use regex::Regex;
use std::convert::TryFrom;
use std::num::ParseIntError;
use thiserror::Error;

#[derive(Debug, Clone, Error)]
pub enum RegionParseError {
    #[error("Regex Error '{0}'")]
    RegexError(#[from] regex::Error),
    #[error("Int parse error '{0}'")]
    IntParseError(#[from] ParseIntError),
    #[error("Cannot parse region file name '{0}'")]
    RegionNameParseFailure(String),
}

/// Struct to store information about the region
pub struct Region {
    /// x position of the region
    pub x: i64,
    /// y position of the region
    pub y: i64,
}

impl TryFrom<String> for Region {
    type Error = RegionParseError;

    /// Try from string
    fn try_from(value: String) -> Result<Self, Self::Error> {
        let re = Regex::new(r"r\.(?P<x>-?[0-9]*)+\.(?P<y>-?[0-9]*)")?;
        if re.is_match(&value) {
            let captures = re.captures(value.as_str()).unwrap();

            return Ok(Region {
                x: captures["x"].parse::<i64>()?,
                y: captures["y"].parse::<i64>()?,
            });
        }

        Err(RegionParseError::RegionNameParseFailure(value))
    }
}

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

    #[test]
    fn test_parse_success() {
        let region_x = 5;
        let region_y = -15;
        let region_string = format!("r.{region_x}.{region_y}");

        let region = Region::try_from(region_string).unwrap();

        assert_eq!(region.x, region_x);
        assert_eq!(region.y, region_y);
    }

    #[test]
    fn test_parse_failure() {
        let region_y = -15;
        let region_string = format!("r.pb.{region_y}");

        assert!(Region::try_from(region_string).is_err());
    }
}