use super::Complex;
use num_traits::{AsPrimitive, FromPrimitive, Num, NumCast, ToPrimitive};

macro_rules! impl_to_primitive {
    ($ty:ty, $to:ident) => {
        #[inline]
        fn $to(&self) -> Option<$ty> {
            if self.im.is_zero() {
                self.re.$to()
            } else {
                None
            }
        }
    };
} // impl_to_primitive

// Returns None if Complex part is non-zero
impl<T: ToPrimitive + Num> ToPrimitive for Complex<T> {
    impl_to_primitive!(usize, to_usize);
    impl_to_primitive!(isize, to_isize);
    impl_to_primitive!(u8, to_u8);
    impl_to_primitive!(u16, to_u16);
    impl_to_primitive!(u32, to_u32);
    impl_to_primitive!(u64, to_u64);
    impl_to_primitive!(i8, to_i8);
    impl_to_primitive!(i16, to_i16);
    impl_to_primitive!(i32, to_i32);
    impl_to_primitive!(i64, to_i64);
    impl_to_primitive!(u128, to_u128);
    impl_to_primitive!(i128, to_i128);
    impl_to_primitive!(f32, to_f32);
    impl_to_primitive!(f64, to_f64);
}

macro_rules! impl_from_primitive {
    ($ty:ty, $from_xx:ident) => {
        #[inline]
        fn $from_xx(n: $ty) -> Option<Self> {
            Some(Complex {
                re: T::$from_xx(n)?,
                im: T::zero(),
            })
        }
    };
} // impl_from_primitive

impl<T: FromPrimitive + Num> FromPrimitive for Complex<T> {
    impl_from_primitive!(usize, from_usize);
    impl_from_primitive!(isize, from_isize);
    impl_from_primitive!(u8, from_u8);
    impl_from_primitive!(u16, from_u16);
    impl_from_primitive!(u32, from_u32);
    impl_from_primitive!(u64, from_u64);
    impl_from_primitive!(i8, from_i8);
    impl_from_primitive!(i16, from_i16);
    impl_from_primitive!(i32, from_i32);
    impl_from_primitive!(i64, from_i64);
    impl_from_primitive!(u128, from_u128);
    impl_from_primitive!(i128, from_i128);
    impl_from_primitive!(f32, from_f32);
    impl_from_primitive!(f64, from_f64);
}

impl<T: NumCast + Num> NumCast for Complex<T> {
    fn from<U: ToPrimitive>(n: U) -> Option<Self> {
        Some(Complex {
            re: T::from(n)?,
            im: T::zero(),
        })
    }
}

impl<T, U> AsPrimitive<U> for Complex<T>
where
    T: AsPrimitive<U>,
    U: 'static + Copy,
{
    fn as_(self) -> U {
        self.re.as_()
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn test_to_primitive() {
        let a: Complex<u32> = Complex { re: 3, im: 0 };
        assert_eq!(a.to_i32(), Some(3_i32));
        let b: Complex<u32> = Complex { re: 3, im: 1 };
        assert_eq!(b.to_i32(), None);
        let x: Complex<f32> = Complex { re: 1.0, im: 0.1 };
        assert_eq!(x.to_f32(), None);
        let y: Complex<f32> = Complex { re: 1.0, im: 0.0 };
        assert_eq!(y.to_f32(), Some(1.0));
        let z: Complex<f32> = Complex { re: 1.0, im: 0.0 };
        assert_eq!(z.to_i32(), Some(1));
    }

    #[test]
    fn test_from_primitive() {
        let a: Complex<f32> = FromPrimitive::from_i32(2).unwrap();
        assert_eq!(a, Complex { re: 2.0, im: 0.0 });
    }

    #[test]
    fn test_num_cast() {
        let a: Complex<f32> = NumCast::from(2_i32).unwrap();
        assert_eq!(a, Complex { re: 2.0, im: 0.0 });
    }

    #[test]
    fn test_as_primitive() {
        let a: Complex<f32> = Complex { re: 2.0, im: 0.2 };
        let a_: i32 = a.as_();
        assert_eq!(a_, 2_i32);
    }
}