package ws

import (
	"fmt"
	"io"
	"log"
	"net/http"
	_ "net/http/pprof"
	"strings"
	"time"

	"github.com/gorilla/websocket"
	"github.com/net-byte/vtun/common/cipher"
	"github.com/net-byte/vtun/common/config"
	"github.com/net-byte/vtun/common/netutil"
	"github.com/net-byte/vtun/register"
	"github.com/net-byte/vtun/tun"
	"github.com/patrickmn/go-cache"
	"github.com/songgao/water"
	"github.com/songgao/water/waterutil"
)

var upgrader = websocket.Upgrader{
	ReadBufferSize:  1500,
	WriteBufferSize: 1500,
	CheckOrigin: func(r *http.Request) bool {
		return true
	},
}

// StartServer starts ws server
func StartServer(config config.Config) {
	if config.Pprof {
		go func() {
			log.Printf("pprof server on :6060")
			if err := http.ListenAndServe(":6060", nil); err != nil {
				log.Printf("pprof failed: %v", err)
			}
		}()
	}
	iface := tun.CreateTun(config)
	c := cache.New(30*time.Minute, 10*time.Minute)
	// server -> client
	go toClient(config, iface, c)
	// client -> server
	http.HandleFunc("/way-to-freedom", func(w http.ResponseWriter, r *http.Request) {
		wsConn, err := upgrader.Upgrade(w, r, nil)
		if err != nil {
			return
		}
		toServer(config, wsConn, iface, c)
	})

	http.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
		io.WriteString(w, "Hello，世界！")
	})

	http.HandleFunc("/ip", func(w http.ResponseWriter, req *http.Request) {
		ip := req.Header.Get("X-Forwarded-For")
		if ip == "" {
			ip = strings.Split(req.RemoteAddr, ":")[0]
		}
		resp := fmt.Sprintf("%v", ip)
		io.WriteString(w, resp)
	})

	http.HandleFunc("/register/pick/ip", func(w http.ResponseWriter, req *http.Request) {
		key := req.Header.Get("key")
		if key != config.Key {
			error403(w, req)
			return
		}
		ip, pl := register.PickClientIP(config.CIDR)
		resp := fmt.Sprintf("%v/%v", ip, pl)
		io.WriteString(w, resp)
	})

	http.HandleFunc("/register/delete/ip", func(w http.ResponseWriter, req *http.Request) {
		key := req.Header.Get("key")
		if key != config.Key {
			error403(w, req)
			return
		}
		ip := req.URL.Query().Get("ip")
		if ip != "" {
			register.DeleteClientIP(ip)
		}
		io.WriteString(w, "OK")
	})

	http.HandleFunc("/register/keepalive/ip", func(w http.ResponseWriter, req *http.Request) {
		key := req.Header.Get("key")
		if key != config.Key {
			error403(w, req)
			return
		}
		ip := req.URL.Query().Get("ip")
		if ip != "" {
			register.KeepAliveClientIP(ip)
		}
		io.WriteString(w, "OK")
	})

	http.HandleFunc("/register/list/ip", func(w http.ResponseWriter, req *http.Request) {
		key := req.Header.Get("key")
		if key != config.Key {
			error403(w, req)
			return
		}
		io.WriteString(w, strings.Join(register.ListClientIP(), "\r\n"))
	})
	log.Printf("vtun ws server started on %v", config.LocalAddr)
	http.ListenAndServe(config.LocalAddr, nil)
}

func error403(w http.ResponseWriter, r *http.Request) {
	w.WriteHeader(http.StatusForbidden)
	w.Write([]byte("No permission"))
}

func toClient(config config.Config, iface *water.Interface, c *cache.Cache) {
	buffer := make([]byte, 1500)
	for {
		n, err := iface.Read(buffer)
		if err != nil || err == io.EOF || n == 0 {
			continue
		}
		b := buffer[:n]
		if !waterutil.IsIPv4(b) {
			continue
		}
		srcAddr, dstAddr := netutil.GetAddr(b)
		if srcAddr == "" || dstAddr == "" {
			continue
		}
		key := strings.Join([]string{dstAddr, srcAddr}, "->")
		if v, ok := c.Get(key); ok {
			if config.Obfuscate {
				b = cipher.XOR(b)
			}
			v.(*websocket.Conn).WriteMessage(websocket.BinaryMessage, b)
		}
	}
}

func toServer(config config.Config, wsConn *websocket.Conn, iface *water.Interface, c *cache.Cache) {
	defer netutil.CloseWS(wsConn)
	for {
		wsConn.SetReadDeadline(time.Now().Add(time.Duration(30) * time.Second))
		_, b, err := wsConn.ReadMessage()
		if err != nil || err == io.EOF {
			break
		}
		if config.Obfuscate {
			b = cipher.XOR(b)
		}
		if !waterutil.IsIPv4(b) {
			continue
		}
		srcAddr, dstAddr := netutil.GetAddr(b)
		if srcAddr == "" || dstAddr == "" {
			continue
		}
		key := strings.Join([]string{srcAddr, dstAddr}, "->")
		c.Set(key, wsConn, cache.DefaultExpiration)
		iface.Write(b[:])
	}
}