use super::Texture;
use crate::core::LinearColor;
use crate::Point2D;
use serde::Deserialize;

/// A texture with the same color on all points.
#[derive(Clone, Debug, PartialEq, Deserialize)]
pub struct UniformTexture {
    color: LinearColor,
}

impl UniformTexture {
    /// Creates a new `UniformTexture`.
    ///
    /// # Examples
    ///
    /// ```
    /// # use pathtracer::texture::UniformTexture;
    /// # use pathtracer::core::LinearColor;
    /// #
    /// let uni_text = UniformTexture::new(LinearColor::new(0.5, 0.5, 0.5));
    /// ```
    pub fn new(color: LinearColor) -> Self {
        UniformTexture { color }
    }
}

impl Texture for UniformTexture {
    fn texel_color(&self, _: Point2D) -> LinearColor {
        self.color.clone()
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn new_works() {
        let color = LinearColor::new(0.2, 0.4, 0.6);
        let texture = UniformTexture::new(color.clone());
        assert_eq!(texture, UniformTexture { color })
    }

    fn simple_texture() -> UniformTexture {
        UniformTexture::new(LinearColor::new(0.25, 0.5, 1.))
    }

    #[test]
    fn texel_color_works() {
        let texture = simple_texture();
        assert_eq!(
            texture.texel_color(Point2D::origin()),
            LinearColor::new(0.25, 0.5, 1.)
        )
    }

    #[test]
    fn deserialization_works() {
        let yaml = r#"
            color: {r: 1.0, g: 0.5, b: 0.25}
        "#;
        let texture: UniformTexture = serde_yaml::from_str(yaml).unwrap();
        assert_eq!(
            texture,
            UniformTexture::new(LinearColor::new(1., 0.5, 0.25))
        )
    }
}