Add capabilities API (#54)

* Add capabilities API

* Fix property

* lint

src/MatrixClient.ts

@@ -48,10 +48,12 @@ import { IKeyBackupInfo, IKeyBackupInfoRetrieved, IKeyBackupInfoUnsigned, IKeyBa
 import { MatrixError } from "./models/MatrixError";
 import { MXCUrl } from "./models/MXCUrl";
 import { MatrixContentScannerClient } from "./MatrixContentScannerClient";
+import { MatrixCapabilities } from "./models/Capabilities";
 
 const SYNC_BACKOFF_MIN_MS = 5000;
 const SYNC_BACKOFF_MAX_MS = 15000;
 const VERSIONS_CACHE_MS = 7200000; // 2 hours
+const CAPABILITES_CACHE_MS = 7200000; // 2 hours
 
 /**
  * A client that is capable of interacting with a matrix homeserver.
@@ -106,6 +108,8 @@ export class MatrixClient extends EventEmitter {
     private readonly unstableApisInstance = new UnstableApis(this);
     private cachedVersions: ServerVersions;
     private versionsLastFetched = 0;
+    private cachedCapabilites: MatrixCapabilities;
+    private capabilitesLastFetched = 0;
 
     /**
      * Set this to true to have the client only persist the sync token after the sync
@@ -275,6 +279,20 @@ export class MatrixClient extends EventEmitter {
         return event;
     }
 
+    /**
+     * Get the set of capabilites for the authenticated client.
+     * @returns {Promise<MatrixCapabilities>} Resolves to the server's supported versions.
+     */
+    @timedMatrixClientFunctionCall()
+    public async getCapabilities(): Promise<MatrixCapabilities> {
+        if (!this.cachedCapabilites || (Date.now() - this.capabilitesLastFetched) >= CAPABILITES_CACHE_MS) {
+            this.cachedCapabilites = (await this.doRequest("GET", "/_matrix/client/v3/capabilities")).capabilities;
+            this.capabilitesLastFetched = Date.now();
+        }
+
+        return this.cachedCapabilites;
+    }
+
     /**
      * Retrieves the server's supported specification versions and unstable features.
      * @returns {Promise<ServerVersions>} Resolves to the server's supported versions.

src/models/Capabilities.ts

@@ -0,0 +1,37 @@
+
+type BooleanCapability = { enabled: boolean };
+
+export interface MatrixCapabilities {
+    /**
+     * Is the user able to add, remove, or change 3PID associations on their account .
+     */
+    "m.3pid_changes"?: BooleanCapability;
+    /**
+     * Is the user able to change their own password.
+     */
+    "m.change_password"?: BooleanCapability;
+    /**
+     * Is the user able to generate single-use, time-limited tokens via the API.
+     */
+    "m.get_login_token"?: BooleanCapability;
+    /**
+     * Is the user able to change their own avatar_url via profile endpoints.
+     */
+    "m.set_avatar_url"?: BooleanCapability;
+    /**
+     * Is the user able to change their own display name via profile endpoints.
+     */
+    "m.set_displayname"?: BooleanCapability;
+    /**
+     * Describes the default and available room versions a server supports, and at what level of stability.
+     *
+     * Any room version not marked as "stable" should be considered "unstable"
+     */
+    "m.room_versions"?: {
+        "available": {
+            [version: string]: "stable"|string;
+        };
+        "default": string;
+    };
+    [key: string]: unknown;
+}