kcp2k 0.0.1-beta

use crate::kcp2k::Kcp2K;
use bytes::Bytes;
use rand::TryRngCore;
use socket2::{SockAddr, Socket};
use std::hash::{DefaultHasher, Hash, Hasher};
use std::io::Error;
use std::sync::Arc;
use std::time::{SystemTime, UNIX_EPOCH};
use tklog::info;

#[derive(Debug, PartialEq, Copy, Clone)]
pub enum Kcp2KMode {
    Client,
    Server,
}

// sock_addr hash
pub fn connection_hash(sock_addr: &SockAddr) -> u64 {
    // cookie 与 sock_addr 一起生成一个唯一的连接 ID
    let mut hasher = DefaultHasher::new();
    sock_addr.hash(&mut hasher);
    hasher.finish()
}

// 生成一个随机的 4 字节 cookie
pub fn generate_cookie() -> Bytes {
    let mut rng = rand::rngs::OsRng;
    let mut buffer = [0u8; 4];
    let _ = rng.try_fill_bytes(&mut buffer);
    Bytes::copy_from_slice(&buffer)
}

// 如果连接在重负载下下降，请增加到 OS 限制。
// 如果仍然不够，请增加 OS 限制。
pub fn configure_socket_buffers(
    socket: &Socket,
    recv_buffer_size: usize,
    send_buffer_size: usize,
    kcp2k_mode: Arc<Kcp2KMode>,
) -> Result<(), Error> {
    // 记录初始大小以进行比较
    let initial_receive = socket.recv_buffer_size()?;
    let initial_send = socket.send_buffer_size()?;

    // 设置为配置的大小
    socket.set_recv_buffer_size(recv_buffer_size)?;
    socket.set_send_buffer_size(send_buffer_size)?;

    info!(format!(
        "[KCP2K] {:?} RecvBuf = {}=>{} ({}x) SendBuf = {}=>{} ({}x)",
        kcp2k_mode,
        initial_receive,
        socket.recv_buffer_size()?,
        socket.recv_buffer_size()? / initial_receive,
        initial_send,
        socket.send_buffer_size()?,
        socket.send_buffer_size()? / initial_send
    ));
    Ok(())
}

// 获取当前时间戳（秒）
#[allow(dead_code)]
pub fn get_current_timestamp_secs() -> u64 {
    let start = SystemTime::now();
    let since_the_epoch = start
        .duration_since(UNIX_EPOCH)
        .expect("Time went backwards");
    since_the_epoch.as_secs()
}

// 获取当前时间戳（毫秒）
#[allow(dead_code)]
pub fn get_current_timestamp_millis() -> u128 {
    let start = SystemTime::now();
    let since_the_epoch = start
        .duration_since(UNIX_EPOCH)
        .expect("Time went backwards");
    since_the_epoch.as_millis()
}

#[allow(dead_code)]
pub fn update_client_times(amount: usize, client: &mut Kcp2K, interval: u64) {
    for _ in 0..amount {
        client.tick();
        std::thread::sleep(std::time::Duration::from_millis(interval));
    }
}

#[allow(dead_code)]
pub fn update_server_times(amount: usize, server: &mut Kcp2K, interval: u64) {
    for _ in 0..amount {
        server.tick();
        std::thread::sleep(std::time::Duration::from_millis(interval));
    }
}

#[allow(dead_code)]
pub fn update_times(amount: usize, client: &mut Kcp2K, server: &mut Kcp2K, interval: u64) {
    for _ in 0..amount {
        client.tick();
        server.tick();
        std::thread::sleep(std::time::Duration::from_millis(interval));
    }
}