/*
 * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
 * Copyright (C) 2007 Alp Toker <alp@atoker.com>
 *
 * 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 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 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 "Gradient.h"

#if USE(CG)

#include "GraphicsContextCG.h"
#include <pal/spi/cg/CoreGraphicsSPI.h>
#include <wtf/RetainPtr.h>

namespace WebCore {

void Gradient::platformDestroy()
{
    CGGradientRelease(m_gradient);
    m_gradient = nullptr;
}

CGGradientRef Gradient::platformGradient()
{
    if (m_gradient)
        return m_gradient;

    sortStopsIfNecessary();

    auto colorsArray = adoptCF(CFArrayCreateMutable(0, m_stops.size(), &kCFTypeArrayCallBacks));
    unsigned numStops = m_stops.size();

    const int reservedStops = 3;
    Vector<CGFloat, reservedStops> locations;
    locations.reserveInitialCapacity(numStops);

    Vector<CGFloat, 4 * reservedStops> colorComponents;
    colorComponents.reserveInitialCapacity(numStops * 4);

    bool hasExtendedColors = false;
    for (const auto& stop : m_stops) {

        // If all the stops are sRGB, it is faster to create a gradient using
        // components than CGColors.
        // FIXME: Rather than just check for extended colors, we should check the actual
        // color space, and whether or not the components are outside [0-1].
        // <rdar://problem/32926606>

        if (stop.color.isExtended())
            hasExtendedColors = true;

        auto [colorSpace, components] = stop.color.colorSpaceAndComponents();
        auto [r, g, b, a] = components;
        colorComponents.uncheckedAppend(r);
        colorComponents.uncheckedAppend(g);
        colorComponents.uncheckedAppend(b);
        colorComponents.uncheckedAppend(a);

        CFArrayAppendValue(colorsArray.get(), cachedCGColor(stop.color));
        locations.uncheckedAppend(stop.offset);
    }

    if (hasExtendedColors)
        m_gradient = CGGradientCreateWithColors(extendedSRGBColorSpaceRef(), colorsArray.get(), locations.data());
    else
        m_gradient = CGGradientCreateWithColorComponents(sRGBColorSpaceRef(), colorComponents.data(), locations.data(), numStops);

    return m_gradient;
}

void Gradient::fill(GraphicsContext& context, const FloatRect& rect)
{
    context.clip(rect);
    paint(context);
}

void Gradient::paint(GraphicsContext& context)
{
    paint(context.platformContext());
}

void Gradient::paint(CGContextRef platformContext)
{
    CGGradientDrawingOptions extendOptions = kCGGradientDrawsBeforeStartLocation | kCGGradientDrawsAfterEndLocation;
    CGGradientRef gradient = platformGradient();

    WTF::switchOn(m_data,
        [&] (const LinearData& data) {
            switch (m_spreadMethod) {
            case GradientSpreadMethod::Repeat:
            case GradientSpreadMethod::Reflect: {
                CGContextStateSaver saveState(platformContext);

                FloatPoint gradientVectorNorm(data.point1 - data.point0);
                gradientVectorNorm.normalize();
                CGFloat angle = acos(gradientVectorNorm.dot({ 1, 0 }));
                CGContextRotateCTM(platformContext, angle);

                CGAffineTransform transform = CGAffineTransformMakeRotation(-angle);
                FloatPoint point0 = CGPointApplyAffineTransform(data.point0, transform);
                FloatPoint point1 = CGPointApplyAffineTransform(data.point1, transform);

                CGRect boundingBox = CGContextGetClipBoundingBox(platformContext);
                CGFloat width = point1.x() - point0.x();
                CGFloat pixelSize = CGFAbs(CGContextConvertSizeToUserSpace(platformContext, CGSizeMake(1, 1)).width);

                if (width > 0 && !CGRectIsInfinite(boundingBox) && !CGRectIsEmpty(boundingBox)) {
                    extendOptions = 0;
                    if (width < pixelSize)
                        width = pixelSize;

                    CGFloat gradientStart = point0.x();
                    CGFloat gradientEnd = point1.x();
                    bool flip = m_spreadMethod == GradientSpreadMethod::Reflect;

                    // Find first gradient position to the left of the bounding box
                    int n = CGFloor((boundingBox.origin.x - gradientStart) / width);
                    gradientStart += n * width;
                    if (!(n % 2))
                        flip = false;

                    gradientEnd -= CGFloor((gradientEnd - CGRectGetMaxX(boundingBox)) / width) * width;

                    for (CGFloat start = gradientStart; start <= gradientEnd; start += width) {
                        CGPoint left = CGPointMake(flip ? start + width : start, boundingBox.origin.y);
                        CGPoint right = CGPointMake(flip ? start : start + width, boundingBox.origin.y);

                        CGContextDrawLinearGradient(platformContext, gradient, left, right, extendOptions);

                        if (m_spreadMethod == GradientSpreadMethod::Reflect)
                            flip = !flip;
                    }

                    break;
                }

                FALLTHROUGH;
            }
            case GradientSpreadMethod::Pad:
                CGContextDrawLinearGradient(platformContext, gradient, data.point0, data.point1, extendOptions);
            }
        },
        [&] (const RadialData& data) {
            bool needScaling = data.aspectRatio != 1;
            if (needScaling) {
                CGContextSaveGState(platformContext);
                // Scale from the center of the gradient. We only ever scale non-deprecated gradients,
                // for which point0 == point1.
                ASSERT(data.point0 == data.point1);
                CGContextTranslateCTM(platformContext, data.point0.x(), data.point0.y());
                CGContextScaleCTM(platformContext, 1, 1 / data.aspectRatio);
                CGContextTranslateCTM(platformContext, -data.point0.x(), -data.point0.y());
            }

            CGContextDrawRadialGradient(platformContext, gradient, data.point0, data.startRadius, data.point1, data.endRadius, extendOptions);

            if (needScaling)
                CGContextRestoreGState(platformContext);
        },
        [&] (const ConicData& data) {
// FIXME: Seems like this should be HAVE(CG_CONTEXT_DRAW_CONIC_GRADIENT).
// FIXME: Can we change tvOS to be like the other Cocoa platforms?
#if PLATFORM(COCOA) && !PLATFORM(APPLETV)
            CGContextSaveGState(platformContext);
            CGContextTranslateCTM(platformContext, data.point0.x(), data.point0.y());
            CGContextRotateCTM(platformContext, (CGFloat)-M_PI_2);
            CGContextTranslateCTM(platformContext, -data.point0.x(), -data.point0.y());
            CGContextDrawConicGradient(platformContext, platformGradient(), data.point0, data.angleRadians);
            CGContextRestoreGState(platformContext);
#else
            UNUSED_PARAM(data);
#endif
        }
    );
}

}

#endif