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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::{Allocator, ArgminZero, ArgminZeroLike};

use num_traits::Zero;

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

impl<N, R, C> ArgminZeroLike for OMatrix<N, R, C>
where
    N: Scalar + Zero + ArgminZero,
    R: Dim,
    C: Dim,
    DefaultAllocator: Allocator<N, R, C>,
{
    #[inline]
    fn zero_like(&self) -> OMatrix<N, R, C> {
        Self::zeros_generic(R::from_usize(self.nrows()), C::from_usize(self.ncols()))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use approx::assert_relative_eq;
    use nalgebra::{DVector, Matrix2, Vector2, Vector4};
    use paste::item;

    macro_rules! make_test {
        ($t:ty) => {
            item! {
                #[test]
                fn [<test_zero_like_ $t>]() {
                    let t: DVector<$t> = DVector::from_vec(vec![]);
                    let a = t.zero_like();
                    assert_eq!(t, a);
                }
            }

            item! {
                #[test]
                fn [<test_zero_like_2_ $t>]() {
                    let a = Vector4::new(42 as $t, 42 as $t, 42 as $t, 42 as $t).zero_like();
                    for i in 0..4 {
                        assert_relative_eq!(0 as f64, a[i] as f64, epsilon = f64::EPSILON);
                    }
                }
            }

            item! {
                #[test]
                fn [<test_2d_zero_like_ $t>]() {
                    let t: Vector2<$t> = Vector2::zeros();
                    let a = t.zero_like();
                    assert_eq!(t, a);
                }
            }

            item! {
                #[test]
                fn [<test_2d_zero_like_2_ $t>]() {
                    let a = Matrix2::new(
                      42 as $t, 42 as $t,
                      42 as $t, 42 as $t
                    ).zero_like();

                    for i in 0..2 {
                        for j in 0..2 {
                            assert_relative_eq!(0 as f64, a[(i, j)] as f64, epsilon = f64::EPSILON);
                        }
                    }
                }
            }
        };
    }

    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);
}