use clap::{Parser, Subcommand};
use rustyline::{error::ReadlineError, DefaultEditor};

use mute::{eval, parse, Environment, Node, Result};

#[derive(Debug, Parser)]
#[clap(version, author, about)]
struct Args {
    #[clap(subcommand)]
    command: Command,
}

#[derive(Debug, Subcommand)]
enum Command {
    #[clap(name = "-c", about = "Run a program passed in as a string")]
    RunCmd { command: String },

    #[clap(about = "Run a Mute file")]
    Run { file: String },

    #[clap(about = "Start a REPL")]
    Repl,
}

fn main() {
    let args = Args::parse();

    match args.command {
        Command::Run { file } => {
            let input = std::fs::read_to_string(file).unwrap();
            let env = Environment::default();
            let res = run(&env, &input);
            match res {
                Ok(expressions) => expressions.into_iter().for_each(|expr| println!("{expr}")),
                Err(err) => println!("{}", err),
            }
        }
        Command::RunCmd { command } => {
            let env = Environment::default();
            let res = run(&env, &command);
            match res {
                Ok(expressions) => expressions.into_iter().for_each(|expr| println!("{expr}")),
                Err(err) => println!("{}", err),
            }
        }
        Command::Repl => repl(),
    }
}

fn run(env: &Environment, command: &str) -> Result<Vec<Node>> {
    let ast = parse(command)?;
    eval(env, ast)
}

fn repl() {
    let env = Environment::default();
    let mut rl = DefaultEditor::new().unwrap();

    println!("Mute -- REPL");

    loop {
        let readline = rl.readline("> ");

        match readline {
            Ok(line) => {
                rl.add_history_entry(line.as_str()).unwrap();

                match run(&env, &line) {
                    Ok(expressions) => expressions.into_iter().for_each(|expr| println!("{expr}")),
                    Err(err) => println!("error: {}", err),
                }
            }
            Err(ReadlineError::Interrupted) => {
                continue;
            }
            Err(ReadlineError::Eof) => {
                break;
            }
            Err(err) => {
                println!("Error: {:?}", err);
                break;
            }
        }
    }
}