Convert shouldHideEvent to TS

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

src/shouldHideEvent.ts

@@ -0,0 +1,71 @@
+/*
+ Copyright 2017 Michael Telatynski <7t3chguy@gmail.com>
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ */
+
+import {MatrixEvent} from "matrix-js-sdk/src/models/event";
+
+import SettingsStore from "./settings/SettingsStore";
+
+interface IDiff {
+    isMemberEvent: boolean;
+    isJoin?: boolean;
+    isPart?: boolean;
+    isDisplaynameChange?: boolean;
+    isAvatarChange?: boolean;
+}
+
+function memberEventDiff(ev: MatrixEvent): IDiff {
+    const diff: IDiff = {
+        isMemberEvent: ev.getType() === 'm.room.member',
+    };
+
+    // If is not a Member Event then the other checks do not apply, so bail early.
+    if (!diff.isMemberEvent) return diff;
+
+    const content = ev.getContent();
+    const prevContent = ev.getPrevContent();
+
+    const isMembershipChanged = content.membership !== prevContent.membership;
+    diff.isJoin = isMembershipChanged && content.membership === 'join';
+    diff.isPart = isMembershipChanged && content.membership === 'leave' && ev.getStateKey() === ev.getSender();
+
+    const isJoinToJoin = !isMembershipChanged && content.membership === 'join';
+    diff.isDisplaynameChange = isJoinToJoin && content.displayname !== prevContent.displayname;
+    diff.isAvatarChange = isJoinToJoin && content.avatar_url !== prevContent.avatar_url;
+    return diff;
+}
+
+export default function shouldHideEvent(ev: MatrixEvent): boolean {
+    // Wrap getValue() for readability. Calling the SettingsStore can be
+    // fairly resource heavy, so the checks below should avoid hitting it
+    // where possible.
+    const isEnabled = (name) => SettingsStore.getValue(name, ev.getRoomId());
+
+    // Hide redacted events
+    if (ev.isRedacted() && !isEnabled('showRedactions')) return true;
+
+    // Hide replacement events since they update the original tile (if enabled)
+    if (ev.isRelation("m.replace")) return true;
+
+    const eventDiff = memberEventDiff(ev);
+
+    if (eventDiff.isMemberEvent) {
+        if ((eventDiff.isJoin || eventDiff.isPart) && !isEnabled('showJoinLeaves')) return true;
+        if (eventDiff.isAvatarChange && !isEnabled('showAvatarChanges')) return true;
+        if (eventDiff.isDisplaynameChange && !isEnabled('showDisplaynameChanges')) return true;
+    }
+
+    return false;
+}