/*
   Copyright 2020 XiaochengTech

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

package connections

import (
	"io"
	"net"
	"time"
)

// UDP读取缓冲区的长度
const UDP_BUFFER_SIZE = 4 * 1024

// UDP连接实现
type ConnectionUDP struct {
	DefaultConnection
}

// (接口)主动连接
func (m *ConnectionUDP) Connect(addr string) (err error) {
	m.address = addr
	// 连接
	if m.connectTimeout > 0 {
		m.conn, err = net.DialTimeout(UDP, addr, m.connectTimeout)
	} else {
		m.conn, err = net.Dial(UDP, addr)
	}
	// 事件回调
	if m.onConnect != nil {
		m.onConnect(m.identifier, addr)
	}
	return
}

// (接口)写入信息
func (m ConnectionUDP) Write(buf []byte) (n int, err error) {
	// 判断连接是否已关闭
	if m.closed {
		// 被动模式直接返回
		if m.isPassive {
			return
		}
		// 主动模式自动重连
		if err = m.Connect(m.address); err != nil {
			return
		}
	}
	// 判断是否有写超时
	if m.writeTimeout > 0 {
		if err = m.conn.SetWriteDeadline(time.Now().Add(m.writeTimeout)); err != nil {
			return
		}
	}
	// 写入实际连接
	n, err = m.conn.Write(buf)
	// 通知外界
	if m.onWrite != nil {
		m.onWrite(m.identifier, buf, n, err)
	}
	return
}

// UDP被动连接读取数据包
func (m ConnectionUDP) udpPassiveReader(receiver chan []byte) {
	for {
		buf, ok := <-receiver
		if !ok {
			return
		}
		m.readBuf <- buf
	}
}

// UDP主动连接读取数据包
func (m ConnectionUDP) udpActiveReader() {
	buf := make([]byte, UDP_BUFFER_SIZE)
	for {
		// 连接关闭
		if m.closed {
			if err := m.Connect(m.address); err != nil {
				time.Sleep(1 * time.Second)
				continue
			}
		}
		// 判断读超时
		if m.readTimeout > 0 {
			if e := m.conn.SetReadDeadline(time.Now().Add(m.readTimeout)); e != nil {
				continue
			}
		}
		// 接收数据包
		n, err := m.conn.Read(buf)
		if err != nil {
			if err == io.EOF {
				m.Close()
				continue
			}
			m.readError <- err
			continue
		}
		m.readBuf <- buf[0:n]
	}
}