.cAccumRedBits   = (BYTE) pixelFormat.accumulationBufferRedBits;
        pfd.cAccumGreenBits = (BYTE) pixelFormat.accumulationBufferGreenBits;
        pfd.cAccumBlueBits  = (BYTE) pixelFormat.accumulationBufferBlueBits;
        pfd.cAccumAlphaBits = (BYTE) pixelFormat.accumulationBufferAlphaBits;
    }

    static HGLRC createRenderContext (OpenGLVersion version, HDC dcIn)
    {
        const auto components = [&]() -> Optional<Version>
        {
            switch (version)
            {
                case OpenGLVersion::openGL3_2: return Version { 3, 2 };
                case OpenGLVersion::openGL4_1: return Version { 4, 1 };
                case OpenGLVersion::openGL4_3: return Version { 4, 3 };

                case OpenGLVersion::defaultGLVersion: break;
            }

            return {};
        }();

        if (components.hasValue() && wglCreateContextAttribsARB != nullptr)
        {
           #if JUCE_DEBUG
            constexpr auto contextFlags = WGL_CONTEXT_DEBUG_BIT_ARB;
           #else
            constexpr auto contextFlags = 0;
           #endif

            const int attribs[] =
            {
                WGL_CONTEXT_MAJOR_VERSION_ARB, components->major,
                WGL_CONTEXT_MINOR_VERSION_ARB, components->minor,
                WGL_CONTEXT_PROFILE_MASK_ARB,  WGL_CONTEXT_CORE_PROFILE_BIT_ARB,
                WGL_CONTEXT_FLAGS_ARB,         contextFlags,
                0
            };

            const auto c = wglCreateContextAttribsARB (dcIn, nullptr, attribs);

            if (c != nullptr)
                return c;
        }

        return wglCreateContext (dcIn);
    }

    //==============================================================================
    struct DummyComponent  : public Component
    {
        DummyComponent (NativeContext& c) : context (c) {}

        // The windowing code will call this when a paint callback happens
        void handleCommandMessage (int) override   { context.triggerRepaint(); }

        NativeContext& context;
    };

    //==============================================================================
    void nativeScaleFactorChanged (double newScaleFactor) override
    {
        if (approximatelyEqual (newScaleFactor, nativeScaleFactor)
            || safeComponent == nullptr)
            return;

        if (auto* peer = safeComponent->getTopLevelComponent()->getPeer())
        {
            nativeScaleFactor = newScaleFactor;
            updateWindowPosition (peer->getAreaCoveredBy (*safeComponent));
        }
    }

    void createNativeWindow (Component& component)
    {
        auto* topComp = component.getTopLevelComponent();

        {
            auto* parentHWND = topComp->getWindowHandle();

            ScopedThreadDPIAwarenessSetter setter { parentHWND };
            nativeWindow.reset (createNonRepaintingEmbeddedWindowsPeer (*dummyComponent, parentHWND));
        }

        if (auto* peer = topComp->getPeer())
        {
            safeComponent = Component::SafePointer<Component> (&component);

            nativeScaleFactor = peer->getPlatformScaleFactor();
            updateWindowPosition (peer->getAreaCoveredBy (component));
            peer->addScaleFactorListener (this);
        }

        nativeWindow->setVisible (true);
        dc = std::unique_ptr<std::remove_pointer_t<HDC>, DeviceContextDeleter> { GetDC ((HWND) nativeWindow->getNativeHandle()),
                                                                                 DeviceContextDeleter { (HWND) nativeWindow->getNativeHandle() } };
    }

    int wglChoosePixelFormatExtension (const OpenGLPixelFormat& pixelFormat) const
    {
        int format = 0;

        if (wglChoosePixelFormatARB != nullptr)
        {
            int atts[64];
            int n = 0;

            atts[n++] = WGL_DRAW_TO_WINDOW_ARB;   atts[n++] = GL_TRUE;
            atts[n++] = WGL_SUPPORT_OPENGL_ARB;   atts[n++] = GL_TRUE;
            atts[n++] = WGL_DOUBLE_BUFFER_ARB;    atts[n++] = GL_TRUE;
            atts[n++] = WGL_PIXEL_TYPE_ARB;       atts[n++] = WGL_TYPE_RGBA_ARB;
            atts[n++] = WGL_ACCELERATION_ARB;
            atts[n++] = WGL_FULL_ACCELERATION_ARB;

            atts[n++] = WGL_COLOR_BITS_ARB;  atts[n++] = pixelFormat.redBits + pixelFormat.greenBits + pixelFormat.blueBits;
            atts[n++] = WGL_RED_BITS_ARB;    atts[n++] = pixelFormat.redBits;
            atts[n++] = WGL_GREEN_BITS_ARB;  atts[n++] = pixelFormat.greenBits;
            atts[n++] = WGL_BLUE_BITS_ARB;   atts[n++] = pixelFormat.blueBits;
            atts[n++] = WGL_ALPHA_BITS_ARB;  atts[n++] = pixelFormat.alphaBits;
            atts[n++] = WGL_DEPTH_BITS_ARB;  atts[n++] = pixelFormat.depthBufferBits;

            atts[n++] = WGL_STENCIL_BITS_ARB;       atts[n++] = pixelFormat.stencilBufferBits;
            atts[n++] = WGL_ACCUM_RED_BITS_ARB;     atts[n++] = pixelFormat.accumulationBufferRedBits;
            atts[n++] = WGL_ACCUM_GREEN_BITS_ARB;   atts[n++] = pixelFormat.accumulationBufferGreenBits;
            atts[n++] = WGL_ACCUM_BLUE_BITS_ARB;    atts[n++] = pixelFormat.accumulationBufferBlueBits;
            atts[n++] = WGL_ACCUM_ALPHA_BITS_ARB;   atts[n++] = pixelFormat.accumulationBufferAlphaBits;

            if (pixelFormat.multisamplingLevel > 0
                  && OpenGLHelpers::isExtensionSupported ("GL_ARB_multisample"))
            {
                atts[n++] = WGL_SAMPLE_BUFFERS_ARB;
                atts[n++] = 1;
                atts[n++] = WGL_SAMPLES_ARB;
                atts[n++] = pixelFormat.multisamplingLevel;
            }

            atts[n++] = 0;
            jassert (n <= numElementsInArray (atts));

            UINT formatsCount = 0;
            wglChoosePixelFormatARB (dc.get(), atts, nullptr, 1, &format, &formatsCount);
        }

        return format;
    }

    //==============================================================================
    #define JUCE_DECLARE_WGL_EXTENSION_FUNCTION(name, returnType, params) \
        typedef returnType (__stdcall *type_ ## name) params; static type_ ## name name;

    JUCE_DECLARE_WGL_EXTENSION_FUNCTION (wglChoosePixelFormatARB,    BOOL,  (HDC, const int*, const FLOAT*, UINT, int*, UINT*))
    JUCE_DECLARE_WGL_EXTENSION_FUNCTION (wglSwapIntervalEXT,         BOOL,  (int))
    JUCE_DECLARE_WGL_EXTENSION_FUNCTION (wglGetSwapIntervalEXT,      int,   ())
    JUCE_DECLARE_WGL_EXTENSION_FUNCTION (wglCreateContextAttribsARB, HGLRC, (HDC, HGLRC, const int*))
    #undef JUCE_DECLARE_WGL_EXTENSION_FUNCTION

    //==============================================================================
    struct RenderContextDeleter
    {
        void operator() (HGLRC ptr) const { wglDeleteContext (ptr); }
    };

    struct DeviceContextDeleter
    {
        void operator() (HDC ptr) const { ReleaseDC (hwnd, ptr); }
        HWND hwnd;
    };

    std::unique_ptr<DummyComponent> dummyComponent;
    std::unique_ptr<ComponentPeer> nativeWindow;
    std::unique_ptr<ScopedThreadDPIAwarenessSetter> threadAwarenessSetter;
    Component::SafePointer<Component> safeComponent;
    std::unique_ptr<std::remove_pointer_t<HGLRC>, RenderContextDeleter> renderContext;
    std::unique_ptr<std::remove_pointer_t<HDC>, DeviceContextDeleter> dc;
    OpenGLContext* context = nullptr;
    double nativeScaleFactor = 1.0;

    //==============================================================================
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (NativeContext)
};


//==============================================================================
bool OpenGLHelpers::isContextActive()
{
    return wglGetCurrentContext() != nullptr;
}

} // namespace juce
