package tscipher

import (
	"bytes"
	"fmt"
	"github.com/TransX/log"
	"github.com/TransX/utils"
	"io"
	"net"
	"strconv"
	"strings"
)

var StartMark = []byte("#2v!") //should be constant
var EndMark = []byte("_=1z")   //should be constant

type LackDataError struct {
	e string
}

type NotPackageError struct {
	e string
}

func (this *LackDataError) Error() string {
	return this.e
}

func (this *NotPackageError) Error() string {
	return this.e
}

type Cipher interface {
	Decrypt(data []byte) (decrypted []byte, err error)
	Encrypt(data []byte) (encryped []byte, err error)
}

type Carrier struct {
	Conn             net.Conn
	Cipher           Cipher
	Cache            []byte
	AttachedTunnelID string
	receiveBuff      []byte
}

func NewCarrier(conn net.Conn, cipher Cipher, cache []byte, id string) *Carrier {
	t := new(Carrier)
	t.Conn = conn
	t.Cipher = cipher
	t.Cache = cache
	t.AttachedTunnelID = id
	t.receiveBuff = make([]byte, 0, len(cache))
	return t
}

func (this *Carrier) GetReceiveBuff() []byte {
	log.Debug("id %d receivebuff Get, len %d", this.AttachedTunnelID, len(this.receiveBuff))
	buff := this.receiveBuff
	_b := make([]byte, len(buff), cap(buff)) //必须这样写，没错。
	copy(_b, buff)
	return _b
}

func (this *Carrier) SetReceiveBuff(buff []byte) {
	this.receiveBuff = buff
	log.Debug("id %d receivebuff set, len %d", this.AttachedTunnelID, len(this.receiveBuff))
}

func NewCipher(cipherName string) (cipher Cipher) {
	if cipherName == "default" {
		return NewChaCha()
	}
	if cipherName == "AES" {
		return NewAES()
	}
	if cipherName == "XOR" {
		return NewXOR([]byte("fasdfasdf!3297!jfsl12*&!HHHFds"))
	}
	return nil //TODO:临时这样处理
}

func WrapPackage(data []byte) []byte { //把要加密传输的数据打包成一定的格式，避免发送了100自己，只收到90字节的问题。
	sizeOfData := len(data)
	binSize := utils.Int2binary(sizeOfData, 10)
	// header := make([]byte, 18)
	// header = append(append(append(header, StartMark...), binSize...), EndMark...)
	header := append(append(StartMark, binSize...), EndMark...)
	// log.Error("size of header %d %x", len(header), header)
	//加密
	key := []byte("#2GD+.>dt`Qdp")
	key = key
	cipheredHeader := make([]byte, len(header))
	for i, v := range header {
		cipheredHeader[i] = v ^ key[i%len(key)]
	}
	return append(cipheredHeader, data...)
}

func UnwrapPackage(pacakge []byte) (data []byte, rest []byte, err error) {
	//前14个字节是header
	cipheredHeader := pacakge[:18]
	header := make([]byte, len(cipheredHeader))
	key := []byte("#2GD+.>dt`Qdp")
	key = key
	for i, v := range cipheredHeader {
		header[i] = v ^ key[i%len(key)]
	}
	// log.Error("receive header %d %x", len(header), header)
	// log.Error("receive pacakge %d %x", len(pacakge[:180]), pacakge[:180])
	start := header[:4]
	end := header[14:]
	binSize := header[4:14]
	packageSize := 0
	if bytes.Compare(start, StartMark) == 0 && bytes.Compare(end, EndMark) == 0 {
		packageSize = utils.Binary2Int(binSize)
		if len(pacakge[18:]) < packageSize {
			packageSize = 0
			data = nil
			rest = nil
			err = &LackDataError{"LackDataError"}
			return
		}
		data = pacakge[18 : 18+packageSize]
		rest = pacakge[18+len(data):]
		err = nil
	} else {
		packageSize = 0
		data = nil
		rest = nil
		if strings.Contains(string(pacakge), "#2v!") && strings.Contains(string(pacakge), "_=1z") {
			a := strings.Index(string(pacakge), "#2v!")
			b := strings.Index(string(pacakge), "_=1z")
			err = &NotPackageError{"NotPackageError(contains)" + "start:" + string(start) + " end:" + string(end) + "pacakge " + strconv.Itoa(len(pacakge)) + "start" + strconv.Itoa(a) + "end" + strconv.Itoa(b)}
		} else {
			err = &NotPackageError{fmt.Sprintf("NotPackageError start: %s end: %s whole %x", string(start), string(end), header)}
		}
	}
	return

}

func SendData(carrier *Carrier, nByte int) (n int, err error) {
	if len(carrier.Cache) < nByte {
		log.Panic("Cache of send is too small")
	}
	if carrier.Cipher == nil {
		n, err = carrier.Conn.Write(carrier.Cache[:nByte])
		return
	}
	encrypedByte, err := carrier.Cipher.Encrypt(carrier.Cache[:nByte])
	if err != nil {
		n = 0
		return
	}
	//打包
	wraped := WrapPackage(encrypedByte[:nByte])
	n, err = carrier.Conn.Write(wraped)
	log.Debug("Ready to write id %s, 18 byte %s", carrier.AttachedTunnelID, string(wraped[:18]))
	copy(carrier.Cache, encrypedByte[:nByte]) // in case of debugging
	return
}

func RowReceiveData(carrier *Carrier) (n int, err error) {
	n, err = carrier.Conn.Read(carrier.Cache)
	if err != nil {
		n = 0

	}
	return
}

func ReceiveData(carrier *Carrier) (n int, err error) {
	// defer func() {
	// 	if r := recover(); r != nil {
	// 		log.Error("ReceiveData err %s", r)
	// 	}
	// }()
	log.Debug("id %s wrapedPackage := carrier.GetReceiveBuff()", carrier.AttachedTunnelID)
	wrapedPackage := carrier.GetReceiveBuff() //make([]byte, 0, cap(carrier.Cache))
	var packageData []byte
	var _rest []byte
	for {
		//首先检查这个是不是完整的包，是就返回好了，免得被阻塞
		data, rest, err := UnwrapPackage(wrapedPackage)
		packageData = data
		_rest = rest
		if err, ok := err.(*NotPackageError); len(wrapedPackage) >= 18 && ok {
			log.Debug("return NotPackageError %s", carrier.AttachedTunnelID)
			return 0, err
		}
		log.Debug("id %s length of package %d", carrier.AttachedTunnelID, len(packageData))
		if err == nil {
			//够一个完整的包
			log.Debug("id %s capBuff := cap(carrier.GetReceiveBuff())", carrier.AttachedTunnelID)
			capBuff := cap(carrier.GetReceiveBuff())
			_buff := make([]byte, 0, capBuff) //释放
			_buff = append(_buff, _rest...)
			log.Debug("id %s carrier.SetReceiveBuff(_buff)", carrier.AttachedTunnelID)
			carrier.SetReceiveBuff(_buff)
			break
		}
		//如果读到的数据不够一个完整的包
		log.Debug("id %s to read wrapedPackage %d", carrier.AttachedTunnelID, len(wrapedPackage))
		if len(wrapedPackage) > 0 {
			n, err = carrier.Conn.Read(carrier.Cache)
			if err != nil {
				log.Error("ERROR %s", err)
			}
			log.Debug("id %s to Conn.Read %d", carrier.AttachedTunnelID, n)
		} else {
			n, err = io.ReadAtLeast(carrier.Conn, carrier.Cache, 18)
			log.Debug("id %s to ReadAtLeast", carrier.AttachedTunnelID)
		}

		if err != nil {
			n = 0
			return n, err
		}
		wrapedPackage = append(wrapedPackage, carrier.Cache[:n]...)

		log.Debug("id %s length of conn %d", carrier.AttachedTunnelID, n)
		log.Debug("id %s first 18 %s from %s", carrier.AttachedTunnelID, string(wrapedPackage[:18]), carrier.Conn.RemoteAddr().String())

	}

	if len(carrier.GetReceiveBuff()) > 0 {
		log.Debug("id %s trailing %d from %s", carrier.AttachedTunnelID, len(carrier.GetReceiveBuff()), carrier.Conn.RemoteAddr().String())
		log.Debug("id %s 18 byte of trailing %s", carrier.AttachedTunnelID, string(carrier.GetReceiveBuff()[:18]))
	}
	decrypted, err := carrier.Cipher.Decrypt(packageData)
	if err != nil {
		n = 0
		return
	}
	n = len(decrypted)
	copy(carrier.Cache, decrypted)
	return
}