Add maySendStateEvent method, ported from react-sdk (but fixed). Plus tests.

lib/models/room-state.js

@@ -224,6 +224,52 @@ RoomState.prototype.getUserIdsWithDisplayName = function(displayName) {
     return this._displayNameToUserIds[displayName] || [];
 };
 
+/**
+ * Returns true if the given user ID has permission to send a state
+ * event of type `stateEventType` into this room.
+ * @param {string} type The type of state events to test
+ * @param {string} userId The user ID of the user to test permission for
+ * @return {boolean} true if the given user ID should be permitted to send
+ *                        the given type of state event into this room,
+ *                        according to the room's state.
+ */
+RoomState.prototype.maySendStateEvent = function(stateEventType, userId) {
+    if (!this.getMember(userId)) { return false; }
+
+    var power_levels_event = this.getStateEvents('m.room.power_levels', '');
+
+    var power_levels;
+    var events_levels = {};
+
+    var default_user_level = 0;
+    var user_levels = [];
+    var current_user_level = 0;
+
+    var state_default = 0;
+    if (power_levels_event) {
+        power_levels = power_levels_event.getContent();
+        events_levels = power_levels.events || {};
+
+        default_user_level = parseInt(power_levels.users_default || 0);
+        user_levels = power_levels.users || {};
+        current_user_level = user_levels[userId];
+
+        if (current_user_level === undefined) { current_user_level = default_user_level; }
+
+        if (power_levels.state_default !== undefined) {
+            state_default = power_levels.state_default;
+        } else {
+            state_default = 50;
+        }
+    }
+
+    var state_event_level = state_default;
+    if (events_levels[stateEventType] !== undefined) {
+        state_event_level = events_levels[stateEventType];
+    }
+    return current_user_level >= state_event_level;
+};
+
 /**
  * The RoomState class.
  */

spec/unit/room-state.spec.js

@@ -279,4 +279,85 @@ describe("RoomState", function() {
             );
         });
     });
+
+    describe("maySendStateEvent", function() {
+        it("should say non-joined members may not send state",
+        function() {
+            expect(state.maySendStateEvent('m.room.name', "@nobody:nowhere")).toEqual(false);
+        });
+
+        it("should say any member may send state with no power level event",
+        function() {
+            expect(state.maySendStateEvent('m.room.name', userA)).toEqual(true);
+        });
+
+        it("should say members with power >=50 may send state with power level event "+
+        "but no state default",
+        function() {
+            var powerLevelEvent = {
+                type: "m.room.power_levels", room: roomId, user: userA, event: true,
+                content: {
+                    users_default: 10,
+                    // state_default: 50, "intentionally left blank"
+                    events_default: 25,
+                    users: {
+                    }
+                }
+            };
+            powerLevelEvent.content.users[userA] = 50;
+
+            state.setStateEvents([utils.mkEvent(powerLevelEvent)]);
+
+            expect(state.maySendStateEvent('m.room.name', userA)).toEqual(true);
+            expect(state.maySendStateEvent('m.room.name', userB)).toEqual(false);
+        });
+
+        it("should obey state_default",
+        function() {
+            var powerLevelEvent = {
+                type: "m.room.power_levels", room: roomId, user: userA, event: true,
+                content: {
+                    users_default: 10,
+                    state_default: 30,
+                    events_default: 25,
+                    users: {
+                    }
+                }
+            };
+            powerLevelEvent.content.users[userA] = 30;
+            powerLevelEvent.content.users[userB] = 29;
+
+            state.setStateEvents([utils.mkEvent(powerLevelEvent)]);
+
+            expect(state.maySendStateEvent('m.room.name', userA)).toEqual(true);
+            expect(state.maySendStateEvent('m.room.name', userB)).toEqual(false);
+        });
+
+        it("should honour explicit event power levels in the power_levels event",
+        function() {
+            var powerLevelEvent = {
+                type: "m.room.power_levels", room: roomId, user: userA, event: true,
+                content: {
+                    events: {
+                        "m.room.other_thing": 76
+                    },
+                    users_default: 10,
+                    state_default: 50,
+                    events_default: 25,
+                    users: {
+                    }
+                }
+            };
+            powerLevelEvent.content.users[userA] = 80;
+            powerLevelEvent.content.users[userB] = 50;
+
+            state.setStateEvents([utils.mkEvent(powerLevelEvent)]);
+
+            expect(state.maySendStateEvent('m.room.name', userA)).toEqual(true);
+            expect(state.maySendStateEvent('m.room.name', userB)).toEqual(true);
+
+            expect(state.maySendStateEvent('m.room.other_thing', userA)).toEqual(true);
+            expect(state.maySendStateEvent('m.room.other_thing', userB)).toEqual(false);
+        });
+    });
 });