/*

 * Copyright (c) Radzivon Bartoshyk, 10/2024. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without modification,

 * are permitted provided that the following conditions are met:

 *

 * 1.  Redistributions of source code must retain the above copyright notice, this

 * list of conditions and the following disclaimer.

 *

 * 2.  Redistributions in binary form must reproduce the above copyright notice,

 * this list of conditions and the following disclaimer in the documentation

 * and/or other materials provided with the distribution.

 *

 * 3.  Neither the name of the copyright holder nor the names of its

 * contributors may be used to endorse or promote products derived from

 * this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

use crate::math::consts::ConstPI;

use crate::math::sinc::sinc;

use num_traits::{AsPrimitive, Float};

use std::ops::Mul;

#[inline(always)]

pub(crate) fn blackman_window<V: Copy + ConstPI + 'static + Mul<Output = V> + Float>(x: V) -> V

where

    f32: AsPrimitive<V>,

{

    let pi = V::const_pi();

    0.42f32.as_() - 0.49656062f32.as_() * (2f32.as_() * pi * x).cos()

        + 0.07684867f32.as_() * (4f32.as_() * pi * x).cos()

}

#[inline(always)]

pub(crate) fn blackman<V: Copy + ConstPI + 'static + Mul<Output = V> + Float>(x: V) -> V

where

    f32: AsPrimitive<V>,

{

    let x = x.abs();

    if x < 2.0f32.as_() {

        sinc(x) * blackman_window(x / 2f32.as_())

    } else {

        0f32.as_()

    }

}