this_algorithm/spatial-coordinate-systems/src/utm.rs

use crate::{
    common::{parse_direction, parse_f64}, LatLon,
};
use nom::{
    bytes::complete::{take},
    character::complete::{self, space0, space1},
    combinator::{map_opt, opt},
    sequence::{tuple},
    IResult,
};
use std::str::FromStr;


#[derive(PartialEq, Debug)]
pub struct Coordinate {
    pub zone_num: u8,
    pub zone_letter: char,
    pub easting: f64,
    pub northing: f64,
}

impl Coordinate {
    /// ```rust
    /// use spatial_coordinate_systems::utm::Coordinate;
    ///
    /// assert!(Coordinate::parse("10S 706832mE 4344683mN").is_ok());
    /// assert!(Coordinate::parse("10S 706832mE 4344683N").is_ok());
    /// assert!(Coordinate::parse("10S 706832E 4344683N").is_ok());
    /// assert!(Coordinate::parse("10S706832mE 4344683mN").is_err());
    /// assert!(Coordinate::parse("10S 706832mE 4344683m").is_err());
    /// ```
    pub fn parse(i: &str) -> IResult<&str, Self> {
        map_opt(
            tuple((
                complete::u8,
                space0,
                take(1_usize),
                space1,
                parse_f64,
                // TODO: Can there be spaces around the m here or no?
                opt(complete::char('m')),
                parse_direction,
                space1,
                parse_f64,
                opt(complete::char('m')),
                parse_direction,
            )),
            |(
                zone_num,
                _,
                zone_letter,
                _,
                easting,
                _,
                _easting_direction,
                _,
                northing,
                _,
                _northing_direction,
            )| {
                let ret = Coordinate {
                    easting,
                    northing,
                    zone_num,
                    zone_letter: zone_letter.chars().next()?,
                };

                // Ensure it can be parsed first
                utm::wsg84_utm_to_lat_lon(ret.easting, ret.northing, ret.zone_num, ret.zone_letter)
                    .ok()
                    .and(Some(ret))
            },
        )(i)
    }
}

impl FromStr for Coordinate {
    type Err = ();

    fn from_str(i: &str) -> Result<Self, Self::Err> {
        Self::parse(i).map_err(|_| ()).map(|(_, ret)| ret)
    }
}

impl TryInto<LatLon> for Coordinate {
    type Error = ();

    fn try_into(self) -> Result<LatLon, Self::Error> {
        LatLon::try_from(
            utm::wsg84_utm_to_lat_lon(self.easting, self.northing, self.zone_num, self.zone_letter)
                // TODO: Return the actual error
                .map_err(|_| ())?,
        )
    }
}

impl TryFrom<LatLon> for Coordinate {
    type Error = ();

    fn try_from(value: LatLon) -> Result<Self, Self::Error> {
        // TODO: This does not feel right
        let zone_num = utm::lat_lon_to_zone_number(value.lat, value.lon);
        let zone_letter = utm::lat_to_zone_letter(value.lat).ok_or(())?;
        let (easting, northing, _) = utm::to_utm_wgs84(value.lat, value.lon, zone_num);

        Ok(Self {
            zone_num,
            zone_letter,
            easting,
            northing,
        })
    }
}