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// Copyright 2018-2024 argmin developers
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.

use crate::ArgminEye;

use num_traits::{One, Zero};

use nalgebra::{
    base::{allocator::Allocator, dimension::Dim},
    DefaultAllocator, OMatrix, Scalar,
};

impl<N, R, C> ArgminEye for OMatrix<N, R, C>
where
    N: Scalar + Zero + One,
    R: Dim,
    C: Dim,
    DefaultAllocator: Allocator<N, R, C>,
{
    #[inline]
    fn eye_like(&self) -> OMatrix<N, R, C> {
        assert!(self.is_square());
        Self::identity_generic(R::from_usize(self.nrows()), C::from_usize(self.ncols()))
    }

    #[inline]
    fn eye(n: usize) -> OMatrix<N, R, C> {
        Self::identity_generic(R::from_usize(n), C::from_usize(n))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use approx::assert_relative_eq;
    use nalgebra::{Matrix2x3, Matrix3};
    use paste::item;

    macro_rules! make_test {
        ($t:ty) => {
            item! {
                #[test]
                fn [<test_eye_ $t>]() {
                    let e: Matrix3<$t> = <Matrix3<$t> as ArgminEye>::eye(3);
                    let res = Matrix3::new(
                        1 as $t, 0 as $t, 0 as $t,
                        0 as $t, 1 as $t, 0 as $t,
                        0 as $t, 0 as $t, 1 as $t
                    );
                    for i in 0..3 {
                        for j in 0..3 {
                            assert_relative_eq!(res[(i, j)] as f64, e[(i, j)] as f64, epsilon = std::f64::EPSILON);
                        }
                    }
                }
            }

            item! {
                #[test]
                fn [<test_eye_like_ $t>]() {
                    let a = Matrix3::new(
                        0 as $t, 2 as $t, 6 as $t,
                        3 as $t, 2 as $t, 7 as $t,
                        9 as $t, 8 as $t, 1 as $t
                    );
                    let e: Matrix3<$t> = a.eye_like();
                    let res = Matrix3::new(
                        1 as $t, 0 as $t, 0 as $t,
                        0 as $t, 1 as $t, 0 as $t,
                        0 as $t, 0 as $t, 1 as $t
                    );
                    for i in 0..3 {
                        for j in 0..3 {
                            assert_relative_eq!(res[(i, j)] as f64, e[(i, j)] as f64, epsilon = std::f64::EPSILON);
                        }
                    }
                }
            }

            item! {
                #[test]
                #[should_panic]
                #[allow(unused)]
                fn [<test_eye_like_panic_ $t>]() {
                    let a = Matrix2x3::new(
                        0 as $t, 2 as $t, 6 as $t,
                        3 as $t, 2 as $t, 7 as $t,
                    );
                    let e: Matrix2x3<$t> = a.eye_like();
                }
            }
        };
    }

    make_test!(i8);
    make_test!(u8);
    make_test!(i16);
    make_test!(u16);
    make_test!(i32);
    make_test!(u32);
    make_test!(i64);
    make_test!(u64);
    make_test!(f32);
    make_test!(f64);
}