package ngkrok

import (
	"context"
	"crypto/rand"
	"io"
	"log"
	"net"
	"net/http"
	"strings"

	vhost "github.com/inconshreveable/go-vhost"
	"github.com/progrium/qmux/golang/session"
)

const (
	SERVER_VERSION      = "v0.5"
	HEADER_CLIENT_TOKEN = "X-Client-App-Token"
	HEADER_PUBLIC_HOST  = "X-Public-Host"
)

type Server struct {
	addr string
	host string
	port string
	VMux *vhost.HTTPMuxer
}

func NewServer(addr, host, port string, vmux *vhost.HTTPMuxer) *Server {
	return &Server{addr, host, port, vmux}
}

func (s *Server) Serve() {
	ml, err := s.VMux.Listen(net.JoinHostPort(s.host, s.port))
	if err != nil {
		log.Fatal(err)
	}

	srv := &http.Server{}
	// http.HandleFunc("/", s.mainHandler)
	http.HandleFunc("/register", s.registerHandler)

	srv.Serve(ml)
}

// func (s *Server) mainHandler(w http.ResponseWriter, r *http.Request) {
// 	log.Println("mainHandler")
// 	return
// }

func (s *Server) registerHandler(w http.ResponseWriter, r *http.Request) {
	subdomain := newSubdomain(r) + s.host
	publicHost := strings.TrimSuffix(net.JoinHostPort(subdomain, s.port), ":80")
	pl, err := s.VMux.Listen(publicHost)
	if err != nil {
		log.Fatal(err)
	}
	defer pl.Close()

	w.Header().Add(HEADER_PUBLIC_HOST, subdomain)
	w.Header().Add("Connection", "close")
	w.WriteHeader(http.StatusOK)

	conn, _, _ := w.(http.Hijacker).Hijack()
	sess := session.New(conn)
	defer sess.Close()
	log.Printf("%s: start session", subdomain)

	go func() {
		for {
			conn, err := pl.Accept()
			if err != nil {
				log.Println("Accept:", err)
				return
			}
			defer conn.Close()

			ch, err := sess.Open(context.Background())
			if err != nil {
				log.Println("sess.Open:", err)
				return
			}
			defer ch.Close()

			go join(ch, conn)
		}
	}()

	sess.Wait()
	log.Printf("%s: end session", subdomain)
}

func join(a io.ReadWriteCloser, b io.ReadWriteCloser) {
	go io.Copy(b, a)
	io.Copy(a, b)
	a.Close()
	b.Close()
}

func newSubdomain(r *http.Request) string {
	clientToken := r.Header.Get(HEADER_CLIENT_TOKEN)

	if clientToken == "ghd7H8H*&6tg8*tg68" { // hardcoded token for dev tests....
		return "test."
	}

	b := make([]byte, 10)
	if _, err := rand.Read(b); err != nil {
		panic(err)
	}
	letters := []rune("abcdefghijklmnopqrstuvwxyz1234567890")
	rune := make([]rune, 10)
	for i := range rune {
		rune[i] = letters[int(b[i])*len(letters)/256]
	}

	return string(rune) + "."
}