use serde_derive::{Serialize, Deserialize};

#[derive(Debug, Eq, PartialEq, Serialize, Deserialize)]
pub struct Colour {
    pub red: u8,
    pub green: u8,
    pub blue: u8,
    pub alpha: u8,
}

impl Colour {
    pub fn from(colours: Vec<u8>) -> Colour {
        const ZERO: u8 = 0;
        Colour {
            red:   *colours.get(0).unwrap_or(&ZERO),
            green: *colours.get(1).unwrap_or(&ZERO),
            blue:  *colours.get(2).unwrap_or(&ZERO),
            alpha: *colours.get(3).unwrap_or(&255),
        }
    }

    pub fn to_vec(&self) -> Vec<u8> {
        vec![self.red, self.green, self.blue, self.alpha]
    }
}

#[cfg(test)]
mod test {
    use crate::Colour;

    #[test]
    fn test_colour_from_intermediate() {
        let output = Colour::from(vec![64, 128, 192, 255]);
        let expected = Colour { red: 64, green: 128, blue: 192, alpha: 255 };
        assert_eq!(output, expected);
    }

    #[test]
    fn test_colour_to_intermediate() {
        let output = Colour { red: 64, green: 128, blue: 192, alpha: 255 }.to_vec();
        let expected = vec![64, 128, 192, 255];
        assert_eq!(output, expected);
    }
}