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use crate::noise_fns::NoiseFn;

/// Noise function that scales the coordinates of the input value before
/// returning the output value from the source function.
///
/// The get() method multiplies the coordinates of the input value with a
/// scaling factor before returning the output value from the source function.
pub struct ScalePoint<Source> {
    /// Source function that outputs a value
    pub source: Source,

    /// Scaling factor applied to the _x_ coordinate of the input value. The
    /// default scaling factor is set to 1.0.
    pub x_scale: f64,

    /// Scaling factor applied to the _y_ coordinate of the input value. The
    /// default scaling factor is set to 1.0.
    pub y_scale: f64,

    /// Scaling factor applied to the _z_ coordinate of the input value. The
    /// default scaling factor is set to 1.0.
    pub z_scale: f64,

    /// Scaling factor applied to the _u_ coordinate of the input value. The
    /// default scaling factor is set to 1.0.
    pub u_scale: f64,
}

impl<Source> ScalePoint<Source> {
    pub fn new(source: Source) -> Self {
        Self {
            source,
            x_scale: 1.0,
            y_scale: 1.0,
            z_scale: 1.0,
            u_scale: 1.0,
        }
    }

    /// Sets the scaling factor to apply to the _x_ coordinate of the input
    /// value.
    pub fn set_x_scale(self, x_scale: f64) -> Self {
        Self { x_scale, ..self }
    }

    /// Sets the scaling factor to apply to the _x_ coordinate of the input
    /// value.
    pub fn set_y_scale(self, y_scale: f64) -> Self {
        Self { y_scale, ..self }
    }

    /// Sets the scaling factor to apply to the _x_ coordinate of the input
    /// value.
    pub fn set_z_scale(self, z_scale: f64) -> Self {
        Self { z_scale, ..self }
    }

    /// Sets the scaling factor to apply to the _x_ coordinate of the input
    /// value.
    pub fn set_u_scale(self, u_scale: f64) -> Self {
        Self { u_scale, ..self }
    }

    /// Sets the scaling factor to apply to all coordinates of the input value.
    pub fn set_scale(self, scale: f64) -> Self {
        Self {
            x_scale: scale,
            y_scale: scale,
            z_scale: scale,
            u_scale: scale,
            ..self
        }
    }

    /// Sets the individual scaling factors to apply to each coordinate of the
    /// input value.
    pub fn set_all_scales(self, x_scale: f64, y_scale: f64, z_scale: f64, u_scale: f64) -> Self {
        Self {
            x_scale,
            y_scale,
            z_scale,
            u_scale,
            ..self
        }
    }
}

impl<Source> NoiseFn<f64, 2> for ScalePoint<Source>
where
    Source: NoiseFn<f64, 2>,
{
    fn get(&self, point: [f64; 2]) -> f64 {
        self.source
            .get([point[0] * self.x_scale, point[1] * self.y_scale])
    }
}

impl<Source> NoiseFn<f64, 3> for ScalePoint<Source>
where
    Source: NoiseFn<f64, 3>,
{
    fn get(&self, point: [f64; 3]) -> f64 {
        self.source.get([
            point[0] * self.x_scale,
            point[1] * self.y_scale,
            point[2] * self.z_scale,
        ])
    }
}

impl<Source> NoiseFn<f64, 4> for ScalePoint<Source>
where
    Source: NoiseFn<f64, 4>,
{
    fn get(&self, point: [f64; 4]) -> f64 {
        self.source.get([
            point[0] * self.x_scale,
            point[1] * self.y_scale,
            point[2] * self.z_scale,
            point[3] * self.u_scale,
        ])
    }
}

#[cfg(test)]
mod tests {
    use super::{super::super::Perlin, *};

    #[test]
    fn test_pass_by_ref() {
        let source = Perlin::default();
        let transformed_by_ref = ScalePoint::new(&source)
            .set_x_scale(0.8)
            .set_y_scale(0.1)
            .set_z_scale(0.4)
            .set_u_scale(0.2);
        let mut zero_count = 0;

        for x in 0..10 {
            for y in 0..10 {
                for z in 0..10 {
                    for u in 0..10 {
                        let point: [f64; 4] = [
                            (x as f64) / 10.0,
                            (y as f64) / 10.0,
                            (z as f64) / 10.0,
                            (u as f64) / 10.0,
                        ];
                        let source_value = source.get(point);
                        let transform_value = transformed_by_ref.get(point);

                        if source_value != 0.0 {
                            assert_ne!(source_value, transform_value);
                        } else {
                            zero_count += 1;
                        }
                    }
                }
            }
        }

        assert!(zero_count < 10 * 10 * 10 * 10);
    }
}