bevy_symbios_shape 0.4.0

//! Ergonomic command extension for spawning CGA shape grammar results as Bevy entities.
//!
//! # Usage
//!
//! ```ignore
//! use bevy::prelude::*;
//! use bevy_symbios_shape::prelude::*;
//! use symbios_shape::{Interpreter, Scope, grammar::parse_ops};
//!
//! fn setup(
//!     mut commands: Commands,
//!     registry: Res<ShapeRegistry>,
//!     mut meshes: ResMut<Assets<Mesh>>,
//!     mut materials: ResMut<Assets<StandardMaterial>>,
//!     mut cache: ResMut<ShapeMeshCache>,
//! ) {
//!     let mut interp = Interpreter::new();
//!     interp.add_rule("Lot", parse_ops("Extrude(12) I(\"Building\")").unwrap());
//!
//!     let footprint = Scope::new(
//!         symbios_shape::Vec3::ZERO,
//!         symbios_shape::Quat::IDENTITY,
//!         symbios_shape::Vec3::new(10.0, 0.0, 10.0),
//!     );
//!
//!     commands
//!         .spawn_shape(&interp, footprint, "Lot", &registry, &mut meshes, &mut materials, &mut cache)
//!         .unwrap();
//! }
//! ```

use bevy::color::Color;
use bevy::prelude::*;
use symbios_shape::{Interpreter, Scope, ShapeError};

use crate::cache::{MeshCacheKey, ProfileKey, ShapeMeshCache};
use crate::mass::TerminalMass;
use crate::mesh::build_profiled_mesh;
use crate::query::LastDerivedModel;
use crate::registry::ShapeRegistry;
use crate::snap::{SnapPlane, SnapPlanes};
use crate::transform::scope_to_transform;

/// Extension trait on [`Commands`] for spawning CGA shape grammar outputs as Bevy entities.
#[allow(clippy::too_many_arguments)]
pub trait SpawnShapeExt {
    /// Derives the shape grammar starting from `root_scope` / `root_rule`, then
    /// spawns the resulting [`Terminal`] nodes as a hierarchy of Bevy entities.
    ///
    /// Returns the root [`Entity`] (a spatial grouping node at world origin) on
    /// success, or a [`ShapeError`] if derivation fails.
    ///
    /// # Asset resolution
    ///
    /// For each terminal:
    /// - If `mesh_id` is registered in `registry` → spawn a [`SceneRoot`] child.
    /// - Otherwise → generate a procedural mesh via [`build_profiled_mesh`]
    ///   (supports tapered prisms, triangles, trapezoids, and arbitrary polygons)
    ///   and spawn [`Mesh3d`] + [`MeshMaterial3d`].
    ///
    /// [`build_profiled_mesh`]: crate::mesh::build_profiled_mesh
    ///
    /// For materials:
    /// - If `terminal.material` is registered in `registry` → use that handle.
    /// - Otherwise → use `registry.default_material`, or a generated grey material.
    ///
    /// # Transform
    ///
    /// Each terminal's [`Transform`] is computed by [`scope_to_transform`], which
    /// converts the double-precision scope (corner-anchored) to a Bevy centroid-
    /// anchored `Transform` with proper f64→f32 downcasting.
    ///
    /// [`Terminal`]: symbios_shape::Terminal
    fn spawn_shape(
        &mut self,
        interpreter: &Interpreter,
        root_scope: Scope,
        root_rule: &str,
        registry: &ShapeRegistry,
        meshes: &mut Assets<Mesh>,
        materials: &mut Assets<StandardMaterial>,
        cache: &mut ShapeMeshCache,
    ) -> Result<Entity, ShapeError>;
}

impl SpawnShapeExt for Commands<'_, '_> {
    fn spawn_shape(
        &mut self,
        interpreter: &Interpreter,
        root_scope: Scope,
        root_rule: &str,
        registry: &ShapeRegistry,
        meshes: &mut Assets<Mesh>,
        materials: &mut Assets<StandardMaterial>,
        cache: &mut ShapeMeshCache,
    ) -> Result<Entity, ShapeError> {
        let model = interpreter.derive(root_scope, root_rule)?;

        // Surface this derivation's snap-plane recordings as a resource so
        // downstream systems can read them. Last-spawn wins; consumers that
        // need to retain older planes should clone in a post-update system.
        let snap_planes: Vec<SnapPlane> = model.snap_planes.iter().map(SnapPlane::from).collect();
        self.insert_resource(SnapPlanes(snap_planes));

        // Root grouping entity — children use world-space transforms as their local
        // transforms, so the root sits at the world origin with no offset.
        // Visibility is required so that `commands.entity(root).insert(Visibility::Hidden)`
        // propagates through the hierarchy via InheritedVisibility/ViewVisibility.
        let root = self
            .spawn((Transform::default(), Visibility::default()))
            .id();

        for terminal in &model.terminals {
            let transform = scope_to_transform(&terminal.scope);

            let child = if let Some(scene_handle) = registry.get_mesh(&terminal.mesh_id) {
                // Registered asset: spawn as a scene child.
                // The scene is assumed to be unit-scale; scope_to_transform provides scale.
                self.spawn((SceneRoot(scene_handle.clone()), transform))
                    .id()
            } else {
                // Procedural fallback: generate a tapered cuboid mesh.
                let size = Vec3::new(
                    terminal.scope.size.x as f32,
                    terminal.scope.size.y as f32,
                    terminal.scope.size.z as f32,
                );

                let stretch_uvs = registry.should_stretch_uvs(
                    &terminal.mesh_id,
                    terminal.material.as_ref().map(|m| m.id.as_str()),
                );

                let mesh_key = MeshCacheKey {
                    profile: ProfileKey::from_profile(&terminal.face_profile),
                    size_x_bits: size.x.to_bits(),
                    size_y_bits: size.y.to_bits(),
                    size_z_bits: size.z.to_bits(),
                    stretch_uvs,
                };

                let mesh_handle = cache.get_or_insert_with(mesh_key, || {
                    meshes.add(build_profiled_mesh(
                        &terminal.face_profile,
                        size,
                        stretch_uvs,
                    ))
                });

                let material_handle = registry
                    .resolve_material(terminal.material.as_ref().map(|m| m.id.as_str()))
                    .unwrap_or_else(|| {
                        // Derive a stable grey-ish color from the mesh_id string so
                        // different unknown IDs are visually distinguishable.
                        let hue = string_to_hue(&terminal.mesh_id);
                        materials.add(StandardMaterial {
                            base_color: Color::hsl(hue, 0.4, 0.6),
                            ..Default::default()
                        })
                    });

                self.spawn((
                    Mesh3d(mesh_handle),
                    MeshMaterial3d(material_handle),
                    transform,
                ))
                .id()
            };

            if let Some(mp) = terminal.mass_properties.as_ref() {
                self.entity(child).insert(TerminalMass::from(mp));
            }

            self.entity(root).add_child(child);
        }

        // Hand the full derivation to downstream systems for spatial queries.
        // Moves the model after the for-loop borrow ends.
        self.insert_resource(LastDerivedModel(model));

        Ok(root)
    }
}

/// Maps a string to a hue value in `[0, 360)` via a simple hash,
/// giving visually distinct but stable colors for unknown mesh IDs.
fn string_to_hue(s: &str) -> f32 {
    let hash = s.bytes().fold(5381u32, |acc, b| {
        acc.wrapping_mul(31).wrapping_add(b as u32)
    });
    (hash % 360) as f32
}

#[cfg(test)]
mod tests {
    use super::*;
    use bevy::ecs::system::RunSystemOnce;
    use symbios_shape::grammar::parse_ops;
    use symbios_shape::{Interpreter, Quat as DQuat, Scope, Vec3 as DVec3};

    #[test]
    fn string_to_hue_is_in_range() {
        for id in ["Window", "Door", "Roof", "Ground", "Wall", ""] {
            let h = string_to_hue(id);
            assert!((0.0..360.0).contains(&h), "hue {h} out of range for '{id}'");
        }
    }

    #[test]
    fn string_to_hue_is_stable() {
        assert_eq!(string_to_hue("Building"), string_to_hue("Building"));
    }

    /// Builds a minimal Bevy world with the asset registries needed by `spawn_shape`.
    fn make_app() -> App {
        let mut app = App::new();
        app.add_plugins(bevy::asset::AssetPlugin::default())
            .init_resource::<Assets<Mesh>>()
            .init_resource::<Assets<StandardMaterial>>()
            .init_resource::<Assets<Scene>>()
            .init_resource::<ShapeRegistry>()
            .init_resource::<ShapeMeshCache>();
        app
    }

    #[test]
    fn mass_component_inserted_when_density_present() {
        let mut interp = Interpreter::new();
        interp.add_rule(
            "Lot",
            parse_ops(r#"Extrude(2) Mat("Stone", 1800) I("Wall")"#).unwrap(),
        );
        let footprint = Scope::new(DVec3::ZERO, DQuat::IDENTITY, DVec3::new(2.0, 0.0, 2.0));

        let mut app = make_app();
        app.world_mut()
            .run_system_once(
                move |mut commands: Commands,
                      registry: Res<ShapeRegistry>,
                      mut meshes: ResMut<Assets<Mesh>>,
                      mut materials: ResMut<Assets<StandardMaterial>>,
                      mut cache: ResMut<ShapeMeshCache>| {
                    commands
                        .spawn_shape(
                            &interp,
                            footprint,
                            "Lot",
                            &registry,
                            &mut meshes,
                            &mut materials,
                            &mut cache,
                        )
                        .unwrap();
                },
            )
            .unwrap();

        let count = app
            .world_mut()
            .query::<&TerminalMass>()
            .iter(app.world())
            .count();
        assert!(
            count >= 1,
            "expected at least one TerminalMass component, got {count}"
        );
        let masses: Vec<_> = app
            .world_mut()
            .query::<&TerminalMass>()
            .iter(app.world())
            .map(|m| m.mass)
            .collect();
        assert!(
            masses.iter().all(|&m| m > 0.0 && m.is_finite()),
            "expected positive finite masses, got {masses:?}"
        );
    }

    #[test]
    fn snap_planes_resource_populated_after_spawn() {
        // RegSnap("walls") records all six face planes of the current scope.
        let mut interp = Interpreter::new();
        interp.add_rule(
            "Lot",
            parse_ops(r#"Extrude(2) RegSnap("walls") I("Wall")"#).unwrap(),
        );
        let footprint = Scope::new(DVec3::ZERO, DQuat::IDENTITY, DVec3::new(2.0, 0.0, 2.0));

        let mut app = make_app();
        app.world_mut()
            .run_system_once(
                move |mut commands: Commands,
                      registry: Res<ShapeRegistry>,
                      mut meshes: ResMut<Assets<Mesh>>,
                      mut materials: ResMut<Assets<StandardMaterial>>,
                      mut cache: ResMut<ShapeMeshCache>| {
                    commands
                        .spawn_shape(
                            &interp,
                            footprint,
                            "Lot",
                            &registry,
                            &mut meshes,
                            &mut materials,
                            &mut cache,
                        )
                        .unwrap();
                },
            )
            .unwrap();

        let planes = app.world().resource::<SnapPlanes>();
        assert_eq!(planes.len(), 6, "RegSnap should record 6 face planes");
        assert!(
            planes.iter().all(|p| p.label == "walls"),
            "all planes should carry the RegSnap label"
        );
        assert!(
            planes.iter().all(|p| p.normal.length() > 0.99),
            "normals should be unit length"
        );
    }

    #[test]
    fn last_derived_model_populated_and_overlaps_query_works() {
        let mut interp = Interpreter::new();
        // Single terminal at the origin spanning (2, 2, 2).
        interp.add_rule("Lot", parse_ops(r#"Extrude(2) I("Wall")"#).unwrap());
        let footprint = Scope::new(DVec3::ZERO, DQuat::IDENTITY, DVec3::new(2.0, 0.0, 2.0));

        let mut app = make_app();
        app.world_mut()
            .run_system_once(
                move |mut commands: Commands,
                      registry: Res<ShapeRegistry>,
                      mut meshes: ResMut<Assets<Mesh>>,
                      mut materials: ResMut<Assets<StandardMaterial>>,
                      mut cache: ResMut<ShapeMeshCache>| {
                    commands
                        .spawn_shape(
                            &interp,
                            footprint,
                            "Lot",
                            &registry,
                            &mut meshes,
                            &mut materials,
                            &mut cache,
                        )
                        .unwrap();
                },
            )
            .unwrap();

        let derived = app.world().resource::<LastDerivedModel>();
        assert!(
            !derived.model().terminals.is_empty(),
            "expected at least one terminal in LastDerivedModel"
        );

        // A query scope sitting on top of the terminal must overlap.
        let near = Scope::new(
            DVec3::new(0.5, 0.5, 0.5),
            DQuat::IDENTITY,
            DVec3::new(0.5, 0.5, 0.5),
        );
        assert!(derived.overlaps(&near), "near scope should overlap");

        // A query scope 100 units away must not overlap.
        let far = Scope::new(
            DVec3::new(100.0, 100.0, 100.0),
            DQuat::IDENTITY,
            DVec3::new(0.5, 0.5, 0.5),
        );
        assert!(!derived.overlaps(&far), "far scope should not overlap");
    }

    #[test]
    fn snap_planes_resource_empty_when_no_regsnap() {
        let mut interp = Interpreter::new();
        interp.add_rule("Lot", parse_ops(r#"Extrude(2) I("Wall")"#).unwrap());
        let footprint = Scope::new(DVec3::ZERO, DQuat::IDENTITY, DVec3::new(2.0, 0.0, 2.0));

        let mut app = make_app();
        app.world_mut()
            .run_system_once(
                move |mut commands: Commands,
                      registry: Res<ShapeRegistry>,
                      mut meshes: ResMut<Assets<Mesh>>,
                      mut materials: ResMut<Assets<StandardMaterial>>,
                      mut cache: ResMut<ShapeMeshCache>| {
                    commands
                        .spawn_shape(
                            &interp,
                            footprint,
                            "Lot",
                            &registry,
                            &mut meshes,
                            &mut materials,
                            &mut cache,
                        )
                        .unwrap();
                },
            )
            .unwrap();

        let planes = app.world().resource::<SnapPlanes>();
        assert!(
            planes.is_empty(),
            "expected no snap planes, got {}",
            planes.len()
        );
    }

    #[test]
    fn mesh_cache_reuses_handles_across_spawns() {
        // Same grammar, two spawns: the second spawn should hit the cache for
        // every procedural mesh it generates. Interpreter isn't Clone, so we
        // build it twice with the same rules.
        fn make_interp() -> Interpreter {
            let mut interp = Interpreter::new();
            interp.add_rule("Lot", parse_ops(r#"Extrude(2) I("Wall")"#).unwrap());
            interp
        }
        let footprint = Scope::new(DVec3::ZERO, DQuat::IDENTITY, DVec3::new(2.0, 0.0, 2.0));

        let mut app = make_app();
        let interp = make_interp();
        app.world_mut()
            .run_system_once(
                move |mut commands: Commands,
                      registry: Res<ShapeRegistry>,
                      mut meshes: ResMut<Assets<Mesh>>,
                      mut materials: ResMut<Assets<StandardMaterial>>,
                      mut cache: ResMut<ShapeMeshCache>| {
                    commands
                        .spawn_shape(
                            &interp,
                            footprint,
                            "Lot",
                            &registry,
                            &mut meshes,
                            &mut materials,
                            &mut cache,
                        )
                        .unwrap();
                },
            )
            .unwrap();

        let (hits_after_first, misses_after_first, len_after_first) = {
            let cache = app.world().resource::<ShapeMeshCache>();
            (cache.hits(), cache.misses(), cache.len())
        };
        assert!(
            misses_after_first >= 1,
            "first spawn should miss at least once"
        );
        assert_eq!(hits_after_first, 0, "first spawn should not hit");

        // Second spawn with an identical grammar.
        let interp = make_interp();
        app.world_mut()
            .run_system_once(
                move |mut commands: Commands,
                      registry: Res<ShapeRegistry>,
                      mut meshes: ResMut<Assets<Mesh>>,
                      mut materials: ResMut<Assets<StandardMaterial>>,
                      mut cache: ResMut<ShapeMeshCache>| {
                    commands
                        .spawn_shape(
                            &interp,
                            footprint,
                            "Lot",
                            &registry,
                            &mut meshes,
                            &mut materials,
                            &mut cache,
                        )
                        .unwrap();
                },
            )
            .unwrap();

        let cache = app.world().resource::<ShapeMeshCache>();
        assert_eq!(
            cache.misses(),
            misses_after_first,
            "second spawn must not miss (no new keys)"
        );
        assert!(
            cache.hits() > hits_after_first,
            "second spawn must register hits"
        );
        assert_eq!(
            cache.len(),
            len_after_first,
            "cache size should not grow on identical second spawn"
        );
    }

    #[test]
    fn mass_component_absent_when_no_density() {
        let mut interp = Interpreter::new();
        // No Mat() => no density => no MassProperties => no TerminalMass.
        interp.add_rule("Lot", parse_ops(r#"Extrude(2) I("Wall")"#).unwrap());
        let footprint = Scope::new(DVec3::ZERO, DQuat::IDENTITY, DVec3::new(2.0, 0.0, 2.0));

        let mut app = make_app();
        app.world_mut()
            .run_system_once(
                move |mut commands: Commands,
                      registry: Res<ShapeRegistry>,
                      mut meshes: ResMut<Assets<Mesh>>,
                      mut materials: ResMut<Assets<StandardMaterial>>,
                      mut cache: ResMut<ShapeMeshCache>| {
                    commands
                        .spawn_shape(
                            &interp,
                            footprint,
                            "Lot",
                            &registry,
                            &mut meshes,
                            &mut materials,
                            &mut cache,
                        )
                        .unwrap();
                },
            )
            .unwrap();

        let count = app
            .world_mut()
            .query::<&TerminalMass>()
            .iter(app.world())
            .count();
        assert_eq!(count, 0, "expected no TerminalMass components, got {count}");
    }
}