package main

import (
	"context"
	"log"
	"net/http"
	"strconv"
	"sync"
	"time"

	"github.com/julienschmidt/httprouter"
	"nhooyr.io/websocket"
	"nhooyr.io/websocket/wsjson"
)

var (
	WSClients      = map[int64][]WSClient{}
	WSClientsMutex = sync.RWMutex{}
	WSAdmin        = []WSClient{}
	WSAdminMutex   = sync.RWMutex{}
)

func init() {
	router.GET("/api/surveys/:sid/ws", rawAuthHandler(SurveyWS, loggedUser))
	router.GET("/api/surveys/:sid/ws-admin", rawAuthHandler(SurveyWSAdmin, adminRestricted))

	router.GET("/api/surveys/:sid/ws/stats", apiHandler(surveyHandler(func(s Survey, body []byte) HTTPResponse {
		return APIResponse{
			WSSurveyStats(s.Id),
		}
	}), adminRestricted))
}

func WSSurveyStats(sid int64) map[string]interface{} {
	var users []string
	var nb int

	WSClientsMutex.RLock()
	defer WSClientsMutex.RUnlock()
	if w, ok := WSClients[sid]; ok {
		nb = len(w)
		for _, ws := range w {
			users = append(users, ws.u.Login)
		}
	}

	return map[string]interface{}{
		"nb_clients": nb,
		"users":      users,
	}
}

type WSClient struct {
	ws  *websocket.Conn
	c   chan WSMessage
	u   *User
	sid int64
}

func SurveyWS_run(ws *websocket.Conn, c chan WSMessage, sid int64, u *User) {
	for {
		msg, ok := <-c
		if !ok {
			break
		}

		ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
		defer cancel()

		err := wsjson.Write(ctx, ws, msg)
		if err != nil {
			log.Println("Error on WebSocket:", err)
			ws.Close(websocket.StatusInternalError, "error on write")
			break
		}
	}
	ws.Close(websocket.StatusNormalClosure, "end")

	WSClientsMutex.Lock()
	defer WSClientsMutex.Unlock()

	for i, clt := range WSClients[sid] {
		if clt.ws == ws {
			WSClients[sid][i] = WSClients[sid][len(WSClients[sid])-1]
			WSClients[sid] = WSClients[sid][:len(WSClients[sid])-1]
			break
		}
	}
	log.Println(u.Login, "disconnected")
}

func msgCurrentState(survey *Survey) (msg WSMessage) {
	if *survey.Direct == 0 {
		msg = WSMessage{
			Action: "pause",
		}
	} else {
		msg = WSMessage{
			Action:     "new_question",
			QuestionId: survey.Direct,
		}
	}
	return
}

func SurveyWS(w http.ResponseWriter, r *http.Request, ps httprouter.Params, u *User, body []byte) {
	if sid, err := strconv.Atoi(string(ps.ByName("sid"))); err != nil {
		http.Error(w, "{\"errmsg\": \"Invalid survey identifier\"}", http.StatusBadRequest)
		return
	} else if survey, err := getSurvey(sid); err != nil {
		http.Error(w, "{\"errmsg\": \"Survey not found\"}", http.StatusNotFound)
		return
	} else if survey.Direct == nil {
		http.Error(w, "{\"errmsg\": \"Not a direct survey\"}", http.StatusBadRequest)
		return
	} else {
		ws, err := websocket.Accept(w, r, nil)
		if err != nil {
			log.Fatal("error get connection", err)
		}

		log.Println(u.Login, "is now connected to WS", sid)

		c := make(chan WSMessage, 1)

		WSClientsMutex.Lock()
		defer WSClientsMutex.Unlock()
		WSClients[survey.Id] = append(WSClients[survey.Id], WSClient{ws, c, u, survey.Id})

		// Send current state
		c <- msgCurrentState(&survey)

		go SurveyWS_run(ws, c, survey.Id, u)
	}
}

func WSWriteAll(message WSMessage) {
	WSClientsMutex.RLock()
	defer WSClientsMutex.RUnlock()

	for _, wss := range WSClients {
		for _, ws := range wss {
			ws.c <- message
		}
	}
}

type WSMessage struct {
	Action     string                 `json:"action"`
	SurveyId   *int64                 `json:"survey,omitempty"`
	QuestionId *int64                 `json:"question,omitempty"`
	Stats      map[string]interface{} `json:"stats,omitempty"`
	UserId     *int64                 `json:"user,omitempty"`
	Response   string                 `json:"value,omitempty"`
}

func (s *Survey) WSWriteAll(message WSMessage) {
	WSClientsMutex.RLock()
	defer WSClientsMutex.RUnlock()

	if wss, ok := WSClients[s.Id]; ok {
		for _, ws := range wss {
			ws.c <- message
		}
	}
}

func (s *Survey) WSCloseAll(message string) {
	WSClientsMutex.RLock()
	defer WSClientsMutex.RUnlock()

	if wss, ok := WSClients[s.Id]; ok {
		for _, ws := range wss {
			close(ws.c)
		}
	}
}

// Admin //////////////////////////////////////////////////////////////

func SurveyWSAdmin_run(ctx context.Context, ws *websocket.Conn, c chan WSMessage, sid int64, u *User) {
	ct := time.Tick(25000 * time.Millisecond)
loopadmin:
	for {
		select {
		case <-ct:
			ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
			defer cancel()

			err := wsjson.Write(ctx, ws, WSMessage{
				Action: "stats",
				Stats:  WSSurveyStats(sid),
			})
			if err != nil {
				log.Println("Error on WebSocket:", err)
				ws.Close(websocket.StatusInternalError, "error on write")
				break
			}

		case msg, ok := <-c:
			if !ok {
				break loopadmin
			}

			ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
			defer cancel()

			err := wsjson.Write(ctx, ws, msg)
			if err != nil {
				log.Println("Error on WebSocket:", err)
				ws.Close(websocket.StatusInternalError, "error on write")
				break
			}
		}
	}
	ws.Close(websocket.StatusNormalClosure, "end")

	WSAdminMutex.Lock()
	defer WSAdminMutex.Unlock()

	for i, clt := range WSAdmin {
		if clt.ws == ws {
			WSAdmin[i] = WSAdmin[len(WSAdmin)-1]
			WSAdmin = WSAdmin[:len(WSAdmin)-1]
			break
		}
	}
	log.Println(u.Login, "admin disconnected")
}

func SurveyWSAdmin(w http.ResponseWriter, r *http.Request, ps httprouter.Params, u *User, body []byte) {
	if sid, err := strconv.Atoi(string(ps.ByName("sid"))); err != nil {
		http.Error(w, "{\"errmsg\": \"Invalid survey identifier\"}", http.StatusBadRequest)
		return
	} else if survey, err := getSurvey(sid); err != nil {
		http.Error(w, "{\"errmsg\": \"Survey not found\"}", http.StatusNotFound)
		return
	} else if survey.Direct == nil {
		http.Error(w, "{\"errmsg\": \"Not a direct survey\"}", http.StatusBadRequest)
		return
	} else {
		ws, err := websocket.Accept(w, r, nil)
		if err != nil {
			log.Fatal("error get connection", err)
		}

		log.Println(u.Login, "is now connected to WS-admin", sid)

		c := make(chan WSMessage, 2)

		WSAdminMutex.Lock()
		defer WSAdminMutex.Unlock()
		WSAdmin = append(WSAdmin, WSClient{ws, c, u, survey.Id})

		// Send current state
		c <- msgCurrentState(&survey)

		go SurveyWSAdmin_run(r.Context(), ws, c, survey.Id, u)
		go func(c chan WSMessage, sid int) {
			var v WSMessage
			var err error
			for {
				err = wsjson.Read(context.Background(), ws, &v)
				if err != nil {
					log.Println("Error when receiving message:", err)
					close(c)
					break
				}

				if v.Action == "new_question" && v.QuestionId != nil {
					if survey, err := getSurvey(sid); err != nil {
						log.Println("Unable to retrieve survey:", err)
					} else {
						survey.Direct = v.QuestionId
						_, err = survey.Update()
						if err != nil {
							log.Println("Unable to update survey:", err)
						}

						survey.WSWriteAll(v)
						v.SurveyId = &survey.Id
						WSAdminWriteAll(v)
					}
				} else if v.Action == "pause" {
					if survey, err := getSurvey(sid); err != nil {
						log.Println("Unable to retrieve survey:", err)
					} else {
						var u int64 = 0
						survey.Direct = &u
						_, err = survey.Update()
						if err != nil {
							log.Println("Unable to update survey:", err)
						}

						survey.WSWriteAll(v)
						v.SurveyId = &survey.Id
						WSAdminWriteAll(v)
					}
				} else if v.Action == "end" {
					if survey, err := getSurvey(sid); err != nil {
						log.Println("Unable to retrieve survey:", err)
					} else {
						survey.Direct = nil
						_, err = survey.Update()
						if err != nil {
							log.Println("Unable to update survey:", err)
						}

						survey.WSCloseAll("Fin du live")
						v.SurveyId = &survey.Id
						WSAdminWriteAll(v)
					}
				} else if v.Action == "get_stats" {
					err = wsjson.Write(context.Background(), ws, WSMessage{Action: "stats", Stats: WSSurveyStats(int64(sid))})
				} else if v.Action == "get_responses" {
					if survey, err := getSurvey(sid); err != nil {
						log.Println("Unable to retrieve survey:", err)
					} else if questions, err := survey.GetQuestions(); err != nil {
						log.Println("Unable to retrieve questions:", err)
					} else {
						for _, q := range questions {
							if responses, err := q.GetResponses(); err != nil {
								log.Println("Unable to retrieve questions:", err)
							} else {
								for _, r := range responses {
									wsjson.Write(context.Background(), ws, WSMessage{Action: "new_response", UserId: &r.IdUser, QuestionId: &q.Id, Response: r.Answer})
								}
							}
						}
					}
				} else {
					log.Println("Unknown admin action:", v.Action)
				}
			}
		}(c, sid)
	}
}

func WSAdminWriteAll(message WSMessage) {
	WSAdminMutex.RLock()
	defer WSAdminMutex.RUnlock()

	for _, ws := range WSAdmin {
		ws.c <- message
	}
}

func (s *Survey) WSAdminWriteAll(message WSMessage) {
	WSAdminMutex.RLock()
	defer WSAdminMutex.RUnlock()

	for _, ws := range WSAdmin {
		log.Println("snd", message, ws.sid, s.Id)
		if ws.sid == s.Id {
			ws.c <- message
		}
	}
}