use crate::syntax::content::{Lexeme, Parseable};

#[derive(Debug, Clone, Eq, PartialEq)]
pub struct Oblique {
    open: bool,
}

impl Oblique {
    pub const fn new(open: bool) -> Oblique { Oblique { open } }
}

impl Parseable for Oblique {
    fn probe(lexeme: &Lexeme) -> bool { lexeme.text() == "_" }

    fn lex(_lexeme: &Lexeme) -> Oblique {
        panic!("Attempt to lex an oblique tag directly from a lexeme")
    }

    fn render(&self) -> String {
        if self.open {
            String::from("<em>")
        } else {
            String::from("</em>")
        }
    }

    fn flatten(&self) -> String { String::default() }
}

impl std::fmt::Display for Oblique {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        let display_open_state = if self.open { "open" } else { "closed" };
        write!(f, "Oblique [{display_open_state}]")
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::syntax::content::parser::Token;

    #[test]
    fn render() {
        let code_open = Oblique::new(true);
        assert_eq!(code_open.render(), "<em>");

        let code_closed = Oblique::new(false);
        assert_eq!(code_closed.render(), "</em>");
    }

    #[test]
    #[should_panic(
        expected = "Attempt to lex an oblique tag directly from a lexeme"
    )]
    fn lex() { Oblique::lex(&Lexeme::default()); }

    #[test]
    fn token_display() {
        let mut oblique = Oblique::new(true);
        assert_eq!(
            format!("{}", Token::Oblique(oblique.clone())),
            "Tk:Oblique [open]"
        );

        oblique.open = false;
        assert_eq!(
            format!("{}", Token::Oblique(oblique)),
            "Tk:Oblique [closed]"
        );
    }

    #[test]
    fn flatten() {
        let oblique = Oblique::new(false);
        assert_eq!(oblique.flatten(), "");

        let token = Token::Oblique(oblique);
        assert_eq!(token.flatten(), "");
    }
}