use std::{ fmt::Display, io::{BufRead, BufReader, Read, Write}, net::TcpListener };
use anyhow::Result;
use thiserror::Error;

#[derive(Clone, Debug, Error)]
enum E {
    #[error("Invalid request data found during parsing")]
    InvalidRequest,
}

fn main() -> Result<()> {
    let listener = TcpListener::bind("127.0.0.1:4221").unwrap();

    for stream in listener.incoming() {
        match stream {
            Ok(mut stream) => {
                let buf_reader = BufReader::new(&mut stream);

                let mut data = buf_reader
                    .lines()
                    .map(|result| result.unwrap())
                    .take_while(|line| !line.is_empty());

                let (_method, path, _ver) = {
                    let start_line = data.next().ok_or(E::InvalidRequest)?; // should be 500;
                    let mut parts = start_line.split_whitespace().map(ToOwned::to_owned);
                    let method = parts.next().ok_or(E::InvalidRequest)?;
                    let path = parts.next().ok_or(E::InvalidRequest)?;
                    let ver = parts.next().ok_or(E::InvalidRequest)?;

                    (method, path, ver)
                };

                let code = match path.as_str() {
                    "/" => "200 OK",
                    _ => "404 Not Found",
                };

                println!("accepted new connection");
                let resp = create_response_simple(code);

                let _ = stream.write(&resp);
                let _ = stream.flush();

            }
            Err(e) => {
                println!("error: {}", e);
            }
        }
    }

    Ok(())
}


fn create_response_simple <T> (code: T) -> Vec<u8> where T: Display {
    format!("HTTP/1.1 {code}\r\n\r\n").into()
}