//! Abutment geometry — PureRustKernel.
//! Breast wall + footing + wing walls (simplified rectangular shapes).

use cimery_ir::AbutmentIR;
use crate::{KernelError, Mesh, sweep};

pub fn build_abutment_mesh(ir: &AbutmentIR) -> Result<Mesh, KernelError> {
    if ir.breast_wall_height <= 0.0 {
        return Err(KernelError::InvalidInput(
            format!("breast_wall_height must be > 0, got {}", ir.breast_wall_height),
        ));
    }

    let bw_h  = ir.breast_wall_height as f32;
    let bw_t  = ir.breast_wall_thickness as f32;
    let bw_w  = ir.breast_wall_width as f32;
    let ft_l  = ir.footing_length as f32;
    let ft_w  = ir.footing_width as f32;
    let ft_t  = ir.footing_thickness as f32;

    let mut parts: Vec<Mesh> = Vec::new();

    // Breast wall: along transverse (Z), thickness along span (X), height (Y)
    parts.push(sweep::centred_box(0.0, bw_h * 0.5, bw_t * 0.5, bw_h * 0.5, bw_w));

    // Footing: below grade, spans along X (span direction)
    {
        let profile = vec![
            [-ft_l * 0.5, -ft_t],
            [ ft_l * 0.5, -ft_t],
            [ ft_l * 0.5,  0.0 ],
            [-ft_l * 0.5,  0.0 ],
        ];
        parts.push(sweep::sweep_profile_flat(&profile, ft_w));
    }

    // Wing walls (left and right)
    for side in [&ir.wing_wall_left, &ir.wing_wall_right] {
        let wl = side.length as f32;
        let wh = side.height as f32;
        let wt = side.thickness as f32;
        // Simplified: vertical rectangle, oriented in XY, length along Z
        parts.push(sweep::centred_box(0.0, wh * 0.5, wt * 0.5, wh * 0.5, wl));
    }

    Ok(sweep::merge_meshes(parts))
}

#[cfg(test)]
mod tests {
    use super::*;
    use cimery_core::{AbutmentType, MaterialGrade};
    use cimery_ir::{AbutmentIR, FeatureId, WingWallIR};

    fn test_ir() -> AbutmentIR {
        let wing = WingWallIR { length: 4000.0, height: 3000.0, thickness: 500.0 };
        AbutmentIR {
            id: FeatureId::new(),
            station: 0.0, skew_angle: 0.0,
            abutment_type: AbutmentType::ReverseT,
            breast_wall_height: 5000.0, breast_wall_thickness: 800.0,
            breast_wall_width: 12000.0,
            footing_length: 4000.0, footing_width: 13000.0, footing_thickness: 1000.0,
            wing_wall_left: wing.clone(), wing_wall_right: wing,
            material: MaterialGrade::C40,
        }
    }

    #[test]
    fn produces_mesh() {
        let mesh = build_abutment_mesh(&test_ir()).unwrap();
        assert!(mesh.triangle_count() > 0);
    }

    #[test]
    fn zero_height_fails() {
        let mut ir = test_ir();
        ir.breast_wall_height = 0.0;
        assert!(build_abutment_mesh(&ir).is_err());
    }
}