package clientapi_test

import (
	"fmt"
	"net/http"
	"net/url"
	"testing"
	"time"
)

// The /sync tests. They go through HTTP rather than calling the syncapi
// directly, because what is worth pinning down is the response a client
// sees: the shape of the body, which section a room lands in, and whether a
// token handed back can be handed in again.

// syncResult is the handful of things these tests read out of a response.
// It is a typed struct rather than a map because a sync response is nested
// four deep, and `body["rooms"].(map[string]any)["join"]` repeated thirty
// times is unreadable.
type syncResult struct {
	NextBatch string `json:"next_batch"`
	Rooms     struct {
		Join map[string]struct {
			Timeline struct {
				Events    []syncEvent `json:"events"`
				Limited   bool        `json:"limited"`
				PrevBatch string      `json:"prev_batch"`
			} `json:"timeline"`
			State struct {
				Events []syncEvent `json:"events"`
			} `json:"state"`
			Ephemeral struct {
				Events []syncEvent `json:"events"`
			} `json:"ephemeral"`
			AccountData struct {
				Events []syncEvent `json:"events"`
			} `json:"account_data"`
			Summary *struct {
				Heroes             []string `json:"m.heroes"`
				JoinedMemberCount  int      `json:"m.joined_member_count"`
				InvitedMemberCount int      `json:"m.invited_member_count"`
			} `json:"summary"`
		} `json:"join"`
		Invite map[string]struct {
			InviteState struct {
				Events []syncEvent `json:"events"`
			} `json:"invite_state"`
		} `json:"invite"`
		Leave map[string]struct {
			Timeline struct {
				Events []syncEvent `json:"events"`
			} `json:"timeline"`
			State struct {
				Events []syncEvent `json:"events"`
			} `json:"state"`
		} `json:"leave"`
	} `json:"rooms"`
	Presence struct {
		Events []syncEvent `json:"events"`
	} `json:"presence"`
	AccountData struct {
		Events []syncEvent `json:"events"`
	} `json:"account_data"`
	ToDevice struct {
		Events []syncEvent `json:"events"`
	} `json:"to_device"`
	DeviceLists struct {
		Changed []string `json:"changed"`
		Left    []string `json:"left"`
	} `json:"device_lists"`
}

type syncEvent struct {
	EventID  string         `json:"event_id"`
	RoomID   string         `json:"room_id"`
	Type     string         `json:"type"`
	StateKey *string        `json:"state_key"`
	Sender   string         `json:"sender"`
	Content  map[string]any `json:"content"`
}

// sync performs one /sync, with no timeout: every test but the long-poll
// ones wants the answer as it stands.
func (ts *testServer) sync(acc account, since string) syncResult {
	ts.t.Helper()
	return ts.syncWith(acc, url.Values{"since": {since}})
}

// syncWith performs a /sync with arbitrary query parameters.
func (ts *testServer) syncWith(acc account, query url.Values) syncResult {
	ts.t.Helper()

	path := "/_matrix/client/v3/sync"
	if encoded := query.Encode(); encoded != "" {
		path += "?" + encoded
	}
	rec := ts.get(path, acc.AccessToken)
	expectStatus(ts.t, rec, http.StatusOK)

	result := decode[syncResult](ts.t, rec)
	if result.NextBatch == "" {
		ts.t.Fatalf("/sync returned no next_batch: %s", rec.Body.String())
	}
	return result
}

// sendMessage sends an m.room.message and returns its event ID.
func (ts *testServer) sendMessage(acc account, roomID, body string) string {
	ts.t.Helper()

	path := fmt.Sprintf("/_matrix/client/v3/rooms/%s/send/m.room.message/%s",
		url.PathEscape(roomID), url.PathEscape(fmt.Sprintf("txn-%s-%d", body, time.Now().UnixNano())))
	rec := ts.put(path, acc.AccessToken, map[string]any{"msgtype": "m.text", "body": body})
	expectStatus(ts.t, rec, http.StatusOK)

	eventID, _ := jsonBody(ts.t, rec)["event_id"].(string)
	if eventID == "" {
		ts.t.Fatalf("send returned no event ID: %s", rec.Body.String())
	}
	return eventID
}

// bodiesOf projects timeline events onto their message bodies, which is
// what most of these tests actually assert on.
func bodiesOf(events []syncEvent) []string {
	out := make([]string, 0, len(events))
	for _, e := range events {
		if body, ok := e.Content["body"].(string); ok {
			out = append(out, body)
		}
	}
	return out
}

// typesOf projects events onto their types.
func typesOf(events []syncEvent) []string {
	out := make([]string, 0, len(events))
	for _, e := range events {
		out = append(out, e.Type)
	}
	return out
}

func contains(haystack []string, needle string) bool {
	for _, s := range haystack {
		if s == needle {
			return true
		}
	}
	return false
}

func TestSyncInitialReportsTheRoomAndItsHistory(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	roomID := ts.createRoom(alice, map[string]any{"name": "Rome"})
	ts.sendMessage(alice, roomID, "hello")

	result := ts.sync(alice, "")

	room, ok := result.Rooms.Join[roomID]
	if !ok {
		t.Fatalf("the room is not in the join section: %+v", result.Rooms.Join)
	}
	if got := bodiesOf(room.Timeline.Events); !contains(got, "hello") {
		t.Errorf("timeline bodies = %v, want it to contain \"hello\"", got)
	}

	// The room was created and filled in fewer events than the default
	// timeline limit, so the whole of it is in the timeline and there is
	// nothing before it to report as state.
	if room.Timeline.Limited {
		t.Error("a room shorter than the timeline limit must not be reported as limited")
	}

	// A sync's events carry no room_id: they are already nested under the
	// room they belong to.
	for _, e := range room.Timeline.Events {
		if e.RoomID != "" {
			t.Errorf("%s carries a room_id in a sync response", e.Type)
			break
		}
	}

	// device_lists is empty until Phase 7 and must still be present: a
	// client reads a missing one as a malformed response.
	if result.DeviceLists.Changed == nil || result.DeviceLists.Left == nil {
		t.Error("device_lists must carry both lists even when empty")
	}
}

func TestSyncIncrementalReturnsOnlyWhatIsNew(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	roomID := ts.createRoom(alice, nil)
	ts.sendMessage(alice, roomID, "first")

	first := ts.sync(alice, "")
	ts.sendMessage(alice, roomID, "second")
	second := ts.sync(alice, first.NextBatch)

	room, ok := second.Rooms.Join[roomID]
	if !ok {
		t.Fatalf("the room is not in the join section: %+v", second.Rooms.Join)
	}
	got := bodiesOf(room.Timeline.Events)
	if len(got) != 1 || got[0] != "second" {
		t.Errorf("timeline bodies = %v, want exactly [second]", got)
	}

	// An incremental sync with no gap reports no state: every state change
	// in the window is a timeline event the client already has.
	if len(room.State.Events) != 0 {
		t.Errorf("state = %v, want none on a gapless incremental sync", typesOf(room.State.Events))
	}
}

func TestSyncIncrementalIsEmptyWhenNothingHappened(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	roomID := ts.createRoom(alice, nil)

	first := ts.sync(alice, "")
	second := ts.sync(alice, first.NextBatch)

	if len(second.Rooms.Join) != 0 {
		t.Errorf("join = %v, want nothing when nothing happened", second.Rooms.Join)
	}
	_ = roomID
}

func TestSyncTokenRoundTripsThroughTheClient(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	roomID := ts.createRoom(alice, nil)

	first := ts.sync(alice, "")
	// Syncing twice from the same token must give the same answer: a token
	// is a position, not a cursor the server advances for itself.
	a := ts.sync(alice, first.NextBatch)
	ts.sendMessage(alice, roomID, "once")
	b := ts.sync(alice, first.NextBatch)
	c := ts.sync(alice, first.NextBatch)

	if len(a.Rooms.Join) != 0 {
		t.Error("the first re-sync should have been empty")
	}
	if got := bodiesOf(b.Rooms.Join[roomID].Timeline.Events); len(got) != 1 {
		t.Errorf("second re-sync timeline = %v, want one event", got)
	}
	if got := bodiesOf(c.Rooms.Join[roomID].Timeline.Events); len(got) != 1 {
		t.Errorf("third re-sync timeline = %v, want the same one event", got)
	}
}

func TestSyncRejectsAnUnreadableToken(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")

	// "s-1" is not here: a negative event position is a /messages token
	// from inside backfilled history, and a valid ?since=. Only the event
	// stream goes below zero.
	for _, since := range []string{"nonsense", "s1_-1", "sx", "s1_2_3_4_5_6_7"} {
		rec := ts.get("/_matrix/client/v3/sync?since="+url.QueryEscape(since), alice.AccessToken)
		expectError(t, rec, http.StatusBadRequest, "M_INVALID_PARAM")
	}
}

func TestSyncAcceptsATokenFromAnOlderServer(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	roomID := ts.createRoom(alice, nil)
	ts.sendMessage(alice, roomID, "hello")

	// A token with only the event position in it, as a client stored
	// before the other streams existed. It must be read as "seen nothing"
	// of those streams rather than refused.
	result := ts.syncWith(alice, url.Values{"since": {"s1"}})
	if len(result.Rooms.Join) == 0 {
		t.Error("a short token must still sync")
	}
}

func TestSyncLongPollWakesOnAnEvent(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	roomID := ts.createRoom(alice, nil)
	since := ts.sync(alice, "").NextBatch

	done := make(chan syncResult, 1)
	go func() {
		done <- ts.syncWith(alice, url.Values{
			"since":   {since},
			"timeout": {"10000"},
		})
	}()

	// The sync has to be blocked before the event is sent, or it would
	// find the event without ever having waited and the test would pass
	// without testing anything.
	waitForListener(t, ts)
	ts.sendMessage(alice, roomID, "woken")

	select {
	case result := <-done:
		got := bodiesOf(result.Rooms.Join[roomID].Timeline.Events)
		if !contains(got, "woken") {
			t.Errorf("timeline = %v, want it to contain \"woken\"", got)
		}
	case <-time.After(5 * time.Second):
		t.Fatal("a blocked /sync was not woken by an event in its room")
	}
}

func TestSyncLongPollReturnsEmptyOnTimeout(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	ts.createRoom(alice, nil)
	since := ts.sync(alice, "").NextBatch

	start := time.Now()
	result := ts.syncWith(alice, url.Values{"since": {since}, "timeout": {"150"}})
	elapsed := time.Since(start)

	if len(result.Rooms.Join) != 0 {
		t.Errorf("join = %v, want nothing", result.Rooms.Join)
	}
	if elapsed < 100*time.Millisecond {
		t.Errorf("a 150ms long poll returned after %v; it did not wait", elapsed)
	}
}

// waitForListener blocks until a /sync has registered with the notifier, so
// that a test can be sure the sync it started is actually waiting.
func waitForListener(t *testing.T, ts *testServer) {
	t.Helper()

	deadline := time.Now().Add(5 * time.Second)
	for time.Now().Before(deadline) {
		if ts.syncAPI.Notifier().Listeners() > 0 {
			return
		}
		time.Sleep(time.Millisecond)
	}
	t.Fatal("no /sync ever blocked on the notifier")
}

func TestSyncReportsAnInviteAsStrippedState(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	bob := ts.register("bob", "hunter2-hunter2-hunter2")
	roomID := ts.createRoom(alice, map[string]any{"name": "Carthage"})

	rec := ts.post("/_matrix/client/v3/rooms/"+url.PathEscape(roomID)+"/invite",
		alice.AccessToken, map[string]any{"user_id": bob.UserID})
	expectStatus(t, rec, http.StatusOK)

	result := ts.sync(bob, "")
	invite, ok := result.Rooms.Invite[roomID]
	if !ok {
		t.Fatalf("the room is not in the invite section: %+v", result.Rooms.Invite)
	}
	if !contains(typesOf(invite.InviteState.Events), "m.room.name") {
		t.Errorf("invite_state = %v, want it to name the room", typesOf(invite.InviteState.Events))
	}
	if !contains(typesOf(invite.InviteState.Events), "m.room.member") {
		t.Error("invite_state must carry the member events that make the invite legible")
	}
	// An invitee gets no timeline at all: they are not a member.
	if _, joined := result.Rooms.Join[roomID]; joined {
		t.Error("an invited room must not be in the join section")
	}
}

func TestSyncReportsALeaveAndThenStops(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	bob := ts.register("bob", "hunter2-hunter2-hunter2")
	roomID := ts.createRoom(alice, map[string]any{"preset": "public_chat"})

	expectStatus(t, ts.post("/_matrix/client/v3/rooms/"+url.PathEscape(roomID)+"/join",
		bob.AccessToken, map[string]any{}), http.StatusOK)
	ts.sendMessage(alice, roomID, "while bob is here")

	since := ts.sync(bob, "").NextBatch
	expectStatus(t, ts.post("/_matrix/client/v3/rooms/"+url.PathEscape(roomID)+"/leave",
		bob.AccessToken, map[string]any{}), http.StatusOK)

	afterLeave := ts.sync(bob, since)
	if _, ok := afterLeave.Rooms.Leave[roomID]; !ok {
		t.Fatalf("the leave was not reported: %+v", afterLeave.Rooms)
	}

	// Everything after the leave is somebody else's business.
	ts.sendMessage(alice, roomID, "after bob left")
	quiet := ts.sync(bob, afterLeave.NextBatch)
	for _, section := range []any{quiet.Rooms.Join[roomID], quiet.Rooms.Leave[roomID]} {
		_ = section
	}
	if left, ok := quiet.Rooms.Leave[roomID]; ok {
		if got := bodiesOf(left.Timeline.Events); contains(got, "after bob left") {
			t.Errorf("a departed member was sent %v", got)
		}
	}
}

func TestSyncSummaryNamesARoomWithNoName(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	bob := ts.register("bob", "hunter2-hunter2-hunter2")
	roomID := ts.createRoom(alice, map[string]any{
		"preset": "trusted_private_chat",
		"invite": []string{bob.UserID},
	})

	result := ts.sync(alice, "")
	room := result.Rooms.Join[roomID]
	if room.Summary == nil {
		t.Fatal("a room with no name must carry a summary to name it by")
	}
	if !contains(room.Summary.Heroes, bob.UserID) {
		t.Errorf("heroes = %v, want it to name %s", room.Summary.Heroes, bob.UserID)
	}
	if room.Summary.JoinedMemberCount != 1 {
		t.Errorf("joined_member_count = %d, want 1", room.Summary.JoinedMemberCount)
	}
	if room.Summary.InvitedMemberCount != 1 {
		t.Errorf("invited_member_count = %d, want 1", room.Summary.InvitedMemberCount)
	}
}

func TestSyncLimitedTimelineCarriesTheStateBeforeIt(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	roomID := ts.createRoom(alice, nil)

	since := ts.sync(alice, "").NextBatch

	// A state change and then more messages than the timeline limit, so
	// the state change falls into the gap and has to be reported
	// separately.
	expectStatus(t, ts.put("/_matrix/client/v3/rooms/"+url.PathEscape(roomID)+"/state/m.room.topic",
		alice.AccessToken, map[string]any{"topic": "in the gap"}), http.StatusOK)
	for i := range 5 {
		ts.sendMessage(alice, roomID, fmt.Sprintf("message %d", i))
	}

	result := ts.syncWith(alice, url.Values{
		"since":  {since},
		"filter": {`{"room":{"timeline":{"limit":2}}}`},
	})
	room := result.Rooms.Join[roomID]
	if !room.Timeline.Limited {
		t.Fatal("a timeline cut short by the limit must say so")
	}
	if room.Timeline.PrevBatch == "" {
		t.Error("a limited timeline must carry a prev_batch to close the gap with")
	}
	if !contains(typesOf(room.State.Events), "m.room.topic") {
		t.Errorf("state = %v, want the topic change that fell into the gap",
			typesOf(room.State.Events))
	}
}

func TestSyncFullStateReturnsEverythingAgain(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	roomID := ts.createRoom(alice, map[string]any{"name": "Thebes"})

	since := ts.sync(alice, "").NextBatch
	result := ts.syncWith(alice, url.Values{
		"since":      {since},
		"full_state": {"true"},
		"filter":     {`{"room":{"timeline":{"limit":1}}}`},
	})

	room, ok := result.Rooms.Join[roomID]
	if !ok {
		t.Fatalf("full_state must report every room: %+v", result.Rooms.Join)
	}
	if !contains(typesOf(room.State.Events), "m.room.create") {
		t.Errorf("state = %v, want the whole state including m.room.create",
			typesOf(room.State.Events))
	}
}

func TestSyncLazyLoadingLeavesOutUninvolvedMembers(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	bob := ts.register("bob", "hunter2-hunter2-hunter2")
	roomID := ts.createRoom(alice, map[string]any{"preset": "public_chat"})
	expectStatus(t, ts.post("/_matrix/client/v3/rooms/"+url.PathEscape(roomID)+"/join",
		bob.AccessToken, map[string]any{}), http.StatusOK)

	// Only Alice speaks, so only Alice's member event is needed to render
	// the timeline.
	for i := range 4 {
		ts.sendMessage(alice, roomID, fmt.Sprintf("line %d", i))
	}

	result := ts.syncWith(alice, url.Values{
		"filter": {`{"room":{"timeline":{"limit":2,"lazy_load_members":true}}}`},
	})
	room := result.Rooms.Join[roomID]

	members := map[string]bool{}
	for _, e := range room.State.Events {
		if e.Type == "m.room.member" && e.StateKey != nil {
			members[*e.StateKey] = true
		}
	}
	if !members[alice.UserID] {
		t.Error("lazy loading must still send the member event of a timeline sender")
	}
	if members[bob.UserID] {
		t.Error("lazy loading must leave out a member who does not appear in the timeline")
	}
}

func TestSyncAppliesATypeFilter(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	roomID := ts.createRoom(alice, nil)
	since := ts.sync(alice, "").NextBatch

	ts.sendMessage(alice, roomID, "a message")
	expectStatus(t, ts.put("/_matrix/client/v3/rooms/"+url.PathEscape(roomID)+"/state/m.room.topic",
		alice.AccessToken, map[string]any{"topic": "a topic"}), http.StatusOK)

	result := ts.syncWith(alice, url.Values{
		"since":  {since},
		"filter": {`{"room":{"timeline":{"not_types":["m.room.message"]}}}`},
	})
	got := typesOf(result.Rooms.Join[roomID].Timeline.Events)
	if contains(got, "m.room.message") {
		t.Errorf("timeline = %v, want the message excluded", got)
	}
	if !contains(got, "m.room.topic") {
		t.Errorf("timeline = %v, want the topic kept", got)
	}
}

func TestSyncUsesAnUploadedFilter(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	roomID := ts.createRoom(alice, nil)

	rec := ts.post("/_matrix/client/v3/user/"+url.PathEscape(alice.UserID)+"/filter",
		alice.AccessToken, map[string]any{
			"room": map[string]any{
				"timeline": map[string]any{"types": []string{"m.room.message"}},
			},
		})
	expectStatus(t, rec, http.StatusOK)
	filterID, _ := jsonBody(t, rec)["filter_id"].(string)
	if filterID == "" {
		t.Fatalf("no filter ID was returned: %s", rec.Body.String())
	}

	// It comes back exactly as it was uploaded.
	rec = ts.get("/_matrix/client/v3/user/"+url.PathEscape(alice.UserID)+"/filter/"+filterID,
		alice.AccessToken)
	expectStatus(t, rec, http.StatusOK)

	ts.sendMessage(alice, roomID, "kept")
	result := ts.syncWith(alice, url.Values{"filter": {filterID}})

	got := typesOf(result.Rooms.Join[roomID].Timeline.Events)
	if !contains(got, "m.room.message") {
		t.Errorf("timeline = %v, want the message", got)
	}
	if contains(got, "m.room.create") {
		t.Errorf("timeline = %v, want only messages", got)
	}
}

func TestGetUnknownFilterIsNotFound(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")

	rec := ts.get("/_matrix/client/v3/user/"+url.PathEscape(alice.UserID)+"/filter/nope",
		alice.AccessToken)
	expectError(t, rec, http.StatusNotFound, "M_NOT_FOUND")
}

func TestFilterBelongsToItsOwner(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	bob := ts.register("bob", "hunter2-hunter2-hunter2")

	rec := ts.post("/_matrix/client/v3/user/"+url.PathEscape(bob.UserID)+"/filter",
		alice.AccessToken, map[string]any{})
	expectError(t, rec, http.StatusForbidden, "M_FORBIDDEN")
}

func TestSyncReportsAccountData(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	since := ts.sync(alice, "").NextBatch

	expectStatus(t, ts.put("/_matrix/client/v3/user/"+url.PathEscape(alice.UserID)+
		"/account_data/m.direct", alice.AccessToken, map[string]any{"@bob:warp.example": []string{}}),
		http.StatusOK)

	result := ts.sync(alice, since)
	if !contains(typesOf(result.AccountData.Events), "m.direct") {
		t.Errorf("account_data = %v, want m.direct", typesOf(result.AccountData.Events))
	}
	// Account data is not an event: it has a type and a content and
	// nothing else.
	for _, e := range result.AccountData.Events {
		if e.EventID != "" || e.Sender != "" {
			t.Errorf("account data was reported as an event: %+v", e)
		}
	}
}

func TestMembersAtAnEarlierPosition(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	bob := ts.register("bob", "hunter2-hunter2-hunter2")
	roomID := ts.createRoom(alice, map[string]any{"preset": "public_chat"})

	// A token from before Bob joined.
	before := ts.sync(alice, "").NextBatch
	expectStatus(t, ts.post("/_matrix/client/v3/rooms/"+url.PathEscape(roomID)+"/join",
		bob.AccessToken, map[string]any{}), http.StatusOK)

	membersAt := func(at string) []string {
		t.Helper()
		path := "/_matrix/client/v3/rooms/" + url.PathEscape(roomID) + "/members"
		if at != "" {
			path += "?at=" + url.QueryEscape(at)
		}
		rec := ts.get(path, alice.AccessToken)
		expectStatus(t, rec, http.StatusOK)

		body := decode[struct {
			Chunk []syncEvent `json:"chunk"`
		}](t, rec)

		out := make([]string, 0, len(body.Chunk))
		for _, e := range body.Chunk {
			if e.StateKey != nil {
				out = append(out, *e.StateKey)
			}
		}
		return out
	}

	if got := membersAt(""); !contains(got, bob.UserID) {
		t.Errorf("current members = %v, want it to include %s", got, bob.UserID)
	}
	if got := membersAt(before); contains(got, bob.UserID) {
		t.Errorf("members at an earlier position = %v, want it to leave out %s", got, bob.UserID)
	}
}

func TestMembersRejectsABadAtToken(t *testing.T) {
	ts := newTestServer(t, nil)
	alice := ts.register("alice", "correct-horse-battery-staple")
	roomID := ts.createRoom(alice, nil)

	rec := ts.get("/_matrix/client/v3/rooms/"+url.PathEscape(roomID)+"/members?at=nonsense",
		alice.AccessToken)
	expectError(t, rec, http.StatusBadRequest, "M_INVALID_PARAM")
}