Add some permission checks to the communities v2 prototype

Prototype behaviour:
* If you can't create a room in the community, say so.
  * The UX for this could probably be improved, but for now the intention is to not break muscle memory by hiding the create room option.
* If you can't change settings in the community, or can't invite people, don't show those respective options.
  * Breaking muscle memory here is moderately okay.

src/components/structures/MatrixChat.tsx

@@ -80,6 +80,8 @@ import { leaveRoomBehaviour } from "../../utils/membership";
 import CreateCommunityPrototypeDialog from "../views/dialogs/CreateCommunityPrototypeDialog";
 import ThreepidInviteStore, { IThreepidInvite, IThreepidInviteWireFormat } from "../../stores/ThreepidInviteStore";
 import {UIFeature} from "../../settings/UIFeature";
+import { CommunityPrototypeStore } from "../../stores/CommunityPrototypeStore";
+import GroupStore from "../../stores/GroupStore";
 
 /** constants for MatrixChat.state.view */
 export enum Views {
@@ -1016,6 +1018,18 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
     }
 
     private async createRoom(defaultPublic = false) {
+        const communityId = CommunityPrototypeStore.instance.getSelectedCommunityId();
+        if (communityId) {
+            // double check the user will have permission to associate this room with the community
+            if (CommunityPrototypeStore.instance.isAdminOf(communityId)) {
+                Modal.createTrackedDialog('Pre-failure to create room', '', ErrorDialog, {
+                    title: _t("Cannot create rooms in this community"),
+                    description: _t("You do not have permission to create rooms in this community."),
+                });
+                return;
+            }
+        }
+
         const CreateRoomDialog = sdk.getComponent('dialogs.CreateRoomDialog');
         const modal = Modal.createTrackedDialog('Create Room', '', CreateRoomDialog, { defaultPublic });
 

src/components/structures/UserMenu.tsx

@@ -343,6 +343,7 @@ export default class UserMenu extends React.Component<IProps, IState> {
         let secondarySection = null;
 
         if (prototypeCommunityName) {
+            const communityId = CommunityPrototypeStore.instance.getSelectedCommunityId();
             primaryHeader = (
                 <div className="mx_UserMenu_contextMenu_name">
                     <span className="mx_UserMenu_contextMenu_displayName">
@@ -350,24 +351,36 @@ export default class UserMenu extends React.Component<IProps, IState> {
                     </span>
                 </div>
             );
-            primaryOptionList = (
-                <IconizedContextMenuOptionList>
+            let settingsOption;
+            let inviteOption;
+            if (CommunityPrototypeStore.instance.canInviteTo(communityId)) {
+                inviteOption = (
+                    <IconizedContextMenuOption
+                        iconClassName="mx_UserMenu_iconInvite"
+                        label={_t("Invite")}
+                        onClick={this.onCommunityInviteClick}
+                    />
+                );
+            }
+            if (CommunityPrototypeStore.instance.isAdminOf(communityId)) {
+                settingsOption = (
                     <IconizedContextMenuOption
                         iconClassName="mx_UserMenu_iconSettings"
                         label={_t("Settings")}
                         aria-label={_t("Community settings")}
                         onClick={this.onCommunitySettingsClick}
                     />
+                );
+            }
+            primaryOptionList = (
+                <IconizedContextMenuOptionList>
+                    {settingsOption}
                     <IconizedContextMenuOption
                         iconClassName="mx_UserMenu_iconMembers"
                         label={_t("Members")}
                         onClick={this.onCommunityMembersClick}
                     />
-                    <IconizedContextMenuOption
-                        iconClassName="mx_UserMenu_iconInvite"
-                        label={_t("Invite")}
-                        onClick={this.onCommunityInviteClick}
-                    />
+                    {inviteOption}
                 </IconizedContextMenuOptionList>
             );
             secondarySection = (

src/i18n/strings/en_EN.json

@@ -2057,6 +2057,8 @@
     "Create a Group Chat": "Create a Group Chat",
     "Explore rooms": "Explore rooms",
     "Failed to reject invitation": "Failed to reject invitation",
+    "Cannot create rooms in this community": "Cannot create rooms in this community",
+    "You do not have permission to create rooms in this community.": "You do not have permission to create rooms in this community.",
     "This room is not public. You will not be able to rejoin without an invite.": "This room is not public. You will not be able to rejoin without an invite.",
     "Are you sure you want to leave the room '%(roomName)s'?": "Are you sure you want to leave the room '%(roomName)s'?",
     "Failed to forget room %(errCode)s": "Failed to forget room %(errCode)s",

src/stores/CommunityPrototypeStore.ts

@@ -24,9 +24,9 @@ import * as utils from "matrix-js-sdk/src/utils";
 import { UPDATE_EVENT } from "./AsyncStore";
 import FlairStore from "./FlairStore";
 import TagOrderStore from "./TagOrderStore";
-import { MatrixClientPeg } from "../MatrixClientPeg";
 import GroupStore from "./GroupStore";
 import dis from "../dispatcher/dispatcher";
+import { isNullOrUndefined } from "matrix-js-sdk/src/utils";
 
 interface IState {
     // nothing of value - we use account data
@@ -77,7 +77,7 @@ export class CommunityPrototypeStore extends AsyncStoreWithClient<IState> {
 
     public getGeneralChat(communityId: string): Room {
         const rooms = GroupStore.getGroupRooms(communityId)
-            .map(r => MatrixClientPeg.get().getRoom(r.roomId))
+            .map(r => this.matrixClient.getRoom(r.roomId))
             .filter(r => !!r);
         let chat = rooms.find(r => {
             const idState = r.currentState.getStateEvents("im.vector.general_chat", "");
@@ -88,6 +88,26 @@ export class CommunityPrototypeStore extends AsyncStoreWithClient<IState> {
         return chat; // can be null
     }
 
+    public isAdminOf(communityId: string): boolean {
+        const members = GroupStore.getGroupMembers(communityId);
+        const myMember = members.find(m => m.userId === this.matrixClient.getUserId());
+        return myMember?.isPrivileged;
+    }
+
+    public canInviteTo(communityId: string): boolean {
+        const generalChat = this.getGeneralChat(communityId);
+        if (!generalChat) return this.isAdminOf(communityId);
+
+        const myMember = generalChat.getMember(this.matrixClient.getUserId());
+        if (!myMember) return this.isAdminOf(communityId);
+
+        const pl = generalChat.currentState.getStateEvents("m.room.power_levels", "");
+        if (!pl) return this.isAdminOf(communityId);
+
+        const invitePl = isNullOrUndefined(pl.invite) ? 50 : Number(pl.invite);
+        return invitePl <= myMember.powerLevel;
+    }
+
     protected async onAction(payload: ActionPayload): Promise<any> {
         if (!this.matrixClient || !SettingsStore.getValue("feature_communities_v2_prototypes")) {
             return;