//! Tests the lexer
use doughlang::{
    ast::{Anno, Pat, Ty},
    parser::PPrec,
};
#[allow(unused_imports)]
use doughlang::{
    ast::{
        Expr,
        macro_matcher::{Match, Subst},
    },
    lexer::{EOF, LexError, Lexer},
    parser::{ParseError, Parser},
    span::Span,
    token::{TKind, Token},
};
use repline::prebaked::*;
use std::{
    error::Error,
    io::{IsTerminal, stdin},
};

fn main() -> Result<(), Box<dyn Error>> {
    if stdin().is_terminal() {
        read_and("\x1b[32m", ".>", " >", |line| match line.trim_end() {
            "" => Ok(Response::Continue),
            "exit" => Ok(Response::Break),
            "clear" => {
                print!("\x1b[H\x1b[2J");
                Ok(Response::Deny)
            }
            "lex" => {
                lex()?;
                Ok(Response::Deny)
            }
            "expr" => {
                exprs()?;
                Ok(Response::Deny)
            }
            "pat" => {
                pats()?;
                Ok(Response::Deny)
            }
            "ty" => {
                tys()?;
                Ok(Response::Deny)
            }
            "macro" => {
                if let Err(e) = subst() {
                    println!("\x1b[31m{e}\x1b[0m");
                }
                Ok(Response::Deny)
            }
            _ if line.ends_with("\n\n") => {
                parse(line);
                Ok(Response::Accept)
            }
            _ => Ok(Response::Continue),
        })?;
    } else {
        let doc = std::io::read_to_string(stdin())?;
        // lex(&doc);
        parse(&doc);
    }
    Ok(())
}

fn lex() -> Result<(), Box<dyn Error>> {
    read_and("\x1b[93m", " >", "?>", |line| {
        let mut lexer = Lexer::new(line);
        if line.trim().is_empty() {
            return Ok(Response::Break);
        }
        loop {
            match lexer.scan() {
                Err(LexError { res: EOF, .. }) => {
                    break Ok(Response::Accept);
                }
                Err(e) => {
                    println!("\x1b[31m{e}\x1b[0m");
                    break Ok(Response::Deny);
                }
                Ok(Token { lexeme, kind, span: Span { head, tail } }) => {
                    println!("{kind:?}\x1b[11G {head:<4} {tail:<4} {lexeme:?}")
                }
            }
        }
    })?;
    Ok(())
}

fn exprs() -> Result<(), Box<dyn Error>> {
    read_and("\x1b[93m", ".>", " >", |line| {
        let mut parser = Parser::new(Lexer::new(line));
        if line.trim().is_empty() {
            return Ok(Response::Break);
        }
        for idx in 0.. {
            match parser.parse::<Anno<Expr>>(0) {
                Err(ParseError::FromLexer(LexError { res: EOF, .. })) => {
                    return Ok(Response::Accept);
                }
                Err(e) => {
                    println!("\x1b[31m{e}\x1b[0m");
                    return Ok(Response::Deny);
                }
                Ok(v) => println!("{idx}: {v}\n{v:#?}"),
            }
        }
        Ok(Response::Accept)
    })?;
    Ok(())
}

fn pats() -> Result<(), Box<dyn Error>> {
    read_and("\x1b[94m", " >", "?>", |line| {
        let mut parser = Parser::new(Lexer::new(line));
        if line.trim().is_empty() {
            return Ok(Response::Break);
        }
        loop {
            match parser.parse::<Pat>(PPrec::Min) {
                Err(ParseError::FromLexer(LexError { res: EOF, .. })) => {
                    break Ok(Response::Accept);
                }
                Err(e) => {
                    println!("\x1b[31m{e}\x1b[0m");
                    break Ok(Response::Deny);
                }
                Ok(v) => println!("{v}\n{v:#?}"),
            }
        }
    })?;
    Ok(())
}

fn tys() -> Result<(), Box<dyn Error>> {
    read_and("\x1b[94m", ".>", " >", |line| {
        let mut parser = Parser::new(Lexer::new(line));
        if line.trim().is_empty() {
            return Ok(Response::Break);
        }
        loop {
            match parser.parse::<Ty>(()) {
                Err(ParseError::FromLexer(LexError { res: EOF, .. })) => {
                    break Ok(Response::Accept);
                }
                Err(e) => {
                    println!("\x1b[31m{e}\x1b[0m");
                    break Ok(Response::Deny);
                }
                Ok(v) => println!("{v}\n{v:#?}"),
            }
        }
    })?;
    Ok(())
}

fn subst() -> Result<(), Box<dyn Error>> {
    let mut rl = repline::Repline::new("\x1b[35mexp", " >", "?>");
    let exp = rl.read()?;
    let mut exp: Expr = Parser::new(Lexer::new(&exp)).parse(0)?;
    println!("\x1b[G\x1b[J{exp}");

    rl.accept();

    loop {
        rl.set_color("\x1b[36mpat");
        let pat = rl.read()?;
        rl.accept();
        print!("\x1b[G\x1b[J");
        let mut p = Parser::new(Lexer::new(&pat));

        let Ok(pat) = p.parse::<Expr>(0) else {
            println!("{exp}");
            continue;
        };

        if p.next_if(TKind::Arrow).is_err() {
            let Some(Subst { exp, pat }) = exp.construct(&pat) else {
                println!("Match failed: {exp} <- {pat}");
                continue;
            };
            let mut pats: Vec<_> = pat.into_iter().collect();
            pats.sort_by(|(a, _), (b, _)| a.cmp(b));
            for (name, pat) in pats {
                println!("{name}: {pat}")
            }
            let mut exprs: Vec<_> = exp.into_iter().collect();
            exprs.sort_by(|(a, _), (b, _)| a.cmp(b));
            for (name, expr) in exprs.iter() {
                println!("{name}: {expr}")
            }
            continue;
        }

        let sub: Expr = p.parse(0)?;
        if exp.apply_rule(&pat, &sub) {
            println!("{exp}");
        } else {
            println!("No match: {pat} in {exp}\n")
        }
    }
}

fn parse(document: &str) {
    let mut parser = Parser::new(Lexer::new(document));
    let isatty = std::io::stdin().is_terminal();
    for idx in 0.. {
        match parser.parse::<Expr>(0) {
            Err(e @ ParseError::EOF(s)) if s.tail == document.len() as _ => {
                println!("\x1b[92m{e} (total {} bytes)\x1b[0m", document.len());
                break;
            }
            Err(e @ ParseError::EOF(_)) => {
                println!("\x1b[93m{e} (total {} bytes)\x1b[0m", document.len());
                break;
            }
            Err(e) => {
                println!("\x1b[91m{e}\x1b[0m");
                break;
            }
            Ok(v) if isatty => {
                println!("\x1b[{}m{v}", (idx + 5) % 6 + 31);
            }
            _ => {}
        }
    }
}