skia_rs_path/

path.rs

//! Path data structure and iteration.

use skia_rs_core::{Point, Rect, Scalar};
use smallvec::SmallVec;
use std::sync::atomic::{AtomicU8, Ordering};

/// Path fill type.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
#[repr(u8)]
pub enum FillType {
    /// Non-zero winding rule.
    #[default]
    Winding = 0,
    /// Even-odd rule.
    EvenOdd,
    /// Inverse non-zero winding.
    InverseWinding,
    /// Inverse even-odd.
    InverseEvenOdd,
}

impl FillType {
    /// Check if this is an inverse fill type.
    #[inline]
    pub const fn is_inverse(&self) -> bool {
        matches!(self, FillType::InverseWinding | FillType::InverseEvenOdd)
    }

    /// Convert to the inverse fill type.
    #[inline]
    pub const fn inverse(&self) -> Self {
        match self {
            FillType::Winding => FillType::InverseWinding,
            FillType::EvenOdd => FillType::InverseEvenOdd,
            FillType::InverseWinding => FillType::Winding,
            FillType::InverseEvenOdd => FillType::EvenOdd,
        }
    }
}

/// Path verb (command type).
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
#[repr(u8)]
pub enum Verb {
    /// Move to a point.
    Move = 0,
    /// Line to a point.
    Line,
    /// Quadratic bezier.
    Quad,
    /// Conic (weighted quadratic).
    Conic,
    /// Cubic bezier.
    Cubic,
    /// Close the current contour.
    Close,
}

impl Verb {
    /// Number of points consumed by this verb.
    #[inline]
    pub const fn point_count(&self) -> usize {
        match self {
            Verb::Move | Verb::Line => 1,
            Verb::Quad | Verb::Conic => 2,
            Verb::Cubic => 3,
            Verb::Close => 0,
        }
    }
}

/// Path direction (clockwise or counter-clockwise).
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
#[repr(u8)]
pub enum PathDirection {
    /// Clockwise direction.
    #[default]
    CW = 0,
    /// Counter-clockwise direction.
    CCW,
}

/// Path convexity.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
#[repr(u8)]
pub enum PathConvexity {
    /// Unknown convexity.
    #[default]
    Unknown = 0,
    /// Path is convex.
    Convex = 1,
    /// Path is concave.
    Concave = 2,
}

impl PathConvexity {
    fn from_u8(v: u8) -> Self {
        match v {
            1 => PathConvexity::Convex,
            2 => PathConvexity::Concave,
            _ => PathConvexity::Unknown,
        }
    }
}

/// A 2D geometric path.
#[derive(Debug)]
pub struct Path {
    /// Path verbs.
    pub(crate) verbs: SmallVec<[Verb; 16]>,
    /// Path points.
    pub(crate) points: SmallVec<[Point; 32]>,
    /// Conic weights.
    pub(crate) conic_weights: SmallVec<[Scalar; 4]>,
    /// Fill type.
    pub(crate) fill_type: FillType,
    /// Cached bounds (lazily computed).
    pub(crate) bounds: Option<Rect>,
    /// Cached convexity (stored as u8 for Send+Sync via AtomicU8).
    pub(crate) convexity: AtomicU8,
}

impl Default for Path {
    fn default() -> Self {
        Self {
            verbs: SmallVec::new(),
            points: SmallVec::new(),
            conic_weights: SmallVec::new(),
            fill_type: FillType::default(),
            bounds: None,
            convexity: AtomicU8::new(PathConvexity::Unknown as u8),
        }
    }
}

impl Clone for Path {
    fn clone(&self) -> Self {
        Self {
            verbs: self.verbs.clone(),
            points: self.points.clone(),
            conic_weights: self.conic_weights.clone(),
            fill_type: self.fill_type,
            bounds: self.bounds,
            convexity: AtomicU8::new(self.convexity.load(Ordering::Relaxed)),
        }
    }
}

impl PartialEq for Path {
    fn eq(&self, other: &Self) -> bool {
        self.verbs == other.verbs
            && self.points == other.points
            && self.conic_weights == other.conic_weights
            && self.fill_type == other.fill_type
    }
}

#[inline]
fn axis_of(p: Point, axis: usize) -> Scalar {
    if axis == 0 { p.x } else { p.y }
}

#[inline]
fn record_axis_bound(
    axis: usize,
    val: Scalar,
    min_x: &mut Scalar,
    max_x: &mut Scalar,
    min_y: &mut Scalar,
    max_y: &mut Scalar,
) {
    if axis == 0 {
        if val < *min_x { *min_x = val; }
        if val > *max_x { *max_x = val; }
    } else {
        if val < *min_y { *min_y = val; }
        if val > *max_y { *max_y = val; }
    }
}

impl Path {
    /// Create a new empty path.
    #[inline]
    pub fn new() -> Self {
        Self::default()
    }

    /// Get the fill type.
    #[inline]
    pub fn fill_type(&self) -> FillType {
        self.fill_type
    }

    /// Set the fill type.
    #[inline]
    pub fn set_fill_type(&mut self, fill_type: FillType) {
        self.fill_type = fill_type;
    }

    /// Check if the path is empty.
    #[inline]
    pub fn is_empty(&self) -> bool {
        self.verbs.is_empty()
    }

    /// Get the number of verbs.
    #[inline]
    pub fn verb_count(&self) -> usize {
        self.verbs.len()
    }

    /// Get the number of points.
    #[inline]
    pub fn point_count(&self) -> usize {
        self.points.len()
    }

    /// Get the bounds of the path.
    pub fn bounds(&self) -> Rect {
        if let Some(bounds) = self.bounds {
            return bounds;
        }

        if self.points.is_empty() {
            return Rect::EMPTY;
        }

        let mut min_x = self.points[0].x;
        let mut min_y = self.points[0].y;
        let mut max_x = min_x;
        let mut max_y = min_y;

        for p in &self.points[1..] {
            min_x = min_x.min(p.x);
            min_y = min_y.min(p.y);
            max_x = max_x.max(p.x);
            max_y = max_y.max(p.y);
        }

        Rect::new(min_x, min_y, max_x, max_y)
    }

    /// Clear the path.
    #[inline]
    pub fn reset(&mut self) {
        self.verbs.clear();
        self.points.clear();
        self.conic_weights.clear();
        self.bounds = None;
    }

    /// Iterate over the path elements.
    pub fn iter(&self) -> PathIter<'_> {
        PathIter {
            path: self,
            verb_index: 0,
            point_index: 0,
            weight_index: 0,
        }
    }

    /// Get the verbs slice.
    #[inline]
    pub fn verbs(&self) -> &[Verb] {
        &self.verbs
    }

    /// Get the points slice.
    #[inline]
    pub fn points(&self) -> &[Point] {
        &self.points
    }

    /// Get the last point in the path.
    #[inline]
    pub fn last_point(&self) -> Option<Point> {
        self.points.last().copied()
    }

    /// Get the number of contours in the path.
    pub fn contour_count(&self) -> usize {
        self.verbs.iter().filter(|v| **v == Verb::Move).count()
    }

    /// Check if the path is closed.
    pub fn is_closed(&self) -> bool {
        self.verbs.last() == Some(&Verb::Close)
    }

    /// Check if the path represents a line.
    pub fn is_line(&self) -> bool {
        self.verbs.len() == 2 && self.verbs[0] == Verb::Move && self.verbs[1] == Verb::Line
    }

    /// Check if the path represents a rectangle.
    pub fn is_rect(&self) -> Option<Rect> {
        // A rectangle has: Move, Line, Line, Line, Line, Close (or just 4 lines)
        if self.verbs.len() < 5 {
            return None;
        }

        let mut line_count = 0;
        let mut has_close = false;

        for verb in &self.verbs {
            match verb {
                Verb::Move => {}
                Verb::Line => line_count += 1,
                Verb::Close => has_close = true,
                _ => return None,
            }
        }

        if line_count != 4 || !has_close {
            return None;
        }

        // Check if points form a rectangle
        if self.points.len() < 5 {
            return None;
        }

        let p0 = self.points[0];
        let p1 = self.points[1];
        let p2 = self.points[2];
        let p3 = self.points[3];
        let p4 = self.points[4];

        // Check for axis-aligned rectangle
        let is_horizontal_1 = (p0.y - p1.y).abs() < 0.001;
        let is_vertical_2 = (p1.x - p2.x).abs() < 0.001;
        let is_horizontal_3 = (p2.y - p3.y).abs() < 0.001;
        let is_vertical_4 = (p3.x - p4.x).abs() < 0.001;

        if is_horizontal_1 && is_vertical_2 && is_horizontal_3 && is_vertical_4 {
            let left = p0.x.min(p1.x).min(p2.x).min(p3.x);
            let top = p0.y.min(p1.y).min(p2.y).min(p3.y);
            let right = p0.x.max(p1.x).max(p2.x).max(p3.x);
            let bottom = p0.y.max(p1.y).max(p2.y).max(p3.y);
            return Some(Rect::new(left, top, right, bottom));
        }

        None
    }

    /// Returns true if this path is a simple oval (ellipse).
    ///
    /// Verifies both verb structure (Move, 4 curves, Close) AND that the
    /// curve endpoints lie on the cardinal points of the bounding ellipse
    /// (left, right, top, bottom). This rejects 4-cubic paths that share
    /// the verb pattern but have arbitrary geometry.
    pub fn is_oval(&self) -> bool {
        let elements: Vec<_> = self.iter().collect();
        if elements.len() != 6 {
            return false;
        }

        let start = match elements[0] {
            PathElement::Move(p) => p,
            _ => return false,
        };
        if !matches!(elements[5], PathElement::Close) {
            return false;
        }

        let all_cubic = elements[1..5]
            .iter()
            .all(|e| matches!(e, PathElement::Cubic(_, _, _)));
        let all_conic = elements[1..5]
            .iter()
            .all(|e| matches!(e, PathElement::Conic(_, _, _)));
        if !all_cubic && !all_conic {
            return false;
        }

        let bounds = self.bounds();
        let cx = (bounds.left + bounds.right) * 0.5;
        let cy = (bounds.top + bounds.bottom) * 0.5;
        if bounds.right - bounds.left <= 0.0 || bounds.bottom - bounds.top <= 0.0 {
            return false;
        }

        let tolerance = ((bounds.right - bounds.left) + (bounds.bottom - bounds.top)) * 1e-4;
        let on_cardinal = |p: Point| -> bool {
            let on_h = (p.y - cy).abs() < tolerance
                && ((p.x - bounds.left).abs() < tolerance
                    || (p.x - bounds.right).abs() < tolerance);
            let on_v = (p.x - cx).abs() < tolerance
                && ((p.y - bounds.top).abs() < tolerance
                    || (p.y - bounds.bottom).abs() < tolerance);
            on_h || on_v
        };

        if !on_cardinal(start) {
            return false;
        }

        for elem in &elements[1..5] {
            let end = match *elem {
                PathElement::Cubic(_, _, p) => p,
                PathElement::Conic(_, p, _) => p,
                _ => return false,
            };
            if !on_cardinal(end) {
                return false;
            }
        }

        true
    }

    /// Get the convexity of the path.
    pub fn convexity(&self) -> PathConvexity {
        let cached = PathConvexity::from_u8(self.convexity.load(Ordering::Relaxed));
        if cached != PathConvexity::Unknown {
            return cached;
        }

        // Simple convexity check based on cross product signs
        if self.points.len() < 3 {
            let result = PathConvexity::Convex;
            self.convexity.store(result as u8, Ordering::Relaxed);
            return result;
        }

        let mut sign = 0i32;
        let n = self.points.len();

        for i in 0..n {
            let p0 = self.points[i];
            let p1 = self.points[(i + 1) % n];
            let p2 = self.points[(i + 2) % n];

            let cross = (p1.x - p0.x) * (p2.y - p1.y) - (p1.y - p0.y) * (p2.x - p1.x);

            if cross.abs() > 0.001 {
                let current_sign = if cross > 0.0 { 1 } else { -1 };
                if sign == 0 {
                    sign = current_sign;
                } else if sign != current_sign {
                    let result = PathConvexity::Concave;
                    self.convexity.store(result as u8, Ordering::Relaxed);
                    return result;
                }
            }
        }

        let result = PathConvexity::Convex;
        self.convexity.store(result as u8, Ordering::Relaxed);
        result
    }

    /// Check if the path is convex.
    #[inline]
    pub fn is_convex(&self) -> bool {
        self.convexity() == PathConvexity::Convex
    }

    /// Get the direction of the first contour.
    pub fn direction(&self) -> Option<PathDirection> {
        if self.points.len() < 3 {
            return None;
        }

        // Calculate signed area using shoelace formula
        let mut signed_area = 0.0;
        let n = self.points.len();

        for i in 0..n {
            let p0 = self.points[i];
            let p1 = self.points[(i + 1) % n];
            signed_area += (p1.x - p0.x) * (p1.y + p0.y);
        }

        if signed_area.abs() < 0.001 {
            return None;
        }

        Some(if signed_area > 0.0 {
            PathDirection::CW
        } else {
            PathDirection::CCW
        })
    }

    /// Reverse the path direction.
    pub fn reverse(&mut self) {
        if self.verbs.is_empty() {
            return;
        }

        // Reverse points
        self.points.reverse();

        // Reverse conic weights
        self.conic_weights.reverse();

        // Reverse verbs (keeping structure)
        // This is a simplified implementation
        let mut new_verbs = SmallVec::new();
        let mut i = self.verbs.len();

        while i > 0 {
            i -= 1;
            match self.verbs[i] {
                Verb::Move => {
                    if !new_verbs.is_empty() {
                        new_verbs.push(Verb::Close);
                    }
                    new_verbs.push(Verb::Move);
                }
                Verb::Close => {
                    // Skip, will be added before next Move
                }
                v => new_verbs.push(v),
            }
        }

        if !new_verbs.is_empty() && self.is_closed() {
            new_verbs.push(Verb::Close);
        }

        self.verbs = new_verbs;
        self.bounds = None;
        self.convexity.store(PathConvexity::Unknown as u8, Ordering::Relaxed);
    }

    /// Transform the path by a matrix.
    pub fn transform(&mut self, matrix: &skia_rs_core::Matrix) {
        for point in &mut self.points {
            *point = matrix.map_point(*point);
        }
        self.bounds = None;
        self.convexity.store(PathConvexity::Unknown as u8, Ordering::Relaxed);
    }

    /// Create a transformed copy of the path.
    pub fn transformed(&self, matrix: &skia_rs_core::Matrix) -> Self {
        let mut result = self.clone();
        result.transform(matrix);
        result
    }

    /// Offset the path by (dx, dy).
    pub fn offset(&mut self, dx: Scalar, dy: Scalar) {
        for point in &mut self.points {
            point.x += dx;
            point.y += dy;
        }
        if let Some(ref mut bounds) = self.bounds {
            bounds.left += dx;
            bounds.right += dx;
            bounds.top += dy;
            bounds.bottom += dy;
        }
    }

    /// Check if a point is inside the path (using fill rule).
    pub fn contains(&self, point: Point) -> bool {
        use crate::flatten::{flatten_cubic_adaptive, flatten_conic_adaptive, flatten_quad_adaptive};

        // Ray casting algorithm
        if !self.bounds().contains(point) {
            return false;
        }

        let mut crossings = 0;
        let mut current = Point::zero();
        let mut contour_start = Point::zero();
        const TOL: Scalar = 0.1;
        let mut pts: Vec<Point> = Vec::with_capacity(32);

        for element in self.iter() {
            match element {
                PathElement::Move(p) => {
                    current = p;
                    contour_start = p;
                }
                PathElement::Line(end) => {
                    if ray_crosses_segment(point, current, end) {
                        crossings += 1;
                    }
                    current = end;
                }
                PathElement::Quad(ctrl, end) => {
                    pts.clear();
                    flatten_quad_adaptive(&mut pts, current, ctrl, end, TOL);
                    let mut prev = current;
                    for pt in &pts {
                        if ray_crosses_segment(point, prev, *pt) {
                            crossings += 1;
                        }
                        prev = *pt;
                    }
                    current = end;
                }
                PathElement::Conic(ctrl, end, w) => {
                    pts.clear();
                    flatten_conic_adaptive(&mut pts, current, ctrl, end, w, TOL);
                    let mut prev = current;
                    for pt in &pts {
                        if ray_crosses_segment(point, prev, *pt) {
                            crossings += 1;
                        }
                        prev = *pt;
                    }
                    current = end;
                }
                PathElement::Cubic(c1, c2, end) => {
                    pts.clear();
                    flatten_cubic_adaptive(&mut pts, current, c1, c2, end, TOL);
                    let mut prev = current;
                    for pt in &pts {
                        if ray_crosses_segment(point, prev, *pt) {
                            crossings += 1;
                        }
                        prev = *pt;
                    }
                    current = end;
                }
                PathElement::Close => {
                    if ray_crosses_segment(point, current, contour_start) {
                        crossings += 1;
                    }
                    current = contour_start;
                }
            }
        }

        match self.fill_type {
            FillType::Winding => crossings != 0,
            FillType::EvenOdd => crossings % 2 != 0,
            FillType::InverseWinding => crossings == 0,
            FillType::InverseEvenOdd => crossings % 2 == 0,
        }
    }

    /// Returns the tight bounding rectangle of this path.
    ///
    /// Unlike `bounds()`, this computes the bounds from the actual curve
    /// extents, not the control-point bounding box. For cubic and quadratic
    /// Bezier curves with control points outside the actual curve range,
    /// tight_bounds() may be significantly smaller than bounds().
    ///
    /// Conics fall back to control-polygon bounds (exact extrema for rational
    /// curves would require solving a quartic).
    pub fn tight_bounds(&self) -> Rect {
        if self.verbs.is_empty() {
            return Rect::EMPTY;
        }

        let mut min_x = Scalar::INFINITY;
        let mut min_y = Scalar::INFINITY;
        let mut max_x = Scalar::NEG_INFINITY;
        let mut max_y = Scalar::NEG_INFINITY;

        let include = |p: Point, min_x: &mut Scalar, min_y: &mut Scalar, max_x: &mut Scalar, max_y: &mut Scalar| {
            if p.x < *min_x { *min_x = p.x; }
            if p.y < *min_y { *min_y = p.y; }
            if p.x > *max_x { *max_x = p.x; }
            if p.y > *max_y { *max_y = p.y; }
        };

        let mut current = Point::new(0.0, 0.0);

        for elem in self.iter() {
            match elem {
                PathElement::Move(p) | PathElement::Line(p) => {
                    include(p, &mut min_x, &mut min_y, &mut max_x, &mut max_y);
                    current = p;
                }
                PathElement::Quad(c, p) => {
                    include(current, &mut min_x, &mut min_y, &mut max_x, &mut max_y);
                    include(p, &mut min_x, &mut min_y, &mut max_x, &mut max_y);
                    // Quadratic extremum per axis: t = (start - ctrl) / (start - 2*ctrl + end)
                    for axis in 0..2 {
                        let s = axis_of(current, axis);
                        let cv = axis_of(c, axis);
                        let e = axis_of(p, axis);
                        let denom = s - 2.0 * cv + e;
                        if denom.abs() > 1e-9 {
                            let t = (s - cv) / denom;
                            if t > 0.0 && t < 1.0 {
                                let mt = 1.0 - t;
                                let val = mt * mt * s + 2.0 * mt * t * cv + t * t * e;
                                record_axis_bound(axis, val, &mut min_x, &mut max_x, &mut min_y, &mut max_y);
                            }
                        }
                    }
                    current = p;
                }
                PathElement::Cubic(c1, c2, p) => {
                    include(current, &mut min_x, &mut min_y, &mut max_x, &mut max_y);
                    include(p, &mut min_x, &mut min_y, &mut max_x, &mut max_y);
                    // Cubic extrema per axis: solve 3*a*t^2 + 2*b*t + c = 0 where
                    // B'(t) = 3*(1-t)^2*(c1-s) + 6*(1-t)*t*(c2-c1) + 3*t^2*(e-c2)
                    // Expanding into quadratic: a*t^2 + b*t + cc
                    for axis in 0..2 {
                        let s = axis_of(current, axis);
                        let c1v = axis_of(c1, axis);
                        let c2v = axis_of(c2, axis);
                        let e = axis_of(p, axis);
                        let a = 3.0 * (e - 3.0 * c2v + 3.0 * c1v - s);
                        let b = 6.0 * (c2v - 2.0 * c1v + s);
                        let cc = 3.0 * (c1v - s);

                        let mut roots: [Scalar; 2] = [Scalar::NAN, Scalar::NAN];
                        let mut n_roots = 0;

                        if a.abs() < 1e-9 {
                            // Linear: b*t + cc = 0
                            if b.abs() > 1e-9 {
                                let t = -cc / b;
                                roots[0] = t;
                                n_roots = 1;
                            }
                        } else {
                            let disc = b * b - 4.0 * a * cc;
                            if disc >= 0.0 {
                                let sqrt_disc = disc.sqrt();
                                roots[0] = (-b + sqrt_disc) / (2.0 * a);
                                roots[1] = (-b - sqrt_disc) / (2.0 * a);
                                n_roots = 2;
                            }
                        }

                        for i in 0..n_roots {
                            let t = roots[i];
                            if t.is_finite() && t > 0.0 && t < 1.0 {
                                let mt = 1.0 - t;
                                let val = mt * mt * mt * s
                                    + 3.0 * mt * mt * t * c1v
                                    + 3.0 * mt * t * t * c2v
                                    + t * t * t * e;
                                record_axis_bound(axis, val, &mut min_x, &mut max_x, &mut min_y, &mut max_y);
                            }
                        }
                    }
                    current = p;
                }
                PathElement::Conic(c, p, _w) => {
                    // Rational extrema require quartic solve; use control polygon
                    // as a correct (if looser) upper bound.
                    include(current, &mut min_x, &mut min_y, &mut max_x, &mut max_y);
                    include(c, &mut min_x, &mut min_y, &mut max_x, &mut max_y);
                    include(p, &mut min_x, &mut min_y, &mut max_x, &mut max_y);
                    current = p;
                }
                PathElement::Close => {}
            }
        }

        if min_x == Scalar::INFINITY {
            return Rect::EMPTY;
        }
        Rect::new(min_x, min_y, max_x, max_y)
    }

    /// Get the total length of the path.
    pub fn length(&self) -> Scalar {
        use crate::flatten::{flatten_cubic_adaptive, flatten_conic_adaptive, flatten_quad_adaptive};

        let mut total = 0.0;
        let mut current = Point::zero();
        let mut contour_start = Point::zero();
        const TOL: Scalar = 0.25;
        let mut pts: Vec<Point> = Vec::with_capacity(32);

        for element in self.iter() {
            match element {
                PathElement::Move(p) => {
                    current = p;
                    contour_start = p;
                }
                PathElement::Line(end) => {
                    total += current.distance(&end);
                    current = end;
                }
                PathElement::Quad(ctrl, end) => {
                    pts.clear();
                    flatten_quad_adaptive(&mut pts, current, ctrl, end, TOL);
                    let mut prev = current;
                    for pt in &pts {
                        total += prev.distance(pt);
                        prev = *pt;
                    }
                    current = end;
                }
                PathElement::Conic(ctrl, end, w) => {
                    pts.clear();
                    flatten_conic_adaptive(&mut pts, current, ctrl, end, w, TOL);
                    let mut prev = current;
                    for pt in &pts {
                        total += prev.distance(pt);
                        prev = *pt;
                    }
                    current = end;
                }
                PathElement::Cubic(c1, c2, end) => {
                    pts.clear();
                    flatten_cubic_adaptive(&mut pts, current, c1, c2, end, TOL);
                    let mut prev = current;
                    for pt in &pts {
                        total += prev.distance(pt);
                        prev = *pt;
                    }
                    current = end;
                }
                PathElement::Close => {
                    total += current.distance(&contour_start);
                    current = contour_start;
                }
            }
        }

        total
    }
}

/// Check if a horizontal ray from point crosses the segment.
fn ray_crosses_segment(point: Point, p0: Point, p1: Point) -> bool {
    // Ensure p0 is below p1
    let (p0, p1) = if p0.y <= p1.y { (p0, p1) } else { (p1, p0) };

    // Check if point is in y-range of segment
    if point.y < p0.y || point.y >= p1.y {
        return false;
    }

    // Calculate x-coordinate of intersection
    let t = (point.y - p0.y) / (p1.y - p0.y);
    let x_intersect = p0.x + t * (p1.x - p0.x);

    x_intersect > point.x
}

/// A path element from iteration.
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum PathElement {
    /// Move to point.
    Move(Point),
    /// Line to point.
    Line(Point),
    /// Quadratic bezier (control, end).
    Quad(Point, Point),
    /// Conic (control, end, weight).
    Conic(Point, Point, Scalar),
    /// Cubic bezier (control1, control2, end).
    Cubic(Point, Point, Point),
    /// Close the path.
    Close,
}

/// Iterator over path elements.
pub struct PathIter<'a> {
    path: &'a Path,
    verb_index: usize,
    point_index: usize,
    weight_index: usize,
}

impl<'a> Iterator for PathIter<'a> {
    type Item = PathElement;

    fn next(&mut self) -> Option<Self::Item> {
        if self.verb_index >= self.path.verbs.len() {
            return None;
        }

        let verb = self.path.verbs[self.verb_index];
        self.verb_index += 1;

        let element = match verb {
            Verb::Move => {
                let p = self.path.points[self.point_index];
                self.point_index += 1;
                PathElement::Move(p)
            }
            Verb::Line => {
                let p = self.path.points[self.point_index];
                self.point_index += 1;
                PathElement::Line(p)
            }
            Verb::Quad => {
                let p1 = self.path.points[self.point_index];
                let p2 = self.path.points[self.point_index + 1];
                self.point_index += 2;
                PathElement::Quad(p1, p2)
            }
            Verb::Conic => {
                let p1 = self.path.points[self.point_index];
                let p2 = self.path.points[self.point_index + 1];
                let w = self.path.conic_weights[self.weight_index];
                self.point_index += 2;
                self.weight_index += 1;
                PathElement::Conic(p1, p2, w)
            }
            Verb::Cubic => {
                let p1 = self.path.points[self.point_index];
                let p2 = self.path.points[self.point_index + 1];
                let p3 = self.path.points[self.point_index + 2];
                self.point_index += 3;
                PathElement::Cubic(p1, p2, p3)
            }
            Verb::Close => PathElement::Close,
        };

        Some(element)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::PathBuilder;

    #[test]
    fn test_is_oval_true_for_actual_oval() {
        let mut builder = PathBuilder::new();
        builder.add_oval(&Rect::new(0.0, 0.0, 100.0, 50.0));
        let path = builder.build();
        assert!(path.is_oval(), "add_oval result should report is_oval=true");
    }

    #[test]
    fn test_is_oval_false_for_random_cubics() {
        // 4 cubics with arbitrary control points — should NOT be detected.
        let mut builder = PathBuilder::new();
        builder.move_to(0.0, 0.0);
        builder.cubic_to(10.0, 0.0, 20.0, 5.0, 30.0, 10.0);
        builder.cubic_to(40.0, 15.0, 50.0, 20.0, 60.0, 25.0);
        builder.cubic_to(70.0, 30.0, 80.0, 35.0, 90.0, 40.0);
        builder.cubic_to(95.0, 45.0, 100.0, 47.0, 0.0, 0.0);
        builder.close();
        let path = builder.build();
        assert!(!path.is_oval(), "Random 4-cubic path should not be detected as oval");
    }

    #[test]
    fn test_path_convexity_returns_consistent_result() {
        let mut builder = PathBuilder::new();
        builder.move_to(0.0, 0.0);
        builder.line_to(10.0, 0.0);
        builder.line_to(10.0, 10.0);
        builder.line_to(0.0, 10.0);
        builder.close();
        let path = builder.build();

        let c1 = path.convexity();
        let c2 = path.convexity();
        assert_eq!(c1, c2);
    }

    #[test]
    fn test_tight_bounds_smaller_than_bounds_for_curves() {
        // A cubic Bezier where control points extend far beyond the actual curve.
        // The "loose" bounds (bounds()) include control points; tight should be tighter.
        let mut builder = PathBuilder::new();
        builder.move_to(0.0, 0.0);
        builder.cubic_to(50.0, 100.0, 50.0, -100.0, 100.0, 0.0);
        let path = builder.build();

        let loose = path.bounds();
        let tight = path.tight_bounds();

        // Loose bounds include y=±100 control points
        assert!(
            loose.top <= -99.0 || loose.bottom >= 99.0,
            "Loose bounds should include control points (top={}, bottom={})",
            loose.top, loose.bottom
        );

        // Tight bounds should be strictly tighter on at least one of top/bottom
        assert!(
            tight.top > loose.top || tight.bottom < loose.bottom,
            "Tight bounds should be tighter than loose for this off-axis cubic"
        );

        // For this symmetric S-cubic, actual extrema are approximately ±19.245
        assert!(
            tight.bottom < 30.0 && tight.top > -30.0,
            "Tight bounds should reflect actual curve range (got top={}, bottom={})",
            tight.top, tight.bottom
        );
    }

    #[test]
    fn test_tight_bounds_same_as_bounds_for_lines() {
        // For line-only paths, tight_bounds should equal bounds
        let mut builder = PathBuilder::new();
        builder.move_to(10.0, 20.0);
        builder.line_to(30.0, 40.0);
        let path = builder.build();

        let loose = path.bounds();
        let tight = path.tight_bounds();
        assert!((loose.left - tight.left).abs() < 1e-4);
        assert!((loose.right - tight.right).abs() < 1e-4);
        assert!((loose.top - tight.top).abs() < 1e-4);
        assert!((loose.bottom - tight.bottom).abs() < 1e-4);
    }

    #[test]
    fn test_length_quarter_circle_close_to_pi_over_2() {
        // Quarter-circle arc as a conic with weight sqrt(2)/2.
        // Radius 1, circumference of full circle = 2π, quarter = π/2 ≈ 1.5708.
        let mut builder = PathBuilder::new();
        builder.move_to(1.0, 0.0);
        builder.conic_to(1.0, 1.0, 0.0, 1.0, std::f32::consts::FRAC_1_SQRT_2);
        let path = builder.build();
        let len = path.length();
        let expected = std::f32::consts::FRAC_PI_2;
        assert!(
            (len - expected).abs() < 0.05,
            "expected ~π/2 = {}, got {}",
            expected,
            len
        );
    }

    #[test]
    fn test_length_tight_cubic_less_than_control_polygon() {
        // Straight-line cubic: all 4 control points collinear. Length = chord length.
        // Control polygon length = 3x chord length. Old impl would return 3x.
        let mut builder = PathBuilder::new();
        builder.move_to(0.0, 0.0);
        builder.cubic_to(1.0, 0.0, 2.0, 0.0, 3.0, 0.0);
        let path = builder.build();
        let len = path.length();
        assert!(
            (len - 3.0).abs() < 0.1,
            "expected 3.0, got {}",
            len
        );
    }

    #[test]
    fn test_contains_conic_honors_weight() {
        // A quarter-circle conic + closing lines forms a filled quarter-disk.
        // A point inside the arc but outside the control triangle should still be contained.
        let mut builder = PathBuilder::new();
        builder.move_to(1.0, 0.0);
        builder.conic_to(1.0, 1.0, 0.0, 1.0, std::f32::consts::FRAC_1_SQRT_2);
        builder.line_to(0.0, 0.0);
        builder.close();
        let path = builder.build();

        // Point at (0.7, 0.3) is inside the quarter-circle (r = sqrt(0.49 + 0.09) ≈ 0.76 < 1)
        assert!(
            path.contains(Point::new(0.7, 0.3)),
            "point inside quarter-disk should be contained"
        );

        // Point at (0.9, 0.9) is outside the arc (r = sqrt(0.81 + 0.81) ≈ 1.27 > 1)
        assert!(
            !path.contains(Point::new(0.9, 0.9)),
            "point outside quarter-disk should not be contained"
        );
    }
}