/* relish: versatile lisp shell
 * Copyright (C) 2021 Aidan Hahn
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

use rustyline::error::ReadlineError;
use rustyline::Editor;
use dirs::home_dir;
use std::rc::Rc;
use std::cell::RefCell;
use relish::ast::{VTable, FTable, Ctr, lex, eval, ast_to_string};
use relish::stdlib::{get_stdlib};

fn main() {
    let mut rl = Editor::<()>::new();

    const HIST_FILE: &str = ".relish_hist";
    //const CONFIG_FILE: &str = ".relishrc";

    let mut hist: String = "".to_owned();

    if let Some(home) = home_dir() {
        if let Some(h) = home.to_str() {
            hist = h.to_owned() + HIST_FILE;
        }
    }

    if hist != "" {
        // ignore result. it loads or it doesnt.
        let _ = rl.load_history(&hist);
    }

    let vt = Rc::new(RefCell::new(VTable::new()));
    // if we fail to get stdlib we can just use this one
    let mut ft = Rc::new(RefCell::new(FTable::new()));
    match get_stdlib() {
        Ok(f) => ft = f,
        Err(s) => println!("{}", s)
    }

    loop {
        // TODO: configurable prompt
        let readline = rl.readline("λ ");
        match readline {
            Ok(line) => {
                rl.add_history_entry(line.as_str());
                let mut l = line.as_str().to_owned();
                if !l.starts_with("(") {
                    l = "(".to_owned() + &l;
                }

                if !l.ends_with(")") {
                    l = l + ")";
                }

                match lex(l) {
                    Ok(a) => {
                        match eval(a.clone(), vt.clone(), ft.clone(), false) {
                            Ok(a) => {
                                match a {
                                    Ctr::Symbol(s)  => println!("{}", s),
                                    Ctr::String(s)  => println!("{}", s),
                                    Ctr::Integer(i) => println!("{}", i),
                                    Ctr::Float(f)   => println!("{}", f),
                                    Ctr::Bool(b)    => println!("{}", b),
                                    Ctr::Seg(c)     => println!("{}", ast_to_string(c.clone())),
                                    Ctr::None       => ()
                                }
                            },
                            Err(s) => {
                                println!("{}", s);
                            }
                        }
                    },
                    Err(s) => {
                        println!("{}", s);
                    }
                }
            },

            Err(ReadlineError::Interrupted) => {
                break
            },

            Err(ReadlineError::Eof) => {
                return
            },
            Err(err) => {
                eprintln!("Prompt error: {:?}", err);
                break
            }
        }
    }
    if hist != "" {
        rl.save_history(&hist).unwrap();
    }
}