use nom::{
    bytes::complete::tag,
    character::complete::space0,
    error::ErrorKind,
    sequence::{delimited, tuple},
    IResult, InputTakeAtPosition, Parser,
};

pub fn account(input: &str) -> IResult<&str, &str> {
    input.split_at_position1_complete(|item| item == ' ' || item == '\t', ErrorKind::AlphaNumeric)
}

pub fn metadatum(input: &str) -> IResult<&str, (&str, &str)> {
    tuple((
        delimited(tag("-"), delimited(space0, key, space0), tag(":")),
        value,
    ))
    .map(|v| (v.0, v.1.trim()))
    .parse(input)
}

pub fn key(input: &str) -> IResult<&str, &str> {
    input.split_at_position1_complete(|item| item == ':', ErrorKind::AlphaNumeric)
}

pub fn value(input: &str) -> IResult<&str, &str> {
    input.split_at_position1_complete(|_| false, ErrorKind::AlphaNumeric)
}

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

    #[test]
    fn parse_metadatum() {
        assert_eq!(
            metadatum("- key: value").unwrap().1,
            ("key".into(), "value".into())
        );
        assert_eq!(
            metadatum("- key space: value space").unwrap().1,
            ("key space".into(), "value space".into())
        );
    }

    #[test]
    fn parse_metadatum_invalid() {
        assert!(metadatum("- key:").is_err());
        assert!(metadatum("-  : value").is_err());
        assert!(metadatum("-  : ").is_err());
    }
}