use async_std::{
    fs,
    io::BufReader,
    net::{TcpListener, TcpStream},
    prelude::*,
    task,
};
use std::path::PathBuf;

type Result<T> = std::result::Result<T, Box<dyn std::error::Error + Send + Sync>>;

pub fn start(addr: &str, root: &str) -> Result<()> {
    task::block_on(async {
        let listener = TcpListener::bind(addr).await?;
        let mut incoming = listener.incoming();
        while let Some(stream) = incoming.next().await {
            let stream = stream?;
            println!("-> Connection from: {}", stream.peer_addr()?);
            let root = root.to_string();
            task::spawn(client_loop(stream, root));
        }
        Ok(())
    })
}

async fn client_loop(mut stream: TcpStream, root: String) -> Result<()> {
    let reader = BufReader::new(&stream);
    let mut lines = reader.lines();

    if let Some(Ok(line)) = lines.next().await {
        println!("-> client sent: {:?}", line);
        respond(&mut stream, &line, &root).await?;
    }
    Ok(())
}

async fn respond(stream: &mut TcpStream, selector: &str, root: &str) -> Result<()> {
    let mut path = PathBuf::from(root);
    path.push(selector.replace("..", "."));
    let mut response = format!("iPath: {}\r\n", path.to_string_lossy());
    let mut dir = fs::read_dir(path.clone()).await?;

    while let Some(Ok(entry)) = dir.next().await {
        if let Ok(metadata) = entry.metadata().await {
            let file_type = if metadata.is_file() {
                '0'
            } else if metadata.is_dir() {
                '1'
            } else {
                '3'
            };
            response.push_str(&format!(
                "{}{}\t{}\tlocalhost\t7070\r\n",
                file_type,
                entry.file_name().into_string().unwrap(),
                entry.path().to_string_lossy(),
            ));
        }
    }
    stream.write_all(response.as_bytes()).await?;
    Ok(())
}