use std::error::Error;
use std::fmt;
use std::str::FromStr;

#[derive(Debug, Eq, PartialEq)]
pub struct Position {
    pub x: u8,
    pub y: u8,
}

impl Error for Position {}

impl FromStr for Position {
    type Err = String;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let mut parts = s.split(',');
        let x = parts.next().unwrap().parse();
        let y = parts.next().unwrap().parse();

        if x.is_err() {
            Err("bad x supplied for position".to_string())
        } else if y.is_err() {
            Err("bad y supplied for position".to_string())
        } else {
            let x = x.unwrap();
            let y = y.unwrap();
            Ok(Position { x, y })
        }
    }
}

impl fmt::Display for Position {
    #[inline]
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{},{}", self.x, self.y)
    }
}

#[cfg(test)]
mod test {
    use crate::position::Position;
    use std::str::FromStr;

    #[test]
    fn test_position_from_str() {
        assert_eq!(
            Position::from_str(&"4,12").unwrap(),
            Position { x: 4, y: 12 }
        );
    }

    #[test]
    fn test_position_to_string() {
        assert_eq!(Position { x: 4, y: 12 }.to_string(), "4,12".to_string())
    }
}