use clap::Parser;
use std::fs::File;
use std::io::{self, BufRead, Write};

#[derive(Parser, Debug)]
#[command(version, about, long_about = None)]
struct Args {
    /// Script to run
    #[arg(short, long)]
    script: Option<String>,
}

fn run(lines: io::Lines<io::BufReader<File>>) -> () {
    for line in lines {
        println!("Line: {}", line.unwrap());
    }
}

fn run_file(script: String) -> Result<(), io::Error> {
    let file = File::open(script)?;
    run(io::BufReader::new(file).lines());

    Ok(())
}

fn run_prompt() -> Result<(), io::Error> {
    loop {
        print!("> ");
        io::stdout().flush()?;

        let mut buffer = String::new();
        io::stdin().read_line(&mut buffer)?;
        if buffer.len() == 0 {
            break;
        }
        println!("input: '{}', {}", buffer, buffer.len());
    }

    Ok(())
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let args = Args::parse();

    if let Some(script) = args.script {
        run_file(script)?;
    } else {
        run_prompt()?;
    }

    Ok(())
}