package xstream

import (
	"context"
	"errors"
	"fmt"
	"net"
	"time"

	"github.com/gomodule/redigo/redis"
	"qoobing.com/gomod/log"
	"qoobing.com/gomod/redis/sentinel"
	"qoobing.com/gomod/str"
)

//////////////////////////////////////////////////////////////////////////////////
/////////////////////////  example  //////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////////
//////  const (
//////  	CORESERVER_NEWACCOUNT_GROUP = "groupid-coreserver-newaccount"
//////  	CORESERVER_NEWACCOUNT_QUEUE = "coreserver.newaccount"
//////  )
//////
//////  type NewAccountMessage struct {
//////  	Sign       string    `json:"sign"`
//////  	Appid      string    `json:"appid"`
//////  	Userid     int64     `json:"userid"`
//////  	Account    string    `json:"account"`
//////  	CreateTime time.Time `json:"createtime"`
//////  }
//////
//////  func Run(ctx context.Context) {
//////  	var SLEEP_TIME = 10 * time.Second
//////  	go func() {
//////  		for {
//////  			log.Infof("start run newaccount marketing engine ...")
//////  			runNewAccountMarketingEngine(ctx)
//////  			log.Infof("newaccount marketing engine exit unexpected, retry %s later again", SLEEP_TIME.String())
//////  			time.Sleep(SLEEP_TIME)
//////  		}
//////  	}()
//////  }
//////
//////  func runNewAccountMarketingEngine(ctx context.Context) {
//////  	// r read message from redis
//////  	cfg := config.Instance()
//////  	r := xstream.NewReader(xstream.Config{
//////  		Group:    CORESERVER_NEWACCOUNT_GROUP,
//////  		Stream:   CORESERVER_NEWACCOUNT_QUEUE,
//////  		Sentinel: cfg.CoreserverRedis,
//////  	})
//////  	defer r.Close()
//////
//////  	// w write message to kafka
//////  	w := &kafka.Writer{
//////  		Addr:     kafka.TCP(cfg.MarketingKafka.Addresses...),
//////  		Balancer: &kafka.LeastBytes{},
//////  	}
//////  	defer w.Close()
//////
//////  	var error_wait_time = 0 * time.Millisecond
//////  	for {
//////  		// Step 0. wait a moment if need
//////  		if error_wait_time > 0 {
//////  			time.Sleep(error_wait_time)
//////  		}
//////
//////  		// Step 1. fetch message
//////  		var err error = nil
//////  		var msg xstream.Message
//////  		var newacctMsg NewAccountMessage
//////  		log.Infof("waiting fetch newaccount message from redis queue...")
//////  		if msg, err = r.FetchMessage(ctx); err != nil {
//////  			log.Errorf("failed fetch message from redis queue, err:%s", err)
//////  			//error_wait_time = 1000 * time.Millisecond
//////  			break
//////  		}
//////
//////          // Step 2. decode message
//////          if err := json.Unmarshal(msg.Value, &newacctMsg); err != nil {
//////          	log.Errorf("failed json.unmarshal message[%s], err:%s", string(msg.Value), err)
//////          	continue
//////          } else if newacctMsg.Userid == 0 || newacctMsg.Account == "" {
//////          	log.Errorf("invalid newaccount message, userid=[%d]", newacctMsg.Userid)
//////          	continue
//////          }
//////          log.Infof("fetch newaccount message success, account=[%s]", newacctMsg.Account)
//////
//////          // Step 3. handle message
//////          // xxxxxxx handle message xxxxxxxxxxxxxxxxxxxxxxxx
//////          // xxxxxxx handle message xxxxxxxxxxxxxxxxxxxxxxxx
//////          // xxxxxxx handle message xxxxxxxxxxxxxxxxxxxxxxxx
//////          // xxxxxxx handle message xxxxxxxxxxxxxxxxxxxxxxxx
//////          // xxxxxxx handle message xxxxxxxxxxxxxxxxxxxxxxxx
//////  		// Step 4. send ack to coreserver redis
//////  		if err := r.CommitMessages(ctx, msg); err != nil {
//////  			log.Errorf("failed commit message to redis, err:%s", err)
//////  			error_wait_time = 1000 * time.Millisecond
//////  			continue
//////  		}
//////  	}
//////  }
///////////////////////////// end example ////////////////////////////////////////////

var (
	redisPools = map[string]*redis.Pool{}
)

type Config struct {
	Group    string          `toml:"group"`
	Stream   string          `toml:"stream"`
	Sentinel sentinel.Config `toml:"sentinel"`
}

type Message struct {
	Id    string
	Value []byte
}

type xstreamReader struct {
	cfg      Config
	id       string
	name     string
	conn     redis.Conn
	connPool *redis.Pool
	closed   bool
	restart  bool
}

func NewReader(cfg Config) (r *xstreamReader) {
	// redis pool
	poolId := cfg.Sentinel.Sentinels
	if _, ok := redisPools[poolId]; !ok {
		redisPools[poolId] = sentinel.NewPool(cfg.Sentinel)
	}

	// initialize
	connPool := redisPools[poolId]
	r = &xstreamReader{
		cfg:      cfg,
		conn:     connPool.Get(),
		connPool: connPool,
		closed:   false,
		restart:  true,
	}
	r.id = str.GetRandomNumString(12)
	r.name = newName(r.conn, r.id, cfg.Group, cfg.Stream)
	if err := r.initGroup(); err != nil {
		panic(fmt.Sprintf("initGroup failed: error:%s", err))
	}

	// heart beat
	go func() {
		beatconn := redisPools[poolId].Get()
		defer beatconn.Close()
		for !r.closed {
			id, err := redis.String(beatconn.Do("GETEX", r.name, "EX", 120))
			if err != nil {
				log.Warningf("redis GETEX failed, err:%s", err)
				r.Close()
			} else if id != r.id {
				log.Warningf("name id in redis (%s) not equal to local name id(%s)", id, r.id)
				r.Close()
			}
			time.Sleep(15 * time.Second)
		}
	}()

	return r
}

func newName(conn redis.Conn, id, group, xstream string) string {
	var (
		mkeys            = []any{}
		prefix           = fmt.Sprintf("xstream[%s]-group[%s]-", xstream, group)
		consumer         = func(i int) string { return fmt.Sprintf("%s%03d", prefix, i) }
		consumers        = map[string]string{}
		MAX_CONSUMER_NUM = 30
	)

	// get all name
	for i := 0; i < MAX_CONSUMER_NUM; i++ {
		mkeys = append(mkeys, consumer(i))
	}
	ret, err := redis.Strings(conn.Do("MGET", mkeys...))
	if err != nil {
		log.Warningf("redis MGET error: %s", err)
		panic("redis MGET error")
	}
	for i, s := range ret {
		if s != "" {
			name := consumer(i)
			consumers[name] = s
		}
	}

	var (
		i          = 0
		retry      = 0
		consumer_i = ""
	)
LOOP:
	// get unused name
	for ; i < MAX_CONSUMER_NUM; i++ {
		if _, ok := consumers[consumer(i)]; !ok {
			consumer_i = consumer(i)
			break
		}
	}
	if i == MAX_CONSUMER_NUM {
		panic(fmt.Sprintf("too many consumer(more than %d)???", MAX_CONSUMER_NUM))
	}

	// set to redis (try lock)
	success, err := redis.Int(conn.Do("SETNX", consumer_i, id))
	conn.Do("GETEX", consumer_i, "EX", 120) /* for SETNX failed forever */
	if err != nil && retry >= 2 {
		log.Warningf("redis SETNX(%s,%s) error: %s", consumer_i, id, err)
		panic(fmt.Sprintf("redis SETNX error after try [%d] times", retry))
	}

	// return or retry if something error
	if err != nil /*&& retry < 2*/ {
		retry++
		log.Warningf("redis SETNX(%s,%s) error: %s, retry(%d)", consumer_i, id, err, retry)
		goto LOOP
	}
	if success == 0 {
		i++
		retry++
		log.Warningf("consumer name(%s) used by others, retry(%d)", consumer_i, retry)
		goto LOOP
	}
	log.Infof("success to get new consumer-name:[%s]", consumer_i)
	return consumer_i
}

func (r *xstreamReader) Close() {
	// delete client consumer name
	id, err := redis.String(r.redisDo("GETEX", r.name, "EX", 120))
	if err == nil && id == r.id {
		r.redisDo("DEL", r.name)
	}

	// clonse redis connection(put to pool)
	r.closed = true
	r.conn.Close()
}

func (r *xstreamReader) fetchMessage() (ret []any, err error) {
	// func (r *xstreamReader) fetchMessage(ctx context.Context) (ret []any, err error) {
	args := []interface{}{
		"GROUP", r.cfg.Group, r.name,
		"COUNT", 1,
		"BLOCK", 864000000,
		"STREAMS", r.cfg.Stream,
	}
	if r.restart {
		args = append(args, "0-0")
	} else {
		args = append(args, ">")
	}

	ret, err = redis.Values(r.redisDo("XREADGROUP", args...))

	if err != nil {
		return ret, err
	} else if ret == nil {
		return ret, nil
	}
	if len(ret) != 1 {
		panic("len(ret) is not 1")
	}
	return ret, nil
}

func (r *xstreamReader) FetchMessage(ctx context.Context) (msg Message, err error) {
	// func (r *xstreamReader) FetchMessage(ctx context.Context) (msg xstreamMessage, err error) {
	// Step 1. get result from redis xstream
	var ret, qmsg, msgs []any = nil, nil, nil
	for {
		ret, err = r.fetchMessage()
		//////////////////////////////////////////////////////////////////////
		////ret format example:
		////  [["coreserver.txneedrepair", [["1675180029481-0", ["a", "b"]]]]]
		//////////////////////////////////////////////////////////////////////
		if err != nil {
			log.Warningf("fetchMessage meassage err:%s", err)
			return msg, errors.New("fetchMessage meassage err")
		}
		if len(ret) == 0 {
			log.Warningf("redis stream result length is 0, which shoud bigger than 0")
			return msg, errors.New("redis fetchMessage ret length is 0")
		}

		qmsg, _ = redis.Values(ret[0], nil)  // ["coreserver.txneedrepair", [["1675180029481-0", ["a", "b"]]]]
		msgs, _ = redis.Values(qmsg[1], nil) // [["1675180029481-0", ["a", "b"]]]

		if len(msgs) == 0 && r.restart {
			r.restart = false
			continue
		}
		if len(msgs) != 1 {
			log.Warningf("meassage length from xstream is not 1(but %d)", len(msgs))
			return msg, errors.New("no new msg")
		}
		break
	}

	// Step 2. parse xstream item result
	var (
		amsg, _   = redis.Values(msgs[0], nil) // ["1675180029481-0", ["a", "b"]]
		rmsg, _   = redis.Values(amsg[1], nil) // ["a", "b"]
		msgid, _  = redis.String(amsg[0], nil) // "1675180029481-0"
		msgval, _ = redis.String(rmsg[1], nil) // "b"
	)
	msg.Id = msgid
	msg.Value = []byte(msgval)
	log.Infof("success fetched meassage '%s': %s", msg.Id, msgval)
	return msg, nil
}

func (r *xstreamReader) CommitMessages(ctx context.Context, msg Message) (err error) {
	args := []interface{}{
		r.cfg.Stream, // key
		r.cfg.Group,  // group
		msg.Id,       // id
	}

	if cnt, err := redis.Int(r.redisDo("XACK", args...)); err != nil {
		return err
	} else if cnt != 1 {
		log.Warningf("attention: 'XACK' return %d (not 1), but we trade as success", cnt)
	}
	return nil
}

func (r *xstreamReader) redisDo(cmd string, args ...any) (reply any, err error) {
	if r.closed {
		return nil, net.ErrClosed
	} else if r.conn.Err() != nil {
		log.Warningf("redis connection closed/unavaliable, we will get new one from pool")
		oldconn := r.conn
		newconn := r.connPool.Get()
		r.conn = newconn
		oldconn.Close()
	}

	return r.conn.Do(cmd, args...)
}

func (r *xstreamReader) initGroup() error {
	groups, err := r.redisDo("XINfO", "GROUPS", r.cfg.Stream)
	groupInfosInf, _ := groups.([]interface{})
	if err != nil || len(groupInfosInf) == 0 {
		log.Infof("create group, name: %s", r.cfg.Group)
		_, err = r.redisDo("XGROUP", "CREATE", r.cfg.Stream, r.cfg.Group, "$", "MKSTREAM")
		return err
	}

	for _, groupInfo := range groupInfosInf {
		groupInfoInf := groupInfo.([]interface{})
		groupName := string(groupInfoInf[1].([]uint8))
		log.Infof("group name: %s", groupName)
		if groupName == r.cfg.Group {
			return nil
		}
	}
	log.Infof("create group, name: %s", r.cfg.Group)
	_, err = r.redisDo("XGROUP", "CREATE", r.cfg.Stream, r.cfg.Group, "$", "MKSTREAM")
	return err
}