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use core::ops::{Add, Div, Mul, Sub};
use num_traits::Signed;

#[inline]
pub fn intersect<T>(s1: &[T; 2], s2: &[T; 2], c1: &[T; 2], c2: &[T; 2]) -> Option<([T; 2], T, T)>
where
    T: Signed + PartialEq + PartialOrd,
    for<'a, 'b> &'a T: Div<&'b T, Output = T>
        + Sub<&'b T, Output = T>
        + Add<&'b T, Output = T>
        + Mul<&'b T, Output = T>,
{
    let den = &(&c2[1] - &c1[1]) * &(&s2[0] - &s1[0]) - &(&c2[0] - &c1[0]) * &(&s2[1] - &s1[1]);

    if &den == &T::zero() {
        None
    } else {
        let us = &(&(&c2[0] - &c1[0]) * &(&s1[1] - &c1[1])
            - &(&c2[1] - &c1[1]) * &(&s1[0] - &c1[0])) / &den;
        let uc = &(&(&s2[0] - &s1[0]) * &(&s1[1] - &c1[1])
            - &(&s2[1] - &s1[1]) * &(&s1[0] - &c1[0])) / &den;

        if (&us == &T::zero() || &us == &T::one()) && (&T::zero() <= &uc && &uc <= &T::one())
            || (&uc == &T::zero() || &uc == &T::one()) && (&T::zero() <= &us && &us <= &T::one())
        {
            None
        } else if (&T::zero() < &us && &us < &T::one()) && (&T::zero() < &uc && &uc < &T::one()) {
            let x = &s1[0] + &(&us * &(&s2[0] - &s1[0]));
            let y = &s1[1] + &(&us * &(&s2[1] - &s1[1]));
            Some(([x, y], us, uc))
        } else {
            None
        }
    }
}