package core

import (
	"context"
	"errors"
	"io"
	"net"
	"net/http"
	"reflect"
	"strings"
	"sync"

	"repositories.action2quare.com/ayo/gocommon"
	"repositories.action2quare.com/ayo/gocommon/logger"
	"repositories.action2quare.com/ayo/gocommon/wshandler"

	"github.com/go-redis/redis/v8"
	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/bsonrw"
	"go.mongodb.org/mongo-driver/bson/primitive"
)

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

func writeBsonArr(w io.Writer, src []bson.M) error {
	return writeBsonDoc(w, bson.M{
		"r": src,
	})
}

func onlineGroupQueryKey(prefix string) string {
	return prefix + "_olg"
}

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.RegionStorageConfig `json:",inline"`

	GroupTypes       map[string]*groupConfig `json:"tavern_group_types"`
	MaingateApiToken string                  `json:"maingate_api_token"`
	RedisURL         string                  `json:"tavern_redis_url"`
	macAddr          string
}

var config TavernConfig

type connectionMap struct {
	sync.Mutex
	conns map[primitive.ObjectID]*connection
}

func (cm *connectionMap) add(accid accountID, alias string) {
	cm.Lock()
	defer cm.Unlock()

	old := cm.conns[accid]
	if old != nil {
		old.cleanup()
	}
	cm.conns[accid] = &connection{
		alias:   alias,
		onClose: make(map[string]func()),
	}
}

func (cm *connectionMap) remove(accid accountID) {
	cm.Lock()
	defer cm.Unlock()

	old := cm.conns[accid]
	if old != nil {
		delete(cm.conns, accid)
		old.cleanup()
	}
}

func (cm *connectionMap) get(accid accountID) *connection {
	cm.Lock()
	defer cm.Unlock()

	return cm.conns[accid]
}

type Tavern struct {
	subTaverns []*subTavern
	wsh        *wshandler.WebsocketHandler
}

type subTavern struct {
	mongoClient gocommon.MongoClient
	wsh         *wshandler.WebsocketHandler
	region      string
	groups      map[string]group
	methods     map[string]reflect.Method
	cm          connectionMap

	redisClient *redis.Client
}

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,
	}

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

	return tv, nil
}

func (tv *Tavern) Cleanup() {
	for _, st := range tv.subTaverns {
		st.mongoClient.Close()
	}
}

// func (tv *Tavern) SocketMessageReceived(accid primitive.ObjectID, alias string, messageType wshandler.WebSocketMessageType, body io.Reader) {
// 	switch messageType {
// 	case wshandler.Connected:

// 	case wshandler.Disconnected:
// 	}
// 	// 				gidtype := msg.Conn.GetTag("gid")
// 	// 				if len(gidtype) > 0 {
// 	// 					tokens := strings.SplitN(gidtype, "@", 2)
// 	// 					gidobj, _ := primitive.ObjectIDFromHex(tokens[0])
// 	// 					gtype := tokens[1]
// 	// 					group := sub.groups[gtype]
// 	// 					if group != nil {
// 	// 						group.PauseMember(gidobj, msg.Alias, msg.Conn)
// 	// 					}
// }

func (tv *Tavern) prepare(ctx context.Context) error {
	redisClient, err := gocommon.NewRedisClient(config.RedisURL, 0)
	if err != nil {
		logger.Error("config tavern_redis_url is not valid or missing")
		return err
	}

	for region := range config.RegionStorage {
		var dbconn gocommon.MongoClient
		var err error
		var groupinstance group

		var tmp *subTavern
		methods := make(map[string]reflect.Method)
		tp := reflect.TypeOf(tmp)
		for i := 0; i < tp.NumMethod(); i++ {
			method := tp.Method(i)
			methods[method.Name] = method
		}

		sub := &subTavern{
			wsh:         tv.wsh,
			mongoClient: dbconn,
			region:      region,
			methods:     methods,
			redisClient: redisClient,
			cm: connectionMap{
				conns: make(map[primitive.ObjectID]*connection),
			},
		}

		groups := make(map[string]group)
		for typename, cfg := range config.GroupTypes {
			cfg.Name = typename
			if cfg.Transient {
				groupinstance, err = cfg.prepareInMemory(ctx, typename, sub)
				//} else {
				// TODO : db
				// if !dbconn.Connected() {
				// 	dbconn, err = gocommon.NewMongoClient(ctx, url.Mongo, region)
				// 	if err != nil {
				// 		return err
				// 	}
				// }
				// groupinstance, err = cfg.preparePersistent(ctx, region, dbconn, tv.wsh)
			}
			if err != nil {
				return err
			}
			groups[typename] = groupinstance
		}
		sub.groups = groups

		tv.subTaverns = append(tv.subTaverns, sub)
	}

	return nil
}

func (tv *Tavern) RegisterHandlers(ctx context.Context, serveMux *http.ServeMux, prefix string) error {
	for _, sub := range tv.subTaverns {
		tv.wsh.RegisterReceiver(sub.region, sub.clientMessageReceived)
		var pattern string
		if sub.region == "default" {
			pattern = gocommon.MakeHttpHandlerPattern(prefix, "api")
		} else {
			pattern = gocommon.MakeHttpHandlerPattern(prefix, sub.region, "api")
		}
		serveMux.HandleFunc(pattern, sub.api)
	}

	return nil
}

func (sub *subTavern) clientMessageReceived(sender *wshandler.Sender, messageType wshandler.WebSocketMessageType, body io.Reader) {
	if messageType == wshandler.Connected {
		sub.cm.add(sender.Accid, sender.Alias)
	} else if messageType == wshandler.Disconnected {
		sub.cm.remove(sender.Accid)
	}
}

func (sub *subTavern) 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
	}

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

	method, ok := sub.methods[operation]
	if !ok {
		// 없는 operation
		logger.Println("fail to call api. operation is not valid :", operation)
		w.WriteHeader(http.StatusBadRequest)
		return
	}

	if r.PostForm == nil {
		r.ParseMultipartForm(defaultMaxMemory)
	}

	args := []reflect.Value{
		reflect.ValueOf(sub),
		reflect.ValueOf(w),
		reflect.ValueOf(r),
	}

	method.Func.Call(args)
}