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use std::ops::{Deref, Neg};
use float_cmp::{Ulps, ApproxEq};
use super::{Vec2, Vec3, Vec4};
use {Angle, FullFloat};

/// Direction vector in 2-dimensions (normalized)
#[repr(C)]
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
#[derive(Serialize, Deserialize)]
pub struct Direction2<F>(Vec2<F>);

/// Direction vector in 3-dimensions (normalized)
#[repr(C)]
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
#[derive(Serialize, Deserialize)]
pub struct Direction3<F>(Vec3<F>);

pub const X_AXIS_F32: Direction3<f32> = Direction3::<f32>(
    Vec3::<f32> { x: 1.0, y: 0.0, z: 0.0 }
);
pub const Y_AXIS_F32: Direction3<f32> = Direction3::<f32>(
    Vec3::<f32> { x: 0.0, y: 1.0, z: 0.0 }
);
pub const Z_AXIS_F32: Direction3<f32> = Direction3::<f32>(
    Vec3::<f32> { x: 0.0, y: 0.0, z: 1.0 }
);
pub const X_AXIS_F64: Direction3<f64> = Direction3::<f64>(
    Vec3::<f64> { x: 1.0, y: 0.0, z: 0.0 }
);
pub const Y_AXIS_F64: Direction3<f64> = Direction3::<f64>(
    Vec3::<f64> { x: 0.0, y: 1.0, z: 0.0 }
);
pub const Z_AXIS_F64: Direction3<f64> = Direction3::<f64>(
    Vec3::<f64> { x: 0.0, y: 0.0, z: 1.0 }
);

impl<F: FullFloat> Direction2<F> {
    #[inline]
    pub fn new_isnormal(x: F, y: F) -> Direction2<F> {
        let d = Direction2(Vec2::new(x,y));
        assert!(d.0.is_normal());
        d
    }
}

impl<F: FullFloat> Direction3<F> {
    #[inline]
    pub fn new_isnormal(x: F, y: F, z: F) -> Direction3<F> {
        let d = Direction3(Vec3::new(x,y,z));
        assert!(d.0.is_normal());
        d
    }
}

impl<F: FullFloat> Deref for Direction2<F> {
    type Target = Vec2<F>;

    fn deref(&self) -> &Vec2<F>
    {
        &self.0
    }
}

impl<F: FullFloat> Deref for Direction3<F> {
    type Target = Vec3<F>;

    fn deref(&self) -> &Vec3<F>
    {
        &self.0
    }
}

impl<F: FullFloat> From<Direction2<F>> for Vec2<F> {
    fn from(v: Direction2<F>) -> Vec2<F> {
        v.0
    }
}
impl<F: FullFloat> From<Direction3<F>> for Vec3<F> {
    fn from(v: Direction3<F>) -> Vec3<F> {
        v.0
    }
}
impl<F: FullFloat> From<Direction3<F>> for Vec4<F> {
    fn from(v: Direction3<F>) -> Vec4<F> {
        Vec4::new(v.0.x, v.0.y, v.0.z, F::zero())
    }
}

impl<F: FullFloat> From<Vec2<F>> for Direction2<F> {
    fn from(mut v: Vec2<F>) -> Direction2<F> {
        let mag = v.magnitude();
        v.x /= mag;
        v.y /= mag;
        Direction2(v)
    }
}
impl<F: FullFloat> From<Vec3<F>> for Direction3<F> {
    fn from(mut v: Vec3<F>) -> Direction3<F> {
        let mag = v.magnitude();
        v.x /= mag;
        v.y /= mag;
        v.z /= mag;
        Direction3(v)
    }
}

impl<F: FullFloat> Direction3<F> {
    #[allow(dead_code)]
    #[inline]
    fn from_vec4(v: Vec4<F>) -> Option<Direction3<F>> {
        if v.w != F::zero() { return None; }
        Some(Direction3(v.truncate_w()))
    }
}

impl<F: FullFloat> Direction3<F> {
    #[inline]
    pub fn cross(&self, rhs: Direction3<F>) -> Vec3<F> {
        self.0.cross(rhs.0)
    }
}

impl<F: FullFloat> Direction3<F> {
    #[inline]
    pub fn dot(&self, rhs: Direction3<F>) -> F {
        self.0.dot(rhs.0)
    }
}

impl<F: FullFloat> Neg for Direction3<F> {
    type Output = Direction3<F>;

    #[inline]
    fn neg(self) -> Direction3<F> {
        Direction3(-self.0)
    }
}

impl<F: FullFloat> ApproxEq for Direction2<F> {
    type Flt = F;

    fn approx_eq(&self, other: &Self,
                 epsilon: <F as ApproxEq>::Flt,
                 ulps: <<F as ApproxEq>::Flt as Ulps>::U) -> bool
    {
        self.0.approx_eq(&other.0, epsilon, ulps)
    }
}

impl<F: FullFloat> ApproxEq for Direction3<F> {
    type Flt = F;

    fn approx_eq(&self, other: &Self,
                 epsilon: <F as ApproxEq>::Flt,
                 ulps: <<F as ApproxEq>::Flt as Ulps>::U) -> bool
    {
        self.0.approx_eq(&other.0, epsilon, ulps)
    }
}

impl<F: FullFloat> Direction3<F> {
    pub fn from_lat_long(latitude: Angle<F>, longitude: Angle<F>) -> Direction3<F>
    {
        let (slat,clat) = latitude.as_radians().sin_cos();
        let (slon,clon) = longitude.as_radians().sin_cos();
        Direction3(Vec3 {
            x: clat * slon,
            y: slat,
            z: slat * clon,
        })
    }

    pub fn to_lat_long(&self) -> (Angle<F>, Angle<F>) {
        let lat = self.0.y.acos();
        let lon = (self.0.z / self.0.y).acos();
        (Angle::from_radians(lat), Angle::from_radians(lon))
    }
}