/* relish: versatile lisp shell
 * Copyright (C) 2021 Ava Affine
 *
 * 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 dirs::home_dir;
use relish::ast::{ast_to_string, eval, func_call, lex, new_ast, Ctr, FTable, VTable};
use relish::aux::configure;
use rustyline::error::ReadlineError;
use rustyline::Editor;
use std::cell::RefCell;
use std::env;
use std::rc::Rc;

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

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

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

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

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

    let vt = Rc::new(RefCell::new(VTable::new()));
    let conf_file;
    let ft;
    match env::var("RELISH_CFG_FILE") {
        Ok(s) => {
            conf_file = s
        },
        Err(e) => {
            eprintln!("{}", e);
            conf_file = cfg;
        },
    }

    match configure(conf_file, vt.clone()) {
        Ok(f) => ft = f,
        Err(e) => {
            ft = Rc::new(RefCell::new(FTable::new()));
            eprintln!("{}", e);
        },
    }

    loop {
        let readline: Result<String, ReadlineError>;
        // Rust is pain
        let tmp_ft_clone = ft.clone();
        // this is not okay
        let t_ft_c_b = tmp_ft_clone.borrow();
        let pfunc = t_ft_c_b.get("CFG_RELISH_PROMPT");
        if let Some(fnc) = pfunc {
            match func_call(
                fnc.clone(),
                new_ast(Ctr::None, Ctr::None),
                vt.clone(),
                ft.clone(),
            ) {
                Err(s) => {
                    eprintln!("Couldnt generate prompt: {}", s);
                    readline = rl.readline("");
                }

                Ok(c) => match c {
                    Ctr::Symbol(s) => readline = rl.readline(&s.to_owned()),
                    Ctr::String(s) => readline = rl.readline(&s),
                    Ctr::Integer(i) => readline = rl.readline(&format!("{}", i)),
                    Ctr::Float(f) => readline = rl.readline(&format!("{}", f)),
                    Ctr::Bool(b) => readline = rl.readline(&format!("{}", b)),
                    Ctr::Seg(c) => readline = rl.readline(&ast_to_string(c.clone())),
                    Ctr::None => readline = rl.readline(""),
                },
            }
        } else {
            readline = rl.readline("");
        }

        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();
    }
}