//! Layout tree.

//!

//! The idea is to take the DOM tree and produce a layout tree with SVG concepts.

use std::rc::Rc;

use cssparser::Color;

use float_cmp::approx_eq;

use crate::aspect_ratio::AspectRatio;

use crate::bbox::BoundingBox;

use crate::cairo_path::CairoPath;

use crate::coord_units::CoordUnits;

use crate::dasharray::Dasharray;

use crate::document::AcquiredNodes;

use crate::element::{Element, ElementData};

use crate::filter::FilterValueList;

use crate::length::*;

use crate::node::*;

use crate::paint_server::{PaintSource, UserSpacePaintSource};

use crate::path_builder::Path as SvgPath;

use crate::properties::{

    self, ClipRule, ComputedValues, Direction, FillRule, FontFamily, FontStretch, FontStyle,

    FontVariant, FontWeight, ImageRendering, Isolation, MixBlendMode, Opacity, Overflow,

    PaintOrder, ShapeRendering, StrokeDasharray, StrokeLinecap, StrokeLinejoin, StrokeMiterlimit,

    TextDecoration, TextRendering, UnicodeBidi, VectorEffect, XmlLang,

};

use crate::rect::Rect;

use crate::rsvg_log;

use crate::session::Session;

use crate::surface_utils::shared_surface::SharedImageSurface;

use crate::transform::Transform;

use crate::unit_interval::UnitInterval;

use crate::viewbox::ViewBox;

use crate::{borrow_element_as, is_element_of_type};

/// SVG Stacking context, an inner node in the layout tree.

///

/// <https://www.w3.org/TR/SVG2/render.html#EstablishingStackingContex>

///

/// This is not strictly speaking an SVG2 stacking context, but a

/// looser version of it.  For example. the SVG spec mentions that a

/// an element should establish a stacking context if the `filter`

/// property applies to the element and is not `none`.  In that case,

/// the element is rendered as an "isolated group" -

/// <https://www.w3.org/TR/2015/CR-compositing-1-20150113/#csscompositingrules_SVG>

///

/// Here we store all the parameters that may lead to the decision to actually

/// render an element as an isolated group.

pub struct StackingContext {

    pub element_name: String,

    pub transform: Transform,

    pub opacity: Opacity,

    pub filter: Option<Filter>,

    pub clip_rect: Option<Rect>,

    pub clip_in_user_space: Option<Node>,

    pub clip_in_object_space: Option<Node>,

    pub mask: Option<Node>,

    pub mix_blend_mode: MixBlendMode,

    pub isolation: Isolation,

    /// Target from an `<a>` element

    pub link_target: Option<String>,

}

/// The item being rendered inside a stacking context.

pub struct Layer {

    pub kind: LayerKind,

    pub stacking_ctx: StackingContext,

}

pub enum LayerKind {

    Shape(Box<Shape>),

    Text(Box<Text>),

    Image(Box<Image>),

    Group(Box<Group>),

}

pub struct Group {

    pub children: Vec<Layer>,

    pub is_visible: bool, // FIXME: move to Layer?  All of them have this...

    pub establish_viewport: Option<LayoutViewport>,

}

/// Used for elements that need to establish a new viewport, like `<svg>`.

pub struct LayoutViewport {

    // transform goes in the group's layer's StackingContext

    /// Position and size of the element, per its x/y/width/height properties.

    /// For markers, this is markerWidth/markerHeight.

    pub geometry: Rect,

    /// viewBox attribute

    pub vbox: Option<ViewBox>,

    /// preserveAspectRatio attribute

    pub preserve_aspect_ratio: AspectRatio,

    /// overflow property

    pub overflow: Overflow,

}

/// Stroke parameters in user-space coordinates.

pub struct Stroke {

    pub width: f64,

    pub miter_limit: StrokeMiterlimit,

    pub line_cap: StrokeLinecap,

    pub line_join: StrokeLinejoin,

    pub dash_offset: f64,

    pub dashes: Box<[f64]>,

    // https://svgwg.org/svg2-draft/painting.html#non-scaling-stroke

    pub non_scaling: bool,

}

/// A path that has been validated for being suitable for Cairo.

///

/// As of 2024/Sep/25, Cairo converts path coordinates to fixed point, but it has several problems:

///

/// * For coordinates that are outside of the representable range in

///   fixed point, Cairo just clamps them.  It is not able to return

///   this condition as an error to the caller.

///

/// * Then, it has multiple cases of possible arithmetic overflow

///   while processing the paths for rendering.  Fixing this is an

///   ongoing project.

///

/// While Cairo gets better in these respects, librsvg will try to do

/// some mitigations, mainly about catching problematic coordinates

/// early and not passing them on to Cairo.

pub enum Path {

    /// Path that has been checked for being suitable for Cairo.

    ///

    /// Note that this also keeps a reference to the original [SvgPath], in addition to

    /// the lowered [CairoPath].  This is because the markers code still needs the former.

    Validated {

        cairo_path: CairoPath,

        path: Rc<SvgPath>,

        extents: Option<Rect>,

        stroke_paint: UserSpacePaintSource,

        fill_paint: UserSpacePaintSource,

    },

    /// Reason why the path was determined to be not suitable for Cairo.  This

    /// is just used for logging purposes.

    Invalid(String),

}

/// Paths and basic shapes resolved to a path.

pub struct Shape {

    pub path: Path,

    pub is_visible: bool,

    pub paint_order: PaintOrder,

    pub stroke: Stroke,

    pub fill_rule: FillRule,

    pub clip_rule: ClipRule,

    pub shape_rendering: ShapeRendering,

    pub marker_start: Marker,

    pub marker_mid: Marker,

    pub marker_end: Marker,

}

pub struct Marker {

    pub node_ref: Option<Node>,

    pub context_stroke: Rc<PaintSource>,

    pub context_fill: Rc<PaintSource>,

}

/// Image in user-space coordinates.

pub struct Image {

    pub surface: SharedImageSurface,

    pub is_visible: bool,

    pub rect: Rect,

    pub aspect: AspectRatio,

    pub overflow: Overflow,

    pub image_rendering: ImageRendering,

}

/// A single text span in user-space coordinates.

pub struct TextSpan {

    pub layout: pango::Layout,

    pub gravity: pango::Gravity,

    pub bbox: Option<BoundingBox>,

    pub is_visible: bool,

    pub x: f64,

    pub y: f64,

    pub paint_order: PaintOrder,

    pub stroke: Stroke,

    pub stroke_paint: UserSpacePaintSource,

    pub fill_paint: UserSpacePaintSource,

    pub text_rendering: TextRendering,

    pub link_target: Option<String>,

}

/// Fully laid-out text in user-space coordinates.

pub struct Text {

    pub spans: Vec<TextSpan>,

}

/// Font-related properties extracted from `ComputedValues`.

pub struct FontProperties {

    pub xml_lang: XmlLang,

    pub unicode_bidi: UnicodeBidi,

    pub direction: Direction,

    pub font_family: FontFamily,

    pub font_style: FontStyle,

    pub font_variant: FontVariant,

    pub font_weight: FontWeight,

    pub font_stretch: FontStretch,

    pub font_size: f64,

    pub letter_spacing: f64,

    pub text_decoration: TextDecoration,

}

pub struct Filter {

    pub filter_list: FilterValueList,

    pub current_color: Color,

    pub stroke_paint_source: Rc<PaintSource>,

    pub fill_paint_source: Rc<PaintSource>,

    pub normalize_values: NormalizeValues,

}

    values: &ComputedValues,

    acquired_nodes: &mut AcquiredNodes<'_>,

    session: &Session,

) -> Option<Filter> {

            filter_list,

            acquired_nodes,

            values,

            session,

        )),

    }

    filter_list: FilterValueList,

    acquired_nodes: &mut AcquiredNodes<'_>,

    values: &ComputedValues,

    session: &Session,

) -> Filter {

        acquired_nodes,

        current_color,

        session,

        acquired_nodes,

        current_color,

        session,

        current_color,

        normalize_values,

    }

impl StackingContext {

        session: &Session,

        acquired_nodes: &mut AcquiredNodes<'_>,

        element: &Element,

        transform: Transform,

        clip_rect: Option<Rect>,

        values: &ComputedValues,

    ) -> StackingContext {

        let opacity;

        let filter;

            // "The opacity, filter and display properties do not apply to the mask element"

            // https://drafts.fxtf.org/css-masking-1/#MaskElement

            }

            }

        }

                    .acquire(node_id)

                    .ok()

                }

                    _ => {

                        rsvg_log!(

                            "element {} references \"{}\" which is not a mask",

                            element,

                            mask_id

                        );

                    }

                }

                rsvg_log!(

                    "element {} references nonexistent mask \"{}\"",

                    element,

                    mask_id

                );

            }

            transform,

            clip_rect,

            mix_blend_mode,

            isolation,

        }

        session: &Session,

        acquired_nodes: &mut AcquiredNodes<'_>,

        element: &Element,

        transform: Transform,

        values: &ComputedValues,

        link_target: Option<String>,

    ) -> StackingContext {

        // Note that the clip_rect=Some(...) argument is only used by the markers code,

        // hence it is None here.  Something to refactor later.

            Isolation::Auto => {

        }

}

impl Stroke {

                .iter()

        };

            width,

            miter_limit,

            line_cap,

            line_join,

            dash_offset,

            non_scaling,

        }

}

impl FontProperties {

    /// Collects font properties from a `ComputedValues`.

    ///

    /// The `writing-mode` property is passed separately, as it must come from the `<text>` element,

    /// not the `<tspan>` whose computed values are being passed.

}