McChatClient/src/run.rs

use std::{
    io::{Read as _, Write as _},
    net::TcpStream,
};

use varint_rs::{VarintReader, VarintWriter as _};

use crate::{
    Connected, Server,
    error::Result,
    readers::{read_packet, read_string},
    text::Message,
};

pub enum Packet {
    KeepAlive([u8; 4]),
    Chat(Vec<Message>),
    Disconnect,
    Other(usize, Vec<u8>),
}

impl Server<Connected> {
    pub fn run(self) -> Result<()> {
        let Self {
            mut stream,
            lang,
            state: Connected { .. },
            ..
        } = self;
        loop {
            let packet = read_packet(&mut stream, parse_packet)?;
            match packet {
                Packet::KeepAlive(id) => handle_keepalive(&mut stream, id)?,
                Packet::Chat(m) => {
                    for m in m {
                        println!("{}", m.format(&lang))
                    }
                }
                Packet::Disconnect => break,
                Packet::Other(_, _) => {}
            }
        }
        Ok(())
    }
}

fn parse_packet(packet: &mut &[u8]) -> Result<Packet> {
    let id = packet.read_usize_varint()?;
    match id {
        0x00 => {
            let mut id = [0u8; 4];
            packet.read_exact(&mut id)?;
            Ok(Packet::KeepAlive(id))
        }
        0x02 => {
            let msg = read_string(packet)?;
            let msg = Message::from_string(msg).unwrap();
            Ok(Packet::Chat(msg))
        }
        0x40 => Ok(Packet::Disconnect),
        i => Ok(Packet::Other(i, packet.to_vec())),
    }
}

fn handle_keepalive(stream: &mut TcpStream, id: [u8; 4]) -> Result<()> {
    let mut buf: Vec<u8> = Vec::new();
    buf.write_u8_varint(0)?;
    buf.write_all(&id)?;

    stream.write_usize_varint(buf.len())?;
    stream.write_all(&buf)?;
    Ok(())
}