use once_cell::sync::Lazy;
use std::net::UdpSocket;
use std::sync::RwLock;

use rmodbus::{
    server::{storage::ModbusStorageFull, ModbusFrame},
    ModbusFrameBuf, ModbusProto,
};

static CONTEXT: Lazy<RwLock<ModbusStorageFull>> = Lazy::new(<_>::default);

pub fn udpserver(unit: u8, listen: &str) {
    let socket = UdpSocket::bind(listen).unwrap();
    loop {
        let mut buf: ModbusFrameBuf = [0; 256];
        let (_amt, src) = socket.recv_from(&mut buf).unwrap();
        println!("got packet");
        let mut response = Vec::new();
        let mut frame = ModbusFrame::new(unit, &buf, ModbusProto::TcpUdp, &mut response);
        if frame.parse().is_err() {
            println!("server error");
            continue;
        }
        if frame.processing_required {
            let result = if frame.readonly {
                frame.process_read(&*CONTEXT.read().unwrap())
            } else {
                frame.process_write(&mut *CONTEXT.write().unwrap())
            };
            if result.is_err() {
                println!("frame processing error");
                continue;
            }
        }
        if frame.response_required {
            frame.finalize_response().unwrap();
            println!("{:x?}", response.as_slice());
            socket.send_to(response.as_slice(), src).unwrap();
        }
    }
}