package core

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net"
	"net/http"
	"reflect"
	"strings"
	"time"

	"github.com/go-redis/redis/v8"
	"repositories.action2quare.com/ayo/gocommon"
	"repositories.action2quare.com/ayo/gocommon/flagx"
	"repositories.action2quare.com/ayo/gocommon/logger"
	"repositories.action2quare.com/ayo/gocommon/wshandler"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/bsonrw"
)

var devflag = flagx.Bool("dev", false, "")

const (
	defaultMaxMemory = 32 << 10 // 32 KB
)

func writeBsonDoc[T any](w io.Writer, src T) error {
	rw, err := bsonrw.NewBSONValueWriter(w)
	if err != nil {
		return err
	}

	enc, err := bson.NewEncoder(rw)
	if err != nil {
		return err
	}

	return enc.Encode(src)
}

func readBsonDoc(r io.Reader, src any) error {
	body, err := io.ReadAll(r)
	if err != nil {
		return err
	}

	if len(body) == 0 {
		return nil
	}

	decoder, err := bson.NewDecoder(bsonrw.NewBSONDocumentReader(body))
	if err != nil {
		return err
	}

	err = decoder.Decode(src)
	if err != nil {
		return err
	}

	return nil
}

type TavernConfig struct {
	gocommon.StorageAddr `json:"storage"`

	SessionTTL     int64  `json:"maingate_session_ttl"`
	SessionStorage string `json:"maingate_session_storage"`

	Group            map[string]configDocument `json:"tavern_group_types"`
	MaingateApiToken string                    `json:"maingate_api_token"`
	RedisURL         string                    `json:"tavern_redis_url"`
	macAddr          string
}

var config TavernConfig

type Tavern struct {
	wsh         *wshandler.WebsocketHandler
	mongoClient gocommon.MongoClient
	redison     *gocommon.RedisonHandler
	groups      map[string]group
	apiFuncs    *apiFuncsContainer
}

func getMacAddr() (string, error) {
	ifas, err := net.Interfaces()
	if err != nil {
		return "", err
	}

	for _, ifa := range ifas {
		a := ifa.HardwareAddr.String()
		if a != "" {
			a = strings.ReplaceAll(a, ":", "")
			return a, nil
		}
	}
	return "", errors.New("no net interface")
}

// New :
func New(context context.Context, wsh *wshandler.WebsocketHandler, inconfig *TavernConfig) (*Tavern, error) {
	if inconfig == nil {
		var loaded TavernConfig
		if err := gocommon.LoadConfig(&loaded); err != nil {
			return nil, err
		}
		inconfig = &loaded
	}

	config = *inconfig
	macaddr, err := getMacAddr()
	if err != nil {
		return nil, err
	}
	config.macAddr = macaddr
	tv := &Tavern{
		wsh: wsh,
		apiFuncs: &apiFuncsContainer{
			normfuncs: make(map[string]apiFuncType),
			funcs:     make(map[string][]apiFuncType),
		},
	}

	if err = tv.prepare(context); err != nil {
		logger.Println("tavern prepare() failed :", err)
		return nil, err
	}

	return tv, nil
}

func (tv *Tavern) Cleanup() {
	tv.mongoClient.Close()
}

func (tv *Tavern) prepare(ctx context.Context) error {
	redisClient, err := gocommon.NewRedisClient(config.StorageAddr.Redis["tavern"])
	if err != nil {
		return err
	}

	tv.redison = gocommon.NewRedisonHandler(redisClient.Context(), redisClient)

	groups := make(map[string]group)
	for typename, cfg := range config.Group {
		gtype, ok := groupTypeContainer()[typename]
		if !ok {
			return fmt.Errorf("%s group type is not valid", typename)
		}

		if !gtype.Implements(reflect.TypeOf((*group)(nil)).Elem()) {
			return fmt.Errorf("%s is not implement proper interface", typename)
		}
		ptrvalue := reflect.New(gtype.Elem())
		instance := ptrvalue.Interface().(group)
		if err := instance.Initialize(tv, cfg); err != nil {
			return err
		}
		groups[typename] = instance
	}

	tv.groups = groups
	tv.apiFuncs.normalize()

	return nil
}

func (tv *Tavern) RegisterHandlers(ctx context.Context, serveMux *http.ServeMux, prefix string) error {
	tv.wsh.RegisterReceiver(tv)
	pattern := gocommon.MakeHttpHandlerPattern(prefix, "api")
	serveMux.HandleFunc(pattern, tv.api)

	return nil
}

func (tv *Tavern) OnClientMessageReceived(sender *wshandler.Sender, messageType wshandler.WebSocketMessageType, body io.Reader) {
	if messageType == wshandler.Connected {
		logger.Println("OnClientMessageReceived : connected ", sender.Accid.Hex())
		tv.redison.HSet(tv.redison.Context(), sender.Accid.Hex(), "_ts", time.Now().UTC().Unix()).Result()
		for _, gt := range tv.groups {
			gt.ClientMessageReceived(sender, messageType, nil)
		}
	} else if messageType == wshandler.Disconnected {
		var rooms []string
		dec := json.NewDecoder(body)
		if err := dec.Decode(&rooms); err == nil {
			for _, gt := range tv.groups {
				gt.ClientMessageReceived(sender, messageType, rooms)
			}
		}
		tv.redison.Del(tv.redison.Context(), sender.Accid.Hex()).Result()
		logger.Println("OnClientMessageReceived : disconnected ", sender.Accid.Hex())
	} else if messageType == wshandler.BinaryMessage {
		var commandline []any
		dec := json.NewDecoder(body)
		if err := dec.Decode(&commandline); err == nil {
			cmd := commandline[0].(string)
			args := commandline[1:]
			switch cmd {
			case "EnterChannel":
				tv.wsh.EnterRoom(args[0].(string), sender.Accid)

			case "LeaveChannel":
				tv.wsh.LeaveRoom(args[0].(string), sender.Accid)

			default:
				for _, gt := range tv.groups {
					gt.ClientMessageReceived(sender, messageType, commandline)
				}
			}
		}
	}
}

func (tv *Tavern) OnRoomCreated(name string) {
	cnt, err := tv.redison.IncrBy(tv.redison.Context(), "_ref_"+name, 1).Result()
	if err != nil && !errors.Is(err, redis.Nil) {
		logger.Println("OnRoomCreated JSONSet failed :", err)
		return
	}

	if cnt == 1 {
		tv.redison.JSONSet(name, "$", map[string]any{}, gocommon.RedisonSetOptionNX)
	}
}

func (tv *Tavern) OnRoomDestroyed(name string) {
	cnt, err := tv.redison.IncrBy(tv.redison.Context(), "_ref_"+name, -1).Result()
	if err != nil {
		logger.Println("OnRoomDestroyed JSONNumIncrBy failed :", err)
	} else if cnt == 0 {
		tv.redison.Del(tv.redison.Context(), "_ref_"+name)
		tv.redison.JSONDel(name, "$")
	}
}

func (tv *Tavern) api(w http.ResponseWriter, r *http.Request) {
	defer func() {
		s := recover()
		if s != nil {
			logger.Error(s)
		}
		io.Copy(io.Discard, r.Body)
		r.Body.Close()
	}()

	// 서버에서 오는 요청만 처리
	apitoken := r.Header.Get("MG-X-API-TOKEN")
	if apitoken != config.MaingateApiToken {
		// 서버가 보내는 쿼리만 허용
		logger.Println("MG-X-API-TOKEN is missing")
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	if r.PostForm == nil {
		r.ParseMultipartForm(defaultMaxMemory)
	}

	operation := r.URL.Query().Get("operation")
	if len(operation) == 0 {
		w.WriteHeader(http.StatusBadRequest)
		return
	}

	tv.apiFuncs.call(operation, w, r)
}