// Copyright 2017 gf Author(https://github.com/gogf/gf). All Rights Reserved.
//
// This Source Code Form is subject to the terms of the MIT License.
// If a copy of the MIT was not distributed with this file,
// You can obtain one at https://github.com/gogf/gf.

package gtcp

import (
	"crypto/rand"
	"crypto/tls"
	"github.com/gogf/gf/g/os/gfile"
	"net"
	"time"
)

const (
	gDEFAULT_RETRY_INTERVAL   = 100 // (毫秒)默认重试时间间隔
	gDEFAULT_READ_BUFFER_SIZE = 128 // (byte)默认数据读取缓冲区大小
)

type Retry struct {
	Count    int // 重试次数
	Interval int // 重试间隔(毫秒)
}

// Deprecated.
// 常见的二进制数据校验方式，生成校验结果
func Checksum(buffer []byte) uint32 {
	var checksum uint32
	for _, b := range buffer {
		checksum += uint32(b)
	}
	return checksum
}

// 创建原生TCP链接, addr地址格式形如：127.0.0.1:80
func NewNetConn(addr string, timeout ...int) (net.Conn, error) {
	if len(timeout) > 0 {
		return net.DialTimeout("tcp", addr, time.Duration(timeout[0])*time.Millisecond)
	} else {
		return net.Dial("tcp", addr)
	}
}

// 创建支持TLS的原生TCP链接, addr地址格式形如：127.0.0.1:80
func NewNetConnTLS(addr string, tlsConfig *tls.Config) (net.Conn, error) {
	return tls.Dial("tcp", addr, tlsConfig)
}

// 根据给定的证书和密钥文件创建支持TLS的原生TCP链接, addr地址格式形如：127.0.0.1:80
func NewNetConnKeyCrt(addr, crtFile, keyFile string) (net.Conn, error) {
	tlsConfig, err := LoadKeyCrt(crtFile, keyFile)
	if err != nil {
		return nil, err
	}
	return NewNetConnTLS(addr, tlsConfig)
}

// (面向短链接)发送数据
func Send(addr string, data []byte, retry ...Retry) error {
	conn, err := NewConn(addr)
	if err != nil {
		return err
	}
	defer conn.Close()
	return conn.Send(data, retry...)
}

// (面向短链接)发送数据并等待接收返回数据
func SendRecv(addr string, data []byte, receive int, retry ...Retry) ([]byte, error) {
	conn, err := NewConn(addr)
	if err != nil {
		return nil, err
	}
	defer conn.Close()
	return conn.SendRecv(data, receive, retry...)
}

// (面向短链接)带超时时间的数据发送
func SendWithTimeout(addr string, data []byte, timeout time.Duration, retry ...Retry) error {
	conn, err := NewConn(addr)
	if err != nil {
		return err
	}
	defer conn.Close()
	return conn.SendWithTimeout(data, timeout, retry...)
}

// (面向短链接)发送数据并等待接收返回数据(带返回超时等待时间)
func SendRecvWithTimeout(addr string, data []byte, receive int, timeout time.Duration, retry ...Retry) ([]byte, error) {
	conn, err := NewConn(addr)
	if err != nil {
		return nil, err
	}
	defer conn.Close()
	return conn.SendRecvWithTimeout(data, receive, timeout, retry...)
}

// 判断是否是超时错误
func isTimeout(err error) bool {
	if err == nil {
		return false
	}
	if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
		return true
	}
	return false
}

// 根据证书和密钥生成TLS对象
func LoadKeyCrt(crtFile, keyFile string) (*tls.Config, error) {
	crtPath, err := gfile.Search(crtFile)
	if err != nil {
		return nil, err
	}
	keyPath, err := gfile.Search(keyFile)
	if err != nil {
		return nil, err
	}
	crt, err := tls.LoadX509KeyPair(crtPath, keyPath)
	if err != nil {
		return nil, err
	}
	tlsConfig := &tls.Config{}
	tlsConfig.Certificates = []tls.Certificate{crt}
	tlsConfig.Time = time.Now
	tlsConfig.Rand = rand.Reader
	return tlsConfig, nil
}