// TopicCreateP2P given two users creates a p2p topic
func (a *RethinkDbAdapter) TopicCreateP2P(initiator, invited *t.Subscription) error {
	initiator.Id = initiator.Topic + ":" + initiator.User
	// Don't care if the initiator changes own subscription
	_, err := rdb.DB(a.dbName).Table("subscriptions").Insert(initiator, rdb.InsertOpts{Conflict: "replace"}).
		RunWrite(a.conn)
	if err != nil {
		return err
	}

	// Ensure this is a new subscription. If one already exist, don't overwrite it
	invited.Id = invited.Topic + ":" + invited.User
	_, err = rdb.DB(a.dbName).Table("subscriptions").Insert(invited, rdb.InsertOpts{Conflict: "error"}).
		RunWrite(a.conn)
	if err != nil {
		// Is this a duplicate subscription? If so, ifnore it. Otherwise it's a genuine DB error
		if !rdb.IsConflictErr(err) {
			return err
		}
	}

	topic := &t.Topic{
		ObjHeader: t.ObjHeader{Id: initiator.Topic},
		Access:    t.DefaultAccess{Auth: t.ModeP2P, Anon: t.ModeBanned}}
	topic.ObjHeader.MergeTimes(&initiator.ObjHeader)
	return a.TopicCreate(topic)
}

// UsersForTopic loads users subscribed to the given topic
func (a *RethinkDbAdapter) UsersForTopic(topic string) ([]t.Subscription, error) {
	// Fetch topic subscribers
	// Fetch all subscribed users. The number of users is not large
	q := rdb.DB(a.dbName).Table("subscriptions").GetAllByIndex("Topic", topic).Limit(MAX_RESULTS)
	//log.Printf("RethinkDbAdapter.UsersForTopic q: %+v", q)
	rows, err := q.Run(a.conn)
	if err != nil {
		return nil, err
	}

	// Fetch subscriptions
	var sub t.Subscription
	var subs []t.Subscription
	join := make(map[string]t.Subscription)
	usrq := make([]interface{}, 0, 16)
	for rows.Next(&sub) {
		join[sub.User] = sub
		usrq = append(usrq, sub.User)
	}

	//log.Printf("RethinkDbAdapter.UsersForTopic usrq: %+v, usrq)
	if len(usrq) > 0 {
		subs = make([]t.Subscription, 0, len(usrq))

		// Fetch users by a list of subscriptions
		rows, err = rdb.DB(a.dbName).Table("users").GetAll(usrq...).Run(a.conn)
		if err != nil {
			return nil, err
		}

		var usr t.User
		for rows.Next(&usr) {
			if sub, ok := join[usr.Id]; ok {
				sub.ObjHeader.MergeTimes(&usr.ObjHeader)
				sub.SetPublic(usr.Public)
				subs = append(subs, sub)
			}
		}

		//log.Printf("RethinkDbAdapter.UsersForTopic users: %+v", subs)
	}

	return subs, nil
}

// SubsForTopic fetches all subsciptions for a topic.
func (a *RethinkDbAdapter) SubsForTopic(topic string) ([]t.Subscription, error) {
	//log.Println("Loading subscriptions for topic ", topic)

	// must load User.Public for p2p topics
	var p2p []t.User
	var err error
	if t.GetTopicCat(topic) == t.TopicCat_P2P {
		uid1, uid2, _ := t.ParseP2P(topic)
		if p2p, err = a.UserGetAll(uid1, uid2); err != nil {
			return nil, err
		} else if len(p2p) != 2 {
			return nil, errors.New("failed to load two p2p users")
		}
	}

	q := rdb.DB(a.dbName).Table("subscriptions").GetAllByIndex("Topic", topic).Limit(MAX_RESULTS)
	//log.Println("Loading subscription q=", q)

	rows, err := q.Run(a.conn)
	if err != nil {
		return nil, err
	}

	var subs []t.Subscription
	var ss t.Subscription
	for rows.Next(&ss) {
		if p2p != nil {
			if p2p[0].Id == ss.User {
				ss.SetPublic(p2p[1].Public)
				ss.SetWith(p2p[1].Id)
			} else {
				ss.SetPublic(p2p[0].Public)
				ss.SetWith(p2p[0].Id)
			}
		}
		subs = append(subs, ss)
		//log.Printf("SubsForTopic: loaded sub %#+v", ss)
	}
	return subs, rows.Err()
}

// FindSubs returns a list of users who match given tags, such as "email:[email protected]" or "tel:18003287448".
// Just search the 'users.Tags' for the given tags using respective index.
func (a *RethinkDbAdapter) FindSubs(user t.Uid, query []interface{}) ([]t.Subscription, error) {
	// Query may contain redundant records, i.e. the same email twice.
	// User could be matched on multiple tags, i.e on email and phone#. Thus the query may
	// return duplicate users. Thus the need for distinct.
	if rows, err := rdb.DB(a.dbName).Table("users").GetAllByIndex("Tags", query...).Limit(MAX_RESULTS).
		Pluck("Id", "Access", "CreatedAt", "UpdatedAt", "Public", "Tags").Distinct().Run(a.conn); err != nil {
		return nil, err
	} else {
		index := make(map[string]struct{})
		for _, q := range query {
			if tag, ok := q.(string); ok {
				index[tag] = struct{}{}
			}
		}
		var user t.User
		var sub t.Subscription
		var subs []t.Subscription
		for rows.Next(&user) {
			sub.CreatedAt = user.CreatedAt
			sub.UpdatedAt = user.UpdatedAt
			sub.User = user.Id
			sub.ModeWant, sub.ModeGiven = user.Access.Auth, user.Access.Auth
			sub.SetPublic(user.Public)
			tags := make([]string, 0, 1)
			for _, tag := range user.Tags {
				if _, ok := index[tag]; ok {
					tags = append(tags, tag)
				}
			}
			sub.Private = tags
			subs = append(subs, sub)
		}
		if err = rows.Err(); err != nil {
			return nil, err
		}
		return subs, nil
	}
}

func (SubsObjMapper) Create(sub *types.Subscription) error {
	sub.InitTimes()

	_, err := adaptr.TopicShare([]types.Subscription{*sub})
	return err
}

// CreateP2P creates a P2P topic by generating two user's subsciptions to each other.
func (TopicsObjMapper) CreateP2P(initiator, invited *types.Subscription) error {
	initiator.InitTimes()
	invited.InitTimes()

	return adaptr.TopicCreateP2P(initiator, invited)
}

//.........这里部分代码省略.........
		// t.accessAnon = types.ModeBanned

		// Subscriptions are ephemeral, no need to load subscribers.

		// TODO(gene): handle public more intelligently
		// t.public = nil

		// Publishing to Fh is not supported, history is not supported.
		// t.lastId = 0

		// Request to load an existing or create a new p2p topic, then attach to it.
	} else if strings.HasPrefix(t.original, "usr") || strings.HasPrefix(t.original, "p2p") {
		log.Println("hub: loading or creating p2p topic")

		// Handle the following cases:
		// 1. Neither topic nor subscriptions exist: create a new p2p topic & subscriptions.
		// 2. Topic exists, one of the subscriptions is missing:
		// 2.1 Requester's subscription is missing, recreate it.
		// 2.2 Other user's subscription is missing, treat like a new request for user 2.
		// 3. Topic exists, both subscriptions are missing: should not happen, fail.
		// 4. Topic and both subscriptions exist: attach to topic

		t.cat = types.TopicCat_P2P

		// Check if the topic already exists
		stopic, err := store.Topics.Get(t.name)
		if err != nil {
			log.Println("hub: error while loading topic '" + t.name + "' (" + err.Error() + ")")
			sreg.sess.queueOut(ErrUnknown(sreg.pkt.Id, t.name, timestamp))
			return
		}

		// If topic exists, load subscriptions
		var subs []types.Subscription
		if stopic != nil {
			// Subs already have Public swapped
			if subs, err = store.Topics.GetSubs(t.name); err != nil {
				log.Println("hub: cannot load subscritions for '" + t.name + "' (" + err.Error() + ")")
				sreg.sess.queueOut(ErrUnknown(sreg.pkt.Id, t.name, timestamp))
				return
			}

			// Case 3, fail
			if len(subs) == 0 {
				log.Println("hub: missing both subscriptions for '" + t.name + "' (SHOULD NEVER HAPPEN!)")
				sreg.sess.queueOut(ErrUnknown(sreg.pkt.Id, t.name, timestamp))
				return
			}

			t.created = stopic.CreatedAt
			t.updated = stopic.UpdatedAt

			t.lastId = stopic.SeqId
		}

		// t.owner is blank for p2p topics

		// Ensure that other users are automatically rejected
		t.accessAuth = types.ModeP2P
		t.accessAnon = types.ModeBanned

		// t.public is not used for p2p topics since each user get a different public

		// Custom default access levels set in sreg.pkt.Init.DefaultAcs are ignored

		if stopic != nil && len(subs) == 2 {

// TopicsForUser loads user's contact list: p2p and grp topics, except for 'me' subscription.
func (a *RethinkDbAdapter) TopicsForUser(uid t.Uid) ([]t.Subscription, error) {
	// Fetch user's subscriptions
	// Subscription have Topic.UpdatedAt denormalized into Subscription.UpdatedAt
	q := rdb.DB(a.dbName).Table("subscriptions").GetAllByIndex("User", uid.String()).Limit(MAX_RESULTS)
	//log.Printf("RethinkDbAdapter.TopicsForUser q: %+v", q)
	rows, err := q.Run(a.conn)
	if err != nil {
		return nil, err
	}

	// Fetch subscriptions. Two queries are needed: users table (me & p2p) and topics table (p2p and grp).
	// Prepare a list of Separate subscriptions to users vs topics
	var sub t.Subscription
	join := make(map[string]t.Subscription) // Keeping these to make a join with table for .private and .access
	topq := make([]interface{}, 0, 16)
	usrq := make([]interface{}, 0, 16)
	for rows.Next(&sub) {
		tcat := t.GetTopicCat(sub.Topic)

		// 'me' subscription, skip
		if tcat == t.TopicCat_Me || tcat == t.TopicCat_Fnd {
			continue

			// p2p subscription, find the other user to get user.Public
		} else if tcat == t.TopicCat_P2P {
			uid1, uid2, _ := t.ParseP2P(sub.Topic)
			if uid1 == uid {
				usrq = append(usrq, uid2.String())
			} else {
				usrq = append(usrq, uid1.String())
			}
			topq = append(topq, sub.Topic)

			// grp subscription
		} else {
			topq = append(topq, sub.Topic)
		}
		join[sub.Topic] = sub
	}

	//log.Printf("RethinkDbAdapter.TopicsForUser topq, usrq: %+v, %+v", topq, usrq)
	var subs []t.Subscription
	if len(topq) > 0 || len(usrq) > 0 {
		subs = make([]t.Subscription, 0, len(join))
	}

	if len(topq) > 0 {
		// Fetch grp & p2p topics
		rows, err = rdb.DB(a.dbName).Table("topics").GetAll(topq...).Run(a.conn)
		if err != nil {
			return nil, err
		}

		var top t.Topic
		for rows.Next(&top) {
			sub = join[top.Id]
			sub.ObjHeader.MergeTimes(&top.ObjHeader)
			sub.SetSeqId(top.SeqId)
			sub.SetHardClearId(top.ClearId)
			if t.GetTopicCat(sub.Topic) == t.TopicCat_Grp {
				// all done with a grp topic
				sub.SetPublic(top.Public)
				subs = append(subs, sub)
			} else {
				// put back the updated value of a p2p subsription, will process further below
				join[top.Id] = sub
			}
		}

		//log.Printf("RethinkDbAdapter.TopicsForUser 1: %#+v", subs)
	}

	// Fetch p2p users and join to p2p tables
	if len(usrq) > 0 {
		rows, err = rdb.DB(a.dbName).Table("users").GetAll(usrq...).Run(a.conn)
		if err != nil {
			return nil, err
		}

		var usr t.User
		for rows.Next(&usr) {
			uid2 := t.ParseUid(usr.Id)
			topic := uid.P2PName(uid2)
			if sub, ok := join[topic]; ok {
				sub.ObjHeader.MergeTimes(&usr.ObjHeader)
				sub.SetWith(uid2.UserId())
				sub.SetPublic(usr.Public)
				sub.SetLastSeenAndUA(usr.LastSeen, usr.UserAgent)
				subs = append(subs, sub)
			}
		}

		//log.Printf("RethinkDbAdapter.TopicsForUser 2: %#+v", subs)
	}

	return subs, nil
}