use std::{
    net::{IpAddr, SocketAddr},
    num::NonZeroUsize,
    path::PathBuf,
    sync::Arc,
    thread::available_parallelism,
};

use actix_web::{App, HttpServer};
use clap::{Parser, crate_name, crate_version};

#[derive(Parser, Debug)]
#[clap(name = crate_name!(), version = crate_version!())]
struct Args {
    /// Directory to expose
    #[clap(default_value = ".", value_parser = parse_valid_dir)]
    dir: PathBuf,

    /// IP address to use
    #[clap(default_value = "0.0.0.0")]
    ip: IpAddr,

    /// Port number to connect
    #[clap(default_value = "8080")]
    port: u16,
}

fn parse_valid_dir(dir: &str) -> Result<PathBuf, String> {
    let path = PathBuf::from(dir);
    match std::fs::metadata(&path) {
        Ok(metadata) if metadata.is_dir() => Ok(path),
        Ok(_) => Err(format!("{} is not a directory", path.display())),
        Err(e) => Err(format!("Error accessing {}: {}", path.display(), e)),
    }
}

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    let args = Args::parse();

    let dir = Arc::new(args.dir);
    let sock = SocketAddr::new(args.ip, args.port);

    println!(
        "Starting HTTP server on {sock} exposing dir {}",
        dir.display()
    );

    HttpServer::new(move || {
        let dir = dir.clone();
        App::new().service(
            actix_files::Files::new("/", dir.as_ref())
                .show_files_listing()
                .prefer_utf8(true),
        )
    })
    .workers(available_parallelism().map_or(1, NonZeroUsize::get))
    .bind(sock)?
    .run()
    .await
}