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mod delaunay;
mod polygon;
mod ray;

use fj_interop::{debug::DebugInfo, mesh::Mesh};
use fj_math::Point;

use crate::objects::Face;

use self::polygon::Polygon;

use super::{FaceApprox, Tolerance};

/// Triangulate a shape
pub fn triangulate(
    faces: Vec<Face>,
    tolerance: Tolerance,
    debug_info: &mut DebugInfo,
) -> Mesh<Point<3>> {
    let mut mesh = Mesh::new();

    for face in faces {
        if let Some(triangles) = face.triangles() {
            for &(triangle, color) in triangles {
                mesh.push_triangle(triangle.points(), color);
            }
            continue;
        }

        let surface = face.surface();
        let approx = FaceApprox::new(&face, tolerance);

        let points: Vec<_> = approx.points.into_iter().collect();
        let face_as_polygon = Polygon::new(*surface)
            .with_exterior(
                approx
                    .exterior
                    .points
                    .into_iter()
                    .map(|point| *point.local_form()),
            )
            .with_interiors(approx.interiors.into_iter().map(|interior| {
                interior.points.into_iter().map(|point| *point.local_form())
            }));

        let mut triangles = delaunay::triangulate(points);
        triangles.retain(|triangle| {
            face_as_polygon.contains_triangle(
                triangle.map(|point| *point.local_form()),
                debug_info,
            )
        });

        for triangle in triangles {
            let points = triangle.map(|point| *point.global_form());
            mesh.push_triangle(points, face.color());
        }
    }

    mesh
}

#[cfg(test)]
mod tests {
    use fj_interop::{debug::DebugInfo, mesh::Mesh};
    use fj_math::{Point, Scalar};

    use crate::{
        algorithms::Tolerance,
        objects::{Face, Surface},
    };

    #[test]
    fn simple() -> anyhow::Result<()> {
        let a = [0., 0.];
        let b = [2., 0.];
        let c = [2., 2.];
        let d = [0., 1.];

        let surface = Surface::xy_plane();
        let face = Face::build(surface).polygon_from_points([a, b, c, d]);

        let a = Point::from(a).to_xyz();
        let b = Point::from(b).to_xyz();
        let c = Point::from(c).to_xyz();
        let d = Point::from(d).to_xyz();

        let triangles = triangulate(face)?;

        assert!(triangles.contains_triangle([a, b, d]));
        assert!(triangles.contains_triangle([b, c, d]));
        assert!(!triangles.contains_triangle([a, b, c]));
        assert!(!triangles.contains_triangle([a, c, d]));

        Ok(())
    }

    #[test]
    fn simple_hole() -> anyhow::Result<()> {
        let a = [0., 0.];
        let b = [4., 0.];
        let c = [4., 4.];
        let d = [0., 4.];

        let e = [1., 1.];
        let f = [3., 1.];
        let g = [3., 3.];
        let h = [1., 2.];

        let surface = Surface::xy_plane();
        let face = Face::build(surface)
            .polygon_from_points([a, b, c, d])
            .with_hole([e, f, g, h]);

        let triangles = triangulate(face)?;

        let a = Point::from(a).to_xyz();
        let d = Point::from(d).to_xyz();
        let e = Point::from(e).to_xyz();
        let f = Point::from(f).to_xyz();
        let g = Point::from(g).to_xyz();
        let h = Point::from(h).to_xyz();

        // Should contain some triangles from the polygon. Don't need to test
        // them all.
        assert!(triangles.contains_triangle([a, e, h]));
        assert!(triangles.contains_triangle([a, d, h]));

        // Shouldn't contain any possible triangle from the hole.
        assert!(!triangles.contains_triangle([e, f, g]));
        assert!(!triangles.contains_triangle([e, g, h]));
        assert!(!triangles.contains_triangle([e, f, h]));
        assert!(!triangles.contains_triangle([f, g, h]));

        Ok(())
    }

    #[ignore]
    #[test]
    fn sharp_concave_shape() -> anyhow::Result<()> {
        //
        //                c
        //               /|
        //   e          / |
        //   |\       /   |
        //   | |     /    |
        //   | \   /      |
        //   |  \ /       |
        //   |   d        |
        //   a ---------- b
        //

        let a = Point::from([0., 0.]);
        let b = Point::from([0.4, 0.]);
        //let b = Point::from([0.5, 0.]); // test passes with this change
        let c = Point::from([0.4, 1.0]);
        let d = Point::from([0.1, 0.1]);
        let e = Point::from([0., 0.8]);

        let surface = Surface::xy_plane();
        let face = Face::build(surface).polygon_from_points([a, b, c, d, e]);

        let triangles = triangulate(face)?;

        let a3 = a.to_xyz();
        let b3 = b.to_xyz();
        let c3 = c.to_xyz();
        let d3 = d.to_xyz();
        let e3 = e.to_xyz();

        assert!(triangles.contains_triangle([a3, b3, d3]));
        assert!(triangles.contains_triangle([b3, c3, d3]));
        assert!(triangles.contains_triangle([a3, d3, e3]));

        assert!(!triangles.contains_triangle([b3, e3, d3]));

        Ok(())
    }

    fn triangulate(face: impl Into<Face>) -> anyhow::Result<Mesh<Point<3>>> {
        let tolerance = Tolerance::from_scalar(Scalar::ONE)?;

        let mut debug_info = DebugInfo::new();
        Ok(super::triangulate(
            vec![face.into()],
            tolerance,
            &mut debug_info,
        ))
    }
}