/*

 * Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>

 * Copyright (c) 2023, MacDue <macdue@dueutil.tech>

 *

 * SPDX-License-Identifier: BSD-2-Clause

 */

#include <LibGfx/AntiAliasingPainter.h>

#include <LibWeb/Painting/SVGPathPaintable.h>

#include <LibWeb/Painting/SVGSVGPaintable.h>

namespace Web::Painting {

JS_DEFINE_ALLOCATOR(SVGPathPaintable);

JS::NonnullGCPtr<SVGPathPaintable> SVGPathPaintable::create(Layout::SVGGraphicsBox const& layout_box)

{

    return layout_box.heap().allocate_without_realm<SVGPathPaintable>(layout_box);

}

SVGPathPaintable::SVGPathPaintable(Layout::SVGGraphicsBox const& layout_box)

    : SVGGraphicsPaintable(layout_box)

{

}

Layout::SVGGraphicsBox const& SVGPathPaintable::layout_box() const

{

    return static_cast<Layout::SVGGraphicsBox const&>(layout_node());

}

TraversalDecision SVGPathPaintable::hit_test(CSSPixelPoint position, HitTestType type, Function<TraversalDecision(HitTestResult)> const& callback) const

{

    if (!computed_path().has_value())

        return TraversalDecision::Continue;

    auto transformed_bounding_box = computed_transforms().svg_to_css_pixels_transform().map_to_quad(computed_path()->bounding_box());

    if (!transformed_bounding_box.contains(position.to_type<float>()))

        return TraversalDecision::Continue;

    return SVGGraphicsPaintable::hit_test(position, type, callback);

}

static Gfx::WindingRule to_gfx_winding_rule(SVG::FillRule fill_rule)

{

    switch (fill_rule) {

    case SVG::FillRule::Nonzero:

        return Gfx::WindingRule::Nonzero;

    case SVG::FillRule::Evenodd:

        return Gfx::WindingRule::EvenOdd;

    default:

        VERIFY_NOT_REACHED();

    }

}

void SVGPathPaintable::paint(PaintContext& context, PaintPhase phase) const

{

    if (!is_visible() || !computed_path().has_value())

        return;

    SVGGraphicsPaintable::paint(context, phase);

    if (phase != PaintPhase::Foreground)

        return;

    auto& graphics_element = layout_box().dom_node();

    auto const* svg_node = layout_box().first_ancestor_of_type<Layout::SVGSVGBox>();

    auto svg_element_rect = svg_node->paintable_box()->absolute_rect();

    // FIXME: This should not be trucated to an int.

    DisplayListRecorderStateSaver save_painter { context.display_list_recorder() };

    auto offset = context.floored_device_point(svg_element_rect.location()).to_type<int>().to_type<float>();

    auto maybe_view_box = svg_node->dom_node().view_box();

    auto paint_transform = computed_transforms().svg_to_device_pixels_transform(context);

    Gfx::Path path = computed_path()->copy_transformed(paint_transform);

    // Fills are computed as though all subpaths are closed (https://svgwg.org/svg2-draft/painting.html#FillProperties)

    auto closed_path = [&] {

        // We need to fill the path before applying the stroke, however the filled

        // path must be closed, whereas the stroke path may not necessary be closed.

        // Copy the path and close it for filling, but use the previous path for stroke

        auto copy = path;

        copy.close_all_subpaths();

        return copy;

    };

    // Note: This is assuming .x_scale() == .y_scale() (which it does currently).

    auto viewbox_scale = paint_transform.x_scale();

    auto svg_viewport = [&] {

        if (maybe_view_box.has_value())

            return Gfx::FloatRect { maybe_view_box->min_x, maybe_view_box->min_y, maybe_view_box->width, maybe_view_box->height };

        return Gfx::FloatRect { { 0, 0 }, svg_element_rect.size().to_type<float>() };

    }();

    if (context.draw_svg_geometry_for_clip_path()) {

        // https://drafts.fxtf.org/css-masking/#ClipPathElement:

        // The raw geometry of each child element exclusive of rendering properties such as fill, stroke, stroke-width

        // within a clipPath conceptually defines a 1-bit mask (with the possible exception of anti-aliasing along

        // the edge of the geometry) which represents the silhouette of the graphics associated with that element.

        context.display_list_recorder().fill_path({

            .path = closed_path(),

            .color = Color::Black,

            .winding_rule = to_gfx_winding_rule(graphics_element.clip_rule().value_or(SVG::ClipRule::Nonzero)),

            .translation = offset,

        });

        return;

    }

    SVG::SVGPaintContext paint_context {

        .viewport = svg_viewport,

        .path_bounding_box = computed_path()->bounding_box(),

        .transform = paint_transform

    };

    auto fill_opacity = graphics_element.fill_opacity().value_or(1);

    auto winding_rule = to_gfx_winding_rule(graphics_element.fill_rule().value_or(SVG::FillRule::Nonzero));

    if (auto paint_style = graphics_element.fill_paint_style(paint_context); paint_style.has_value()) {

        context.display_list_recorder().fill_path({

            .path = closed_path(),

            .paint_style = *paint_style,

            .winding_rule = winding_rule,

            .opacity = fill_opacity,

            .translation = offset,

        });

    } else if (auto fill_color = graphics_element.fill_color(); fill_color.has_value()) {

        context.display_list_recorder().fill_path({

            .path = closed_path(),

            .color = fill_color->with_opacity(fill_opacity),

            .winding_rule = winding_rule,

            .translation = offset,

        });

    }

    Gfx::Path::CapStyle cap_style;

    switch (graphics_element.stroke_linecap().value_or(CSS::InitialValues::stroke_linecap())) {

    case CSS::StrokeLinecap::Butt:

        cap_style = Gfx::Path::CapStyle::Butt;

        break;

    case CSS::StrokeLinecap::Round:

        cap_style = Gfx::Path::CapStyle::Round;

        break;

    case CSS::StrokeLinecap::Square:

        cap_style = Gfx::Path::CapStyle::Square;

        break;

    }

    Gfx::Path::JoinStyle join_style;

    switch (graphics_element.stroke_linejoin().value_or(CSS::InitialValues::stroke_linejoin())) {

    case CSS::StrokeLinejoin::Miter:

        join_style = Gfx::Path::JoinStyle::Miter;

        break;

    case CSS::StrokeLinejoin::Round:

        join_style = Gfx::Path::JoinStyle::Round;

        break;

    case CSS::StrokeLinejoin::Bevel:

        join_style = Gfx::Path::JoinStyle::Bevel;

        break;

    }

    auto miter_limit = graphics_element.stroke_miterlimit().value_or(CSS::InitialValues::stroke_miterlimit()).resolved(layout_node());

    auto stroke_opacity = graphics_element.stroke_opacity().value_or(1);

    // Note: This is assuming .x_scale() == .y_scale() (which it does currently).

    float stroke_thickness = graphics_element.stroke_width().value_or(1) * viewbox_scale;

    if (auto paint_style = graphics_element.stroke_paint_style(paint_context); paint_style.has_value()) {

        context.display_list_recorder().stroke_path({

            .cap_style = cap_style,

            .join_style = join_style,

            .miter_limit = static_cast<float>(miter_limit),

            .path = path,

            .paint_style = *paint_style,

            .thickness = stroke_thickness,

            .opacity = stroke_opacity,

            .translation = offset,

        });

    } else if (auto stroke_color = graphics_element.stroke_color(); stroke_color.has_value()) {

        context.display_list_recorder().stroke_path({

            .cap_style = cap_style,

            .join_style = join_style,

            .miter_limit = static_cast<float>(miter_limit),

            .path = path,

            .color = stroke_color->with_opacity(stroke_opacity),

            .thickness = stroke_thickness,

            .translation = offset,

        });

    }

}

}