use acadrust::entities::{mesh::Mesh, polygon_mesh::PolygonMesh, Face3D, PolyfaceMesh};
use cadkernel::geom2d::{triangulate, Tolerance};
use cadkernel::space::{polygon, NurbsSurface3, Plane, Vec3 as KernelVec3};
use glam::Vec3;

use crate::command::EntityTransform;
use crate::entities::common::{
    edit_prop as edit, edit_scalar_prop as edit_scalar, parse_f64, ro_prop as ro,
    square_grip, stepper_prop as stepper,
};
use crate::entities::traits::{Grippable, PropertyEditable, RenderConvertible, Transformable};
use crate::scene::convert::acad_to_render::{RenderEntity, RenderObject};
use crate::scene::model::object::{GripApply, GripDef, PropSection, PropValue, Property};
use crate::scene::model::wire_model::SnapHint;
use crate::t;

/// Triangulate a planar polygon through the kernel.
pub(crate) fn triangulate_planar(poly: &[[f64; 3]]) -> Vec<[f64; 3]> {
    if poly.len() < 3 {
        return Vec::new();
    }
    let origin = KernelVec3::from(poly[0]);
    let tolerance = Tolerance::default().linear();
    let Some(axis) = poly[1..]
        .iter()
        .map(|point| KernelVec3::from(*point) - origin)
        .find(|axis| axis.length() > tolerance)
    else {
        return Vec::new();
    };
    let Some(normal) = polygon::normal(poly) else {
        return Vec::new();
    };
    let Some(plane) = Plane::orthonormal(poly[0], axis.to_array(), normal) else {
        return Vec::new();
    };
    let projected: Vec<[f64; 2]> = poly
        .iter()
        .filter_map(|&point| plane.project(point))
        .collect();
    if projected.len() != poly.len() {
        return Vec::new();
    }
    let (points, triangles) = triangulate(&projected, &[]);
    let source: Vec<usize> = points
        .iter()
        .filter_map(|point| projected.iter().position(|candidate| candidate == point))
        .collect();
    if source.len() != points.len() {
        return Vec::new();
    }
    triangles
        .into_iter()
        .flat_map(|triangle| triangle.map(|index| poly[source[index]]))
        .collect()
}

// ── Face3D ────────────────────────────────────────────────────────────────────

fn v3(v: &acadrust::types::Vector3) -> [f64; 3] {
    [v.x, v.y, v.z]
}

fn dvec3(v: &acadrust::types::Vector3) -> glam::DVec3 {
    glam::DVec3::new(v.x, v.y, v.z)
}

fn v3f32(v: &acadrust::types::Vector3) -> [f32; 3] {
    [v.x as f32, v.y as f32, v.z as f32]
}

fn face3d_fill(corners: [[f64; 3]; 4]) -> Vec<[f64; 3]> {
    let tolerance = Tolerance::default();
    let mut ring = Vec::with_capacity(4);
    for corner in corners {
        if ring.last().is_none_or(|previous| {
            KernelVec3::from(*previous).distance(KernelVec3::from(corner))
                > tolerance.linear()
        }) {
            ring.push(corner);
        }
    }
    if ring.len() > 1
        && KernelVec3::from(ring[0]).distance(KernelVec3::from(*ring.last().unwrap()))
            <= tolerance.linear()
    {
        ring.pop();
    }
    if ring.len() < 3 {
        return Vec::new();
    }

    triangulate_planar(&ring)
}

impl RenderConvertible for Face3D {
    fn to_render(&self, _document: &acadrust::CadDocument) -> Option<RenderEntity> {
        let p0 = v3(&self.first_corner);
        let p1 = v3(&self.second_corner);
        let p2 = v3(&self.third_corner);
        let p3 = v3(&self.fourth_corner);
        let fill_tris = face3d_fill([p0, p1, p2, p3]);
        let p0f = v3f32(&self.first_corner);
        let p1f = v3f32(&self.second_corner);
        let p2f = v3f32(&self.third_corner);
        let p3f = v3f32(&self.fourth_corner);
        let inv = self.invisible_edges;

        // Add edge as a line segment (separated by NaN from previous edges).
        let mut pts: Vec<[f64; 3]> = Vec::new();
        let mut add_edge = |a: [f64; 3], b: [f64; 3]| {
            if !pts.is_empty() {
                pts.push([f64::NAN; 3]);
            }
            pts.push(a);
            pts.push(b);
        };

        if !inv.is_first_invisible() {
            add_edge(p0, p1);
        }
        if !inv.is_second_invisible() {
            add_edge(p1, p2);
        }
        if !inv.is_third_invisible() {
            add_edge(p2, p3);
        }
        if !inv.is_fourth_invisible() {
            add_edge(p3, p0);
        }

        Some(RenderEntity {
            pick_tris: Vec::new(),
            object: RenderObject::Lines(pts),
            snap_pts: vec![
                (Vec3::from(p0f).as_dvec3(), SnapHint::Node),
                (Vec3::from(p1f).as_dvec3(), SnapHint::Node),
                (Vec3::from(p2f).as_dvec3(), SnapHint::Node),
                (Vec3::from(p3f).as_dvec3(), SnapHint::Node),
            ],
            tangent_geoms: vec![],
            key_vertices: vec![p0, p1, p2, p3],
            fill_tris,
        })
    }
}

impl Grippable for Face3D {
    fn grips(&self) -> Vec<GripDef> {
        let mut grips = vec![
            square_grip(0, dvec3(&self.first_corner)),
            square_grip(1, dvec3(&self.second_corner)),
            square_grip(2, dvec3(&self.third_corner)),
        ];
        if !self.is_triangle() {
            grips.push(square_grip(3, dvec3(&self.fourth_corner)));
        }
        grips
    }

    fn apply_grip(&mut self, grip_id: usize, apply: GripApply) {
        let was_triangle = self.is_triangle();
        if was_triangle && grip_id == 3 {
            return;
        }
        let corner = match grip_id {
            0 => &mut self.first_corner,
            1 => &mut self.second_corner,
            2 => &mut self.third_corner,
            3 => &mut self.fourth_corner,
            _ => return,
        };
        let current = dvec3(corner);
        let updated = match apply {
            GripApply::Translate(delta) => current + delta,
            GripApply::Absolute(position) => position,
        };
        if !updated.is_finite() {
            return;
        }
        corner.x = updated.x;
        corner.y = updated.y;
        corner.z = updated.z;
        if was_triangle && grip_id == 2 {
            self.fourth_corner = self.third_corner;
        }
    }
}

impl PropertyEditable for Face3D {
    fn geometry_properties(&self, _text_style_names: &[String]) -> Vec<PropSection> {
        let was_triangle = self.is_triangle();
        let vertex_count = if was_triangle { 3 } else { 4 };
        let current = crate::scene::view::dispatch::prop_current_vertex()
            .min(vertex_count - 1);
        let corner = match current {
            0 => &self.first_corner,
            1 => &self.second_corner,
            2 => &self.third_corner,
            _ => &self.fourth_corner,
        };
        let inv = self.invisible_edges;
        let edge = |label: &str, field: &'static str, hidden: bool| Property {
            label: label.to_string(),
            field,
            value: PropValue::Choice {
                selected: if hidden {
                    t!("Invisible").into_owned()
                } else {
                    t!("Visible").into_owned()
                },
                options: vec![t!("Visible").into_owned(), t!("Invisible").into_owned()],
            },
        };
        vec![PropSection {
            title: t!("Geometry").into_owned(),
            props: vec![
                stepper(
                    t!("Current vertex").as_ref(),
                    "current_vertex",
                    format!("{}", current + 1),
                ),
                edit(t!("Vertex X").as_ref(), "f3_vertex_x", corner.x),
                edit(t!("Vertex Y").as_ref(), "f3_vertex_y", corner.y),
                edit(t!("Vertex Z").as_ref(), "f3_vertex_z", corner.z),
                edge(t!("Edge 1").as_ref(), "f3_edge1", inv.is_first_invisible()),
                edge(t!("Edge 2").as_ref(), "f3_edge2", inv.is_second_invisible()),
                edge(t!("Edge 3").as_ref(), "f3_edge3", inv.is_third_invisible()),
                edge(t!("Edge 4").as_ref(), "f3_edge4", inv.is_fourth_invisible()),
            ],
        }]
    }

    fn apply_geom_prop(&mut self, field: &str, value: &str) {
        if field.starts_with("f3_edge") {
            let invisible = if value == t!("Invisible").as_ref() {
                true
            } else if value == t!("Visible").as_ref() {
                false
            } else {
                return;
            };
            match field {
                "f3_edge1" => self.invisible_edges.set_first_invisible(invisible),
                "f3_edge2" => self.invisible_edges.set_second_invisible(invisible),
                "f3_edge3" => self.invisible_edges.set_third_invisible(invisible),
                "f3_edge4" => self.invisible_edges.set_fourth_invisible(invisible),
                _ => {}
            }
            return;
        }
        let Some(value) = parse_f64(value).filter(|value| value.is_finite()) else {
            return;
        };
        let was_triangle = self.is_triangle();
        let vertex_count = if was_triangle { 3 } else { 4 };
        let current = crate::scene::view::dispatch::prop_current_vertex()
            .min(vertex_count - 1);
        let corner = match current {
            0 => &mut self.first_corner,
            1 => &mut self.second_corner,
            2 => &mut self.third_corner,
            _ => &mut self.fourth_corner,
        };
        match field {
            "f3_vertex_x" => corner.x = value,
            "f3_vertex_y" => corner.y = value,
            "f3_vertex_z" => corner.z = value,
            _ => {}
        }
        if was_triangle && current == 2 {
            self.fourth_corner = self.third_corner;
        }
    }
}

impl Transformable for Face3D {
    fn apply_transform(&mut self, t: &EntityTransform) {
        crate::scene::view::transform::apply_standard_entity_transform(self, t, |entity, p1, p2| {
            for corner in [
                &mut entity.first_corner,
                &mut entity.second_corner,
                &mut entity.third_corner,
                &mut entity.fourth_corner,
            ] {
                crate::scene::view::transform::reflect_xy_point(&mut corner.x, &mut corner.y, p1, p2);
            }
        });
    }
}

// ── PolygonMesh (N×M grid) ────────────────────────────────────────────────────

fn polygon_mesh_display(mesh: &PolygonMesh) -> (Vec<[f64; 3]>, usize, usize) {
    use acadrust::entities::polygon_mesh::SurfaceSmoothType;

    let m = mesh.m_vertex_count.max(0) as usize;
    let n = mesh.n_vertex_count.max(0) as usize;
    let base: Vec<[f64; 3]> = mesh
        .vertices
        .iter()
        .take(m.saturating_mul(n))
        .map(|vertex| v3(&vertex.location))
        .collect();
    if mesh.smooth_type == SurfaceSmoothType::NoSmooth || base.len() < m.saturating_mul(n) {
        return (base, m, n);
    }

    let degree = match mesh.smooth_type {
        SurfaceSmoothType::NoSmooth => return (base, m, n),
        SurfaceSmoothType::Quadratic => 2,
        SurfaceSmoothType::Cubic | SurfaceSmoothType::Bezier => 3,
    };
    let u_degree = degree.min(m.saturating_sub(1));
    let v_degree = degree.min(n.saturating_sub(1));
    if u_degree == 0 || v_degree == 0 {
        return (base, m, n);
    }
    let control_points: Vec<Vec<[f64; 3]>> = base.chunks(n).map(|row| row.to_vec()).collect();
    let Some(surface) = NurbsSurface3::from_control_net(
        u_degree,
        v_degree,
        control_points,
        mesh.is_closed_m(),
        mesh.is_closed_n(),
    ) else {
        return (base, m, n);
    };

    let display_m = usize::try_from(mesh.m_smooth_density.max(2))
        .unwrap_or(2)
        .min(256);
    let display_n = usize::try_from(mesh.n_smooth_density.max(2))
        .unwrap_or(2)
        .min(256);
    let parameter = |index: usize, count: usize, closed: bool| {
        if closed {
            index as f64 / count as f64
        } else {
            index as f64 / count.saturating_sub(1).max(1) as f64
        }
    };
    let mut display = Vec::with_capacity(display_m.saturating_mul(display_n));
    for row in 0..display_m {
        let u = parameter(row, display_m, mesh.is_closed_m());
        for column in 0..display_n {
            let v = parameter(column, display_n, mesh.is_closed_n());
            display.push(surface.point_at(u, v));
        }
    }
    (display, display_m, display_n)
}

impl RenderConvertible for PolygonMesh {
    fn to_render(&self, _document: &acadrust::CadDocument) -> Option<RenderEntity> {
        let (vertices, m, n) = polygon_mesh_display(self);
        if m == 0 || n == 0 || vertices.len() < m * n {
            return None;
        }

        let mut lines = Vec::new();
        let mut add_segment = |a: usize, b: usize| {
            let (Some(&a), Some(&b)) = (vertices.get(a), vertices.get(b)) else {
                return;
            };
            if !lines.is_empty() {
                lines.push([f64::NAN; 3]);
            }
            lines.push(a);
            lines.push(b);
        };

        let m_segments = if self.is_closed_m() { m } else { m.saturating_sub(1) };
        let n_segments = if self.is_closed_n() { n } else { n.saturating_sub(1) };
        for row in 0..m {
            for column in 0..n_segments {
                add_segment(row * n + column, row * n + (column + 1) % n);
            }
        }
        for row in 0..m_segments {
            for column in 0..n {
                add_segment(row * n + column, ((row + 1) % m) * n + column);
            }
        }

        const SNAP_TABLE_MAX_VERTICES: usize = 50_000;
        let snap_pts = if vertices.len() > SNAP_TABLE_MAX_VERTICES {
            Vec::new()
        } else {
            vertices
                .iter()
                .map(|vertex| (glam::DVec3::from_array(*vertex), SnapHint::Node))
                .collect()
        };

        Some(RenderEntity {
            pick_tris: Vec::new(),
            object: RenderObject::Lines(lines),
            snap_pts,
            tangent_geoms: vec![],
            key_vertices: vec![],
            fill_tris: vec![],
        })
    }
}

impl Grippable for PolygonMesh {
    fn grips(&self) -> Vec<GripDef> {
        self.vertices
            .iter()
            .enumerate()
            .map(|(i, v)| {
                square_grip(
                    i,
                    glam::DVec3::new(v.location.x, v.location.y, v.location.z),
                )
            })
            .collect()
    }

    fn apply_grip(&mut self, grip_id: usize, apply: GripApply) {
        if let Some(v) = self.vertices.get_mut(grip_id) {
            let current = glam::DVec3::new(v.location.x, v.location.y, v.location.z);
            let updated = match apply {
                GripApply::Translate(delta) => current + delta,
                GripApply::Absolute(position) => position,
            };
            if !updated.is_finite() {
                return;
            }
            v.location.x = updated.x;
            v.location.y = updated.y;
            v.location.z = updated.z;
        }
    }
}

impl PropertyEditable for PolygonMesh {
    fn geometry_properties(&self, _text_style_names: &[String]) -> Vec<PropSection> {
        use acadrust::entities::polygon_mesh::SurfaceSmoothType;

        let smooth = match self.smooth_type {
            SurfaceSmoothType::NoSmooth => "None",
            SurfaceSmoothType::Quadratic => "Quadratic",
            SurfaceSmoothType::Cubic => "Cubic",
            SurfaceSmoothType::Bezier => "Bezier",
        };
        let vertex_count = self.vertices.len();
        let current = crate::scene::view::dispatch::prop_current_vertex()
            .min(vertex_count.saturating_sub(1));
        let vertex = self.vertices.get(current);
        let display = if vertex_count == 0 {
            "—".to_string()
        } else {
            format!("{} / {}", current + 1, vertex_count)
        };
        let smoothed = self.smooth_type != SurfaceSmoothType::NoSmooth;
        let density_prop = |label: &str, field: &'static str, value: i16| {
            if smoothed {
                edit_scalar(label, field, value as f64)
            } else {
                ro(label, field, value.to_string())
            }
        };
        vec![
            PropSection {
                title: t!("Geometry").into_owned(),
                props: vec![
                    stepper(t!("Current Vertex").as_ref(), "pm_current_vertex", display),
                    edit(t!("Vertex X").as_ref(),
                        "pm_vx",
                        vertex.map_or(0.0, |vertex| vertex.location.x),
                    ),
                    edit(t!("Vertex Y").as_ref(),
                        "pm_vy",
                        vertex.map_or(0.0, |vertex| vertex.location.y),
                    ),
                    edit(t!("Vertex Z").as_ref(),
                        "pm_vz",
                        vertex.map_or(0.0, |vertex| vertex.location.z),
                    ),
                    ro(t!("M vertex count").as_ref(), "pm_m", self.m_vertex_count.to_string()),
                    ro(t!("N vertex count").as_ref(), "pm_n", self.n_vertex_count.to_string()),
                    Property {
                        label: t!("M closed").into_owned(),
                        field: "pm_closed_m",
                        value: PropValue::BoolToggle {
                            field: "pm_closed_m",
                            value: self.is_closed_m(),
                        },
                    },
                    Property {
                        label: t!("N closed").into_owned(),
                        field: "pm_closed_n",
                        value: PropValue::BoolToggle {
                            field: "pm_closed_n",
                            value: self.is_closed_n(),
                        },
                    },
                    density_prop(t!("M density").as_ref(), "pm_smooth_m", self.m_smooth_density),
                    density_prop(t!("N density").as_ref(), "pm_smooth_n", self.n_smooth_density),
                ],
            },
            PropSection {
                title: t!("Misc").into_owned(),
                props: vec![Property {
                    label: t!("Fit/smooth").into_owned(),
                    field: "pm_smooth",
                    value: PropValue::Choice {
                        selected: smooth.to_string(),
                        options: vec![
                            "None".to_string(),
                            "Quadratic".to_string(),
                            "Cubic".to_string(),
                            "Bezier".to_string(),
                        ],
                    },
                }],
            },
        ]
    }

    fn apply_geom_prop(&mut self, field: &str, value: &str) {
        use acadrust::entities::polygon_mesh::{PolygonMeshFlags, SurfaceSmoothType};

        let bool_value = |current: bool| {
            if value == "toggle" {
                Some(!current)
            } else if value.eq_ignore_ascii_case("true")
                || value.eq_ignore_ascii_case("yes")
            {
                Some(true)
            } else if value.eq_ignore_ascii_case("false")
                || value.eq_ignore_ascii_case("no")
            {
                Some(false)
            } else {
                None
            }
        };
        match field {
            "pm_closed_m" => {
                if let Some(closed) = bool_value(self.is_closed_m()) {
                    self.flags.set(PolygonMeshFlags::CLOSED_M, closed);
                }
            }
            "pm_closed_n" => {
                if let Some(closed) = bool_value(self.is_closed_n()) {
                    self.flags.set(PolygonMeshFlags::CLOSED_N, closed);
                }
            }
            "pm_smooth" => {
                let smooth = match value.trim().to_ascii_uppercase().as_str() {
                    "NONE" => SurfaceSmoothType::NoSmooth,
                    "QUADRATIC" => SurfaceSmoothType::Quadratic,
                    "CUBIC" => SurfaceSmoothType::Cubic,
                    "BEZIER" => SurfaceSmoothType::Bezier,
                    _ => return,
                };
                self.smooth_type = smooth;
                if self.smooth_type != SurfaceSmoothType::NoSmooth {
                    if !(2..=256).contains(&self.m_smooth_density) {
                        self.m_smooth_density = 6;
                    }
                    if !(2..=256).contains(&self.n_smooth_density) {
                        self.n_smooth_density = 6;
                    }
                }
            }
            "pm_smooth_m" => {
                if self.smooth_type != SurfaceSmoothType::NoSmooth {
                    if let Ok(density @ 2..=256) = value.trim().parse::<i16>() {
                        self.m_smooth_density = density;
                    }
                }
            }
            "pm_smooth_n" => {
                if self.smooth_type != SurfaceSmoothType::NoSmooth {
                    if let Ok(density @ 2..=256) = value.trim().parse::<i16>() {
                        self.n_smooth_density = density;
                    }
                }
            }
            "pm_vx" | "pm_vy" | "pm_vz" => {
                let Some(number) = parse_f64(value).filter(|number| number.is_finite()) else {
                    return;
                };
                let index = crate::scene::view::dispatch::prop_current_vertex()
                    .min(self.vertices.len().saturating_sub(1));
                if let Some(vertex) = self.vertices.get_mut(index) {
                    match field {
                        "pm_vx" => vertex.location.x = number,
                        "pm_vy" => vertex.location.y = number,
                        "pm_vz" => vertex.location.z = number,
                        _ => {}
                    }
                }
            }
            _ => {}
        }
    }
}

impl Transformable for PolygonMesh {
    fn apply_transform(&mut self, t: &EntityTransform) {
        crate::scene::view::transform::apply_standard_entity_transform(self, 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,
                );
            }
        });
    }
}

// ── PolyfaceMesh (arbitrary faces with 1-based vertex indices) ────────────────

impl RenderConvertible for PolyfaceMesh {
    fn to_render(&self, _document: &acadrust::CadDocument) -> Option<RenderEntity> {
        if self.vertices.is_empty() || self.faces.is_empty() {
            return None;
        }

        Some(RenderEntity {
            pick_tris: Vec::new(),
            object: RenderObject::Lines(Vec::new()),
            snap_pts: vec![],
            tangent_geoms: vec![],
            key_vertices: vec![],
            fill_tris: vec![],
        })
    }
}

impl Grippable for PolyfaceMesh {
    fn grips(&self) -> Vec<GripDef> {
        self.vertices
            .iter()
            .enumerate()
            .map(|(i, v)| {
                square_grip(
                    i,
                    glam::DVec3::new(v.location.x, v.location.y, v.location.z),
                )
            })
            .collect()
    }

    fn apply_grip(&mut self, grip_id: usize, apply: GripApply) {
        if let Some(v) = self.vertices.get_mut(grip_id) {
            match apply {
                GripApply::Translate(d) => {
                    v.location.x += d.x as f64;
                    v.location.y += d.y as f64;
                    v.location.z += d.z as f64;
                }
                GripApply::Absolute(p) => {
                    v.location.x = p.x as f64;
                    v.location.y = p.y as f64;
                    v.location.z = p.z as f64;
                }
            }
        }
    }
}

impl PropertyEditable for PolyfaceMesh {
    fn geometry_properties(&self, _text_style_names: &[String]) -> Vec<PropSection> {
        let smooth = match self.smooth_surface {
            acadrust::entities::PolyfaceSmoothType::None => "None",
            acadrust::entities::PolyfaceSmoothType::Quadratic => "Quadratic",
            acadrust::entities::PolyfaceSmoothType::Cubic => "Cubic",
            acadrust::entities::PolyfaceSmoothType::Bezier => "Bezier",
        };
        let first = self.vertices.first();
        vec![
            PropSection {
                title: t!("Geometry").into_owned(),
                props: vec![
                    ro(t!("Vertex").as_ref(), "pfm_vertex", String::new()),
                    ro(t!("Vertex X").as_ref(),
                        "pfm_vx",
                        first.map(|v| format!("{:.4}", v.location.x)).unwrap_or_default(),
                    ),
                    ro(t!("Vertex Y").as_ref(),
                        "pfm_vy",
                        first.map(|v| format!("{:.4}", v.location.y)).unwrap_or_default(),
                    ),
                    ro(t!("Vertex Z").as_ref(),
                        "pfm_vz",
                        first.map(|v| format!("{:.4}", v.location.z)).unwrap_or_default(),
                    ),
                    // Polyface meshes store an explicit vertex/face list rather
                    // than an M×N grid, so the grid-only rows are not applicable.
                    ro(t!("M vertex count").as_ref(), "pfm_m", String::new()),
                    ro(t!("N vertex count").as_ref(), "pfm_n", String::new()),
                    ro(t!("M closed").as_ref(), "pfm_closed_m", String::new()),
                    ro(t!("N closed").as_ref(), "pfm_closed_n", String::new()),
                    ro(t!("M density").as_ref(), "pfm_density_m", String::new()),
                    ro(t!("N density").as_ref(), "pfm_density_n", String::new()),
                    ro(t!("Vertex count").as_ref(), "pfm_v", self.vertices.len().to_string()),
                    ro(t!("Face count").as_ref(), "pfm_f", self.faces.len().to_string()),
                ],
            },
            PropSection {
                title: t!("Misc").into_owned(),
                props: vec![ro(t!("Fit/smooth").as_ref(), "pfm_smooth", smooth)],
            },
        ]
    }

    fn apply_geom_prop(&mut self, _field: &str, _value: &str) {}
}

impl Transformable for PolyfaceMesh {
    fn apply_transform(&mut self, t: &EntityTransform) {
        crate::scene::view::transform::apply_standard_entity_transform(self, 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,
                );
            }
        });
    }
}

// ── Mesh (SubD mesh) ──────────────────────────────────────────────────────────
//
// Modern subdivision mesh — distinct from PolygonMesh. The render path emits
// the refined per-edge wireframe and triangulates each face into fill_tris so
// solid views draw the same Catmull-Clark surface described by the DWG.

#[derive(Clone)]
struct RefinedMesh {
    vertices: Vec<[f64; 3]>,
    faces: Vec<Vec<usize>>,
    creases: std::collections::HashMap<(usize, usize), f64>,
}

fn edge_key(a: usize, b: usize) -> (usize, usize) {
    if a < b { (a, b) } else { (b, a) }
}

fn add3(a: [f64; 3], b: [f64; 3]) -> [f64; 3] {
    [a[0] + b[0], a[1] + b[1], a[2] + b[2]]
}

fn mul3(a: [f64; 3], scale: f64) -> [f64; 3] {
    [a[0] * scale, a[1] * scale, a[2] * scale]
}

fn mix3(a: [f64; 3], b: [f64; 3], amount: f64) -> [f64; 3] {
    add3(mul3(a, 1.0 - amount), mul3(b, amount))
}

fn mean_points<'a>(points: impl Iterator<Item = &'a [f64; 3]>) -> [f64; 3] {
    let mut sum = [0.0; 3];
    let mut count = 0usize;
    for point in points {
        sum = add3(sum, *point);
        count += 1;
    }
    if count == 0 {
        sum
    } else {
        mul3(sum, 1.0 / count as f64)
    }
}

fn base_refined_mesh(mesh: &Mesh) -> RefinedMesh {
    let vertices: Vec<[f64; 3]> = mesh.vertices.iter().map(|v| [v.x, v.y, v.z]).collect();
    let faces = mesh
        .faces
        .iter()
        .filter_map(|face| {
            let valid: Vec<usize> = face
                .vertices
                .iter()
                .copied()
                .filter(|&index| index < vertices.len())
                .collect();
            (valid.len() >= 3).then_some(valid)
        })
        .collect();
    let creases = mesh
        .edges
        .iter()
        .filter_map(|edge| {
            let sharpness = edge.crease?;
            (edge.start < vertices.len() && edge.end < vertices.len() && sharpness > 0.0)
                .then_some((edge_key(edge.start, edge.end), sharpness))
        })
        .collect();
    RefinedMesh {
        vertices,
        faces,
        creases,
    }
}

fn subdivide_catmull_clark(mesh: &RefinedMesh, blend_crease: bool) -> RefinedMesh {
    use std::collections::{HashMap, HashSet};

    if mesh.faces.is_empty() {
        return mesh.clone();
    }

    let face_points: Vec<[f64; 3]> = mesh
        .faces
        .iter()
        .map(|face| mean_points(face.iter().filter_map(|&index| mesh.vertices.get(index))))
        .collect();

    let mut edge_faces: HashMap<(usize, usize), Vec<usize>> = HashMap::new();
    let mut vertex_faces: Vec<Vec<usize>> = vec![Vec::new(); mesh.vertices.len()];
    let mut vertex_edges: Vec<HashSet<(usize, usize)>> = vec![HashSet::new(); mesh.vertices.len()];
    for (face_index, face) in mesh.faces.iter().enumerate() {
        for &vertex in face {
            if let Some(faces) = vertex_faces.get_mut(vertex) {
                faces.push(face_index);
            }
        }
        for corner in 0..face.len() {
            let a = face[corner];
            let b = face[(corner + 1) % face.len()];
            if a == b {
                continue;
            }
            let key = edge_key(a, b);
            edge_faces.entry(key).or_default().push(face_index);
            if let Some(edges) = vertex_edges.get_mut(a) {
                edges.insert(key);
            }
            if let Some(edges) = vertex_edges.get_mut(b) {
                edges.insert(key);
            }
        }
    }

    let mut vertex_points = Vec::with_capacity(mesh.vertices.len());
    for (vertex_index, &point) in mesh.vertices.iter().enumerate() {
        let incident_edges = &vertex_edges[vertex_index];
        let incident_faces = &vertex_faces[vertex_index];
        if incident_edges.is_empty() || incident_faces.is_empty() {
            vertex_points.push(point);
            continue;
        }

        let face_average =
            mean_points(incident_faces.iter().filter_map(|&index| face_points.get(index)));
        let edge_midpoints: Vec<[f64; 3]> = incident_edges
            .iter()
            .filter_map(|&(a, b)| {
                let other = if a == vertex_index { b } else { a };
                mesh.vertices
                    .get(other)
                    .map(|&p| mul3(add3(point, p), 0.5))
            })
            .collect();
        let edge_average = mean_points(edge_midpoints.iter());
        let n = incident_faces.len() as f64;
        let smooth = mul3(
            add3(add3(face_average, mul3(edge_average, 2.0)), mul3(point, n - 3.0)),
            1.0 / n,
        );

        let mut sharp_neighbours: Vec<(f64, [f64; 3])> = incident_edges
            .iter()
            .filter_map(|&key| {
                let boundary = edge_faces.get(&key).is_some_and(|faces| faces.len() == 1);
                let sharpness = if boundary {
                    f64::INFINITY
                } else {
                    mesh.creases.get(&key).copied().unwrap_or(0.0)
                };
                if sharpness <= 0.0 {
                    return None;
                }
                let other = if key.0 == vertex_index { key.1 } else { key.0 };
                mesh.vertices.get(other).copied().map(|p| (sharpness, p))
            })
            .collect();
        sharp_neighbours.sort_by(|a, b| b.0.total_cmp(&a.0));

        let crease_point = match sharp_neighbours.as_slice() {
            [(_, first), (_, second), ..] => mul3(
                add3(add3(mul3(point, 6.0), *first), *second),
                1.0 / 8.0,
            ),
            _ => smooth,
        };
        let corner_point = if sharp_neighbours.len() >= 3 {
            point
        } else {
            crease_point
        };
        let sharpness = sharp_neighbours
            .get(1)
            .map(|item| item.0)
            .unwrap_or(0.0);
        let amount = if blend_crease {
            sharpness.clamp(0.0, 1.0)
        } else if sharpness > 0.0 {
            1.0
        } else {
            0.0
        };
        vertex_points.push(mix3(smooth, corner_point, amount));
    }

    let mut edge_point_indices = HashMap::with_capacity(edge_faces.len());
    let mut vertices = vertex_points;
    for (&key, adjacent_faces) in &edge_faces {
        let Some((&a, &b)) = mesh.vertices.get(key.0).zip(mesh.vertices.get(key.1)) else {
            continue;
        };
        let midpoint = mul3(add3(a, b), 0.5);
        let smooth = if adjacent_faces.len() == 2 {
            let f0 = face_points[adjacent_faces[0]];
            let f1 = face_points[adjacent_faces[1]];
            mul3(add3(add3(a, b), add3(f0, f1)), 0.25)
        } else {
            midpoint
        };
        let boundary = adjacent_faces.len() != 2;
        let sharpness = mesh.creases.get(&key).copied().unwrap_or(0.0);
        let amount = if boundary {
            1.0
        } else if blend_crease {
            sharpness.clamp(0.0, 1.0)
        } else if sharpness > 0.0 {
            1.0
        } else {
            0.0
        };
        edge_point_indices.insert(key, vertices.len());
        vertices.push(mix3(smooth, midpoint, amount));
    }

    let face_point_start = vertices.len();
    vertices.extend(face_points.iter().copied());
    let mut faces = Vec::new();
    let mut creases = HashMap::new();
    for (face_index, face) in mesh.faces.iter().enumerate() {
        for corner in 0..face.len() {
            let vertex = face[corner];
            let next_key = edge_key(vertex, face[(corner + 1) % face.len()]);
            let prev_key = edge_key(face[(corner + face.len() - 1) % face.len()], vertex);
            let (Some(&next_edge), Some(&prev_edge)) = (
                edge_point_indices.get(&next_key),
                edge_point_indices.get(&prev_key),
            ) else {
                continue;
            };
            faces.push(vec![
                vertex,
                next_edge,
                face_point_start + face_index,
                prev_edge,
            ]);
        }
    }

    for (&key, &sharpness) in &mesh.creases {
        let Some(&edge_point) = edge_point_indices.get(&key) else {
            continue;
        };
        let child_sharpness = (sharpness - 1.0).max(0.0);
        if child_sharpness > 0.0 {
            creases.insert(edge_key(key.0, edge_point), child_sharpness);
            creases.insert(edge_key(edge_point, key.1), child_sharpness);
        }
    }

    RefinedMesh {
        vertices,
        faces,
        creases,
    }
}

fn display_mesh(mesh: &Mesh) -> RefinedMesh {
    let mut refined = base_refined_mesh(mesh);
    for _ in 0..mesh.subdivision_level.clamp(0, 4) {
        refined = subdivide_catmull_clark(&refined, mesh.blend_crease);
    }
    refined
}

fn face_triangle_indices(
    vertices: &[[f64; 3]],
    faces: &[Vec<usize>],
) -> (Vec<u32>, Vec<usize>) {
    let mut indices = Vec::new();
    let mut triangle_faces = Vec::new();
    for (face_index, face) in faces.iter().enumerate() {
        let polygon: Vec<[f64; 3]> = face
            .iter()
            .filter_map(|&index| vertices.get(index).copied())
            .collect();
        if polygon.len() < 3 {
            continue;
        }
        for triangle in triangulate_planar(&polygon).chunks_exact(3) {
            let mut mapped = [0u32; 3];
            let mut valid = true;
            for corner in 0..3 {
                let Some(local) = polygon.iter().position(|point| *point == triangle[corner]) else {
                    valid = false;
                    break;
                };
                mapped[corner] = face[local] as u32;
            }
            if valid && mapped[0] != mapped[1] && mapped[1] != mapped[2] && mapped[2] != mapped[0] {
                indices.extend(mapped);
                triangle_faces.push(face_index);
            }
        }
    }
    (indices, triangle_faces)
}

fn vertex_normals(vertices: &[[f64; 3]], indices: &[u32]) -> Vec<[f32; 3]> {
    let mut normals = vec![[0.0f64; 3]; vertices.len()];
    for triangle in indices.chunks_exact(3) {
        let (Some(&a), Some(&b), Some(&c)) = (
            vertices.get(triangle[0] as usize),
            vertices.get(triangle[1] as usize),
            vertices.get(triangle[2] as usize),
        ) else {
            continue;
        };
        let ab = [b[0] - a[0], b[1] - a[1], b[2] - a[2]];
        let ac = [c[0] - a[0], c[1] - a[1], c[2] - a[2]];
        let normal = [
            ab[1] * ac[2] - ab[2] * ac[1],
            ab[2] * ac[0] - ab[0] * ac[2],
            ab[0] * ac[1] - ab[1] * ac[0],
        ];
        for &index in triangle {
            if let Some(sum) = normals.get_mut(index as usize) {
                *sum = add3(*sum, normal);
            }
        }
    }
    normals
        .into_iter()
        .map(|normal| {
            let length =
                (normal[0] * normal[0] + normal[1] * normal[1] + normal[2] * normal[2]).sqrt();
            if length > 1e-15 {
                [
                    (normal[0] / length) as f32,
                    (normal[1] / length) as f32,
                    (normal[2] / length) as f32,
                ]
            } else {
                [0.0, 0.0, 1.0]
            }
        })
        .collect()
}

fn append_feature_edge(
    edge_verts: &mut Vec<[f32; 3]>,
    edge_verts_low: &mut Vec<[f32; 3]>,
    vertices: &[[f64; 3]],
    a: usize,
    b: usize,
) {
    for index in [a, b] {
        let Some(&[x, y, z]) = vertices.get(index) else {
            continue;
        };
        let high = [x as f32, y as f32, z as f32];
        edge_verts.push(high);
        edge_verts_low.push([
            (x - high[0] as f64) as f32,
            (y - high[1] as f64) as f32,
            (z - high[2] as f64) as f32,
        ]);
    }
}

fn make_mesh_lod_set(
    name: String,
    color: [f32; 4],
    vertices: Vec<[f64; 3]>,
    faces: Vec<Vec<usize>>,
    visible_edges: std::collections::HashSet<(usize, usize)>,
    face_colors: &[Option<[f32; 4]>],
) -> Option<crate::scene::model::mesh_model::MeshLodSet> {
    let (indices, triangle_faces) = face_triangle_indices(&vertices, &faces);
    if indices.is_empty() {
        return None;
    }
    let normals = vertex_normals(&vertices, &indices);
    let triangle_colors = triangle_faces
        .iter()
        .map(|&face| face_colors.get(face).copied().flatten())
        .collect();
    let model = crate::scene::convert::solid3d_tess::finalize_mesh(
        name,
        vertices.clone(),
        normals,
        indices,
        Vec::new(),
        triangle_colors,
        color,
        None,
    );
    let mut set = crate::scene::model::mesh_model::MeshLodSet::from_lods(vec![model]);
    for (a, b) in visible_edges {
        append_feature_edge(
            &mut set.edge_verts,
            &mut set.edge_verts_low,
            &vertices,
            a,
            b,
        );
    }
    Some(set)
}

/// Convert every standard DWG mesh family to the material-aware shaded mesh
/// pipeline. The retained wire entity carries snaps/grips only; fill, normals,
/// depth, materials and face colours live in `MeshLodSet`.
pub(crate) fn tessellate_shaded_mesh(
    entity: &acadrust::EntityType,
    color: [f32; 4],
) -> Option<crate::scene::model::mesh_model::MeshLodSet> {
    use std::collections::HashSet;

    match entity {
        acadrust::EntityType::Mesh(mesh) => {
            let display = display_mesh(mesh);
            let mut edges = HashSet::new();
            for face in &display.faces {
                for corner in 0..face.len() {
                    edges.insert(edge_key(face[corner], face[(corner + 1) % face.len()]));
                }
            }
            make_mesh_lod_set(
                mesh.common.handle.value().to_string(),
                color,
                display.vertices,
                display.faces,
                edges,
                &[],
            )
        }
        acadrust::EntityType::PolygonMesh(mesh) => {
            let (vertices, m, n) = polygon_mesh_display(mesh);
            if m == 0 || n == 0 || vertices.len() < m.saturating_mul(n) {
                return None;
            }
            let closed_m = mesh.is_closed_m();
            let closed_n = mesh.is_closed_n();
            let m_cells = if closed_m { m } else { m.saturating_sub(1) };
            let n_cells = if closed_n { n } else { n.saturating_sub(1) };
            let mut faces = Vec::with_capacity(m_cells.saturating_mul(n_cells));
            let mut edges = HashSet::new();
            for i in 0..m_cells {
                for j in 0..n_cells {
                    let face = vec![
                        i * n + j,
                        ((i + 1) % m) * n + j,
                        ((i + 1) % m) * n + (j + 1) % n,
                        i * n + (j + 1) % n,
                    ];
                    for corner in 0..4 {
                        edges.insert(edge_key(face[corner], face[(corner + 1) % 4]));
                    }
                    faces.push(face);
                }
            }
            make_mesh_lod_set(
                mesh.common.handle.value().to_string(),
                color,
                vertices,
                faces,
                edges,
                &[],
            )
        }
        acadrust::EntityType::PolyfaceMesh(mesh) => {
            let vertices: Vec<[f64; 3]> = mesh
                .vertices
                .iter()
                .map(|vertex| {
                    [
                        vertex.location.x,
                        vertex.location.y,
                        vertex.location.z,
                    ]
                })
                .collect();
            let mut faces = Vec::new();
            let mut face_colors = Vec::new();
            let mut edges = HashSet::new();
            for face in &mesh.faces {
                let raw = [face.index1, face.index2, face.index3, face.index4];
                let indices: Vec<usize> = raw
                    .iter()
                    .filter(|&&index| index != 0)
                    .filter_map(|&index| (index.unsigned_abs() as usize).checked_sub(1))
                    .filter(|&index| index < vertices.len())
                    .collect();
                if indices.len() < 3 {
                    continue;
                }
                for corner in 0..indices.len() {
                    if raw[corner] > 0 {
                        edges.insert(edge_key(indices[corner], indices[(corner + 1) % indices.len()]));
                    }
                }
                faces.push(indices);
                face_colors.push(face.color.as_ref().map(crate::scene::convert::tess_util::aci_to_rgba));
            }
            make_mesh_lod_set(
                mesh.common.handle.value().to_string(),
                color,
                vertices,
                faces,
                edges,
                &face_colors,
            )
        }
        _ => None,
    }
}

impl RenderConvertible for Mesh {
    fn to_render(&self, _document: &acadrust::CadDocument) -> Option<RenderEntity> {
        if self.vertices.is_empty() {
            return None;
        }

        // Per-vertex snap tables cost ~56 B/vertex and are retained in every
        // copy of the wire set. On NWD-scale imports (#358: tens of millions
        // of mesh vertices) that is GBs for snap targets far too dense to
        // pick apart on screen — so past this size ship none, which is what
        // PolyfaceMesh / PolygonMesh already do at any size.
        const SNAP_TABLE_MAX_VERTICES: usize = 50_000;
        let (snap_pts, key_vertices) = if self.vertices.len() > SNAP_TABLE_MAX_VERTICES {
            (Vec::new(), Vec::new())
        } else {
            (
                self.vertices
                    .iter()
                    .map(|v| (glam::DVec3::new(v.x, v.y, v.z), SnapHint::Node))
                    .collect(),
                self.vertices.iter().map(|v| [v.x, v.y, v.z]).collect(),
            )
        };

        Some(RenderEntity {
            pick_tris: Vec::new(),
            object: RenderObject::Lines(Vec::new()),
            snap_pts,
            tangent_geoms: vec![],
            key_vertices,
            fill_tris: vec![],
        })
    }
}

impl Grippable for Mesh {
    fn grips(&self) -> Vec<GripDef> {
        Vec::new()
    }

    fn apply_grip(&mut self, grip_id: usize, apply: GripApply) {
        if let Some(v) = self.vertices.get_mut(grip_id) {
            match apply {
                GripApply::Translate(d) => {
                    v.x += d.x as f64;
                    v.y += d.y as f64;
                    v.z += d.z as f64;
                }
                GripApply::Absolute(p) => {
                    v.x = p.x as f64;
                    v.y = p.y as f64;
                    v.z = p.z as f64;
                }
            }
        }
    }
}

impl PropertyEditable for Mesh {
    fn geometry_properties(&self, _text_style_names: &[String]) -> Vec<PropSection> {
        // Watertight when every face edge is shared by exactly two faces
        // (closed manifold). Empty meshes are not watertight.
        let mut edge_use: std::collections::HashMap<(usize, usize), u32> =
            std::collections::HashMap::new();
        for face in &self.faces {
            let vs = &face.vertices;
            for i in 0..vs.len() {
                let a = vs[i];
                let b = vs[(i + 1) % vs.len()];
                let key = if a < b { (a, b) } else { (b, a) };
                *edge_use.entry(key).or_insert(0) += 1;
            }
        }
        let watertight =
            !self.faces.is_empty() && edge_use.values().all(|&c| c == 2);
        vec![PropSection {
            title: t!("Geometry").into_owned(),
            props: vec![
                Property {
                    label: t!("Level of Smoothness").into_owned(),
                    field: "msh_subdiv_edit",
                    value: PropValue::EditText(self.subdivision_level.to_string()),
                },
                Property {
                    label: t!("Blend Creases").into_owned(),
                    field: "msh_blend_crease",
                    value: PropValue::BoolToggle {
                        field: "msh_blend_crease",
                        value: self.blend_crease,
                    },
                },
                ro(t!("Number of Faces").as_ref(), "msh_f", self.faces.len().to_string()),
                ro(t!("Number of Vertices").as_ref(), "msh_v", self.vertices.len().to_string()),
                ro(t!("Number of Edges").as_ref(), "msh_e", self.edges.len().to_string()),
                ro(t!("Creased Edges").as_ref(),
                    "msh_creased",
                    self.edges
                        .iter()
                        .filter(|edge| edge.crease.is_some_and(|value| value > 0.0))
                        .count()
                        .to_string(),
                ),
                ro(t!("Override Option").as_ref(),
                    "msh_override",
                    self.override_option.to_string(),
                ),
                ro(t!("Number of Grips").as_ref(), "msh_grips", self.vertices.len().to_string()),
                ro(t!("Watertight").as_ref(),
                    "msh_watertight",
                    if watertight { "Yes" } else { "No" },
                ),
            ],
        }]
    }

    fn apply_geom_prop(&mut self, field: &str, value: &str) {
        match field {
            "msh_subdiv_edit" => {
                if let Some(value) = parse_f64(value) {
                    self.subdivision_level = (value.round() as i32).clamp(0, 4);
                }
            }
            "msh_blend_crease" => {
                self.blend_crease = match value {
                    "toggle" => !self.blend_crease,
                    "On" | "Yes" | "true" | "1" => true,
                    "Off" | "No" | "false" | "0" => false,
                    _ => self.blend_crease,
                };
            }
            _ => {}
        }
    }
}

impl Transformable for Mesh {
    fn apply_transform(&mut self, t: &EntityTransform) {
        crate::scene::view::transform::apply_standard_entity_transform(self, t, |entity, p1, p2| {
            for v in &mut entity.vertices {
                crate::scene::view::transform::reflect_xy_point(&mut v.x, &mut v.y, p1, p2);
            }
        });
    }
}