use console::Style;
use logos::Logos;

#[rustfmt::skip]
#[derive(Logos, Debug, PartialEq)]
pub enum Token {
    // keywords
    #[token("struct")] Struct,
    #[token("fn")]     Function,
    #[token("for")]    For,
    #[token("if")]     If,
    #[token("else")]   Else,
    #[token("in")]     In,
    #[token("let")]    Let,
    #[token("var")]    Var,

    // separators
    #[token("{")] BraceOpen,
    #[token("}")] BraceClose,
    #[token("(")] ParanOpen,
    #[token(")")] ParanClose,
    #[token(";")] Semicolon,
    #[token(",")] Comma,
    #[token(".")] Dot,

    // arithmetic operators
    #[token("+")] OpAdd,
    #[token("-")] OpSub,
    #[token("*")] OpMul,
    #[token("/")] OpDiv,
    #[token("=")] OpAssign,

    // comparison operators
    #[token("<")]  OpLess,
    #[token("<=")] OpLessEq,
    #[token(">")]  OpGreater,
    #[token(">=")] OpGreaterEq,
    #[token("==")] OpEq,
    #[token("!=")] OpNeq,

    #[regex(r"[a-zA-Z_][a-zA-Z0-9_]*")]
    Identifier,

    #[regex(r"//[^\n]*")]
    SingleLineComment,

    #[regex(r"0b_*[01][_01]*")]
    BinaryInteger,

    #[regex(r"0o_*[0-7][_0-7]*")]
    OctalInteger,

    #[regex(r"-?[0-9][_'0-9]*")]
    DecimalInteger,

    #[regex(r"[ \t\n\f ]+")] // , logos::skip)]
    Whitespace,

    #[error]
    Error,
}

pub struct ColorTheme {
    normal: Style,
    keyword: Style,
    literal: Style,
    comment: Style,
    error: Style,
}

impl ColorTheme {
    pub fn new() -> Self {
        Self {
            normal: Style::default(),
            keyword: Style::new().blue(),
            literal: Style::new().cyan(),
            comment: Style::new().white(),
            error: Style::new().black().on_red().bold(),
        }
    }

    pub fn token_style(&self, token: &Token) -> &Style {
        use Token::*;
        match token {
            Struct | Function | For | If | Else | In | Let | Var => &self.keyword,
            BinaryInteger | OctalInteger | DecimalInteger => &self.literal,
            SingleLineComment => &self.comment,
            Error => &self.error,
            _ => &self.normal,
        }
    }
}

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

    #[test]
    fn color_file() {
        let source = include_str!("../example.ktn");
        let theme = ColorTheme::new();
        let mut lex = Token::lexer(source);

        while let Some(token) = lex.next() {
            let style = theme.token_style(&token);
            print!("{}", style.apply_to(lex.slice()));
        }
    }
}