dessin 0.8.23

use crate::prelude::*;
use nalgebra::{Point2, Transform2};
use std::f32::consts::TAU;

/// Regular polygons
pub mod polygons {
	use super::Polygon;

	/// Triangle
	pub type Triangle = Polygon<3>;
	/// Square
	pub type Square = Polygon<4>;
	/// Pentagon
	pub type Pentagon = Polygon<5>;
	/// Hexagon
	pub type Hexagon = Polygon<6>;
	/// Heptagon
	pub type Heptagon = Polygon<7>;
	/// Octogon
	pub type Octogon = Polygon<8>;
	/// Nonagon
	pub type Nonagon = Polygon<9>;
	/// Decagon
	pub type Decagon = Polygon<10>;
	/// Dodecagon
	pub type Dodecagon = Polygon<12>;
}

/// N sided regular polygone
#[derive(Default, Debug, Clone, PartialEq, Shape)]
pub struct Polygon<const N: u32> {
	/// [`ShapeOp`]
	#[local_transform]
	pub local_transform: Transform2<f32>,
}
impl<const N: u32> Polygon<N> {
	const STEP: f32 = TAU / N as f32;
}

impl<const N: u32> From<Polygon<N>> for Shape {
	fn from(Polygon { local_transform }: Polygon<N>) -> Self {
		let step = Polygon::<N>::STEP;

		dessin!(
			Curve(
				extend = (0..N).map(|p| Point2::from([
					(p as f32 * step).cos(),
					(p as f32 * step).sin()
				])
				.into()),
				closed,
				transform = local_transform,
			) > ()
		)
	}
}

#[test]
fn triangle() {
	use crate::prelude::*;
	use assert_float_eq::*;

	let sqrt3_over_2 = 3f32.sqrt() / 2.;

	let Shape::Curve(triangle) = polygons::Triangle::default().as_shape() else {
		panic!("Not a curve");
	};

	for (a, b) in triangle.keypoints.iter().zip(
		[
			Point2::new(1., 0.),
			Point2::new(-0.5, sqrt3_over_2),
			Point2::new(-0.5, -sqrt3_over_2),
		]
		.iter(),
	) {
		let Keypoint::Point(p) = a else {
			panic!("Not a point");
		};

		assert_float_absolute_eq!(p.x, b.x, 10e-5);
		assert_float_absolute_eq!(p.y, b.y, 10e-5);
	}
}

#[test]
fn square() {
	use crate::prelude::{polygons::*, *};
	use assert_float_eq::*;

	let Shape::Curve(square) = Square::default().as_shape() else {
		panic!("Not a curve");
	};

	for (a, b) in square.keypoints.iter().zip(
		[
			Point2::new(1., 0.),
			Point2::new(0., 1.),
			Point2::new(-1., 0.),
			Point2::new(0., -1.),
		]
		.iter(),
	) {
		let Keypoint::Point(p) = a else {
			panic!("Not a point");
		};

		assert_float_absolute_eq!(p.x, b.x, 10e-5);
		assert_float_absolute_eq!(p.y, b.y, 10e-5);
	}
}

#[test]
fn triangle_in_group() {
	use crate::prelude::*;
	use assert_float_eq::*;
	use nalgebra::Transform2;

	let sqrt3_over_2 = 3f32.sqrt() / 2.;

	let Shape::Group(Group {
		local_transform,
		shapes,
		..
	}) = dessin!([polygons::Triangle()])
	else {
		panic!("Not a group");
	};
	assert_eq!(shapes.len(), 1);
	assert_eq!(local_transform, Transform2::<f32>::default());

	let Shape::Curve(triangle) = shapes[0].clone() else {
		panic!("Not a curve");
	};

	for (a, b) in triangle.keypoints.iter().zip(
		[
			Point2::new(1., 0.),
			Point2::new(-0.5, sqrt3_over_2),
			Point2::new(-0.5, -sqrt3_over_2),
		]
		.iter(),
	) {
		let Keypoint::Point(p) = a else {
			panic!("Not a point");
		};

		assert_float_absolute_eq!(p.x, b.x, 10e-5);
		assert_float_absolute_eq!(p.y, b.y, 10e-5);
	}
}

#[test]
fn bounding_box() {
	use crate::prelude::*;
	use nalgebra::Rotation2;
	use std::f32::consts::FRAC_PI_4;

	let polys: [(usize, Shape); 4] = [
		(3, polygons::Triangle::default().into()),
		(4, polygons::Square::default().into()),
		(8, polygons::Octogon::default().into()),
		(10, polygons::Decagon::default().into()),
	];

	for (n, mut poly) in polys.into_iter() {
		let bb = poly.local_bounding_box();
		assert!(bb.width() <= 2., "{} <= 2. for {n}-gon", bb.width());
		assert!(bb.height() <= 2., "{} <= 2. for {n}-gon", bb.height());

		poly.rotate(Rotation2::new(FRAC_PI_4));
		let bb = poly.local_bounding_box();
		assert!(bb.width() <= 2., "{} <= 2. for {n}-gon", bb.width());
		assert!(bb.height() <= 2., "{} <= 2. for {n}-gon", bb.height());
		let bb = bb.straigthen();
		assert!(
			2. < bb.width() && bb.width() < 3.,
			"2. > {} < 3.  for {n}-gon",
			bb.width()
		);
		assert!(
			2. < bb.height() && bb.height() < 3.,
			"2. > {} < 3.  for {n}-gon",
			bb.height()
		);
	}
}