use crate::spans::*;
use chumsky::prelude::*;
use std::fmt;

#[derive(Clone, Debug, PartialEq)]
pub enum Token<'src> {
    Nil,
    Number(f64),
    Word(&'src str),
    Boolean(bool),
    Keyword(&'src str),
    String(&'src str),
    // todo: hard code these types
    Reserved(&'src str),
    Punctuation(&'src str),
}

impl fmt::Display for Token<'_> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Token::Number(n) => write!(f, "[Number {}]", n),
            Token::Word(w) => write!(f, "[Word {}]", w),
            Token::Boolean(b) => write!(f, "[Boolean {}]", b),
            Token::Keyword(k) => write!(f, "[Keyword :{}]", k),
            Token::String(s) => write!(f, "[String {}]", s),
            Token::Reserved(r) => write!(f, "[Reserved {}]", r),
            Token::Nil => write!(f, "[nil]"),
            Token::Punctuation(p) => write!(f, "[Punctuation {}]", p),
        }
    }
}

pub fn lexer<'src>(
) -> impl Parser<'src, &'src str, Vec<(Token<'src>, Span)>, extra::Err<Rich<'src, char, Span>>> {
    let number = just('-')
        .or_not()
        .then(text::int(10).then(just('.').then(text::digits(10)).or_not()))
        .to_slice()
        .from_str()
        .unwrapped()
        .map(Token::Number);

    let word = any()
        .filter(char::is_ascii_lowercase)
        .then(
            any()
                .filter(char::is_ascii_alphanumeric)
                .or(one_of("*/?!_"))
                .repeated(),
        )
        .to_slice();

    let reserved_or_word = word.map(|word: &str| match word {
        "true" => Token::Boolean(true),
        "false" => Token::Boolean(false),
        "nil" => Token::Nil,
        // todo: hard code these as type constructors
        "as" | "box" | "do" | "else" | "fn" | "if" | "let" | "loop" | "match" | "panic!"
        | "recur" | "repeat" | "then" | "when" | "with" => Token::Reserved(word),
        _ => Token::Word(word),
    });

    let keyword = just(':').ignore_then(word).map(Token::Keyword);

    let string = just('"')
        .ignore_then(none_of("\"").repeated().to_slice())
        .then_ignore(just('"'))
        .map(Token::String);

    // todo: hard code these as type constructors
    let punctuation = one_of(",=[]{}()>;\n_")
        .to_slice()
        .or(just("->"))
        .or(just("..."))
        .or(just("#{"))
        .or(just("${"))
        .map(Token::Punctuation);

    let token = number
        .or(reserved_or_word)
        .or(keyword)
        .or(string)
        .or(punctuation);

    let comment = just('&')
        .ignore_then(any().and_is(just('\n').not()).repeated())
        .repeated();

    let ludus_ws = just(' ').or(just('\t')).repeated();

    token
        .map_with(|tok, e| (tok, e.span()))
        .padded_by(ludus_ws)
        .padded_by(comment)
        .recover_with(skip_then_retry_until(any().ignored(), end()))
        .repeated()
        .collect()
}