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//! 简易传输协议

#![no_std]
extern crate alloc;
#[macro_use]
extern crate lazy_static;

mod datagram;
mod history;
mod sender;
mod socket;

use alloc::boxed::Box;
use alloc::collections::btree_map::BTreeMap;
use alloc::sync::Arc;
use datagram::{Datagram, Field};
use history::History;
pub use sender::Cfg;
use sender::Sender;
pub use socket::{Addr, Socket};
use spin::RwLock;
use unmp::net::{self, Id};
use unmp::protocol::{protocols, Protocol};

/// 协议ID
pub const PROTOCOL_ID: u8 = 1;
/// 全部端口
pub const PORT_ALL: u8 = 0xFF;

lazy_static! {
    /// 消息序列号
static ref INDEX: RwLock<u16> = RwLock::new(0);
/// 监听器
static ref LISTENERS: RwLock<BTreeMap<u8, Box<dyn Socket + Send + Sync>>> = RwLock::new(BTreeMap::new());
/// 重发器
static ref SENDER: RwLock<Sender> = RwLock::new(Sender::new());
/// 历史记录
static ref HISTORY: RwLock<History> = RwLock::new(History::new());
}

/// 简易传输协议
struct ProtocolEtp {}
impl Protocol for ProtocolEtp {
    fn id(&self) -> u8 {
        PROTOCOL_ID
    }
    fn recv(&self, remote: &Id, data: &[u8]) {
        let datagram = Datagram::try_from_buf(data);
        if let Ok(datagram) = datagram {
            if datagram.control < 0x80 {
                // 响应
                let mut is_repeat = false;
                if datagram.control & (1 << 1) == (1 << 1) {
                    // 需要去重
                    let mut history = HISTORY.write();
                    if history.has(remote, datagram.index) {
                        is_repeat = true;
                    } else {
                        history.add(remote, datagram.index);
                    }
                }
                if datagram.control & (1 << 0) == (1 << 0) {
                    // 需要响应
                    let mut res = Datagram::new();
                    res.set_var(Field::Control, &[0x81 | (is_repeat as u8) << 1]);
                    res.set_var(
                        Field::Index,
                        &[(datagram.index >> 8) as u8, datagram.index as u8],
                    );
                    res.set_var(Field::Srcport, &[datagram.dstport]);
                    res.set_var(Field::Dstport, &[datagram.srcport]);
                    res.set_var(Field::Body, &[]);
                    let buf = res.to_buf();
                    net::send(PROTOCOL_ID, &buf, Some(remote), None);
                }
                // 处理
                if is_repeat {
                    return;
                }
                let addr = Addr(remote.clone(), datagram.srcport);
                let listeners = LISTENERS.read();
                if let Some(listener) = listeners.get(&PORT_ALL) {
                    listener.recv_handle(&addr, &datagram.body);
                }
                if let Some(listener) = listeners.get(&datagram.dstport) {
                    listener.recv_handle(&addr, &datagram.body);
                }
            } else {
                // 收到响应
                let mut sender = SENDER.write();
                sender.finish(datagram.index);
            }
        }
    }
}

/// 创建一个简易传输协议实例
pub fn init() {
    let protocol = ProtocolEtp {};
    protocols::add_protocol(Arc::new(protocol));
}
/// 创建一个socket
pub fn listen(listener: Box<dyn Socket + Send + Sync>) {
    let mut listeners = LISTENERS.write();
    listeners.insert(listener.port(), listener);
}
/// 发送数据到指定设备
pub fn send(port: u8, dst: &Addr, body: &[u8], cfg: Cfg) {
    let mut datagram = Datagram::new();
    datagram.set_var(Field::Control, &[3]);
    let index = {
        let mut index = INDEX.write();
        *index += 1;
        *index
    };
    datagram.set_var(Field::Index, &[(index >> 8) as u8, index as u8]);
    datagram.set_var(Field::Srcport, &[port]);
    datagram.set_var(Field::Dstport, &[dst.1]);
    datagram.set_var(Field::Body, body);
    let buf = datagram.to_buf();

    // 发送
    let mut sender = SENDER.write();
    (*sender).send(index, buf, dst.0, cfg);
}
/// 重发
pub fn resend() {
    let mut sender = SENDER.write();
    (*sender).resend();
}