package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"net/http"

	"github.com/google/uuid"
	"github.com/gorilla/websocket"
)

var wsaddr = flag.String("wsaddr", "localhost:12345", "websocket service address")

type WSMsg struct {
	Mtype   string `json:"mtype"`
	ID      int    `json:"id,omitempty"`
	Payload string `json:"payload,string"`
}

type Handler struct {
	MType    string
	Callback func(WSMsg, *WSPeer) error
}

type WSServer struct {
	upgrader *websocket.Upgrader
	handler  map[string]func(WSMsg, *WSPeer) error
	peers    map[uuid.UUID]*WSPeer
}

func NewWSServer() *WSServer {
	upgrader := websocket.Upgrader{}                                  // use default options
	upgrader.CheckOrigin = func(r *http.Request) bool { return true } // cors-origin '*'
	wss := WSServer{upgrader: &upgrader, peers: map[uuid.UUID]*WSPeer{}}
	return &wss
}

func (wss *WSServer) Write(name string, sendMsg WSMsg) {
	peers := wss.GetPeers(name)
	if len(peers) == 0 {
		log.Println("WSServer:Write - no sendChans for", name)
		return
	}
	for _, peer := range peers {
		peer.Answer(sendMsg)
	}
}

func (wss *WSServer) GetPeers(searchname string) []*WSPeer {
	cons := []*WSPeer{}
	for key, con := range wss.peers {
		username := key.String()
		if username == searchname {
			cons = append(cons, con)
		}
	}
	return cons
}

func (wss *WSServer) CleanPeer(name uuid.UUID) {
	delete(wss.peers, name)
}

func (wss *WSServer) RegisterHandler(handlers []Handler) {
	if wss.handler == nil {
		wss.handler = map[string]func(WSMsg, *WSPeer) error{}
	}
	for _, handler := range handlers {
		log.Println("Registrering handler for MType: ", handler.MType)
		wss.handler[handler.MType] = handler.Callback
	}
}

type WSPeer struct {
	uuid    uuid.UUID
	conn    *websocket.Conn
	answers *chan WSMsg
}

func (peer *WSPeer) WorkAnswers() {
	for {
		msg := WSMsg{}
		msg = <-*peer.answers
		fmt.Println("sending on: ", peer.uuid)
		peer._answer(msg)
	}
}

func (peer *WSPeer) Answer(msg WSMsg) {
	if peer.answers == nil {
		fmt.Println("empty chan for :", peer.uuid)
	}
	*peer.answers <- msg
}

func (peer *WSPeer) _answer(msg WSMsg) error {
	log.Println("sending message: ", msg)
	jsonMsg, err := json.Marshal(msg)
	if err != nil {
		log.Printf("write: err marshalling \"%s\"\n%s", msg, err.Error())
		return err
	}
	err = peer.conn.WriteMessage(websocket.BinaryMessage, jsonMsg)
	if err != nil {
		log.Println("write:", err)
		return err
	}
	return nil
}

func (wss WSServer) WebsocketHandler(w http.ResponseWriter, r *http.Request) {
	log.Println("request on /ws from", r.RemoteAddr)
	c, err := wss.upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Print("upgrade:", err)
		return
	}

	defer c.Close()
	peer := WSPeer{uuid: uuid.New(), conn: c}
	bla := make(chan WSMsg, 10)
	peer.answers = &bla

	go peer.WorkAnswers()
	wss.peers[peer.uuid] = &peer

	for {
		_, message, err := c.ReadMessage()
		if err != nil {
			log.Println("read:", err)
			break
		}
		var rawmsg map[string]interface{}
		err = json.Unmarshal(message, &rawmsg)
		msg := WSMsg{}
		for k, v := range rawmsg {
			switch k {
			case "id":
				id := v.(float64)
				msg.ID = int(id)
			case "mtype":
				msg.Mtype = v.(string)
			case "payload":
				payload, ok := v.(string)
				if !ok {
					payloadmap := v.(map[string]interface{})
					var payloadbyte []byte
					payloadbyte, err = json.Marshal(payloadmap)
					payload = string(payloadbyte)
				}
				msg.Payload = payload
			}
		}

		if err != nil {
			log.Println("error unmarshalling message:", err)
			log.Printf("recv: %s", message)
			return
		}

		handler, ok := wss.handler[msg.Mtype]
		if !ok {
			log.Println("unknown MType", msg.Mtype)
			keys := ""
			for k := range wss.handler {
				keys = fmt.Sprintf("%s\n%s", keys, k)
			}
			log.Println("available MTypes:\n", keys, "----")
			remsg := WSMsg{Mtype: "UNKNOWN", Payload: ""}
			peer.Answer(remsg)
			return
		}
		err = handler(msg, &peer)
		if err != nil {
			log.Println("handler failed", err.Error())
			//writeChan <- msg
		}
		log.Println("message handled")
	}
}