use combine::{many1, parser::char::alpha_num, Parser, Stream};

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Handle {
    pub handle: String,
    pub domain: String,
}

fn at<Input>() -> impl Parser<Input, Output = char>
where
    Input: Stream<Token = char>,
{
    combine::parser::char::char('@')
}

fn handle_part<Input>() -> impl Parser<Input, Output = String>
where
    Input: Stream<Token = char>,
{
    many1(alpha_num())
}

fn domain_part<Input>() -> impl Parser<Input, Output = String>
where
    Input: Stream<Token = char>,
{
    crate::url::domain().map(|d| d.0)
}

pub(crate) fn handle<Input>() -> impl Parser<Input, Output = Handle>
where
    Input: Stream<Token = char>,
{
    at().with(handle_part())
        .skip(at())
        .and(domain_part())
        .map(|(handle, domain)| Handle { handle, domain })
}

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

    #[test]
    fn parse_handle_part() {
        let (_, rest) = handle_part().parse("as123").unwrap();
        assert_eq!(rest, "");
    }

    #[test]
    fn parse_simple_handle() {
        let (_, rest) = handle().parse("@asdf@asdf").unwrap();
        assert_eq!(rest, "");
    }

    #[test]
    fn parse_complex_handle() {
        let (_, rest) = handle()
            .parse("@r2d2@telnet.towel.blinkenlights.nl")
            .unwrap();
        assert_eq!(rest, "");
    }

    #[test]
    fn dont_parse_invalid_handle() {
        assert!(handle().parse("asdf@asdf").is_err())
    }
}