use anyhow::Result;
use clap::{Parser, Subcommand};
use node::Node;
use rustyline::{error::ReadlineError, DefaultEditor};

mod env;
mod error;
mod evaluator;
mod macros;
mod node;
mod parser;

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

#[derive(Debug, Subcommand)]
enum Command {
    Run {
        #[clap(short, long)]
        command: String,
    },
    Repl,
}

impl std::default::Default for Command {
    fn default() -> Self {
        Command::Repl
    }
}

fn main() {
    if std::env::args().len() == 1 {
        repl();
        return;
    }

    let args = Args::parse();

    match args.command {
        Command::Run { command } => {
            let res = run(&command);

            match res {
                Ok(expressions) => expressions.into_iter().for_each(|expr| println!("{expr}")),
                Err(err) => println!("{}", err),
            }
        }
        Command::Repl => repl(),
    }
}

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

fn repl() {
    let env = env::Environment::new();
    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();

                let ast = parser::parse_str(&line).unwrap();
                let res = evaluator::eval(&env, ast);

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