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use number_traits::{ApproxEq, Num, Signed};

use set::identity;

#[inline]
pub fn inverse_mat<'a, 'b, T: Copy + Signed>(
    out: &'a mut [T; 9],
    m11: T,
    m12: T,
    m13: T,
    m21: T,
    m22: T,
    m23: T,
    m31: T,
    m32: T,
    m33: T,
) -> &'a mut [T; 9] {
    let m0 = m22 * m33 - m23 * m32;
    let m3 = m13 * m32 - m12 * m33;
    let m6 = m12 * m23 - m13 * m22;
    let d = m11 * m0 + m21 * m3 + m31 * m6;

    if d != T::zero() {
        let inv_d = T::one() / d;

        out[0] = m0 * inv_d;
        out[1] = (m23 * m31 - m21 * m33) * inv_d;
        out[2] = (m21 * m32 - m22 * m31) * inv_d;

        out[3] = m3 * inv_d;
        out[4] = (m11 * m33 - m13 * m31) * inv_d;
        out[5] = (m12 * m31 - m11 * m32) * inv_d;

        out[6] = m6 * inv_d;
        out[7] = (m13 * m21 - m11 * m23) * inv_d;
        out[8] = (m11 * m22 - m12 * m21) * inv_d;
        out
    } else {
        identity(out)
    }
}
#[test]
fn test_inverse_mat() {
    let mut v = [1, 0, 0, 0, 1, 0, 0, 0, 1];
    inverse_mat(&mut v, 1, 0, 0, 0, 1, 0, 0, 0, 1);
    assert!(v == [1, 0, 0, 0, 1, 0, 0, 0, 1]);
}

pub fn inverse<'a, 'b, T: Copy + Signed>(out: &'a mut [T; 9], a: &'b [T; 9]) -> &'a mut [T; 9] {
    inverse_mat(out, a[0], a[3], a[6], a[1], a[4], a[7], a[2], a[5], a[8])
}
pub fn inverse_mat2<'a, 'b, T: Copy + Signed>(
    out: &'a mut [T; 9],
    a: &'b [T; 4],
) -> &'a mut [T; 9] {
    inverse_mat(
        out,
        a[0],
        a[2],
        T::zero(),
        a[1],
        a[3],
        T::zero(),
        T::zero(),
        T::zero(),
        T::one(),
    )
}
pub fn inverse_mat32<'a, 'b, T: Copy + Signed>(
    out: &'a mut [T; 9],
    a: &'b [T; 6],
) -> &'a mut [T; 9] {
    inverse_mat(
        out,
        a[0],
        a[2],
        T::zero(),
        a[1],
        a[3],
        T::zero(),
        T::zero(),
        T::zero(),
        T::one(),
    )
}
pub fn inverse_mat4<'a, 'b, T: Copy + Signed>(
    out: &'a mut [T; 9],
    a: &'b [T; 16],
) -> &'a mut [T; 9] {
    inverse_mat(out, a[0], a[4], a[8], a[1], a[5], a[9], a[2], a[6], a[10])
}

#[inline]
pub fn determinant<'a, 'b, T: Copy + Num>(out: &'b [T; 9]) -> T {
    let a = out[0];
    let b = out[1];
    let c = out[2];
    let d = out[3];
    let e = out[4];
    let f = out[5];
    let g = out[6];
    let h = out[7];
    let i = out[8];
    return a * e * i - a * f * h - b * d * i + b * f * g + c * d * h - c * e * g;
}
#[test]
fn test_determinant() {
    assert_eq!(determinant(&[1, 0, 0, 0, 1, 0, 0, 0, 1]), 1);
}

#[inline]
pub fn transpose<'a, 'b, T: Copy + Num>(out: &'a mut [T; 9], a: &'b [T; 9]) -> &'a mut [T; 9] {
    out[0] = a[0];
    out[1] = a[3];
    out[2] = a[6];
    out[3] = a[1];
    out[4] = a[4];
    out[5] = a[7];
    out[6] = a[2];
    out[7] = a[5];
    out[8] = a[8];
    out
}
#[test]
fn test_transpose() {
    let mut v = [1, 0, 0, 0, 1, 0, 0, 0, 1];
    transpose(&mut v, &[1, 0, 0, 0, 1, 0, 0, 0, 1]);
    assert_eq!(v, [1, 0, 0, 0, 1, 0, 0, 0, 1]);
}

#[inline]
pub fn eq<'a, T: Copy + Num + ApproxEq>(a: &'a [T; 9], b: &'a [T; 9]) -> bool {
    !ne(a, b)
}

#[inline]
pub fn ne<'a, T: Copy + Num + ApproxEq>(a: &'a [T; 9], b: &'a [T; 9]) -> bool {
    !a[0].approx_eq(&b[0]) || !a[1].approx_eq(&b[1]) || !a[2].approx_eq(&b[2])
        || !a[3].approx_eq(&b[3]) || !a[4].approx_eq(&b[4]) || !a[5].approx_eq(&b[5])
        || !a[6].approx_eq(&b[6]) || !a[7].approx_eq(&b[7]) || !a[8].approx_eq(&b[8])
}
#[test]
fn test_ne() {
    assert_eq!(
        ne(
            &[1f32, 1f32, 1f32, 1f32, 1f32, 1f32, 1f32, 1f32, 1f32],
            &[1f32, 1f32, 1f32, 1f32, 1f32, 1f32, 1f32, 1f32, 1f32]
        ),
        false
    );
    assert_eq!(
        ne(
            &[0f32, 0f32, 0f32, 0f32, 0f32, 0f32, 0f32, 0f32, 0f32],
            &[1f32, 1f32, 1f32, 1f32, 1f32, 1f32, 1f32, 1f32, 1f32]
        ),
        true
    );
}