use acadrust::entities::{LwPolyline, LwVertex};
use cadkernel::geom2d::{
    signed_area, Curve, Polyline, PolylineVertex, RectangleFrame, Tolerance, Vec2,
};

use crate::t;

use crate::command::EntityTransform;
use crate::entities::common::{
    edit_prop as edit, edit_scalar_prop as edit_scalar, format_area, format_length, parse_f64,
    rectangle_grip, ro_prop as ro, square_grip, stepper_prop as stepper, VARIES_LABEL,
};
use crate::entities::traits::RenderConvertible;
use crate::scene::convert::acad_to_render::{extrusion_wall_tris, RenderEntity, RenderObject};
use crate::scene::model::object::{GripApply, GripDef, PropSection, PropValue, Property};
use crate::scene::model::wire_model::TangentGeom;

const TAU: f64 = std::f64::consts::TAU;
const REVCLOUD_BULGE: f64 = 0.5;
const MAX_REVCLOUD_VERTICES: usize = 100_000;
const WIDTH_EPSILON: f64 = 1.0e-9;

pub(crate) fn vertex_segment_widths(vertex: &LwVertex, constant_width: f64) -> (f64, f64) {
    if vertex.start_width > WIDTH_EPSILON || vertex.end_width > WIDTH_EPSILON {
        (vertex.start_width, vertex.end_width)
    } else {
        (constant_width, constant_width)
    }
}

pub(crate) fn lwpolyline_global_width(pline: &LwPolyline) -> Option<f64> {
    let count = pline.vertices.len();
    let seg_count = if pline.is_closed {
        count
    } else {
        count.saturating_sub(1)
    };
    if seg_count == 0 {
        return Some(pline.constant_width);
    }
    let (w0_start, w0_end) = vertex_segment_widths(&pline.vertices[0], pline.constant_width);
    if (w0_start - w0_end).abs() > 1e-6 {
        return None;
    }
    let w0 = w0_start;
    for i in 1..seg_count {
        let (sw, ew) = vertex_segment_widths(&pline.vertices[i], pline.constant_width);
        if (sw - ew).abs() > 1e-6 || (sw - w0).abs() > 1e-6 {
            return None;
        }
    }
    Some(w0)
}

/// Midpoint position on an arc segment defined by its bulge.
fn arc_midpoint(p0: [f64; 2], p1: [f64; 2], bulge: f64) -> [f64; 2] {
    match crate::entities::common::BulgeArc::from_bulge(p0, p1, bulge) {
        Some(arc) => arc.sample(0.5),
        None => [(p0[0] + p1[0]) * 0.5, (p0[1] + p1[1]) * 0.5],
    }
}

/// Compute the DXF bulge for an arc that passes through p0, mid_pt, and p1.
/// Returns None when the three points are collinear (straight segment).
///
/// The sign and sweep follow the p0 → mid → p1 traversal orientation, which
/// keeps it the exact inverse of `BulgeArc::from_bulge` + `sample(0.5)` (a
/// CCW traversal = positive bulge). It used to key off which chord side the
/// midpoint lies on — the opposite convention — so every grip-drag frame
/// flipped the arc to the other side and the radius jumped wildly instead of
/// following the cursor (#339).
fn bulge_from_midpoint(p0: [f64; 2], p1: [f64; 2], mid: [f64; 2]) -> Option<f64> {
    // Circumcircle of (p0, mid, p1)
    let ax = 2.0 * (mid[0] - p0[0]);
    let ay = 2.0 * (mid[1] - p0[1]);
    let bx = 2.0 * (p1[0] - p0[0]);
    let by = 2.0 * (p1[1] - p0[1]);
    let ca = mid[0] * mid[0] + mid[1] * mid[1] - p0[0] * p0[0] - p0[1] * p0[1];
    let cb = p1[0] * p1[0] + p1[1] * p1[1] - p0[0] * p0[0] - p0[1] * p0[1];
    let det = ax * by - ay * bx;
    if det.abs() < 1e-12 {
        return None; // collinear
    }
    let cx = (ca * by - cb * ay) / det;
    let cy = (ax * cb - bx * ca) / det;
    let a0 = (p0[1] - cy).atan2(p0[0] - cx);
    let a1 = (p1[1] - cy).atan2(p1[0] - cx);
    // Arc direction = orientation of the p0 → mid → p1 turn.
    let cross =
        (mid[0] - p0[0]) * (p1[1] - mid[1]) - (mid[1] - p0[1]) * (p1[0] - mid[0]);
    if cross == 0.0 {
        return None;
    }
    // Central angle measured along that direction, in (0, TAU).
    let sweep = if cross > 0.0 {
        (a1 - a0).rem_euclid(TAU)
    } else {
        (a0 - a1).rem_euclid(TAU)
    };
    let bulge = (sweep / 4.0).tan();
    Some(if cross > 0.0 { bulge } else { -bulge })
}

/// Bulges for the two consecutive arcs `p0 → mid` and `mid → p1` on the
/// circle through all three points. Used while placing a vertex inserted into
/// an arc segment so both halves keep meeting at the cursor.
fn split_bulges_from_point(
    p0: [f64; 2],
    mid: [f64; 2],
    p1: [f64; 2],
    original_bulge: f64,
) -> (f64, f64) {
    let d0 = (mid[0] - p0[0]).hypot(mid[1] - p0[1]);
    let d1 = (p1[0] - mid[0]).hypot(p1[1] - mid[1]);
    if d0 < 1e-12 {
        return (0.0, original_bulge);
    }
    if d1 < 1e-12 {
        return (original_bulge, 0.0);
    }
    let ax = 2.0 * (mid[0] - p0[0]);
    let ay = 2.0 * (mid[1] - p0[1]);
    let bx = 2.0 * (p1[0] - p0[0]);
    let by = 2.0 * (p1[1] - p0[1]);
    let ca = mid[0] * mid[0] + mid[1] * mid[1] - p0[0] * p0[0] - p0[1] * p0[1];
    let cb = p1[0] * p1[0] + p1[1] * p1[1] - p0[0] * p0[0] - p0[1] * p0[1];
    let det = ax * by - ay * bx;
    if det.abs() < 1e-12 {
        return (0.0, 0.0);
    }
    let cx = (ca * by - cb * ay) / det;
    let cy = (ax * cb - bx * ca) / det;
    let a0 = (p0[1] - cy).atan2(p0[0] - cx);
    let am = (mid[1] - cy).atan2(mid[0] - cx);
    let a1 = (p1[1] - cy).atan2(p1[0] - cx);
    let cross =
        (mid[0] - p0[0]) * (p1[1] - mid[1]) - (mid[1] - p0[1]) * (p1[0] - mid[0]);
    let bulge = |from: f64, to: f64| {
        if cross > 0.0 {
            ((to - from).rem_euclid(TAU) / 4.0).tan()
        } else {
            -((from - to).rem_euclid(TAU) / 4.0).tan()
        }
    };
    (bulge(a0, am), bulge(am, a1))
}

/// Refit the two arc segments around a newly inserted vertex. The caller
/// ensures this placement originated from an arc, so straight-segment Add
/// Vertex remains two straight segments when the cursor moves off the chord.
pub(crate) fn refit_added_arc_vertex(
    entity: &mut acadrust::EntityType,
    vertex_id: usize,
    original_bulge: f64,
) {
    match entity {
        acadrust::EntityType::LwPolyline(polyline) => {
            let n = polyline.vertices.len();
            if vertex_id == 0 || vertex_id >= n {
                return;
            }
            let next = if vertex_id + 1 < n {
                vertex_id + 1
            } else if polyline.is_closed {
                0
            } else {
                return;
            };
            let prev = vertex_id - 1;
            let p0 = polyline.vertices[prev].location;
            let mid = polyline.vertices[vertex_id].location;
            let p1 = polyline.vertices[next].location;
            let (first, second) = split_bulges_from_point(
                [p0.x, p0.y],
                [mid.x, mid.y],
                [p1.x, p1.y],
                original_bulge,
            );
            polyline.vertices[prev].bulge = first.clamp(-1e6, 1e6);
            polyline.vertices[vertex_id].bulge = second.clamp(-1e6, 1e6);
        }
        acadrust::EntityType::Polyline2D(polyline) => {
            let n = polyline.vertices.len();
            if vertex_id == 0 || vertex_id >= n {
                return;
            }
            let next = if vertex_id + 1 < n {
                vertex_id + 1
            } else if polyline.is_closed() {
                0
            } else {
                return;
            };
            let prev = vertex_id - 1;
            let p0 = &polyline.vertices[prev].location;
            let mid = &polyline.vertices[vertex_id].location;
            let p1 = &polyline.vertices[next].location;
            let (first, second) = split_bulges_from_point(
                [p0.x, p0.y],
                [mid.x, mid.y],
                [p1.x, p1.y],
                original_bulge,
            );
            polyline.vertices[prev].bulge = first.clamp(-1e6, 1e6);
            polyline.vertices[vertex_id].bulge = second.clamp(-1e6, 1e6);
        }
        _ => {}
    }
}

/// Tessellate a thick polyline segment list into NaN-separated Lines geometry.
/// Shared by LwPolyline and Polyline2D thickness paths.
fn thick_segments(
    seg_data: &[(f64, f64, f64, f64)], // (x0, y0, x1, y1) per seg — or use run of (x,y,bulge)
    path_pts: &[[f64; 3]],
    thickness: f64,
    normal: (f64, f64, f64),
    key_verts: Vec<[f64; 3]>,
    tangents: Vec<TangentGeom>,
) -> RenderEntity {
    let (nx, ny, nz) = normal;
    let t = thickness;
    let off = |p: [f64; 3]| -> [f64; 3] { [p[0] + t * nx, p[1] + t * ny, p[2] + t * nz] };
    let mut pts: Vec<[f64; 3]> = Vec::with_capacity(path_pts.len() * 2 + seg_data.len() * 3 + 4);
    // Bottom path
    pts.extend_from_slice(path_pts);
    pts.push([f64::NAN; 3]);
    // Top path
    for &p in path_pts {
        pts.push(off(p));
    }
    // Walls at each vertex (seg_data.0/.1 = start x/y of each seg, last seg appends its end too)
    if !seg_data.is_empty() {
        pts.push([f64::NAN; 3]);
        for (k, &(x0, y0, _x1, _y1)) in seg_data.iter().enumerate() {
            let pb = key_verts[k];
            let _ = (x0, y0); // key_verts already has correct WCS
            pts.push(pb);
            pts.push(off(pb));
            if k + 1 < seg_data.len() {
                pts.push([f64::NAN; 3]);
            }
        }
        // Last wall at the final vertex
        if let Some(&last) = key_verts.last() {
            pts.push([f64::NAN; 3]);
            pts.push(last);
            pts.push(off(last));
        }
    }
    RenderEntity {
        pick_tris: extrusion_wall_tris(path_pts, [t * nx, t * ny, t * nz]),
        object: RenderObject::Lines(pts),
        snap_pts: vec![],
        tangent_geoms: tangents,
        key_vertices: key_verts,
        fill_tris: vec![],
    }
}

/// Extrude a *wide* LwPolyline's band into a 3-D tube: each band segment's outer
/// and inner boundary rises by `thickness` (along the normal) into a wall,
/// leaving the two radial segment-end edges open (they are internal to the
/// band). The flat bottom band is already drawn by the wide-fill path; this
/// adds the vertical walls and their outline. Used instead of `thick_segments`
/// (which extrudes only the centreline) when the polyline carries a width.
fn thick_wide_band(
    pl: &LwPolyline,
    thickness: f64,
    to_wcs: &dyn Fn(f64, f64) -> (f64, f64, f64),
    normal: (f64, f64, f64),
    key_verts: Vec<[f64; 3]>,
    tangents: Vec<TangentGeom>,
) -> RenderEntity {
    let (origin, fills) = wide_fills(pl);
    let (fill_tris, lines) =
        crate::entities::common::thick_band_tube(origin, &fills, thickness, normal, to_wcs);

    RenderEntity {
        pick_tris: fill_tris.clone(),
        object: RenderObject::Lines(lines),
        snap_pts: vec![],
        tangent_geoms: tangents,
        key_vertices: key_verts,
        fill_tris,
    }
}

fn to_render(pline: &LwPolyline, fill_mode: bool) -> RenderEntity {
    let verts = &pline.vertices;
    if verts.is_empty() {
        return RenderEntity {
            pick_tris: Vec::new(),
            object: RenderObject::Lines(Vec::new()),
            snap_pts: vec![],
            tangent_geoms: vec![],
            key_vertices: vec![],
            fill_tris: vec![],
        };
    }

    let elev = pline.elevation;
    let normal = (pline.normal.x, pline.normal.y, pline.normal.z);
    let count = verts.len();
    let seg_count = if pline.is_closed { count } else { count - 1 };
    // Convert OCS (x, y, elevation) to a WCS point.
    let to_wcs = |x: f64, y: f64| -> (f64, f64, f64) {
        crate::scene::view::transform::ocs_point_to_wcs((x, y, elev), normal)
    };
    let to_pt = |v: &LwVertex| -> [f64; 3] {
        let (wx, wy, wz) = to_wcs(v.location.x, v.location.y);
        [wx, wy, wz]
    };

    let band_verts = band_verts(pline);
    if !fill_mode {
        let mut boundary = crate::entities::common::wide_band_outline(
            &band_verts,
            pline.is_closed,
            !pline.plinegen,
            &to_wcs,
        );
        if !boundary.points.is_empty() {
            if pline.thickness.abs() > 1e-10 {
                boundary = crate::entities::common::extrude_wide_band_outline(
                    boundary,
                    [
                        pline.thickness * normal.0,
                        pline.thickness * normal.1,
                        pline.thickness * normal.2,
                    ],
                );
            }
            let (tangent_geoms, key_vertices) = centerline_metadata(pline, &to_wcs);
            return RenderEntity {
                pick_tris: Vec::new(),
                object: RenderObject::BoundaryLines {
                    points: boundary.points,
                    stations: boundary.stations,
                    point_segments: boundary.point_segments,
                    station_pieces: boundary.station_pieces,
                    source_length: boundary.source_length,
                    plinegen: pline.plinegen,
                },
                snap_pts: vec![],
                tangent_geoms,
                key_vertices,
                fill_tris: vec![],
            };
        }
    }

    if pline.thickness.abs() > 1e-10 {
        let mut path: Vec<[f64; 3]> = Vec::new();
        let mut kv: Vec<[f64; 3]> = Vec::new();
        let mut tgs: Vec<TangentGeom> = Vec::new();
        let mut seg_data: Vec<(f64, f64, f64, f64)> = Vec::new();
        // First vertex
        let (w0x, w0y, w0z) = to_wcs(verts[0].location.x, verts[0].location.y);
        path.push([w0x, w0y, w0z]);
        kv.push([w0x, w0y, w0z]);
        for i in 0..seg_count {
            let va = &verts[i];
            let vb = &verts[(i + 1) % count];
            let (ox0, oy0) = (va.location.x, va.location.y);
            let (ox1, oy1) = (vb.location.x, vb.location.y);
            let bulge = va.bulge;
            if bulge.abs() < 1e-9 {
                let (wx, wy, wz) = to_wcs(ox1, oy1);
                path.push([wx, wy, wz]);
                let p1_pt = path[path.len() - 2];
                let p2_pt = *path.last().unwrap();
                tgs.push(TangentGeom::Line {
                    p1: [p1_pt[0] as f32, p1_pt[1] as f32, p1_pt[2] as f32],
                    p2: [p2_pt[0] as f32, p2_pt[1] as f32, p2_pt[2] as f32],
                });
            } else if let Some(arc) =
                crate::entities::common::BulgeArc::from_bulge([ox0, oy0], [ox1, oy1], bulge)
            {
                tgs.push(crate::entities::common::bulge_arc_to_tangent(&arc, &to_wcs, normal));
                for s in arc
                    .tessellate_angle(cadkernel::tessellation::DEFAULT_ANGLE)
                    .into_iter()
                    .skip(1)
                {
                    let (wx, wy, wz) = to_wcs(s[0], s[1]);
                    path.push([wx, wy, wz]);
                }
            }
            let (wbx, wby, wbz) = to_wcs(ox1, oy1);
            kv.push([wbx, wby, wbz]);
            seg_data.push((ox0, oy0, ox1, oy1));
        }
        // A wide polyline extrudes its whole band into a tube (outer + inner
        // walls); a zero-width one just extrudes its centreline.
        let is_wide = pline.constant_width > 1e-9
            || pline
                .vertices
                .iter()
                .any(|v| v.start_width > 1e-9 || v.end_width > 1e-9);
        if is_wide {
            return thick_wide_band(pline, pline.thickness, &to_wcs, normal, kv, tgs);
        }
        return thick_segments(&seg_data, &path, pline.thickness, normal, kv, tgs);
    }

    // A wide polyline whose per-vertex widths VARY renders a smooth taper —
    // handled here, before the PLINEGEN split, so both cases get it. A
    // uniform-width polyline falls through to the constant-band paths below.
    if tapered_band_verts(&band_verts).is_some() {
        let mut kv: Vec<[f64; 3]> = Vec::new();
        let mut tgs: Vec<TangentGeom> = Vec::new();
        for i in 0..seg_count {
            let v0 = &verts[i];
            let v1 = &verts[(i + 1) % count];
            let p0 = to_pt(v0);
            let p1 = to_pt(v1);
            if i == 0 {
                kv.push([p0[0], p0[1], p0[2]]);
            }
            kv.push([p1[0], p1[1], p1[2]]);
            if v0.bulge.abs() < 1e-9 {
                tgs.push(TangentGeom::Line {
                    p1: [p0[0] as f32, p0[1] as f32, p0[2] as f32],
                    p2: [p1[0] as f32, p1[1] as f32, p1[2] as f32],
                });
            } else if let Some(arc) = crate::entities::common::BulgeArc::from_bulge(
                [v0.location.x, v0.location.y],
                [v1.location.x, v1.location.y],
                v0.bulge,
            ) {
                tgs.push(crate::entities::common::bulge_arc_to_tangent(&arc, &to_wcs, normal));
            }
        }
        let (pts, widths) = crate::entities::common::tapered_band_points(
            &band_verts,
            pline.is_closed,
            &to_wcs,
        );
        let (fill_origin, fills) = wide_fills(pline);
        return RenderEntity {
            pick_tris: crate::entities::common::wide_band_tris(fill_origin, &fills),
            object: RenderObject::TaperedLines(pts, widths),
            snap_pts: vec![],
            tangent_geoms: tgs,
            key_vertices: kv,
            fill_tris: vec![],
        };
    }

    // plinegen=false: NaN-separated segments so the linetype pattern restarts per vertex.
    if !pline.plinegen {
        let mut pts: Vec<[f64; 3]> = Vec::new();
        let mut tgs: Vec<TangentGeom> = Vec::new();
        let mut kv: Vec<[f64; 3]> = Vec::new();
        let to_f32 = |p: [f64; 3]| -> [f32; 3] { [p[0] as f32, p[1] as f32, p[2] as f32] };
        for i in 0..seg_count {
            let va = &verts[i];
            let vb = &verts[(i + 1) % count];
            let (ox0, oy0) = (va.location.x, va.location.y);
            let (ox1, oy1) = (vb.location.x, vb.location.y);
            let bulge = va.bulge;
            let (wx0, wy0, wz0) = to_wcs(ox0, oy0);
            let p_start = [wx0, wy0, wz0];
            pts.push(p_start);
            if i == 0 {
                kv.push(p_start);
            }
            if bulge.abs() < 1e-9 {
                let (wx1, wy1, wz1) = to_wcs(ox1, oy1);
                let p_end = [wx1, wy1, wz1];
                pts.push(p_end);
                kv.push(p_end);
                tgs.push(TangentGeom::Line {
                    p1: to_f32(p_start),
                    p2: to_f32(p_end),
                });
            } else if let Some(arc) =
                crate::entities::common::BulgeArc::from_bulge([ox0, oy0], [ox1, oy1], bulge)
            {
                for s in arc
                    .tessellate_angle(cadkernel::tessellation::DEFAULT_ANGLE)
                    .into_iter()
                    .skip(1)
                {
                    let (wx, wy, wz) = to_wcs(s[0], s[1]);
                    pts.push([wx, wy, wz]);
                }
                let (wx1, wy1, wz1) = to_wcs(ox1, oy1);
                kv.push([wx1, wy1, wz1]);
                tgs.push(crate::entities::common::bulge_arc_to_tangent(&arc, &to_wcs, normal));
            }
            if i + 1 < seg_count {
                pts.push([f64::NAN; 3]);
            }
        }
        let (fill_origin, fills) = wide_fills(pline);
        return RenderEntity {
            pick_tris: crate::entities::common::wide_band_tris(fill_origin, &fills),
            object: RenderObject::SegmentedLines(pts),
            snap_pts: vec![],
            tangent_geoms: tgs,
            key_vertices: kv,
            fill_tris: vec![],
        };
    }

    let (tangents, key_verts) = centerline_metadata(pline, &to_wcs);
    let (fill_origin, fills) = wide_fills(pline);
    RenderEntity {
        pick_tris: crate::entities::common::wide_band_tris(fill_origin, &fills),
        // Sampled through the polyline's own curve, so a bulge stays an
        // arc rather than becoming the chord across it.
        object: RenderObject::Lines(
            crate::entities::curve::lwpolyline_curve(pline)
                .map(|planar| crate::entities::curve::curve_points(&planar))
                .unwrap_or_default(),
        ),
        snap_pts: vec![],
        tangent_geoms: tangents,
        key_vertices: key_verts,
        fill_tris: vec![],
    }
}

/// Effective segment widths for an LwPolyline band.
fn band_verts(pline: &LwPolyline) -> Vec<([f64; 2], f64, f64, f64)> {
    let c = pline.constant_width;
    pline
        .vertices
        .iter()
        .map(|v| {
            let (sw, ew) = vertex_segment_widths(v, c);
            ([v.location.x, v.location.y], v.bulge, sw, ew)
        })
        .collect()
}

fn tapered_band_verts(
    band: &[([f64; 2], f64, f64, f64)],
) -> Option<&[([f64; 2], f64, f64, f64)]> {
    let w0 = band.first().map_or(0.0, |v| v.2);
    let varies = band
        .iter()
        .any(|&(_, _, sw, ew)| (sw - w0).abs() > 1e-9 || (ew - w0).abs() > 1e-9);
    // Only a genuine, non-zero-width taper takes the per-point path.
    if varies && w0.max(band.iter().map(|v| v.3).fold(0.0, f64::max)) > 1e-9 {
        Some(band)
    } else {
        None
    }
}

fn centerline_metadata(
    pline: &LwPolyline,
    to_wcs: &dyn Fn(f64, f64) -> (f64, f64, f64),
) -> (Vec<TangentGeom>, Vec<[f64; 3]>) {
    let count = pline.vertices.len();
    let segment_count = if pline.is_closed {
        count
    } else {
        count.saturating_sub(1)
    };
    let mut tangents = Vec::with_capacity(segment_count);
    let mut key_vertices = Vec::with_capacity(segment_count + 1);
    for index in 0..segment_count {
        let start = &pline.vertices[index];
        let end = &pline.vertices[(index + 1) % count];
        let p0 = to_wcs(start.location.x, start.location.y);
        let p1 = to_wcs(end.location.x, end.location.y);
        if start.bulge.abs() < 1e-9 {
            tangents.push(TangentGeom::Line {
                p1: [p0.0 as f32, p0.1 as f32, p0.2 as f32],
                p2: [p1.0 as f32, p1.1 as f32, p1.2 as f32],
            });
        } else if let Some(arc) = crate::entities::common::BulgeArc::from_bulge(
            [start.location.x, start.location.y],
            [end.location.x, end.location.y],
            start.bulge,
        ) {
            let normal = (pline.normal.x, pline.normal.y, pline.normal.z);
            tangents.push(crate::entities::common::bulge_arc_to_tangent(&arc, to_wcs, normal));
        }
        if index == 0 {
            key_vertices.push([p0.0, p0.1, p0.2]);
        }
        key_vertices.push([p1.0, p1.1, p1.2]);
    }
    (tangents, key_vertices)
}

/// Split at vertex `idx`: a closed polyline re-opens there (one piece); an
/// open one splits into two (interior vertices only). `None` when invalid.
pub(crate) fn break_at_vertex(
    p: &acadrust::LwPolyline,
    idx: usize,
) -> Option<Vec<acadrust::EntityType>> {
    use acadrust::EntityType;
    let n = p.vertices.len();
    if n < 3 || idx >= n {
        return None;
    }
    if p.is_closed {
        let mut verts = Vec::with_capacity(n + 1);
        verts.extend_from_slice(&p.vertices[idx..]);
        verts.extend_from_slice(&p.vertices[..=idx]);
        let mut out = p.clone();
        out.common.handle = acadrust::Handle::NULL;
        out.is_closed = false;
        out.vertices = verts;
        return Some(vec![EntityType::LwPolyline(out)]);
    }
    if idx == 0 || idx == n - 1 {
        return None;
    }
    let mut a = p.clone();
    a.common.handle = acadrust::Handle::NULL;
    a.vertices = p.vertices[..=idx].to_vec();
    if let Some(last) = a.vertices.last_mut() {
        last.bulge = 0.0;
    }
    let mut b = p.clone();
    b.common.handle = acadrust::Handle::NULL;
    b.vertices = p.vertices[idx..].to_vec();
    Some(vec![EntityType::LwPolyline(a), EntityType::LwPolyline(b)])
}

fn grips(pline: &LwPolyline) -> Vec<GripDef> {
    let elev = pline.elevation;
    let n = pline.vertices.len();
    let seg_count = if pline.is_closed {
        n
    } else {
        n.saturating_sub(1)
    };

    let mut out: Vec<GripDef> = pline
        .vertices
        .iter()
        .enumerate()
        .map(|(i, v)| square_grip(i, glam::DVec3::new(v.location.x, v.location.y, elev)))
        .collect();

    // One mid-segment stretch grip per segment (straight or arc). The
    // marker is a small box rotated along the chord direction so the
    // shape itself signals which way the segment runs.
    for i in 0..seg_count {
        let v0 = &pline.vertices[i];
        let v1 = &pline.vertices[(i + 1) % n];
        let (mx, my) = if v0.bulge.abs() < 1e-9 {
            (
                (v0.location.x + v1.location.x) * 0.5,
                (v0.location.y + v1.location.y) * 0.5,
            )
        } else {
            let m = arc_midpoint(
                [v0.location.x, v0.location.y],
                [v1.location.x, v1.location.y],
                v0.bulge,
            );
            (m[0], m[1])
        };
        let dx = (v1.location.x - v0.location.x) as f32;
        let dy = (v1.location.y - v0.location.y) as f32;
        let mut g = rectangle_grip(n + i, glam::DVec3::new(mx, my, elev), [dx, dy]);
        // An arc's mid grip re-fits the arc THROUGH the cursor, so it must
        // drag in Absolute mode; only a straight segment's grip translates.
        // Feeding per-frame Translate deltas through the recomputed arc
        // midpoint deadlocks the moment the cursor crosses the chord (#339).
        g.is_midpoint = v0.bulge.abs() < 1e-9;
        out.push(g);
    }
    out
}

pub(crate) fn is_revision_cloud(pline: &LwPolyline) -> bool {
    if !pline.is_closed || pline.vertices.len() < 3 {
        return false;
    }
    let mut sign = 0.0_f64;
    let mut magnitudes = Vec::with_capacity(pline.vertices.len());
    for vertex in &pline.vertices {
        let bulge = vertex.bulge;
        if !bulge.is_finite() || bulge.abs() < 1.0e-9 {
            return false;
        }
        if sign == 0.0 {
            sign = bulge.signum();
        } else if bulge.signum() != sign {
            return false;
        }
        magnitudes.push(bulge.abs());
    }
    magnitudes.sort_by(f64::total_cmp);
    let median = magnitudes[magnitudes.len() / 2];
    (0.35..=0.65).contains(&median)
        && magnitudes
            .iter()
            .filter(|value| (**value - median).abs() <= 0.15)
            .count()
            * 5
            >= magnitudes.len() * 4
}

fn straight_guide(pline: &LwPolyline) -> Curve {
    Curve::Polyline(Polyline {
        vertices: pline
            .vertices
            .iter()
            .map(|vertex| PolylineVertex::straight([vertex.location.x, vertex.location.y]))
            .collect(),
        closed: true,
    })
}

fn revision_cloud_arc_length(pline: &LwPolyline) -> Option<f64> {
    if !is_revision_cloud(pline) {
        return None;
    }
    let total = straight_guide(pline).length();
    (total.is_finite() && total > 0.0)
        .then_some(total / pline.vertices.len() as f64)
}

fn cloud_anchors(curve: &Curve) -> Vec<f64> {
    let segments = curve.segment_count();
    let mut anchors = vec![0.0];
    if segments <= 1 {
        return anchors;
    }
    let delta = 1.0e-6 / segments as f64;
    let corner_cosine = 30.0_f64.to_radians().cos();
    for index in 1..segments {
        let t = index as f64 / segments as f64;
        let incoming = Vec2::from(curve.tangent_at(t - delta)).normalize();
        let outgoing = Vec2::from(curve.tangent_at(t + delta)).normalize();
        if incoming
            .zip(outgoing)
            .is_some_and(|(left, right)| left.dot(right) < corner_cosine)
        {
            anchors.push(curve.length_to(t));
        }
    }
    anchors
}

fn cloud_points(curve: &Curve, requested: f64) -> Option<Vec<[f64; 2]>> {
    if !curve.is_closed() || !requested.is_finite() || requested <= 0.0 {
        return None;
    }
    let total = curve.length();
    if !total.is_finite() || total <= 0.0 {
        return None;
    }
    let anchors = cloud_anchors(curve);
    let spans: Vec<(f64, f64)> = anchors
        .iter()
        .enumerate()
        .map(|(index, start)| {
            let end = anchors.get(index + 1).copied().unwrap_or(total);
            (*start, end)
        })
        .collect();
    let mut counts = Vec::with_capacity(spans.len());
    let mut count_total = 0_usize;
    for (start, end) in &spans {
        let count = ((*end - *start) / requested).round().max(1.0);
        if !count.is_finite() || count > MAX_REVCLOUD_VERTICES as f64 {
            return None;
        }
        count_total = count_total.checked_add(count as usize)?;
        if count_total > MAX_REVCLOUD_VERTICES {
            return None;
        }
        counts.push(count as usize);
    }
    if count_total < 3 {
        let longest = spans
            .iter()
            .enumerate()
            .max_by(|(_, left), (_, right)| {
                (left.1 - left.0).total_cmp(&(right.1 - right.0))
            })?
            .0;
        counts[longest] += 3 - count_total;
    }
    let mut points = Vec::new();
    for ((start, end), count) in spans.into_iter().zip(counts) {
        for step in 0..count {
            points.push(curve.point_at_distance(
                start + (end - start) * step as f64 / count as f64,
            ));
        }
    }
    let tolerance = requested.max(total) * 1.0e-12;
    points.dedup_by(|right, left| Vec2::from(*left).distance((*right).into()) <= tolerance);
    if points.len() >= 2
        && Vec2::from(points[0]).distance((*points.last()?).into()) <= tolerance
    {
        points.pop();
    }
    (points.len() >= 3).then_some(points)
}

fn cloud_vertices(
    points: &[[f64; 2]],
    bulge: f64,
    width_ratios: Option<(f64, f64)>,
) -> Vec<LwVertex> {
    points
        .iter()
        .enumerate()
        .map(|(index, point)| {
            let next = points[(index + 1) % points.len()];
            let chord = Vec2::from(*point).distance(next.into());
            let mut vertex = LwVertex::from_coords(point[0], point[1]);
            vertex.bulge = bulge;
            if let Some((start, end)) = width_ratios {
                vertex.start_width = start * chord;
                vertex.end_width = end * chord;
            }
            vertex
        })
        .collect()
}

pub(crate) fn revision_cloud_from_curve(
    curve: &Curve,
    requested: f64,
    reverse: bool,
    width_ratios: Option<(f64, f64)>,
) -> Option<LwPolyline> {
    let points = cloud_points(curve, requested)?;
    let area = signed_area(&points);
    if !area.is_finite() || area.abs() <= f64::EPSILON {
        return None;
    }
    let sign = if area > 0.0 { 1.0 } else { -1.0 };
    let bulge = REVCLOUD_BULGE * sign * if reverse { -1.0 } else { 1.0 };
    let mut cloud = LwPolyline::new();
    cloud.is_closed = true;
    cloud.vertices = cloud_vertices(&points, bulge, width_ratios);
    Some(cloud)
}

fn median(mut values: Vec<f64>) -> Option<f64> {
    values.sort_by(f64::total_cmp);
    values.get(values.len() / 2).copied()
}

fn set_revision_cloud_arc_length(pline: &mut LwPolyline, requested: f64) {
    if !is_revision_cloud(pline) || !requested.is_finite() || requested <= 0.0 {
        return;
    }
    let guide = straight_guide(pline);
    let points = match cloud_points(&guide, requested) {
        Some(points) => points,
        None => return,
    };
    let sign = pline.vertices[0].bulge.signum();
    let magnitude = match median(
        pline
            .vertices
            .iter()
            .map(|vertex| vertex.bulge.abs())
            .collect(),
    ) {
        Some(value) => value,
        None => return,
    };
    let mut starts = Vec::new();
    let mut ends = Vec::new();
    for (index, vertex) in pline.vertices.iter().enumerate() {
        let next = &pline.vertices[(index + 1) % pline.vertices.len()];
        let chord = Vec2::new(vertex.location.x, vertex.location.y)
            .distance(Vec2::new(next.location.x, next.location.y));
        if chord > 0.0 && (vertex.start_width > 0.0 || vertex.end_width > 0.0) {
            starts.push(vertex.start_width / chord);
            ends.push(vertex.end_width / chord);
        }
    }
    let width_ratios = match (median(starts), median(ends)) {
        (Some(start), Some(end)) => Some((start, end)),
        _ => None,
    };
    pline.vertices = cloud_vertices(&points, magnitude * sign, width_ratios);
}

pub(crate) fn rectangle_frame(
    pline: &LwPolyline,
) -> Option<(RectangleFrame, cadkernel::space::Plane)> {
    let planar = crate::entities::curve::lwpolyline_curve(pline)?;
    let Curve::Polyline(polyline) = &planar.curve else {
        return None;
    };
    let rectangle = polyline.rectangle_frame(Tolerance::default())?;
    Some((rectangle, planar.plane))
}

pub(crate) fn is_rectangle(pline: &LwPolyline) -> bool {
    rectangle_frame(pline).is_some()
}

fn properties(pline: &LwPolyline) -> Vec<PropSection> {
    let n = pline.vertices.len();
    // The panel's Current Vertex focus, clamped to this polyline's range.
    let vi = if n == 0 {
        0
    } else {
        crate::scene::view::dispatch::prop_current_vertex().min(n - 1)
    };
    let v = pline.vertices.get(vi);
    let vx = v.map_or(0.0, |v| v.location.x);
    let vy = v.map_or(0.0, |v| v.location.y);
    let (start_w, end_w) = v.map_or((0.0, 0.0), |v| {
        vertex_segment_widths(v, pline.constant_width)
    });
    let mp = <LwPolyline as crate::entities::traits::MassPropsCalc>::mass_props(pline);
    let cloud_arc_length = revision_cloud_arc_length(pline);
    let vertex_label = if n == 0 {
        "—".to_string()
    } else {
        format!("{}", vi + 1)
    };
    let mut misc_props = vec![
        Property {
            label: t!("Closed").into_owned(),
            field: "closed",
            value: PropValue::BoolToggle {
                field: "closed",
                value: pline.is_closed,
            },
        },
        Property {
            label: t!("Linetype generation").into_owned(),
            field: "plinegen",
            value: PropValue::BoolToggle {
                field: "plinegen",
                value: pline.plinegen,
            },
        },
    ];
    if let Some(arc_length) = cloud_arc_length {
        misc_props.push(edit(
            t!("Arc length").as_ref(),
            "revcloud_arc_length",
            arc_length,
        ));
    }
    let global_width_prop = match lwpolyline_global_width(pline) {
        Some(gw) => edit(t!("Global width").as_ref(), "global_width", gw),
        None => Property {
            label: t!("Global width").into_owned(),
            field: "global_width",
            value: PropValue::EditText(VARIES_LABEL.to_string()),
        },
    };
    let mut geometry_props = vec![
        stepper(t!("Current Vertex").as_ref(), "current_vertex", vertex_label),
        edit(t!("Vertex X").as_ref(), "vertex_x", vx),
        edit(t!("Vertex Y").as_ref(), "vertex_y", vy),
        edit_scalar(t!("Bulge").as_ref(), "bulge", v.map_or(0.0, |vertex| vertex.bulge)),
    ];
    if !is_rectangle(pline) {
        geometry_props.push(edit(t!("Start segment width").as_ref(), "start_width", start_w));
        geometry_props.push(edit(t!("End segment width").as_ref(), "end_width", end_w));
    }
    geometry_props.extend([
        global_width_prop,
        edit(t!("Elevation").as_ref(), "elevation", pline.elevation),
        ro(t!("Area").as_ref(), "area", format_area(mp.area)),
        ro(t!("Length").as_ref(), "length", format_length(mp.perimeter)),
    ]);
    vec![
        PropSection {
            title: t!("Geometry").into_owned(),
            props: geometry_props,
        },
        PropSection {
            title: t!("Misc").into_owned(),
            props: misc_props,
        },
    ]
}

fn apply_geom_prop(pline: &mut LwPolyline, field: &str, value: &str) {
    match field {
        "revcloud_arc_length" => {
            if let Some(value) = parse_f64(value) {
                set_revision_cloud_arc_length(pline, value);
            }
            return;
        }
        "closed" => {
            pline.is_closed = if value == "toggle" {
                !pline.is_closed
            } else {
                value == "true"
            };
            // Closing a polyline whose last vertex already sits on the first
            // would stack two control points there (a polyline drawn back to
            // its start point and then closed) — drop the duplicate so the
            // closing segment replaces it (#421).
            if pline.is_closed && pline.vertices.len() > 2 {
                let (first, last) = (&pline.vertices[0], pline.vertices.last().unwrap());
                let d2 = (first.location.x - last.location.x).powi(2)
                    + (first.location.y - last.location.y).powi(2);
                if d2 < 1e-12 {
                    pline.vertices.pop();
                }
            }
            return;
        }
        "plinegen" => {
            pline.plinegen = if value == "toggle" {
                !pline.plinegen
            } else {
                value == "true"
            };
            return;
        }
        _ => {}
    }
    let Some(v) = parse_f64(value) else {
        return;
    };
    // Per-vertex edits target the vertex the panel is focused on.
    let n = pline.vertices.len();
    let vi = if n == 0 {
        0
    } else {
        crate::scene::view::dispatch::prop_current_vertex().min(n - 1)
    };
    match field {
        "elevation" => pline.elevation = v,
        "global_width" if v.is_finite() && v >= 0.0 => {
            pline.constant_width = v;
            for vtx in &mut pline.vertices {
                vtx.start_width = v;
                vtx.end_width = v;
            }
        }
        "vertex_x" => {
            if let Some(vtx) = pline.vertices.get_mut(vi) {
                vtx.location.x = v;
            }
        }
        "vertex_y" => {
            if let Some(vtx) = pline.vertices.get_mut(vi) {
                vtx.location.y = v;
            }
        }
        "start_width" if v.is_finite() && v >= 0.0 => {
            if pline.constant_width > WIDTH_EPSILON {
                let c = pline.constant_width;
                for vtx in &mut pline.vertices {
                    if vtx.start_width <= WIDTH_EPSILON && vtx.end_width <= WIDTH_EPSILON {
                        vtx.start_width = c;
                        vtx.end_width = c;
                    }
                }
                pline.constant_width = 0.0;
            }
            if let Some(vtx) = pline.vertices.get_mut(vi) {
                vtx.start_width = v;
            }
        }
        "end_width" if v.is_finite() && v >= 0.0 => {
            if pline.constant_width > WIDTH_EPSILON {
                let c = pline.constant_width;
                for vtx in &mut pline.vertices {
                    if vtx.start_width <= WIDTH_EPSILON && vtx.end_width <= WIDTH_EPSILON {
                        vtx.start_width = c;
                        vtx.end_width = c;
                    }
                }
                pline.constant_width = 0.0;
            }
            if let Some(vtx) = pline.vertices.get_mut(vi) {
                vtx.end_width = v;
            }
        }
        "bulge" => {
            if v.is_finite() {
                if let Some(vtx) = pline.vertices.get_mut(vi) {
                    vtx.bulge = v.clamp(-1.0e6, 1.0e6);
                }
            }
        }
        _ => {}
    }
}

fn apply_grip(pline: &mut LwPolyline, grip_id: usize, apply: GripApply) {
    let n = pline.vertices.len();
    if grip_id < n {
        // Vertex position grip
        let v = &mut pline.vertices[grip_id];
        match apply {
            GripApply::Absolute(p) => {
                v.location.x = p.x as f64;
                v.location.y = p.y as f64;
            }
            GripApply::Translate(d) => {
                v.location.x += d.x as f64;
                v.location.y += d.y as f64;
            }
        }
    } else {
        // Mid-segment stretch grip for segment (grip_id - n).
        // Straight segments translate both endpoints by the drag delta
        // (the shared vertices then carry along whichever adjacent
        // segments share them). Arc segments adjust their bulge from
        // the new midpoint position.
        let seg = grip_id - n;
        let count = if pline.is_closed {
            n
        } else {
            n.saturating_sub(1)
        };
        if seg >= count {
            return;
        }
        let i0 = seg;
        let i1 = (seg + 1) % n;
        let is_arc = pline.vertices[i0].bulge.abs() >= 1e-9;
        if !is_arc {
            let d = match apply {
                GripApply::Translate(d) => [d.x as f64, d.y as f64],
                GripApply::Absolute(p) => {
                    let old_mid = (
                        (pline.vertices[i0].location.x + pline.vertices[i1].location.x) * 0.5,
                        (pline.vertices[i0].location.y + pline.vertices[i1].location.y) * 0.5,
                    );
                    [p.x as f64 - old_mid.0, p.y as f64 - old_mid.1]
                }
            };
            pline.vertices[i0].location.x += d[0];
            pline.vertices[i0].location.y += d[1];
            pline.vertices[i1].location.x += d[0];
            pline.vertices[i1].location.y += d[1];
            return;
        }
        let new_mid: [f64; 2] = match apply {
            GripApply::Absolute(p) => [p.x as f64, p.y as f64],
            GripApply::Translate(d) => {
                let v0 = &pline.vertices[i0];
                let v1 = &pline.vertices[i1];
                let old = arc_midpoint(
                    [v0.location.x, v0.location.y],
                    [v1.location.x, v1.location.y],
                    v0.bulge,
                );
                [old[0] + d.x as f64, old[1] + d.y as f64]
            }
        };
        let p0 = [pline.vertices[i0].location.x, pline.vertices[i0].location.y];
        let p1 = [pline.vertices[i1].location.x, pline.vertices[i1].location.y];
        if let Some(new_bulge) = bulge_from_midpoint(p0, p1, new_mid) {
            pline.vertices[i0].bulge = new_bulge.clamp(-1e6, 1e6);
        }
    }
}

fn kernel_polyline(polyline: &LwPolyline) -> Polyline {
    Polyline {
        vertices: polyline
            .vertices
            .iter()
            .map(|vertex| PolylineVertex {
                position: [vertex.location.x, vertex.location.y],
                bulge: vertex.bulge,
            })
            .collect(),
        closed: polyline.is_closed,
    }
}

fn edit_polyline_geometry(
    polyline: &mut LwPolyline,
    edit: impl FnOnce(&mut Polyline) -> bool,
) {
    let mut geometry = kernel_polyline(polyline);
    if edit(&mut geometry) {
        for (target, source) in polyline.vertices.iter_mut().zip(geometry.vertices) {
            target.location = acadrust::types::Vector2::new(source.position[0], source.position[1]);
            target.bulge = source.bulge;
        }
    }
}

fn move_segment_parallel(polyline: &mut LwPolyline, segment: usize, offset: f64) {
    edit_polyline_geometry(polyline, |geometry| {
        cadkernel::geom2d::move_polyline_segment_parallel(geometry, segment, offset)
    });
}

fn resize_arc_concentrically(polyline: &mut LwPolyline, segment: usize, offset: f64) {
    edit_polyline_geometry(polyline, |geometry| {
        geometry
            .segment_arc(segment)
            .is_some_and(|arc| cadkernel::geom2d::resize_polyline_arc(
                geometry,
                segment,
                arc.radius + offset,
            ))
    });
}

fn resize_arc_segment_radius(polyline: &mut LwPolyline, segment: usize, radius: f64) {
    edit_polyline_geometry(polyline, |geometry| {
        cadkernel::geom2d::resize_polyline_arc(geometry, segment, radius)
    });
}
fn apply_transform(pline: &mut LwPolyline, t: &EntityTransform) {
    crate::scene::view::transform::apply_standard_entity_transform(pline, t, |entity, p1, p2| {
        for v in &mut entity.vertices {
            crate::scene::view::transform::reflect_xy_point(&mut v.location.x, &mut v.location.y, p1, p2);
            // Bulge encodes which side the arc bows to; a reflection
            // reverses it or every curved segment flips to the wrong side.
            v.bulge = -v.bulge;
        }
    });
}

impl RenderConvertible for LwPolyline {
    fn to_render(&self, document: &acadrust::CadDocument) -> Option<RenderEntity> {
        Some(to_render(self, document.header.fill_mode))
    }
}

impl crate::entities::traits::Grippable for LwPolyline {
    fn grips(&self) -> Vec<crate::scene::model::object::GripDef> {
        grips(self)
    }
    fn apply_grip(&mut self, grip_id: usize, apply: crate::scene::model::object::GripApply) {
        apply_grip(self, grip_id, apply);
    }
    fn grip_menu(&self, grip_id: usize) -> Vec<crate::scene::model::object::GripMenuItem> {
        use crate::scene::model::object::{GripMenuAction, GripMenuItem};
        let n = self.vertices.len();
        if grip_id < n {
            // Vertex grip. Break only where a split is possible: any vertex
            // of a closed polyline, interior vertices of an open one.
            let breakable = n >= 3 && (self.is_closed || (grip_id > 0 && grip_id < n - 1));
            let mut items = Vec::new();
            if is_rectangle(self) {
                items.push(GripMenuItem {
                    label: "Resize",
                    action: GripMenuAction::RectangleResize,
                });
            }
            items.extend([
                GripMenuItem {
                    label: "Stretch",
                    action: GripMenuAction::Stretch,
                },
                GripMenuItem {
                    label: "Add Vertex",
                    action: GripMenuAction::AddVertex,
                },
                GripMenuItem {
                    label: "Remove Vertex",
                    action: GripMenuAction::RemoveVertex,
                },
            ]);
            if breakable {
                items.push(GripMenuItem {
                    label: "Break",
                    action: GripMenuAction::BreakVertex,
                });
            }
            return items;
        }
        // Segment midpoint grip.
        let seg = grip_id - n;
        let is_arc = self
            .vertices
            .get(seg)
            .map_or(false, |v| v.bulge.abs() >= 1e-9);
        let convert = if is_arc {
            GripMenuItem {
                label: "Convert to Line",
                action: GripMenuAction::ConvertToLine,
            }
        } else {
            GripMenuItem {
                label: "Convert to Arc",
                action: GripMenuAction::ConvertToArc,
            }
        };
        let mut items = Vec::new();
        if is_arc {
            items.push(GripMenuItem {
                label: "Radius",
                action: GripMenuAction::Radius,
            });
        } else {
            items.push(GripMenuItem {
                label: "Move Parallel",
                action: GripMenuAction::MoveParallel,
            });
        }
        if is_rectangle(self) && seg < 4 {
            // Moving an edge changes the dimension perpendicular to it.
            items.push(GripMenuItem {
                label: if seg % 2 == 0 { "Height" } else { "Width" },
                action: if seg % 2 == 0 {
                    GripMenuAction::RectangleHeight
                } else {
                    GripMenuAction::RectangleWidth
                },
            });
        }
        items.extend([
            GripMenuItem {
                label: "Stretch",
                action: GripMenuAction::Stretch,
            },
            GripMenuItem {
                label: "Add Vertex",
                action: GripMenuAction::AddVertex,
            },
            convert,
        ]);
        items
    }

    fn grip_menu_value_prompt(
        &self,
        grip_id: usize,
        action: crate::scene::model::object::GripMenuAction,
    ) -> Option<&'static str> {
        use crate::scene::model::object::GripMenuAction as A;
        let n = self.vertices.len();
        if action == A::MoveParallel && grip_id >= n {
            let seg = grip_id - n;
            let count = if self.is_closed {
                n
            } else {
                n.saturating_sub(1)
            };
            return (seg < count && self.vertices[seg].bulge.abs() < 1.0e-9)
                .then_some("Parallel offset");
        }
        if action == A::Radius && grip_id >= n {
            let seg = grip_id - n;
            let count = if self.is_closed { n } else { n.saturating_sub(1) };
            return (seg < count && self.vertices[seg].bulge.abs() >= 1.0e-9)
                .then_some("New radius");
        }
        (is_rectangle(self)
            && n == 4
            && (n..n + 4).contains(&grip_id)
            && matches!(action, A::RectangleWidth | A::RectangleHeight))
        .then_some(match action {
            A::RectangleWidth => "New width",
            _ => "New height",
        })
    }

    fn grip_menu_point_value(
        &self,
        grip_id: usize,
        action: crate::scene::model::object::GripMenuAction,
        point: glam::DVec3,
    ) -> Option<f64> {
        use crate::scene::model::object::GripMenuAction as A;
        if action == A::Radius {
            let n = self.vertices.len();
            let seg = grip_id.checked_sub(n)?;
            let plane = crate::entities::curve::lwpolyline_curve(self)?.plane;
            let point = Vec2::from(plane.project(point.to_array())?);
            return cadkernel::geom2d::polyline_arc_radius_from_point(
                &kernel_polyline(self),
                seg,
                point.into(),
            );
        }
        if action == A::MoveParallel {
            let n = self.vertices.len();
            let seg = grip_id.checked_sub(n)?;
            let plane = crate::entities::curve::lwpolyline_curve(self)?.plane;
            let point = Vec2::from(plane.project(point.to_array())?);
            return cadkernel::geom2d::polyline_segment_parallel_offset(
                &kernel_polyline(self),
                seg,
                point.into(),
            );
        }
        let (frame, plane) = rectangle_frame(self)?;
        let seg = grip_id.checked_sub(4)?;
        if seg >= 4 {
            return None;
        }
        let axis = match (seg % 2, action) {
            (0, A::RectangleHeight) => Vec2::from(frame.height_axis),
            (1, A::RectangleWidth) => Vec2::from(frame.width_axis),
            _ => return None,
        };
        let opposite_mid = {
            let a = self.vertices[(seg + 2) % 4].location;
            let b = self.vertices[(seg + 3) % 4].location;
            Vec2::new((a.x + b.x) * 0.5, (a.y + b.y) * 0.5)
        };
        let point = Vec2::from(plane.project(point.to_array())?);
        let value = (point - opposite_mid).dot(axis).abs();
        (value > Tolerance::default().linear()).then_some(value)
    }

    fn apply_grip_menu_value(
        &mut self,
        grip_id: usize,
        action: crate::scene::model::object::GripMenuAction,
        value: f64,
    ) {
        use crate::scene::model::object::GripMenuAction as A;
        if action == A::Radius {
            if let Some(seg) = grip_id.checked_sub(self.vertices.len()) {
                resize_arc_segment_radius(self, seg, value);
            }
            return;
        }
        if action == A::MoveParallel {
            if let Some(seg) = grip_id.checked_sub(self.vertices.len()) {
                if self.vertices.get(seg).is_some_and(|vertex| vertex.bulge.abs() < 1.0e-9) {
                    move_segment_parallel(self, seg, value);
                }
            }
            return;
        }
        if value <= Tolerance::default().linear() {
            return;
        }
        let Some((frame, _)) = rectangle_frame(self) else {
            return;
        };
        let Some(seg) = grip_id.checked_sub(4) else {
            return;
        };
        if seg >= 4 {
            return;
        }
        let axis = match (seg % 2, action) {
            (0, A::RectangleHeight) => frame.height_axis,
            (1, A::RectangleWidth) => frame.width_axis,
            _ => return,
        };
        let i0 = seg;
        let i1 = (seg + 1) % 4;
        let o0 = (seg + 3) % 4;
        let o1 = (seg + 2) % 4;
        let selected_mid = (self.vertices[i0].location + self.vertices[i1].location) * 0.5;
        let opposite_mid = (self.vertices[o0].location + self.vertices[o1].location) * 0.5;
        let delta = selected_mid - opposite_mid;
        let signed_distance = delta.x * axis[0] + delta.y * axis[1];
        if signed_distance.abs() <= Tolerance::default().linear() {
            return;
        }
        let direction = acadrust::types::Vector2::new(axis[0], axis[1])
            * signed_distance.signum();
        self.vertices[i0].location = self.vertices[o0].location + direction * value;
        self.vertices[i1].location = self.vertices[o1].location + direction * value;
    }
    fn apply_grip_menu(&mut self, grip_id: usize, action: crate::scene::model::object::GripMenuAction) {
        use crate::scene::model::object::GripMenuAction as A;
        let n = self.vertices.len();
        match action {
            A::Stretch => {}
            A::AddVertex => {
                if n == 0 {
                    return;
                }
                // The last vertex of an open polyline extends the path. Start
                // the provisional vertex on the endpoint; the grip driver then
                // moves it with the cursor until the placement click.
                if grip_id == n - 1 && !self.is_closed {
                    self.vertices[grip_id].bulge = 0.0;
                    let mut new_v = self.vertices[grip_id].clone();
                    new_v.bulge = 0.0;
                    new_v.vertex_id = 0;
                    self.vertices.push(new_v);
                    return;
                }
                // Insert a provisional vertex midway along the following
                // segment. Arc segments are split into two arcs; the grip
                // driver refits both halves while the cursor moves.
                let (i0, i1) = if grip_id < n {
                    let i0 = grip_id;
                    let i1 = (grip_id + 1) % n;
                    (i0, i1)
                } else {
                    let seg = grip_id - n;
                    (seg, (seg + 1) % n)
                };
                if i1 == 0 && !self.is_closed {
                    return;
                }
                let v0 = self.vertices[i0];
                let v1 = self.vertices[i1];
                let midpoint = if v0.bulge.abs() >= 1e-9 {
                    arc_midpoint(
                        [v0.location.x, v0.location.y],
                        [v1.location.x, v1.location.y],
                        v0.bulge,
                    )
                } else {
                    [
                        (v0.location.x + v1.location.x) * 0.5,
                        (v0.location.y + v1.location.y) * 0.5,
                    ]
                };
                let mut new_v = v0;
                new_v.location.x = midpoint[0];
                new_v.location.y = midpoint[1];
                new_v.vertex_id = 0;
                let (effective_start, effective_end) =
                    vertex_segment_widths(&v0, self.constant_width);
                let middle_width = (effective_start + effective_end) * 0.5;
                self.vertices[i0].end_width = middle_width;
                new_v.start_width = middle_width;
                if v0.bulge.abs() >= 1e-9 {
                    let half_bulge = (v0.bulge.atan() * 0.5).tan();
                    self.vertices[i0].bulge = half_bulge;
                    new_v.bulge = half_bulge;
                }
                let insert_at = (i0 + 1).min(self.vertices.len());
                self.vertices.insert(insert_at, new_v);
            }
            A::RemoveVertex if grip_id < n && self.vertices.len() > 2 => {
                self.vertices.remove(grip_id);
            }
            A::ConvertToArc if grip_id >= n => {
                if let Some(v) = self.vertices.get_mut(grip_id - n) {
                    if v.bulge.abs() < 1e-9 {
                        v.bulge = 0.5;
                    }
                }
            }
            A::ConvertToLine if grip_id >= n => {
                if let Some(v) = self.vertices.get_mut(grip_id - n) {
                    v.bulge = 0.0;
                }
            }
            _ => {}
        }
    }
}

impl crate::entities::traits::PropertyEditable for LwPolyline {
    fn geometry_properties(
        &self,
        _text_style_names: &[String],
    ) -> Vec<crate::scene::model::object::PropSection> {
        properties(self)
    }
    fn apply_geom_prop(&mut self, field: &str, value: &str) {
        apply_geom_prop(self, field, value);
    }
}

impl crate::entities::traits::Transformable for LwPolyline {
    fn apply_transform(&mut self, t: &crate::command::EntityTransform) {
        apply_transform(self, t);
    }
}

/// Solid-fill bands for a wide LwPolyline, plus the `world_origin` they are
/// relative to. The band vertices are small f32 offsets from `origin` (the
/// first vertex), so the relative-to-eye hatch fill keeps sub-unit precision at
/// UTM-scale coordinates — building them in absolute f32 collapsed the band into
/// a string of squares far from the origin.
pub(crate) fn wide_fills(pl: &acadrust::entities::LwPolyline) -> ([f64; 2], Vec<Vec<[f32; 2]>>) {
    // Codes 43 / 40 / 41 store the band's FULL width, and
    // `polyline_segment_fill` offsets ±hw about the centreline — so halve it.
    // Feeding the stored width in whole draws every wide polyline twice as wide
    // as the file asks for, which on a donut (a closed 2-vertex bulge-1 polyline)
    // shows up as a disc 1.5× its real radius.
    let verts = &pl.vertices;
    let n = verts.len();
    if n < 2 {
        return ([0.0; 2], vec![]);
    }
    let origin = [verts[0].location.x, verts[0].location.y];
    let seg_count = if pl.is_closed { n } else { n - 1 };
    let mut out = Vec::new();
    for i in 0..seg_count {
        let v0 = &verts[i];
        let v1 = &verts[(i + 1) % n];
        let (sw, ew) = vertex_segment_widths(v0, pl.constant_width);
        let hw0 = sw as f32 * 0.5;
        let hw1 = ew as f32 * 0.5;
        if hw0 < 1e-6 && hw1 < 1e-6 {
            continue;
        }
        let p0 = [
            (v0.location.x - origin[0]) as f32,
            (v0.location.y - origin[1]) as f32,
        ];
        let p1 = [
            (v1.location.x - origin[0]) as f32,
            (v1.location.y - origin[1]) as f32,
        ];
        if let Some(poly) =
            crate::entities::common::polyline_segment_fill(p0, p1, hw0, hw1, v0.bulge as f32)
        {
            out.push(poly);
        }
    }
    (origin, out)
}

impl crate::entities::traits::MassPropsCalc for acadrust::entities::LwPolyline {
    fn mass_props(&self) -> crate::entities::traits::MassProps {
        let p = self;
        let n = p.vertices.len();
        if n < 2 {
            return crate::entities::traits::MassProps {
                area: 0.0,
                perimeter: 0.0,
                cx: 0.0,
                cy: 0.0,
            };
        }
        // Kernel measurement includes bulges and closes open curves only for area.
        let curve = crate::entities::curve::lwpolyline_curve(p)
            .expect("an LwPolyline with at least two vertices has a planar curve");
        let area = curve.curve.enclosed_area().abs();
        let perimeter = curve.length();
        let center = curve
            .curve
            .enclosed_centroid()
            .unwrap_or_else(|| {
                let x = p.vertices.iter().map(|v| v.location.x).sum::<f64>() / n as f64;
                let y = p.vertices.iter().map(|v| v.location.y).sum::<f64>() / n as f64;
                [x, y]
            });
        let [cx, cy, _] = curve.plane.point_at(center);
        crate::entities::traits::MassProps {
            area,
            perimeter,
            cx,
            cy,
        }
    }
}

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

    use crate::entities::traits::{Grippable, PropertyEditable};
    use crate::scene::model::object::GripMenuAction;
    use acadrust::entities::{LwPolyline, LwVertex};
    use acadrust::{Vector2, Vector3};

    fn make_test_lwpolyline(count: usize, constant_width: f64) -> LwPolyline {
        let mut pl = LwPolyline::default();
        pl.constant_width = constant_width;
        for i in 0..count {
            pl.vertices.push(LwVertex::new(Vector2::new(i as f64 * 10.0, 0.0)));
        }
        pl
    }

    fn make_test_rectangle() -> LwPolyline {
        let mut pl = LwPolyline::default();
        pl.is_closed = true;
        pl.vertices = [(0.0, 0.0), (10.0, 0.0), (10.0, 5.0), (0.0, 5.0)]
            .into_iter()
            .map(|(x, y)| LwVertex::new(Vector2::new(x, y)))
            .collect();
        pl
    }

    #[test]
    fn rectangle_midpoint_offers_dimension_before_stretch() {
        let pl = make_test_rectangle();
        let bottom = pl.grip_menu(4);
        assert_eq!(bottom[0].action, GripMenuAction::MoveParallel);
        assert_eq!(bottom[1].action, GripMenuAction::RectangleHeight);
        assert_eq!(bottom[2].action, GripMenuAction::Stretch);

        let right = pl.grip_menu(5);
        assert_eq!(right[0].action, GripMenuAction::MoveParallel);
        assert_eq!(right[1].action, GripMenuAction::RectangleWidth);
        assert_eq!(right[2].action, GripMenuAction::Stretch);
    }

    #[test]
    fn arc_midpoint_offers_radius_first_without_move_parallel() {
        let mut pl = make_test_lwpolyline(2, 0.0);
        pl.vertices[0].bulge = 0.5;
        let menu = pl.grip_menu(2);
        assert_eq!(menu[0].action, GripMenuAction::Radius);
        assert_eq!(menu[1].action, GripMenuAction::Stretch);
        assert!(!menu.iter().any(|item| item.action == GripMenuAction::MoveParallel));
    }

    #[test]
    fn rectangle_corner_offers_resize_before_stretch() {
        let pl = make_test_rectangle();
        let corner = pl.grip_menu(0);
        assert_eq!(corner[0].action, GripMenuAction::RectangleResize);
        assert_eq!(corner[1].action, GripMenuAction::Stretch);
    }

    #[test]
    fn rectangle_dimension_edit_keeps_opposite_edge_fixed() {
        let mut pl = make_test_rectangle();
        pl.apply_grip_menu_value(6, GripMenuAction::RectangleHeight, 8.0);
        assert_eq!(pl.vertices[0].location, Vector2::new(0.0, 0.0));
        assert_eq!(pl.vertices[1].location, Vector2::new(10.0, 0.0));
        assert_eq!(pl.vertices[2].location, Vector2::new(10.0, 8.0));
        assert_eq!(pl.vertices[3].location, Vector2::new(0.0, 8.0));
        assert!(is_rectangle(&pl));
    }

    #[test]
    fn rectangle_point_preview_reports_full_dimension() {
        let pl = make_test_rectangle();
        let value = pl.grip_menu_point_value(
            5,
            GripMenuAction::RectangleWidth,
            glam::DVec3::new(14.0, 2.5, 0.0),
        );
        assert_eq!(value, Some(14.0));
    }

    #[test]
    fn rectangle_point_preview_uses_entity_plane() {
        let mut pl = make_test_rectangle();
        pl.normal = Vector3::new(0.0, 1.0, 0.0);
        pl.elevation = 5.0;
        let (_, plane) = rectangle_frame(&pl).expect("rectangle frame");
        let point = glam::DVec3::from_array(plane.point_at([14.0, 2.5]));

        let value = pl.grip_menu_point_value(5, GripMenuAction::RectangleWidth, point);

        assert_eq!(value, Some(14.0));
    }

    fn polyline(points: &[(f64, f64)], closed: bool) -> LwPolyline {
        let mut pl = LwPolyline::default();
        pl.is_closed = closed;
        pl.vertices = points
            .iter()
            .map(|&(x, y)| LwVertex::new(Vector2::new(x, y)))
            .collect();
        pl
    }

    #[test]
    fn move_parallel_reconnects_internal_edge_to_adjacent_lines() {
        let mut pl = polyline(
            &[(0.0, 0.0), (2.0, 2.0), (8.0, 2.0), (10.0, 0.0)],
            false,
        );
        move_segment_parallel(&mut pl, 1, 2.0);
        assert_eq!(pl.vertices[0].location, Vector2::new(0.0, 0.0));
        assert_eq!(pl.vertices[1].location, Vector2::new(4.0, 4.0));
        assert_eq!(pl.vertices[2].location, Vector2::new(6.0, 4.0));
        assert_eq!(pl.vertices[3].location, Vector2::new(10.0, 0.0));
    }

    #[test]
    fn moving_a_line_parallel_only_changes_the_connected_arcs_length() {
        let mut pl = polyline(&[(-5.0, 0.0), (0.0, 0.0), (5.0, 5.0)], false);
        pl.vertices[1].bulge = -(std::f64::consts::FRAC_PI_2 * 0.25).tan();
        let before = crate::entities::common::BulgeArc::from_bulge(
            [0.0, 0.0], [5.0, 5.0], pl.vertices[1].bulge,
        ).unwrap();

        move_segment_parallel(&mut pl, 0, 1.0);

        let after = crate::entities::common::BulgeArc::from_bulge(
            [pl.vertices[1].location.x, pl.vertices[1].location.y],
            [pl.vertices[2].location.x, pl.vertices[2].location.y],
            pl.vertices[1].bulge,
        ).unwrap();
        assert!(Vec2::from(after.center).distance(Vec2::from(before.center)) < 1.0e-9);
        assert!((after.radius - before.radius).abs() < 1.0e-9);
        assert_eq!(pl.vertices[2].location, Vector2::new(5.0, 5.0));
        assert!((after.sweep - before.sweep).abs() > 1.0e-6);
        assert!((pl.vertices[0].location.y - 1.0).abs() < 1.0e-9);
        assert!((pl.vertices[1].location.y - 1.0).abs() < 1.0e-9);
    }

    #[test]
    fn radius_offsets_arc_concentrically() {
        let mut pl = polyline(&[(0.0, 0.0), (10.0, 0.0)], false);
        pl.vertices[0].bulge = 1.0;
        let original = crate::entities::common::BulgeArc::from_bulge(
            [0.0, 0.0],
            [10.0, 0.0],
            pl.vertices[0].bulge,
        )
        .unwrap();

        resize_arc_concentrically(&mut pl, 0, 2.0);

        let moved = crate::entities::common::BulgeArc::from_bulge(
            [pl.vertices[0].location.x, pl.vertices[0].location.y],
            [pl.vertices[1].location.x, pl.vertices[1].location.y],
            pl.vertices[0].bulge,
        )
        .unwrap();
        assert!(Vec2::from(moved.center).distance(original.center.into()) < 1.0e-9);
        assert!((moved.radius - original.radius - 2.0).abs() < 1.0e-9);
        assert_eq!(moved.sweep.signum(), original.sweep.signum());
    }

    #[test]
    fn radius_allows_an_open_arc_with_a_duplicate_end_vertex() {
        let mut pl = polyline(&[(0.0, 0.0), (10.0, 0.0), (10.0, 0.0)], false);
        pl.vertices[0].bulge = 1.0;

        resize_arc_concentrically(&mut pl, 0, 2.0);

        let moved = crate::entities::common::BulgeArc::from_bulge(
            [pl.vertices[0].location.x, pl.vertices[0].location.y],
            [pl.vertices[1].location.x, pl.vertices[1].location.y],
            pl.vertices[0].bulge,
        ).unwrap();
        assert!((moved.radius - 7.0).abs() < 1.0e-9);
        assert_eq!(pl.vertices[2].location, pl.vertices[1].location);
    }

    #[test]
    fn resizing_an_end_arc_only_changes_the_connected_arcs_length() {
        let shared = Vec2::new(3.0, 4.0);
        let mut pl = polyline(&[(-5.0, 0.0), (shared.x, shared.y), (11.0, 0.0)], false);
        let ccw_bulge = |center: Vec2, start: Vec2, end: Vec2| {
            let a0 = (start.y - center.y).atan2(start.x - center.x);
            let a1 = (end.y - center.y).atan2(end.x - center.x);
            ((a1 - a0).rem_euclid(TAU) * 0.25).tan()
        };
        pl.vertices[0].bulge = ccw_bulge(Vec2::ZERO, Vec2::new(-5.0, 0.0), shared);
        pl.vertices[1].bulge = ccw_bulge(Vec2::new(6.0, 0.0), shared, Vec2::new(11.0, 0.0));
        let before = crate::entities::common::BulgeArc::from_bulge(
            [shared.x, shared.y], [11.0, 0.0], pl.vertices[1].bulge,
        ).unwrap();

        resize_arc_concentrically(&mut pl, 0, 1.0);

        let after = crate::entities::common::BulgeArc::from_bulge(
            [pl.vertices[1].location.x, pl.vertices[1].location.y],
            [pl.vertices[2].location.x, pl.vertices[2].location.y],
            pl.vertices[1].bulge,
        ).unwrap();
        assert!(Vec2::from(after.center).distance(Vec2::from(before.center)) < 1.0e-9);
        assert!((after.radius - before.radius).abs() < 1.0e-9);
        assert_eq!(pl.vertices[2].location, Vector2::new(11.0, 0.0));
        assert!((after.sweep - before.sweep).abs() > 1.0e-6);
    }

    #[test]
    fn radius_menu_resizes_a_corner_as_a_tangent_fillet() {
        let mut pl = polyline(
            &[(0.0, 0.0), (8.0, 0.0), (10.0, 2.0), (10.0, 10.0)], false,
        );
        pl.vertices[1].bulge = (std::f64::consts::FRAC_PI_2 / 4.0).tan();
        let grip = pl.vertices.len() + 1;
        assert!(pl.grip_menu(grip).iter().any(|item| item.action == GripMenuAction::Radius));
        pl.apply_grip_menu_value(grip, GripMenuAction::Radius, 4.0);
        assert_eq!(pl.vertices[0].location, Vector2::new(0.0, 0.0));
        assert!((pl.vertices[1].location.x - 6.0).abs() < 1.0e-9);
        assert!(pl.vertices[1].location.y.abs() < 1.0e-9);
        assert!((pl.vertices[2].location.x - 10.0).abs() < 1.0e-9);
        assert!((pl.vertices[2].location.y - 4.0).abs() < 1.0e-9);
        assert_eq!(pl.vertices[3].location, Vector2::new(10.0, 10.0));
        let arc = crate::entities::common::BulgeArc::from_bulge(
            [pl.vertices[1].location.x, pl.vertices[1].location.y],
            [pl.vertices[2].location.x, pl.vertices[2].location.y],
            pl.vertices[1].bulge,
        ).unwrap();
        assert!((arc.radius - 4.0).abs() < 1.0e-9);
        assert!(arc.sweep > 0.0);
    }

    #[test]
    fn radius_cursor_tracks_the_fillet_midpoint_ray() {
        let mut pl = polyline(
            &[(0.0, 0.0), (8.0, 0.0), (10.0, 2.0), (10.0, 10.0)], false,
        );
        pl.vertices[1].bulge = (std::f64::consts::FRAC_PI_2 / 4.0).tan();
        let arc = crate::entities::common::BulgeArc::from_bulge(
            [pl.vertices[1].location.x, pl.vertices[1].location.y],
            [pl.vertices[2].location.x, pl.vertices[2].location.y],
            pl.vertices[1].bulge,
        ).unwrap();
        let midpoint = Vec2::from(arc.sample(0.5));
        let cursor = Vec2::new(10.0, 0.0) + (midpoint - Vec2::new(10.0, 0.0)) * 2.0;
        let value = pl.grip_menu_point_value(
            pl.vertices.len() + 1, GripMenuAction::Radius,
            glam::DVec3::new(cursor.x, cursor.y, 0.0),
        ).unwrap();
        assert!((value - 4.0).abs() < 1.0e-9);
    }

    #[test]
    fn radius_on_an_open_endpoint_arc_stays_concentric() {
        let mut pl = polyline(&[(0.0, 0.0), (10.0, 0.0)], false);
        pl.vertices[0].bulge = 1.0;
        resize_arc_segment_radius(&mut pl, 0, 8.0);
        let arc = crate::entities::common::BulgeArc::from_bulge(
            [pl.vertices[0].location.x, pl.vertices[0].location.y],
            [pl.vertices[1].location.x, pl.vertices[1].location.y],
            pl.vertices[0].bulge,
        ).unwrap();
        assert!((arc.radius - 8.0).abs() < 1.0e-9);
        assert!(Vec2::from(arc.center).distance(Vec2::new(5.0, 0.0)) < 1.0e-9);
        assert!(arc.sweep > 0.0);
    }

    #[test]
    fn radius_edit_ignores_an_invalid_segment_grip() {
        let mut pl = polyline(&[(0.0, 0.0), (10.0, 0.0)], false);
        pl.vertices[0].bulge = 1.0;
        let before = pl.clone();

        pl.apply_grip_menu_value(99, GripMenuAction::Radius, 8.0);

        assert_eq!(pl, before);
    }

    #[test]
    fn radius_on_a_non_tangent_internal_arc_keeps_center_and_side_angles() {
        let mut pl = polyline(
            &[(0.0, 0.0), (8.0, 0.0), (10.0, 2.0), (10.0, 10.0)], false,
        );
        pl.vertices[1].bulge = 1.0;
        let before = crate::entities::common::BulgeArc::from_bulge(
            [8.0, 0.0], [10.0, 2.0], pl.vertices[1].bulge,
        ).unwrap();
        resize_arc_segment_radius(&mut pl, 1, 4.0);
        let after = crate::entities::common::BulgeArc::from_bulge(
            [pl.vertices[1].location.x, pl.vertices[1].location.y],
            [pl.vertices[2].location.x, pl.vertices[2].location.y],
            pl.vertices[1].bulge,
        ).unwrap();
        assert!(Vec2::from(after.center).distance(Vec2::from(before.center)) < 1.0e-9);
        assert!((after.radius - 4.0).abs() < 1.0e-9);
        let incoming = Vec2::new(
            pl.vertices[1].location.x - pl.vertices[0].location.x,
            pl.vertices[1].location.y - pl.vertices[0].location.y,
        );
        let outgoing = Vec2::new(
            pl.vertices[3].location.x - pl.vertices[2].location.x,
            pl.vertices[3].location.y - pl.vertices[2].location.y,
        );
        assert!(incoming.cross(Vec2::new(1.0, 0.0)).abs() < 1.0e-9);
        assert!(outgoing.cross(Vec2::new(0.0, 1.0)).abs() < 1.0e-9);
    }

    #[test]
    fn move_parallel_translates_free_endpoint_of_open_polyline() {
        let mut pl = polyline(&[(0.0, 0.0), (6.0, 0.0), (8.0, 2.0)], false);
        move_segment_parallel(&mut pl, 0, 2.0);
        assert_eq!(pl.vertices[0].location, Vector2::new(0.0, 2.0));
        assert_eq!(pl.vertices[1].location, Vector2::new(8.0, 2.0));
        assert_eq!(pl.vertices[2].location, Vector2::new(8.0, 2.0));
    }

    #[test]
    fn move_parallel_wraps_closed_polyline_indices() {
        let mut pl = polyline(&[(0.0, 0.0), (4.0, 0.0), (4.0, 4.0), (0.0, 4.0)], true);
        move_segment_parallel(&mut pl, 3, -1.0);
        assert_eq!(pl.vertices[0].location, Vector2::new(-1.0, 0.0));
        assert_eq!(pl.vertices[3].location, Vector2::new(-1.0, 4.0));
        assert_eq!(pl.vertices[1].location, Vector2::new(4.0, 0.0));
        assert_eq!(pl.vertices[2].location, Vector2::new(4.0, 4.0));
    }

    #[test]
    fn move_parallel_rejects_parallel_adjacent_line() {
        let mut pl = polyline(&[(0.0, 0.0), (2.0, 0.0), (5.0, 0.0), (6.0, 2.0)], false);
        let original = pl.vertices.clone();
        move_segment_parallel(&mut pl, 1, 1.0);
        assert_eq!(pl.vertices, original);
    }

    #[test]
    fn test_lwpolyline_uniform_width_shows_global_width() {
        let pl = make_test_lwpolyline(3, 5.0);
        assert_eq!(lwpolyline_global_width(&pl), Some(5.0));

        let props = pl.geometry_properties(&[]);
        let geom_props = &props[0].props;
        let gw = geom_props.iter().find(|p| p.field == "global_width").unwrap();
        match &gw.value {
            PropValue::EditText(val) => assert_eq!(parse_f64(val), Some(5.0)),
            _ => panic!("expected EditText"),
        }
    }

    #[test]
    fn test_lwpolyline_varying_vertex_width_shows_varies() {
        let mut pl = make_test_lwpolyline(3, 5.0);
        pl.vertices[0].start_width = 2.0;
        pl.vertices[0].end_width = 3.0;

        assert_eq!(lwpolyline_global_width(&pl), None);

        let props = pl.geometry_properties(&[]);
        let geom_props = &props[0].props;
        let gw = geom_props.iter().find(|p| p.field == "global_width").unwrap();
        match &gw.value {
            PropValue::EditText(val) => assert_eq!(val, VARIES_LABEL),
            _ => panic!("expected EditText with VARIES_LABEL"),
        }
    }

    #[test]
    fn test_lwpolyline_modifying_global_width_sets_all_vertex_widths() {
        let mut pl = make_test_lwpolyline(3, 5.0);
        pl.vertices[0].start_width = 2.0;
        pl.vertices[0].end_width = 3.0;

        pl.apply_geom_prop("global_width", "10.0");

        assert_eq!(pl.constant_width, 10.0);
        for v in &pl.vertices {
            assert_eq!(v.start_width, 10.0);
            assert_eq!(v.end_width, 10.0);
        }
        assert_eq!(lwpolyline_global_width(&pl), Some(10.0));
    }

    #[test]
    fn test_lwpolyline_modifying_segment_width_materializes_constant_width() {
        let mut pl = make_test_lwpolyline(3, 5.0);
        // Initially constant_width is 5.0, vertices start/end are 0.0
        assert_eq!(pl.vertices[0].start_width, 0.0);

        // Edit start width of current vertex (vertex 0) to 2.0
        pl.apply_geom_prop("start_width", "2.0");

        // Vertex 0 start width should be 2.0, end width materialized to 5.0
        assert_eq!(pl.vertices[0].start_width, 2.0);
        assert_eq!(pl.vertices[0].end_width, 5.0);

        // Vertex 1 and 2 should have materialized 5.0 instead of collapsing to 0.0
        assert_eq!(pl.vertices[1].start_width, 5.0);
        assert_eq!(pl.vertices[1].end_width, 5.0);

        // Global width must now be VARIES
        assert_eq!(lwpolyline_global_width(&pl), None);
    }
}