use crate::geom::about_equal;
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};
use std::{
    cmp::{Eq, PartialEq},
    fmt,
    iter::Sum,
    ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Sub, SubAssign},
};

#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Copy, Clone, Default, Debug)]
///A 2D vector with an arbitrary numeric type
pub struct Vector {
    ///The x coordinate of the vector
    pub x: f32,
    ///The y coordinate of the vector
    pub y: f32,
}

impl Vector {
    /// A vector with x = 0.0, y = 0
    pub const ZERO: Vector = Vector { x: 0f32, y: 0f32 };
    /// A vector with x = 1, y = 0
    pub const X: Vector = Vector { x: 1f32, y: 0f32 };
    /// A vector with x = 0, y = 1
    pub const Y: Vector = Vector { x: 0f32, y: 1f32 };
    /// A vector with x = 1, y = 1
    pub const ONE: Vector = Vector { x: 1f32, y: 1f32 };
}

#[allow(clippy::len_without_is_empty)]
impl Vector {
    ///Create a new vector
    pub fn new(x: f32, y: f32) -> Vector {
        Vector { x, y }
    }

    ///Create a unit vector at a given angle
    pub fn from_angle(angle: f32) -> Vector {
        Vector::new(angle.to_radians().cos(), angle.to_radians().sin())
    }

    ///Get the squared length of the vector (faster than getting the length)
    pub fn len2(self) -> f32 {
        self.x * self.x + self.y * self.y
    }

    ///Get the length of the vector
    pub fn len(self) -> f32 {
        self.len2().sqrt()
    }

    ///Clamp a vector somewhere between a minimum and a maximum
    #[must_use]
    pub fn clamp(self, min_bound: Vector, max_bound: Vector) -> Vector {
        Vector::new(
            max_bound.x.min(min_bound.x.max(self.x)),
            max_bound.y.min(min_bound.y.max(self.y)),
        )
    }

    ///Get the cross product of a vector
    pub fn cross(self, other: Vector) -> f32 {
        self.x * other.y - self.y * other.x
    }

    ///Get the dot product of a vector
    pub fn dot(self, other: Vector) -> f32 {
        self.x * other.x + self.y * other.y
    }

    ///Normalize the vector's length from [0, 1]
    #[must_use]
    pub fn normalize(self) -> Vector {
        self / self.len()
    }

    ///Get only the X component of the Vector, represented as a vector
    #[must_use]
    pub fn x_comp(self) -> Vector {
        Vector::new(self.x, 0f32)
    }

    ///Get only the Y component of the Vector, represented as a vector
    #[must_use]
    pub fn y_comp(self) -> Vector {
        Vector::new(0f32, self.y)
    }

    ///Get the vector equal to Vector(1 / x, 1 / y)
    #[must_use]
    pub fn recip(self) -> Vector {
        Vector::new(self.x.recip(), self.y.recip())
    }

    ///Multiply the components in the matching places
    #[must_use]
    pub fn times(self, other: Vector) -> Vector {
        Vector::new(self.x * other.x, self.y * other.y)
    }

    ///Get the angle a vector forms with the positive x-axis, counter clockwise
    pub fn angle(self) -> f32 {
        self.y.atan2(self.x).to_degrees()
    }

    ///Create a vector with the same angle and the given length
    #[must_use]
    pub fn with_len(self, length: f32) -> Vector {
        self.normalize() * length
    }

    ///Get the Euclidean distance to another vector
    pub fn distance(self, other: Vector) -> f32 {
        ((other.x - self.x).powi(2) + (other.y - self.y).powi(2)).sqrt()
    }

    ///Get a vector with the minimum of each component of this and another vector
    pub fn min(self, other: Vector) -> Vector {
        Vector::new(self.x.min(other.x), self.y.min(other.y))
    }

    ///Get a vector with the maximum of each component of this and another vector
    pub fn max(self, other: Vector) -> Vector {
        Vector::new(self.x.max(other.x), self.y.max(other.y))
    }
}

impl Neg for Vector {
    type Output = Vector;

    fn neg(self) -> Vector {
        Vector::new(-self.x, -self.y)
    }
}

impl Add for Vector {
    type Output = Vector;

    fn add(self, rhs: Vector) -> Vector {
        Vector::new(self.x + rhs.x, self.y + rhs.y)
    }
}

impl AddAssign for Vector {
    fn add_assign(&mut self, rhs: Vector) {
        *self = *self + rhs;
    }
}

impl Sub for Vector {
    type Output = Vector;

    fn sub(self, rhs: Vector) -> Vector {
        self + (-rhs)
    }
}

impl SubAssign for Vector {
    fn sub_assign(&mut self, rhs: Vector) {
        *self = *self - rhs;
    }
}

impl Div<f32> for Vector {
    type Output = Vector;

    fn div(self, rhs: f32) -> Vector {
        Vector::new(self.x / rhs, self.y / rhs)
    }
}

impl DivAssign<f32> for Vector {
    fn div_assign(&mut self, rhs: f32) {
        *self = *self / rhs;
    }
}

impl Mul<f32> for Vector {
    type Output = Vector;

    fn mul(self, rhs: f32) -> Vector {
        Vector::new(self.x * rhs, self.y * rhs)
    }
}

impl MulAssign<f32> for Vector {
    fn mul_assign(&mut self, rhs: f32) {
        *self = *self * rhs;
    }
}

impl Sum for Vector {
    fn sum<I>(iter: I) -> Vector
    where
        I: Iterator<Item = Vector>,
    {
        iter.fold(Vector::ZERO, |a, b| a + b)
    }
}

impl PartialEq for Vector {
    fn eq(&self, other: &Vector) -> bool {
        about_equal(self.x, other.x) && about_equal(self.y, other.y)
    }
}

impl Eq for Vector {}

impl fmt::Display for Vector {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "<{}, {}>", self.x, self.y)
    }
}

impl From<mint::Vector2<f32>> for Vector {
    fn from(other: mint::Vector2<f32>) -> Vector {
        Vector::new(other.x, other.y)
    }
}

impl From<Vector> for mint::Vector2<f32> {
    fn from(vec: Vector) -> mint::Vector2<f32> {
        mint::Vector2 { x: vec.x, y: vec.y }
    }
}

impl From<(f32, f32)> for Vector {
    fn from(other: (f32, f32)) -> Vector {
        Vector::new(other.0, other.1)
    }
}

#[cfg(test)]
mod tests {
    use crate::geom::*;

    #[test]
    fn arithmetic() {
        let a = Vector::new(5.0, 10.0);
        let b = Vector::new(1.0, -2.0);
        assert!((a + b).x == 6f32);
        assert!((a - b).y == 12f32);
    }

    #[test]
    fn equality() {
        assert_eq!(Vector::new(5.0, 5.0), Vector::new(5.0, 5.0));
        assert_ne!(Vector::new(0.0, 5.0), Vector::new(5.0, 5.0));
    }

    #[test]
    fn inverse() {
        let vec = Vector::new(3.0, 5.0);
        let inverse = vec.recip();
        assert_eq!(Vector::new(1.0 / 3.0, 1.0 / 5.0), inverse);
    }

    #[test]
    fn length() {
        let vec = Vector::X * 5.0;
        assert!(about_equal(vec.len2(), 25f32));
        assert!(about_equal(vec.len(), 5f32));
    }

    #[test]
    fn scale() {
        let vec = Vector::new(1.0, 1.0);
        let doubled = Vector::new(2.0, 2.0);
        assert_eq!(vec * 2.0, doubled);
        let halved = Vector::new(0.5, 0.5);
        assert_eq!(vec / 2.0, halved);
    }

    #[test]
    fn clamp() {
        let min = Vector::new(-10.0, -2.0);
        let max = Vector::new(5.0, 6.0);
        let vec = Vector::new(-11.0, 3.0);
        let clamped = vec.clamp(min, max);
        let expected = Vector::new(-10.0, 3.0);
        assert_eq!(clamped, expected);
    }

    #[test]
    fn dot() {
        assert!(about_equal(
            Vector::new(6.0, 5.0).dot(Vector::new(2.0, -8.0)),
            -28f32
        ));
    }

    #[test]
    fn times() {
        let vec = Vector::new(3.0, -2.0);
        let two = Vector::ONE * 2.0;
        assert_eq!(vec.times(two), vec * 2.0);
    }

    #[test]
    fn angle() {
        let a = Vector::X;
        let b = Vector::Y;
        let c = a + b;
        assert_eq!(a.angle(), 0.0);
        assert_eq!(b.angle(), 90.0);
        assert_eq!(c.angle(), 45.0);
    }

    #[test]
    fn distance() {
        let a = Vector::X;
        let b = Vector::Y;
        let c = a + b;
        assert_eq!(a.distance(a), 0.0);
        assert_eq!(a.distance(Vector::ZERO), 1.0);
        assert_eq!(b.distance(a), 2_f32.sqrt());
        assert_eq!(c.distance(Vector::ZERO), 2_f32.sqrt());
    }

    #[test]
    fn sum() {
        let input = vec![
            Vector::new(1.0, 2.0),
            Vector::new(2.0, 3.0),
            Vector::new(3.0, 4.0),
        ];
        let sum = input.into_iter().sum();
        assert_eq!(Vector::new(6.0, 9.0), sum);
    }
}