t5de-proxy/internal/hosted/hosted.go

// Package hosted runs T5DE-hosted rooms for the client (t5de-hub's docs/hosted-rooms.md): rooms that live on T5DE's
// hub, which the client joins and uses like IMVU's rooms. The proxy answers the client's room calls for them
// (XML-RPC), serves their IMQ queues (subscriptions answered here, messages to and from the hub), and adds them to
// the room list. IMVU never hears of them.
//
// A hosted room has a number n; its instance ID is "<owner's IMVU ID>-<2100000000+n>" and its chat ID 2100000000+n.
package hosted

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"sync"
	"time"

	"git.t5de.dev/t5de/t5de-proxy/internal/imq"
	"git.t5de.dev/t5de/t5de-proxy/internal/proxy"
	"git.t5de.dev/t5de/t5de-proxy/internal/xmlrpc"
)

// Base is the first part of hosted rooms' instance IDs, and the start of their chat IDs.
const Base = 2100000000

// Hub is what the rooms need of the hub: its realtime connection and its API.
type Hub interface {
	Send(v any) bool
	Call(ctx context.Context, method, path string, body, out any) error
}

// Room is a hosted room as the hub lists it.
type Room struct {
	N           int64  `json:"n"`
	InstanceID  string `json:"instanceId"`
	ChatID      int64  `json:"chatId"`
	Name        string `json:"name"`
	Description string `json:"description"`
	RoomPid     int64  `json:"roomPid"`
	Rating      string `json:"rating"`
	MaxUsers    int    `json:"maxUsers"`
	OwnerImvuID int64  `json:"ownerImvuId"`
	OwnerName   string `json:"ownerName"`
	Occupancy   int    `json:"occupancy"`
}

// Participant is someone in a hosted room.
type Participant struct {
	ImvuID int64 `json:"imvu_id"`
	Seat   int   `json:"seat"`
}

// Rooms serves hosted rooms to the client.
type Rooms struct {
	Hub  Hub
	Logf func(format string, args ...any)
	// User is the IMVU account the client is signed in as (0 if not yet known).
	User func() int64
	// Deliver gives the client a message from someone in a room (through the products' Incoming).
	Deliver func(c *proxy.IMQConn, m imq.Delivered)
	// OnJoin and OnLeave report being in a room's chat (the room channel, for others' community products).
	OnJoin  func(chat, room string)
	OnLeave func(chat string)
	// LocalProduct and GlobalProduct translate scenes' community products between the hub's IDs and the client's
	// local IDs (false: not a community product, or not here).
	LocalProduct  func(hubID string) (int64, bool)
	GlobalProduct func(local int64) (string, bool)

	mu      sync.Mutex
	rooms   map[int64]*room
	waiting map[int64][]chan joinAnswer
	owners  map[int64]int64 // room -> its owner's IMVU account, as last looked up
	last    int64           // the room the client joined last
}

type room struct {
	chat         int64
	instance     string
	participants []Participant
	sequence     uint64
	conns        map[*proxy.IMQConn]bool // subscribed to the room's chat queue
}

type joinAnswer struct {
	Type         string        `json:"type"`
	Room         int64         `json:"room"`
	Chat         int64         `json:"chat"`
	Participants []Participant `json:"participants"`
	Sequence     uint64        `json:"sequence"`
	Reason       string        `json:"reason"`
	Message      string        `json:"message"`
}

// A hosted room's instance ID is "<owner's IMVU ID>-<Base + n>": the client takes the owner from the first part.
var instancePattern = regexp.MustCompile(`^[1-9][0-9]{0,11}-([0-9]{10})$`)

// RoomNumber is the hosted room an instance ID names.
func RoomNumber(instance string) (int64, bool) {
	m := instancePattern.FindStringSubmatch(instance)
	if m == nil {
		return 0, false
	}
	number, err := strconv.ParseInt(m[1], 10, 64)
	if err != nil {
		return 0, false
	}
	return ChatRoom(number) // the same range as chat IDs
}

// ChatRoom is the hosted room a chat ID belongs to.
func ChatRoom(chat int64) (int64, bool) {
	if chat <= Base || chat > 2147483647 {
		return 0, false
	}
	return chat - Base, true
}

func instanceID(owner, n int64) string { return fmt.Sprintf("%d-%d", owner, Base+n) }

// instanceOf is a room's instance ID, with its owner as last looked up (under mu).
func (r *Rooms) instanceOfLocked(n int64) string { return instanceID(r.owners[n], n) }

// queueRoom is the hosted room a queue belongs to, and which of its queues it is: "chat", "node" (the room's
// inv:/room/room-<instance>) or "occupancy" (room_occupancy/<instance>).
func queueRoom(queue string) (int64, string, bool) {
	switch {
	case strings.HasPrefix(queue, "/chat/"):
		chat, err := strconv.ParseInt(strings.TrimPrefix(queue, "/chat/"), 10, 64)
		if err != nil {
			return 0, "", false
		}
		n, ok := ChatRoom(chat)
		return n, "chat", ok
	case strings.HasPrefix(queue, "inv:/room/room-"):
		n, ok := RoomNumber(strings.TrimPrefix(queue, "inv:/room/room-"))
		return n, "node", ok
	case strings.HasPrefix(queue, "room_occupancy/"):
		n, ok := RoomNumber(strings.TrimPrefix(queue, "room_occupancy/"))
		return n, "occupancy", ok
	}
	return 0, "", false
}

// IsHostedQueue reports whether a queue is a hosted room's.
func IsHostedQueue(queue string) bool {
	_, _, ok := queueRoom(queue)
	return ok
}

func (r *Rooms) logf(format string, args ...any) {
	if r.Logf != nil {
		r.Logf(format, args...)
	}
}

func (r *Rooms) user() int64 {
	if r.User == nil {
		return 0
	}
	return r.User()
}

// --- the hub's messages ---

// FromHub handles a "room.*" message from the hub.
func (r *Rooms) FromHub(data []byte) {
	var m struct {
		joinAnswer
		From    int64  `json:"from"`
		Mount   string `json:"mount"`
		Message string `json:"message"`
	}
	if json.Unmarshal(data, &m) != nil {
		return
	}
	switch m.Type {
	case "room.joined", "room.error":
		m.joinAnswer.Message = m.Message // the outer field takes "message"
		r.mu.Lock()
		if m.Type == "room.joined" {
			rm := r.roomLocked(m.Room)
			rm.chat, rm.participants, rm.sequence = m.Chat, m.Participants, m.Sequence
		}
		waiting := r.waiting[m.Room]
		delete(r.waiting, m.Room)
		r.mu.Unlock()
		for _, w := range waiting {
			w <- m.joinAnswer
		}
		if m.Type == "room.error" {
			r.logf("hosted: room %d: %s (%s)", m.Room, m.Reason, m.Message)
		}
	case "room.participants":
		r.mu.Lock()
		if rm, ok := r.rooms[m.Room]; ok {
			rm.participants = m.Participants
		}
		r.mu.Unlock()
	case "room.message":
		r.mu.Lock()
		rm, ok := r.rooms[m.Room]
		var conns []*proxy.IMQConn
		chat := Base + m.Room
		if ok {
			if m.Sequence > rm.sequence {
				rm.sequence = m.Sequence
			}
			for c := range rm.conns {
				conns = append(conns, c)
			}
		}
		r.mu.Unlock()
		for _, c := range conns {
			d := imq.Delivered{UserID: fmt.Sprintf("/user/%d", m.From), Queue: fmt.Sprintf("/chat/%d", chat),
				Mount: m.Mount, Message: []byte(m.Message), Sequence: m.Sequence}
			if r.Deliver != nil {
				r.Deliver(c, d)
			} else {
				c.Deliver(d)
			}
		}
	case "room.closed":
		r.mu.Lock()
		delete(r.rooms, m.Room)
		r.mu.Unlock()
		if r.OnLeave != nil {
			r.OnLeave(strconv.FormatInt(Base+m.Room, 10))
		}
		r.logf("hosted: room %d was closed", m.Room)
	}
}

func (r *Rooms) roomLocked(n int64) *room {
	if r.rooms == nil {
		r.rooms = map[int64]*room{}
	}
	rm, ok := r.rooms[n]
	if !ok {
		rm = &room{chat: Base + n, instance: r.instanceOfLocked(n), conns: map[*proxy.IMQConn]bool{}}
		r.rooms[n] = rm
	}
	return rm
}

// Reconnected joins the rooms the client is in again (the hub forgets them when the connection drops).
func (r *Rooms) Reconnected() {
	r.mu.Lock()
	var ns []int64
	for n := range r.rooms {
		ns = append(ns, n)
	}
	r.mu.Unlock()
	for _, n := range ns {
		r.Hub.Send(map[string]any{"type": "room.join", "room": n})
	}
}

// join asks the hub to let the client into a room, and waits for the answer.
func (r *Rooms) join(ctx context.Context, n int64) (joinAnswer, error) {
	w := make(chan joinAnswer, 1)
	r.mu.Lock()
	if r.waiting == nil {
		r.waiting = map[int64][]chan joinAnswer{}
	}
	r.waiting[n] = append(r.waiting[n], w)
	r.mu.Unlock()
	if !r.Hub.Send(map[string]any{"type": "room.join", "room": n}) {
		return joinAnswer{}, fmt.Errorf("the hub isn't connected")
	}
	select {
	case a := <-w:
		return a, nil
	case <-ctx.Done():
		return joinAnswer{}, fmt.Errorf("the hub didn't answer")
	}
}

func (r *Rooms) leave(n int64) {
	r.mu.Lock()
	_, in := r.rooms[n]
	delete(r.rooms, n)
	r.mu.Unlock()
	if in {
		r.Hub.Send(map[string]any{"type": "room.leave", "room": n})
		if r.OnLeave != nil {
			r.OnLeave(strconv.FormatInt(Base+n, 10))
		}
	}
}

// --- IMQ ---

// Route takes hosted rooms' queues out of a subscription and answers the client for them (proxy.IMQRouter).
func (r *Rooms) Route(c *proxy.IMQConn, unsubscribe bool, s imq.Subscription) imq.Subscription {
	var rest imq.Subscription
	for _, q := range s.Queues {
		if !r.routeQueue(c, unsubscribe, q, 0, false) {
			rest.Queues = append(rest.Queues, q)
		}
	}
	for _, q := range s.WithResults {
		if !r.routeQueue(c, unsubscribe, q.Queue, q.OpID, true) {
			rest.WithResults = append(rest.WithResults, q)
		}
	}
	return rest
}

func (r *Rooms) routeQueue(c *proxy.IMQConn, unsubscribe bool, queue string, opID uint64, withResult bool) bool {
	n, kind, ok := queueRoom(queue)
	if !ok {
		return false
	}
	me := fmt.Sprintf("/user/%d", r.user())
	if unsubscribe {
		if kind == "chat" {
			r.mu.Lock()
			if rm, ok := r.rooms[n]; ok {
				delete(rm.conns, c)
			}
			r.mu.Unlock()
		}
		if withResult {
			c.Send(imq.G2cResult, imq.Result(opID, 0))
		}
		return true
	}
	switch kind {
	case "chat":
		r.mu.Lock()
		rm := r.roomLocked(n)
		rm.conns[c] = true
		seq := rm.sequence
		r.mu.Unlock()
		c.Send(imq.G2cJoinedQueue, imq.JoinedQueue(me, queue, seq))
		c.Send(imq.G2cCreateMount, imq.CreateMount(queue, "control", imq.MessageMount, nil, seq))
		c.Send(imq.G2cCreateMount, imq.CreateMount(queue, "messages", imq.MessageMount, nil, seq))
		c.Send(imq.G2cCreateMount, imq.CreateMount(queue, "participants", imq.StateMount, nil, seq))
	case "node":
		c.Send(imq.G2cJoinedQueue, imq.JoinedQueue(me, queue, 0))
		c.Send(imq.G2cCreateMount, imq.CreateMount(queue, "node", imq.MessageMount, nil, 0))
	case "occupancy":
		c.Send(imq.G2cJoinedQueue, imq.JoinedQueue(me, queue, 0))
		c.Send(imq.G2cCreateMount, imq.CreateMount(queue, "occupants", imq.StateMount, nil, 0))
	}
	if withResult {
		c.Send(imq.G2cResult, imq.Result(opID, 0))
	}
	return true
}

// Closed forgets a connection's subscriptions.
func (r *Rooms) Closed(c *proxy.IMQConn) {
	r.mu.Lock()
	defer r.mu.Unlock()
	for _, rm := range r.rooms {
		delete(rm.conns, c)
	}
}

// Send sends what the client said or did in a hosted room to the hub (the client's message has already had its
// community products taken out, as in IMVU's rooms). It reports whether the queue was a hosted room's.
func (r *Rooms) Send(queue, mount string, message, original []byte, keep bool) bool {
	n, kind, ok := queueRoom(queue)
	if !ok {
		return false
	}
	if kind != "chat" {
		return true // nothing to say on the others
	}
	// (No echo of the client's own messages: the client handles them as it sends them, and ignores IMVU's.)
	if keep {
		return true
	}
	if mount == "messages" {
		var m struct {
			Message string `json:"message"`
		}
		if json.Unmarshal(message, &m) == nil {
			if seat, ok := roomSeat(m.Message, r.user()); ok {
				r.Hub.Send(map[string]any{"type": "room.seat", "room": n, "seat": seat})
			}
		}
	}
	r.Hub.Send(map[string]any{"type": "room.send", "room": n, "mount": mount, "message": string(message)})
	return true
}

// roomSeat is the room seat a chat line takes: "*seat <n>", or "*msg SeatAssignment <kind> <user> <seat> 0" from
// the client's own user (a seat of the room itself; seats on furniture, with a furniture instance ID, aren't the
// room's). The hub keeps them so people joining get free seats.
func roomSeat(text string, me int64) (int, bool) {
	f := strings.Fields(text)
	var s string
	switch {
	case len(f) == 2 && f[0] == "*seat":
		s = f[1]
	case len(f) == 6 && f[0] == "*msg" && f[1] == "SeatAssignment" && f[3] == strconv.FormatInt(me, 10) && f[5] == "0":
		s = f[4]
	default:
		return 0, false
	}
	seat, err := strconv.Atoi(s)
	return seat, err == nil && seat >= 0 && seat < 100
}

// --- HTTP: XML-RPC, the participant post and the room list ---

var namedRoomPattern = regexp.MustCompile(`([1-9][0-9]{0,11}-21[0-9]{8})(?:[^0-9]|$)`)

var participantPath = regexp.MustCompile(`^/chat/chat-([0-9]+)/participants/`)

// Intercept answers the client's calls about hosted rooms (proxy.Interceptor). It goes before the products'.
func (r *Rooms) Intercept(x *proxy.Exchange) error {
	host, path := strings.ToLower(x.URL.Hostname()), x.URL.Path
	if !strings.HasSuffix(host, ".imvu.com") {
		return nil
	}
	if host == "api.imvu.com" {
		if m := participantPath.FindStringSubmatch(path); m != nil {
			if chat, err := strconv.ParseInt(m[1], 10, 64); err == nil {
				if _, ok := ChatRoom(chat); ok {
					x.Response = proxy.LocalResponse(200, "application/json", []byte(`{"status":"success"}`))
				}
			}
		}
		if x.Response == nil {
			r.keepFromIMVU(x)
		}
		return nil
	}
	switch path {
	case "/api/xmlrpc/chat.php", "/api/xmlrpc/client.php":
		if err := r.interceptXMLRPC(x); err != nil || x.Response != nil {
			return err
		}
	case "/api/rooms/rooms_list_paginated.php":
		r.addToRoomList(x)
		return nil
	case "/api/rooms/room_rating.php":
		if _, ok := RoomNumber(x.URL.Query().Get("room_instance_id")); ok {
			x.Response = proxy.LocalResponse(200, "application/json", []byte(`{"score":0,"result":"success"}`))
			return nil
		}
	}
	r.keepFromIMVU(x)
	return nil
}

// keepFromIMVU answers, rather than sends, any other request to IMVU naming a hosted room (its instance ID, or the
// chat ID of a room the client is in): IMVU doesn't know them, and needn't hear of them.
func (r *Rooms) keepFromIMVU(x *proxy.Exchange) {
	text := x.URL.Path + "?" + x.URL.RawQuery + " " + string(x.Body)
	named := false
	for _, m := range namedRoomPattern.FindAllStringSubmatch(text, -1) {
		if _, ok := RoomNumber(m[1]); ok {
			named = true
		}
	}
	if !named {
		r.mu.Lock()
		for _, rm := range r.rooms {
			if strings.Contains(text, strconv.FormatInt(rm.chat, 10)) {
				named = true
				break
			}
		}
		r.mu.Unlock()
	}
	if !named {
		return
	}
	r.logf("hosted: answered a request to %s%s naming a hosted room (not found)", x.URL.Host, x.URL.Path)
	x.Response = proxy.LocalResponse(404, "application/json", []byte(`{"status":"failure","error":"NOT_FOUND"}`))
}

func xmlrpcAnswer(v xmlrpc.Value) *http.Response {
	return proxy.LocalResponse(200, "text/xml", (&xmlrpc.Response{Params: []xmlrpc.Value{v}}).Marshal())
}

func xmlrpcFault(message string) *http.Response {
	return proxy.LocalResponse(200, "text/xml", (&xmlrpc.Response{Fault: &xmlrpc.Fault{Code: 1, String: message}}).Marshal())
}

func member(s xmlrpc.Struct, name string) string {
	v, ok := s.Get(name)
	if !ok {
		return ""
	}
	switch v := v.(type) {
	case string:
		return v
	case int64:
		return strconv.FormatInt(v, 10)
	case float64:
		return strconv.FormatFloat(v, 'f', -1, 64)
	}
	return ""
}

func (r *Rooms) interceptXMLRPC(x *proxy.Exchange) error {
	call, err := xmlrpc.ParseCall(x.Body)
	if err != nil || len(call.Params) == 0 {
		return nil
	}
	args, _ := call.Params[0].(xmlrpc.Struct)
	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
	defer cancel()
	switch call.Method {
	case "test.getRoomCardInfo", "test.getRoomState", "test.setRoomState":
		n, ok := RoomNumber(member(args, "room_instance_id"))
		if !ok {
			return nil
		}
		switch call.Method {
		case "test.getRoomCardInfo":
			x.Response = r.roomCard(ctx, n)
		case "test.getRoomState":
			x.Response = r.roomState(ctx, n)
		default:
			x.Response = r.saveRoomState(ctx, n, args)
		}
	case "chat.getOrMakeChat":
		n, ok := RoomNumber(strings.TrimPrefix(member(args, "activity"), "publicroom-"))
		if !ok {
			return nil
		}
		x.Response = r.joinChat(ctx, n)
	case "chat.getParticipants", "chat.terminateChat":
		chat, err := strconv.ParseInt(member(args, "chatId"), 10, 64)
		if err != nil {
			return nil
		}
		n, ok := ChatRoom(chat)
		if !ok {
			return nil
		}
		if call.Method == "chat.terminateChat" {
			r.leave(n)
			x.Response = xmlrpcAnswer(true)
			return nil
		}
		x.Response = xmlrpcAnswer(r.others(n))
	}
	return nil
}

func (r *Rooms) getRoom(ctx context.Context, n int64) (*Room, [][3]any, string, error) {
	var out struct {
		Room  Room `json:"room"`
		Scene struct {
			Contents [][3]any `json:"contents"`
			Hash     string   `json:"hash"`
		} `json:"scene"`
	}
	if err := r.Hub.Call(ctx, "GET", fmt.Sprintf("/api/v1/hosted-rooms/%d", n), nil, &out); err != nil {
		return nil, nil, "", err
	}
	r.mu.Lock()
	if r.owners == nil {
		r.owners = map[int64]int64{}
	}
	r.owners[n] = out.Room.OwnerImvuID
	r.mu.Unlock()
	return &out.Room, out.Scene.Contents, out.Scene.Hash, nil
}

// Owner is the IMVU account owning the hosted room the client joined last (0 if none, or not known): the client
// checks the room's products against it (products.HostedOwner).
func (r *Rooms) Owner() int64 {
	r.mu.Lock()
	defer r.mu.Unlock()
	if _, in := r.rooms[r.last]; !in {
		return 0
	}
	return r.owners[r.last]
}

func (r *Rooms) roomCard(ctx context.Context, n int64) *http.Response {
	rm, _, _, err := r.getRoom(ctx, n)
	if err != nil {
		r.logf("hosted: room %d: %v", n, err)
		return xmlrpcFault("This T5DE room isn't available.")
	}
	adult := rm.Rating == "adult"
	return xmlrpcAnswer(xmlrpc.Struct{
		{Name: "owner", Value: plain(rm.OwnerName)}, {Name: "owner_cid", Value: rm.OwnerImvuID},
		{Name: "size", Value: int64(rm.Occupancy)}, {Name: "name", Value: plain(rm.Name)},
		{Name: "lieutenants", Value: []xmlrpc.Value{}}, {Name: "roomOwners", Value: []xmlrpc.Value{}},
		{Name: "allowApProducts", Value: adult}, {Name: "allowRoomShellChange", Value: false},
		{Name: "allowRoomShellOverwrite", Value: false}, {Name: "allowJoinNewRoom", Value: false},
		{Name: "allowLoadNewRoom", Value: false}, {Name: "maxOccupancy", Value: int64(rm.MaxUsers)},
		{Name: "description", Value: plain(rm.Description)}, {Name: "imageUrl", Value: ""}, {Name: "language", Value: ""},
		{Name: "isAP", Value: adult}, {Name: "isVIP", Value: false}, {Name: "allowGames", Value: false},
		{Name: "isFavorite", Value: false}, {Name: "showFavorite", Value: false}, {Name: "showRatings", Value: false},
		{Name: "enableFlagging", Value: false}, {Name: "private", Value: false},
		{Name: "autoBootWhenOwnerLeaves", Value: false}, {Name: "rating", Value: float64(0)},
		{Name: "permission", Value: ""}, {Name: "themedStatus", Value: ""}, {Name: "themeId", Value: ""},
		{Name: "eligibleForThemedRoomSubmission", Value: ""}, {Name: "occupants", Value: []xmlrpc.Value{}},
	})
}

func (r *Rooms) roomState(ctx context.Context, n int64) *http.Response {
	rm, contents, hash, err := r.getRoom(ctx, n)
	if err != nil {
		r.logf("hosted: room %d: %v", n, err)
		return xmlrpcFault("This T5DE room isn't available.")
	}
	var items []xmlrpc.Value
	for _, it := range contents {
		furni, ok1 := it[0].(float64)
		placement, ok2 := it[2].(string)
		if !ok1 || !ok2 {
			continue
		}
		var product int64
		switch p := it[1].(type) {
		case float64:
			product = int64(p)
		case string:
			local, ok := int64(0), false
			if r.LocalProduct != nil {
				local, ok = r.LocalProduct(p)
			}
			if !ok {
				continue // a community product that isn't here
			}
			product = local
			placement = swapToken(placement, p, strconv.FormatInt(local, 10))
		default:
			continue
		}
		items = append(items, []xmlrpc.Value{int64(furni), product, placement})
	}
	if items == nil {
		items = []xmlrpc.Value{}
	}
	return xmlrpcAnswer(xmlrpc.Struct{
		{Name: "room_state", Value: xmlrpc.Struct{
			{Name: "room_info", Value: xmlrpc.Struct{
				{Name: "customers_id", Value: strconv.FormatInt(rm.OwnerImvuID, 10)},
				{Name: "room_instance_id", Value: instanceID(rm.OwnerImvuID, n)},
				{Name: "room_pid", Value: strconv.FormatInt(rm.RoomPid, 10)},
			}},
			{Name: "room_contents", Value: items},
		}},
		{Name: "room_hash", Value: hash},
	})
}

func (r *Rooms) saveRoomState(ctx context.Context, n int64, args xmlrpc.Struct) *http.Response {
	v, _ := args.Get("room_contents")
	list, _ := v.([]xmlrpc.Value)
	contents := [][3]any{}
	for _, item := range list {
		it, ok := item.([]xmlrpc.Value)
		if !ok || len(it) < 3 {
			continue
		}
		furni, ok1 := asInt(it[0])
		product, ok2 := asInt(it[1])
		placement, ok3 := it[2].(string)
		if !ok1 || !ok2 || !ok3 {
			continue
		}
		var p any = product
		if product >= 2000000000 {
			id, ok := "", false
			if r.GlobalProduct != nil {
				id, ok = r.GlobalProduct(product)
			}
			if !ok {
				continue
			}
			p = id
			placement = swapToken(placement, strconv.FormatInt(product, 10), id)
		}
		contents = append(contents, [3]any{furni, p, placement})
	}
	if err := r.Hub.Call(ctx, "PUT", fmt.Sprintf("/api/v1/hosted-rooms/%d/scene", n), map[string]any{"contents": contents}, nil); err != nil {
		r.logf("hosted: saving room %d: %v", n, err)
		return xmlrpcFault("Couldn't save the room on T5DE's hub.")
	}
	return xmlrpcAnswer(true)
}

func asInt(v xmlrpc.Value) (int64, bool) {
	switch v := v.(type) {
	case int64:
		return v, true
	case float64:
		return int64(v), v == float64(int64(v))
	case string:
		n, err := strconv.ParseInt(v, 10, 64)
		return n, err == nil
	}
	return 0, false
}

func (r *Rooms) joinChat(ctx context.Context, n int64) *http.Response {
	a, err := r.join(ctx, n)
	if err != nil {
		r.logf("hosted: joining room %d: %v", n, err)
		return xmlrpcFault("T5DE's hub isn't reachable right now.")
	}
	if a.Type != "room.joined" {
		msg := a.Message
		if msg == "" {
			msg = "You can't join this T5DE room."
		}
		return xmlrpcFault(msg)
	}
	me := r.user()
	taken := map[int]bool{}
	for _, p := range a.Participants {
		if p.ImvuID != me {
			taken[p.Seat] = true
		}
	}
	seat := 1
	for taken[seat] {
		seat++
	}
	// Taken now, so whoever joins next gets another.
	r.Hub.Send(map[string]any{"type": "room.seat", "room": n, "seat": seat})
	r.mu.Lock()
	r.last = n
	_, known := r.owners[n]
	r.mu.Unlock()
	if !known {
		r.getRoom(ctx, n) // its owner, for the room's products
	}
	if r.OnJoin != nil {
		r.mu.Lock()
		instance := r.instanceOfLocked(n)
		r.mu.Unlock()
		r.OnJoin(strconv.FormatInt(a.Chat, 10), instance)
	}
	r.logf("hosted: in room %d (chat %d)", n, a.Chat)
	return xmlrpcAnswer(xmlrpc.Struct{
		{Name: "waiting", Value: int64(0)}, {Name: "lastMessageId", Value: int64(a.Sequence)},
		{Name: "chatId", Value: a.Chat}, {Name: "partnerId", Value: int64(0)}, {Name: "seat", Value: int64(seat)},
		{Name: "participantUrl", Value: fmt.Sprintf("https://api.imvu.com/chat/chat-%d/participants/user-%d", a.Chat, me)},
	})
}

// others is the room's other people, as chat.getParticipants lists them.
func (r *Rooms) others(n int64) []xmlrpc.Value {
	me := r.user()
	r.mu.Lock()
	defer r.mu.Unlock()
	out := []xmlrpc.Value{}
	if rm, ok := r.rooms[n]; ok {
		for _, p := range rm.participants {
			if p.ImvuID != me {
				out = append(out, xmlrpc.Struct{{Name: "userId", Value: p.ImvuID}, {Name: "seat", Value: int64(p.Seat)}})
			}
		}
	}
	return out
}

// addToRoomList adds hosted rooms to the client's room list (rooms_list_paginated.php: one array per field): all
// of them to the first page without a search, and those the client was in this run to recently visited rooms.
func (r *Rooms) addToRoomList(x *proxy.Exchange) {
	q := x.URL.Query()
	if p := q.Get("page"); p != "" && p != "1" && p != "0" {
		return
	}
	if q.Get("keywords") != "" || q.Get("search") != "" {
		return
	}
	recent := q.Get("recent") != ""
	x.ModifyResponse = func(resp *http.Response, body []byte) ([]byte, error) {
		var list map[string]json.RawMessage
		if resp.StatusCode != http.StatusOK || json.Unmarshal(body, &list) != nil {
			return body, nil
		}
		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		var out struct {
			Rooms []Room `json:"rooms"`
		}
		if err := r.Hub.Call(ctx, "GET", "/api/v1/hosted-rooms", nil, &out); err != nil || len(out.Rooms) == 0 {
			return body, nil
		}
		sort.SliceStable(out.Rooms, func(i, j int) bool { return out.Rooms[i].Occupancy > out.Rooms[j].Occupancy })
		r.mu.Lock()
		visited := map[int64]bool{}
		for n := range r.owners {
			visited[n] = true
		}
		r.mu.Unlock()
		for _, rm := range out.Rooms {
			if !recent || visited[rm.N] {
				appendRoom(list, rm)
			}
		}
		return json.Marshal(list)
	}
}

// appendRoom adds a room to each of the list's arrays (fields it doesn't know get an empty value of the array's
// kind).
func appendRoom(list map[string]json.RawMessage, rm Room) {
	adult := "0"
	if rm.Rating == "adult" {
		adult = "1"
	}
	known := map[string]any{
		"customers_room_id": strconv.FormatInt(Base+rm.N, 10), "customers_id": strconv.FormatInt(rm.OwnerImvuID, 10),
		"room_instance_id": instanceID(rm.OwnerImvuID, rm.N), "name": plain(rm.Name), "customers_name": plain(rm.OwnerName),
		"num_participants": strconv.Itoa(rm.Occupancy), "max_users": strconv.Itoa(rm.MaxUsers),
		"description": plain(rm.Description), "image_url": "", "rating": "0", "language": "", "is_ap": adult,
		"is_av": "0", "is_vip": "0", "participants": []any{},
	}
	for name, raw := range list {
		var arr []json.RawMessage
		if json.Unmarshal(raw, &arr) != nil {
			continue
		}
		v, ok := known[name]
		if !ok {
			v = emptyLike(arr)
		} else if str, isString := v.(string); isString && len(arr) > 0 && !strings.HasPrefix(strings.TrimSpace(string(arr[0])), "\"") {
			// The list has numbers here, not strings.
			if n, err := strconv.ParseInt(str, 10, 64); err == nil {
				v = n
			}
		}
		b, _ := json.Marshal(v)
		arr = append(arr, b)
		list[name], _ = json.Marshal(arr)
	}
}

// emptyLike is an empty value of the kind the array holds.
func emptyLike(arr []json.RawMessage) any {
	if len(arr) == 0 {
		return ""
	}
	switch b := strings.TrimSpace(string(arr[0])); {
	case strings.HasPrefix(b, "["):
		return []any{}
	case strings.HasPrefix(b, "{"):
		return map[string]any{}
	case strings.HasPrefix(b, "\""):
		return ""
	case b == "true" || b == "false":
		return false
	case b == "null":
		return nil
	}
	return 0
}

// plain keeps text to what the client's pages can show however they insert it (as in the products package).
func plain(s string) string {
	return strings.Map(func(c rune) rune {
		switch c {
		case '<', '>', '&', '"', '\'', '`':
			return -1
		}
		return c
	}, s)
}

// swapToken replaces a whole space-separated token of a placement (which names its own product).
func swapToken(placement, from, to string) string {
	fields := strings.Split(placement, " ")
	for i, f := range fields {
		if f == from {
			fields[i] = to
		}
	}
	return strings.Join(fields, " ")
}