package net

import (
	"errors"
	"io"
	"net"
	"time"

	log "github.com/sirupsen/logrus"
	"github.com/xvzc/SpoofDPI/doh"
	"github.com/xvzc/SpoofDPI/packet"
)

const BUF_SIZE = 1024

type Conn struct {
	net.TCPConn
}

func (conn *Conn) WriteChunks(c [][]byte) (n int, err error) {
	total := 0
	for i := 0; i < len(c); i++ {
		b, err := conn.Write(c[i])
		if err != nil {
			return 0, nil
		}

		total += b
	}

	return total, nil
}

func (conn *Conn) ReadBytes() ([]byte, error) {
	ret := make([]byte, 0)
	buf := make([]byte, BUF_SIZE)

	for {
		n, err := conn.Read(buf)
		if err != nil {
			switch err.(type) {
			case *net.OpError:
				return nil, errors.New("timed out")
			default:
				return nil, err
			}
		}
		ret = append(ret, buf[:n]...)

		if n < BUF_SIZE {
			break
		}
	}

	if len(ret) == 0 {
		return nil, io.EOF
	}

	return ret, nil
}

func (lConn *Conn) HandleHttp(p *packet.HttpPacket, timeout int) {
	p.Tidy()

	ip, err := doh.Lookup(p.Domain())
	if err != nil {
		log.Error("[HTTP DOH] Error looking up for domain with ", p.Domain(), " ", err)
		lConn.Write([]byte(p.Version() + " 502 Bad Gateway\r\n\r\n"))
		return
	}

	log.Debug("[DOH] Found ", ip, " with ", p.Domain())

	// Create connection to server
	var port = "80"
	if p.Port() != "" {
		port = p.Port()
	}

	rConn, err := DialTCP("tcp", ip, port)
	if err != nil {
		log.Debug("[HTTP] ", err)
		return
	}

	defer func() {
		lConn.Close()
		log.Debug("[HTTP] Closing client Connection.. ", lConn.RemoteAddr())

		rConn.Close()
		log.Debug("[HTTP] Closing server Connection.. ", p.Domain(), " ", rConn.LocalAddr())
	}()

	log.Debug("[HTTP] New connection to the server ", p.Domain(), " ", rConn.LocalAddr())

	go rConn.Serve(lConn, "[HTTP]", lConn.RemoteAddr().String(), p.Domain(), timeout)

	_, err = rConn.Write(p.Raw())
	if err != nil {
		log.Debug("[HTTP] Error sending request to ", p.Domain(), err)
		return
	}

	log.Debug("[HTTP] Sent a request to ", p.Domain())

	lConn.Serve(rConn, "[HTTP]", lConn.RemoteAddr().String(), p.Domain(), timeout)

}

func (lConn *Conn) HandleHttps(p *packet.HttpPacket, timeout int) {
	ip, err := doh.Lookup(p.Domain())
	if err != nil {
		log.Error("[HTTPS DOH] Error looking up for domain: ", p.Domain(), " ", err)
		lConn.Write([]byte(p.Version() + " 502 Bad Gateway\r\n\r\n"))
		return
	}

	log.Debug("[DOH] Found ", ip, " with ", p.Domain())

	// Create a connection to the requested server
	var port = "443"
	if p.Port() != "" {
		port = p.Port()
	}

	rConn, err := DialTCP("tcp4", ip, port)
	if err != nil {
		log.Debug("[HTTPS] ", err)
		return
	}

	defer func() {
		lConn.Close()
		log.Debug("[HTTPS] Closing client Connection.. ", lConn.RemoteAddr())

		rConn.Close()
		log.Debug("[HTTPS] Closing server Connection.. ", p.Domain(), " ", rConn.LocalAddr())
	}()

	log.Debug("[HTTPS] New connection to the server ", p.Domain(), " ", rConn.LocalAddr())

	_, err = lConn.Write([]byte(p.Version() + " 200 Connection Established\r\n\r\n"))
	if err != nil {
		log.Debug("[HTTPS] Error sending 200 Connection Established to the client", err)
		return
	}

	log.Debug("[HTTPS] Sent 200 Connection Estabalished to ", lConn.RemoteAddr())

	// Read client hello
	clientHello, err := lConn.ReadBytes()
	if err != nil {
		log.Debug("[HTTPS] Error reading client hello from the client", err)
		return
	}

	log.Debug("[HTTPS] Client sent hello ", len(clientHello), "bytes")

	// Generate a go routine that reads from the server

	pkt := packet.NewHttpsPacket(clientHello)

	chunks := pkt.SplitInChunks()

	go rConn.Serve(lConn, "[HTTPS]", rConn.RemoteAddr().String(), p.Domain(), timeout)

	if _, err := rConn.WriteChunks(chunks); err != nil {
		log.Debug("[HTTPS] Error writing client hello to ", p.Domain(), err)
		return
	}

	lConn.Serve(rConn, "[HTTPS]", lConn.RemoteAddr().String(), p.Domain(), timeout)
}

func (from *Conn) Serve(to *Conn, proto string, fd string, td string, timeout int) {
	proto += " "

	for {
		if timeout > 0 {
			from.SetReadDeadline(
				time.Now().Add(time.Millisecond * time.Duration(timeout)),
			)
		}

		buf, err := from.ReadBytes()
		if err != nil {
			if err == io.EOF {
				log.Debug(proto, "Finished ", fd)
				return
			}
			log.Debug(proto, "Error reading from ", fd, " ", err)
			return
		}

		if _, err := to.Write(buf); err != nil {
			log.Debug(proto, "Error Writing to ", td)
			return
		}
	}
}