Refactor list creation with MSC3784 support. (#386)

https://github.com/matrix-org/matrix-spec-proposals/pull/3784

This was extracted from the appservice mjolnir work to reduce review burden.

src/commands/CreateBanListCommand.ts

@@ -15,7 +15,7 @@ limitations under the License.
 */
 
 import { Mjolnir } from "../Mjolnir";
-import { SHORTCODE_EVENT_TYPE } from "../models/PolicyList";
+import PolicyList from "../models/PolicyList";
 import { Permalinks, RichReply } from "matrix-bot-sdk";
 
 // !mjolnir list create <shortcode> <alias localpart>
@@ -23,34 +23,12 @@ export async function execCreateListCommand(roomId: string, event: any, mjolnir:
     const shortcode = parts[3];
     const aliasLocalpart = parts[4];
 
-    const powerLevels: { [key: string]: any } = {
-        "ban": 50,
-        "events": {
-            "m.room.name": 100,
-            "m.room.power_levels": 100,
-        },
-        "events_default": 50, // non-default
-        "invite": 0,
-        "kick": 50,
-        "notifications": {
-            "room": 20,
-        },
-        "redact": 50,
-        "state_default": 50,
-        "users": {
-            [await mjolnir.client.getUserId()]: 100,
-            [event["sender"]]: 50
-        },
-        "users_default": 0,
-    };
-
-    const listRoomId = await mjolnir.client.createRoom({
-        preset: "public_chat",
-        room_alias_name: aliasLocalpart,
-        invite: [event['sender']],
-        initial_state: [{ type: SHORTCODE_EVENT_TYPE, state_key: "", content: { shortcode: shortcode } }],
-        power_level_content_override: powerLevels,
-    });
+    const listRoomId = await PolicyList.createList(
+        mjolnir.client,
+        shortcode,
+        [event['sender']],
+        { room_alias_name: aliasLocalpart }
+    );
 
     const roomRef = Permalinks.forRoom(listRoomId);
     await mjolnir.watchList(roomRef);

src/models/PolicyList.ts

@@ -86,6 +86,10 @@ class PolicyList extends EventEmitter {
     // Events that we have already informed the batcher about, that we haven't loaded from the room state yet.
     private batchedEvents = new Set<string /* event id */>();
 
+    /** MSC3784 support. Please note that policy lists predate room types. So there will be lists in the wild without this type. */
+    public static readonly ROOM_TYPE = "support.feline.policy.lists.msc.v1";
+    public static readonly ROOM_TYPE_VARIANTS = [PolicyList.ROOM_TYPE]
+
     /**
      * This is used to annotate state events we store with the rule they are associated with.
      * If we refactor this, it is important to also refactor any listeners to 'PolicyList.update'
@@ -105,6 +109,65 @@ class PolicyList extends EventEmitter {
         this.batcher = new UpdateBatcher(this);
     }
 
+    /**
+     * Create a new policy list.
+     * @param client A MatrixClient that will be used to create the list.
+     * @param shortcode A shortcode to refer to the list with.
+     * @param invite A list of users to invite to the list and make moderator.
+     * @param createRoomOptions Additional room create options such as an alias.
+     * @returns The room id for the newly created policy list.
+     */
+    public static async createList(
+        client: MatrixClient,
+        shortcode: string,
+        invite: string[],
+        createRoomOptions = {}
+    ): Promise<string /* room id */> {
+        const powerLevels: { [key: string]: any } = {
+            "ban": 50,
+            "events": {
+                "m.room.name": 100,
+                "m.room.power_levels": 100,
+            },
+            "events_default": 50, // non-default
+            "invite": 0,
+            "kick": 50,
+            "notifications": {
+                "room": 20,
+            },
+            "redact": 50,
+            "state_default": 50,
+            "users": {
+                [await client.getUserId()]: 100,
+                ...invite.reduce((users, mxid) => ({...users,  [mxid]: 50 }), {}),
+            },
+            "users_default": 0,
+        };
+        const finalRoomCreateOptions = {
+            // Support for MSC3784.
+            creation_content: {
+                type: PolicyList.ROOM_TYPE
+            },
+            preset: "public_chat",
+            invite,
+            initial_state: [
+                {
+                    type: SHORTCODE_EVENT_TYPE,
+                    state_key: "",
+                    content: {shortcode: shortcode}
+                }
+            ],
+            power_level_content_override: powerLevels,
+            ...createRoomOptions
+        };
+        // Guard room type in case someone overwrites it when declaring custom creation_content in future code.
+        if (!PolicyList.ROOM_TYPE_VARIANTS.includes(finalRoomCreateOptions.creation_content.type)) {
+            throw new TypeError(`Creating a policy room with a type other than the policy room type is not supported, you probably don't want to do this.`);
+        }
+        const listRoomId = await client.createRoom(finalRoomCreateOptions);
+        return listRoomId
+    }
+
     /**
      * The code that can be used to refer to this banlist in Mjolnir commands.
      */

test/integration/banListTest.ts

@@ -8,6 +8,7 @@ import { getMessagesByUserIn } from "../../src/utils";
 import { Mjolnir } from "../../src/Mjolnir";
 import { ALL_RULE_TYPES, Recommendation, RULE_SERVER, RULE_USER, SERVER_RULE_TYPES } from "../../src/models/ListRule";
 import AccessControlUnit, { Access, EntityAccess } from "../../src/models/AccessControlUnit";
+import { randomUUID } from "crypto";
 
 /**
  * Create a policy rule in a policy room.
@@ -564,3 +565,31 @@ describe('Test: AccessControlUnit interaction with policy lists.', function() {
         assertAccess(Access.Allowed, aclUnit.getAccessForServer(banMeServer), "Should not longer be any rules");
     })
 })
+
+describe('Test: Creating policy lists.', function() {
+    it('Will automatically invite and op users from invites', async function() {
+        const mjolnir: Mjolnir = this.mjolnir;
+        const testUsers = await Promise.all([...Array(2)].map(_ => newTestUser(this.config.homeserverUrl, { name: { contains: "moderator" } })))
+        const invite = await Promise.all(testUsers.map(client => client.getUserId()));
+        const policyListId = await PolicyList.createList(
+            mjolnir.client,
+            randomUUID(),
+            invite
+        );
+        // Check power levels are right.
+        const powerLevelEvent = await mjolnir.client.getRoomStateEvent(policyListId, "m.room.power_levels", "");
+        assert.equal(Object.keys(powerLevelEvent.users ?? {}).length, invite.length + 1);
+        // Check create event for MSC3784 support.
+        const createEvent = await mjolnir.client.getRoomStateEvent(policyListId, "m.room.create", "");
+        assert.equal(createEvent.type, PolicyList.ROOM_TYPE);
+        // We can't create rooms without forgetting the type.
+        await assert.rejects(
+            async () => {
+                await PolicyList.createList(mjolnir.client, randomUUID(), [], {
+                    creation_content: {}
+                })
+            },
+            TypeError
+        );
+    })
+})