/*
 * Copyright (C) 2024 Igalia S.L.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "PlatformDisplay.h"

#if USE(SKIA)
#include "FontRenderOptions.h"
#include "GLContext.h"

WTF_IGNORE_WARNINGS_IN_THIRD_PARTY_CODE_BEGIN
#include <skia/core/SkColorSpace.h>
#include <skia/gpu/ganesh/GrBackendSurface.h>
#include <skia/gpu/ganesh/SkSurfaceGanesh.h>
#include <skia/gpu/ganesh/gl/GrGLBackendSurface.h>
#include <skia/gpu/ganesh/gl/GrGLDirectContext.h>
#include <skia/gpu/ganesh/gl/GrGLInterface.h>

#if USE(LIBEPOXY)
#include <skia/gpu/ganesh/gl/epoxy/GrGLMakeEpoxyEGLInterface.h>
#else
#include <skia/gpu/ganesh/gl/egl/GrGLMakeEGLInterface.h>
#endif
WTF_IGNORE_WARNINGS_IN_THIRD_PARTY_CODE_BEGIN

#include <wtf/NeverDestroyed.h>
#include <wtf/RunLoop.h>
#include <wtf/ThreadSafeWeakPtr.h>
#include <wtf/text/StringToIntegerConversion.h>
#include <wtf/threads/BinarySemaphore.h>


namespace WebCore {

#if PLATFORM(WPE)
#if CPU(X86) || CPU(X86_64)
// On x86 ot x86_64 we need at least 8 samples for the antialiasing result to be similar
// to non MSAA.
static const unsigned s_defaultSampleCount = 8;
#else
// On embedded, we sacrifice a bit of antialiasing quality to save memory and improve
// performance.
static const unsigned s_defaultSampleCount = 4;
#endif
#else
// Disable MSAA by default.
static const unsigned s_defaultSampleCount = 0;
#endif

#if !(PLATFORM(PLAYSTATION) && USE(COORDINATED_GRAPHICS))
static sk_sp<const GrGLInterface> skiaGLInterface()
{
    static NeverDestroyed<sk_sp<const GrGLInterface>> grGLInterface {
#if USE(LIBEPOXY)
        GrGLInterfaces::MakeEpoxyEGL()
#else
        GrGLInterfaces::MakeEGL()
#endif
    };

    return grGLInterface.get();
}

static thread_local RefPtr<SkiaGLContext> s_skiaGLContext;

unsigned initializeMSAASampleCount(GrDirectContext* grContext)
{
    static std::once_flag onceFlag;
    static int sampleCount = s_defaultSampleCount;

    std::call_once(onceFlag, [grContext] {
        // Let the user override the default sample count if they want to.
        String envString = String::fromLatin1(getenv("WEBKIT_SKIA_MSAA_SAMPLE_COUNT"));
        if (!envString.isEmpty())
            sampleCount = parseInteger<unsigned>(envString).value_or(0);

        if (sampleCount <= 1) {
            // Values of 0 or 1 mean disabling MSAA.
            sampleCount = 0;
            return;
        }

        // Skia checks internally whether MSAA is supported, but also disables it for several platforms where it
        // knows there are bugs. The only way to know whether our sample count will work is trying to create a
        // surface with that value and check whether it works.
        auto imageInfo = SkImageInfo::Make(512, 512, kRGBA_8888_SkColorType, kPremul_SkAlphaType, SkColorSpace::MakeSRGB());
        SkSurfaceProps properties = { 0, FontRenderOptions::singleton().subpixelOrder() };
        auto surface = SkSurfaces::RenderTarget(grContext, skgpu::Budgeted::kNo, imageInfo, sampleCount, kTopLeft_GrSurfaceOrigin, &properties);

        // If the creation of the surface failed, disable MSAA.
        if (!surface)
            sampleCount = 0;
    });

    return sampleCount;
}

class SkiaGLContext : public ThreadSafeRefCountedAndCanMakeThreadSafeWeakPtr<SkiaGLContext> {
public:
    static Ref<SkiaGLContext> create(PlatformDisplay& display)
    {
        return adoptRef(*new SkiaGLContext(display));
    }

    ~SkiaGLContext() = default;

    void invalidate()
    {
        if (&RunLoop::current() == m_runLoop) {
            invalidateOnCurrentThread();
            return;
        }

        BinarySemaphore semaphore;
        m_runLoop->dispatch([&semaphore, this] {
            invalidateOnCurrentThread();
            semaphore.signal();
        });
        semaphore.wait();
    }

    GLContext* skiaGLContext() const
    {
        Locker locker { m_lock };
        return m_skiaGLContext.get();
    }

    GrDirectContext* skiaGrContext() const
    {
        Locker locker { m_lock };
        return m_skiaGrContext.get();
    }

    unsigned sampleCount() const
    {
        return m_sampleCount;
    }

private:
    explicit SkiaGLContext(PlatformDisplay& display)
        : m_runLoop(&RunLoop::current())
    {
        auto glContext = GLContext::createOffscreen(display);
        if (!glContext || !glContext->makeContextCurrent())
            return;

        // FIXME: add GrContextOptions, shader cache, etc.
        if (auto grContext = GrDirectContexts::MakeGL(skiaGLInterface())) {
            m_skiaGLContext = WTFMove(glContext);
            m_skiaGrContext = WTFMove(grContext);
            m_sampleCount = initializeMSAASampleCount(m_skiaGrContext.get());
        }
    }

    void invalidateOnCurrentThread()
    {
        Locker locker { m_lock };
        m_skiaGrContext = nullptr;
        m_skiaGLContext = nullptr;
    }

    RunLoop* m_runLoop { nullptr };
    std::unique_ptr<GLContext> m_skiaGLContext WTF_GUARDED_BY_LOCK(m_lock);
    sk_sp<GrDirectContext> m_skiaGrContext WTF_GUARDED_BY_LOCK(m_lock);
    mutable Lock m_lock;
    unsigned m_sampleCount { 0 };
};
#endif

GLContext* PlatformDisplay::skiaGLContext()
{
#if PLATFORM(GTK) || PLATFORM(WPE) || (PLATFORM(PLAYSTATION) && !USE(COORDINATED_GRAPHICS))
    if (!s_skiaGLContext) {
        s_skiaGLContext = SkiaGLContext::create(*this);
        m_skiaGLContexts.add(*s_skiaGLContext);
    }
    return s_skiaGLContext->skiaGLContext();
#else
    // The PlayStation OpenGL implementation does not dispatch to the context bound to
    // the current thread so Skia cannot use OpenGL with coordinated graphics.
    return nullptr;
#endif
}

GrDirectContext* PlatformDisplay::skiaGrContext()
{
    RELEASE_ASSERT(s_skiaGLContext);
    return s_skiaGLContext->skiaGrContext();
}

unsigned PlatformDisplay::msaaSampleCount() const
{
    return s_skiaGLContext->sampleCount();
}

void PlatformDisplay::invalidateSkiaGLContexts()
{
    auto contexts = WTFMove(m_skiaGLContexts);
    contexts.forEach([](auto& context) {
        context.invalidate();
    });
}

} // namespace WebCore

#endif // USE(SKIA)