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use super::*;
use std::f64::consts::PI;

impl<P> UnitCircle<P> {
    /// constructor
    #[inline]
    pub const fn new() -> Self { Self(std::marker::PhantomData) }
}

impl ParametricCurve for UnitCircle<Point2> {
    type Point = Point2;
    type Vector = Vector2;
    #[inline]
    fn subs(&self, t: f64) -> Self::Point { Point2::new(f64::cos(t), f64::sin(t)) }
    #[inline]
    fn der(&self, t: f64) -> Self::Vector { Vector2::new(-f64::sin(t), f64::cos(t)) }
    #[inline]
    fn der2(&self, t: f64) -> Self::Vector { Vector2::new(-f64::cos(t), -f64::sin(t)) }
}

impl BoundedCurve for UnitCircle<Point2> {
    #[inline]
    fn parameter_range(&self) -> (f64, f64) { (0.0, 2.0 * PI) }
}

impl ParametricCurve for UnitCircle<Point3> {
    type Point = Point3;
    type Vector = Vector3;
    #[inline]
    fn subs(&self, t: f64) -> Self::Point { Point3::new(f64::cos(t), f64::sin(t), 0.0) }
    #[inline]
    fn der(&self, t: f64) -> Self::Vector { Vector3::new(-f64::sin(t), f64::cos(t), 0.0) }
    #[inline]
    fn der2(&self, t: f64) -> Self::Vector { Vector3::new(-f64::cos(t), -f64::sin(t), 0.0) }
}

impl BoundedCurve for UnitCircle<Point3> {
    #[inline]
    fn parameter_range(&self) -> (f64, f64) { (0.0, 2.0 * PI) }
}

impl<P> ParameterDivision1D for UnitCircle<P>
where UnitCircle<P>: ParametricCurve<Point = P>
{
    type Point = P;
    fn parameter_division(&self, range: (f64, f64), tol: f64) -> (Vec<f64>, Vec<P>) {
        nonpositive_tolerance!(tol);
        let tol = f64::min(tol, 0.8);
        let delta = 2.0 * f64::acos(1.0 - tol);
        let n = 1 + ((range.1 - range.0) / delta) as usize;
        let params = (0..=n)
            .map(|i| {
                let t = i as f64 / n as f64;
                range.0 * (1.0 - t) + range.1 * t
            })
            .collect::<Vec<_>>();
        let pts = params.iter().map(|t| self.subs(*t)).collect();
        (params, pts)
    }
}

impl SearchNearestParameter<D1> for UnitCircle<Point2> {
    type Point = Point2;
    fn search_nearest_parameter<H: Into<SPHint1D>>(
        &self,
        pt: Point2,
        _: H,
        _: usize,
    ) -> Option<f64> {
        let v = pt.to_vec();
        if v.magnitude2().so_small2() {
            return None;
        }
        let v = v.normalize();
        let theta = f64::acos(v.x);
        let theta = match v.y > 0.0 {
            true => theta,
            false => 2.0 * PI - theta,
        };
        Some(theta)
    }
}

impl SearchParameter<D1> for UnitCircle<Point2> {
    type Point = Point2;
    fn search_parameter<H: Into<SPHint1D>>(&self, pt: Point2, _: H, _: usize) -> Option<f64> {
        let v = pt.to_vec();
        if !v.magnitude2().near2(&1.0) {
            return None;
        }
        let v = v.normalize();
        let theta = f64::acos(v.x);
        let theta = match v.y > 0.0 {
            true => theta,
            false => 2.0 * PI - theta,
        };
        Some(theta)
    }
}

impl SearchNearestParameter<D1> for UnitCircle<Point3> {
    type Point = Point3;
    fn search_nearest_parameter<H: Into<SPHint1D>>(
        &self,
        pt: Point3,
        _: H,
        _: usize,
    ) -> Option<f64> {
        UnitCircle::<Point2>::new().search_nearest_parameter(Point2::new(pt.x, pt.y), None, 0)
    }
}

impl SearchParameter<D1> for UnitCircle<Point3> {
    type Point = Point3;
    fn search_parameter<H: Into<SPHint1D>>(&self, pt: Point3, _: H, _: usize) -> Option<f64> {
        if !f64::abs(pt.z).so_small() {
            return None;
        }
        UnitCircle::<Point2>::new().search_parameter(Point2::new(pt.x, pt.y), None, 0)
    }
}

#[test]
fn parameter_division() {
    let c = UnitCircle::<Point2>::new();
    let (_div, pts) = c.parameter_division(c.parameter_range(), 0.05);
    for a in pts.windows(2) {
        let p = a[0].midpoint(a[1]);
        assert!(p.to_vec().magnitude() > 0.95);
    }
}