Add /jumptodate slash command

src/SlashCommands.tsx

@@ -19,6 +19,7 @@ limitations under the License.
 
 import * as React from 'react';
 import { User } from "matrix-js-sdk/src/models/user";
+import { Direction } from 'matrix-js-sdk/src/models/event-timeline';
 import { EventType } from "matrix-js-sdk/src/@types/event";
 import * as ContentHelpers from 'matrix-js-sdk/src/content-helpers';
 import { parseFragment as parseHtml, Element as ChildElement } from "parse5";
@@ -286,6 +287,50 @@ export const Commands = [
         category: CommandCategories.admin,
         renderingTypes: [TimelineRenderingType.Room],
     }),
+    new Command({
+        command: 'jumptodate',
+        args: '<date>',
+        description: _td('Jump to the given date in the timeline (YYYY-MM-DD)'),
+        isEnabled: () => SettingsStore.getValue("feature_jump_to_date"),
+        runFn: function(roomId, args) {
+            if (args) {
+                return success((async () => {
+                    const unixTimestamp = Date.parse(args);
+                    if (!unixTimestamp) {
+                        throw new Error(
+                            // FIXME: Use newTranslatableError here instead
+                            // otherwise the rageshake error messages will be
+                            // translated too
+                            _t(
+                                // eslint-disable-next-line max-len
+                                'We were unable to understand the given date (%(inputDate)s). Try using the format YYYY-MM-DD.',
+                                { inputDate: args },
+                            ),
+                        );
+                    }
+
+                    const cli = MatrixClientPeg.get();
+                    const { event_id: eventId, origin_server_ts: originServerTs } = await cli.timestampToEvent(
+                        roomId,
+                        unixTimestamp,
+                        Direction.Forward,
+                    );
+                    logger.log(
+                        `/timestamp_to_event: found ${eventId} (${originServerTs}) for timestamp=${unixTimestamp}`,
+                    );
+                    dis.dispatch({
+                        action: Action.ViewRoom,
+                        eventId,
+                        highlighted: true,
+                        room_id: roomId,
+                    });
+                })());
+            }
+
+            return reject(this.getUsage());
+        },
+        category: CommandCategories.actions,
+    }),
     new Command({
         command: 'nick',
         args: '<display_name>',

src/components/views/settings/tabs/user/LabsUserSettingsTab.tsx

@@ -49,6 +49,7 @@ export class LabsSettingToggle extends React.Component<ILabsSettingToggleProps>
 
 interface IState {
     showHiddenReadReceipts: boolean;
+    showJumpToDate: boolean;
 }
 
 @replaceableComponent("views.settings.tabs.user.LabsUserSettingsTab")
@@ -60,8 +61,13 @@ export default class LabsUserSettingsTab extends React.Component<{}, IState> {
             this.setState({ showHiddenReadReceipts });
         });
 
+        MatrixClientPeg.get().doesServerSupportUnstableFeature("org.matrix.msc2716").then((showJumpToDate) => {
+            this.setState({ showJumpToDate });
+        });
+
         this.state = {
             showHiddenReadReceipts: false,
+            showJumpToDate: false,
         };
     }
 
@@ -135,6 +141,16 @@ export default class LabsUserSettingsTab extends React.Component<{}, IState> {
                 );
             }
 
+            if (this.state.showJumpToDate) {
+                groups.getOrCreate(LabGroup.Messaging, []).push(
+                    <SettingsFlag
+                        key="feature_jump_to_date"
+                        name="feature_jump_to_date"
+                        level={SettingLevel.DEVICE}
+                    />,
+                );
+            }
+
             labsSection = <div className="mx_SettingsTab_section">
                 { sortBy(Array.from(groups.entries()), "0").map(([group, flags]) => (
                     <div key={group}>

src/i18n/strings/en_EN.json

@@ -435,6 +435,8 @@
     "Sends a message as html, without interpreting it as markdown": "Sends a message as html, without interpreting it as markdown",
     "Upgrades a room to a new version": "Upgrades a room to a new version",
     "You do not have the required permissions to use this command.": "You do not have the required permissions to use this command.",
+    "Jump to the given date in the timeline (YYYY-MM-DD)": "Jump to the given date in the timeline (YYYY-MM-DD)",
+    "We were unable to understand the given date (%(inputDate)s). Try using the format YYYY-MM-DD.": "We were unable to understand the given date (%(inputDate)s). Try using the format YYYY-MM-DD.",
     "Changes your display nickname": "Changes your display nickname",
     "Changes your display nickname in the current room only": "Changes your display nickname in the current room only",
     "Changes the avatar of the current room": "Changes the avatar of the current room",
@@ -860,6 +862,7 @@
     "Meta Spaces": "Meta Spaces",
     "Use new room breadcrumbs": "Use new room breadcrumbs",
     "New spotlight search experience": "New spotlight search experience",
+    "Jump to date (adds /jumptodate)": "Jump to date (adds /jumptodate)",
     "Don't send read receipts": "Don't send read receipts",
     "Font size": "Font size",
     "Use custom size": "Use custom size",

src/settings/Settings.tsx

@@ -367,6 +367,15 @@ export const SETTINGS: {[setting: string]: ISetting} = {
         displayName: _td("New spotlight search experience"),
         default: false,
     },
+    "feature_jump_to_date": {
+        // We purposely leave out `isFeature: true` so it doesn't show in Labs
+        // by default. We will conditionally show it depending on whether we can
+        // detect MSC3030 support (see LabUserSettingsTab.tsx).
+        // labsGroup: LabGroup.Messaging,
+        displayName: _td("Jump to date (adds /jumptodate)"),
+        supportedLevels: LEVELS_FEATURE,
+        default: false,
+    },
     "RoomList.backgroundImage": {
         supportedLevels: LEVELS_ACCOUNT_SETTINGS,
         default: null,