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use fj_math::{Point, Scalar, Vector};

use crate::{
    geometry::{path::GlobalPath, surface::SurfaceGeometry},
    partial::PartialSurface,
};

/// Builder API for [`PartialSurface`]
pub trait SurfaceBuilder: Sized {
    /// Build a surface from its two axes
    fn from_axes(u: GlobalPath, v: impl Into<Vector<3>>) -> Self;

    /// Construct a plane from 3 points
    fn plane_from_points(
        points: [impl Into<Point<3>>; 3],
    ) -> (Self, [Point<2>; 3]);
}

impl SurfaceBuilder for PartialSurface {
    fn from_axes(u: GlobalPath, v: impl Into<Vector<3>>) -> Self {
        let v = v.into();

        Self {
            geometry: Some(SurfaceGeometry { u, v }),
        }
    }

    fn plane_from_points(
        points: [impl Into<Point<3>>; 3],
    ) -> (Self, [Point<2>; 3]) {
        let [a, b, c] = points.map(Into::into);

        let (u, u_coords) = GlobalPath::line_from_points([a, b]);
        let v = c - a;

        let coords = {
            let [a, b] = u_coords.map(|point| point.t);
            [[a, Scalar::ZERO], [b, Scalar::ZERO], [a, Scalar::ONE]]
                .map(Point::from)
        };

        (
            Self {
                geometry: Some(SurfaceGeometry { u, v }),
            },
            coords,
        )
    }
}