use std::cell::RefCell;

use rustyline::error::ReadlineError;
use scoped_tls::scoped_thread_local;

use crate::parsing::{Interner, parse};

mod parsing;

#[derive(Default)]
struct Session {
    interner: RefCell<Interner>,
}

scoped_thread_local!(static SESSION: Session);

fn with_session<R>(f: impl FnOnce(&Session) -> R) -> R {
    SESSION.with(f)
}

fn create_session_then<R>(f: impl FnOnce() -> R) -> R {
    assert!(!SESSION.is_set());
    let session = Default::default();
    SESSION.set(&session, f)
}

fn eval(line: &str) {
    for expr in parse(line) {
        println!("{expr:?}");
    }
}

fn main() -> anyhow::Result<()> {
    create_session_then(|| {
        let mut rl = rustyline::DefaultEditor::new()?;

        loop {
            match rl.readline("> ") {
                Ok(line) => {
                    rl.add_history_entry(line.clone())?;
                    eval(&line);
                }
                Err(ReadlineError::Interrupted) => (),
                Err(ReadlineError::Eof) => break Ok(()),
                Err(e) => break Err(e.into()),
            }
        }
    })
}