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messagesActions: Follow tapped /near/ links through message moves
Implementing the algorithm described in the issue and on CZO: #5306 (comment) > When a user clicks a `/near/` link in a message, > > 1. Get the message, either from our local data structures or > (failing that) from a single-message fetch, using the API added > in zulip/zulip#21391. > 2. If the message is currently in the stream and topic encoded in > the `/near/` link, open the topic narrow for that stream/topic, > and scroll to the message*. > 3. If the message was *at some point* in the stream and topic > encoded in the `/near/` link, according to its `edit_history`, > open the topic narrow for the stream/topic that the message is > currently in, and scroll to the message*. > 4. Otherwise (i.e., the message was never in the stream/topic > encoded in the `/near/` link), open the topic narrow for the > stream/topic encoded in the link, and scroll to the message > "nearest" to the message ID*. > > *Actually opening a narrow scrolled to a specific message ID is > blocked on #3604. It actually turned out quite easy to do the special handling for part 4, so that's included here. (The bit about blocking on #3604 is still true.) Fixes: #5306
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‎src/message/messageSelectors.js‎

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@@ -78,3 +78,47 @@ export const getFirstUnreadIdInNarrow: Selector<number | null, Narrow> = createS
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return firstUnread?.id ?? null;
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},
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);
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/**
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* True just if we know the message has, or had, the given topic.
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*
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* Gives null if it doesn't have the topic now, but we can't access
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* the message's edit history to check in the past.
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*/
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export function hasMessageEverHadTopic(message: Message, topic: string): boolean | null {
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if (message.subject === topic) {
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return true;
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}
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// See comments on Message['edit_history'] for the values it takes
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// and what they mean.
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if (message.edit_history === null) {
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return null;
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}
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if (message.edit_history === undefined) {
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return false;
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}
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return message.edit_history.findIndex(messageEdit => topic === messageEdit.prev_topic) >= 0;
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}
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/**
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* True just if we know the message is, or was, in the given stream.
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*
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* Gives null if it's not in the stream now, but we can't access the
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* message's edit history to check in the past.
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*/
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export function hasMessageEverBeenInStream(message: Message, streamId: number): boolean | null {
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if (message.stream_id === streamId) {
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return true;
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}
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// See comments on Message['edit_history'] for the values it takes
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// and what they mean.
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if (message.edit_history === null) {
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return null;
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}
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if (message.edit_history === undefined) {
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return false;
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}
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return message.edit_history.findIndex(messageEdit => streamId === messageEdit.prev_stream) >= 0;
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}

‎src/message/messagesActions.js‎

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Original file line numberDiff line numberDiff line change
@@ -1,7 +1,8 @@
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/* @flow strict-local */
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import * as logging from '../utils/logging';
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import * as NavigationService from '../nav/NavigationService';
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import type { Narrow, ThunkAction } from '../types';
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import { getAuth } from '../selectors';
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import { getAuth, getRealm, getMessages, getZulipFeatureLevel } from '../selectors';
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import { getNearOperandFromLink, getNarrowFromLink } from '../utils/internalLinks';
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import { openLinkWithUserPreference } from '../utils/openLink';
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import { navigateToChat } from '../nav/navActions';
@@ -10,6 +11,16 @@ import { getStreamsById, getStreamsByName } from '../subscriptions/subscriptionS
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import * as api from '../api';
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import { isUrlOnRealm } from '../utils/url';
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import { getOwnUserId } from '../users/userSelectors';
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import {
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isTopicNarrow,
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isStreamNarrow,
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topicNarrow,
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streamIdOfNarrow,
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topicOfNarrow,
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streamNarrow,
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caseNarrowDefault,
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} from '../utils/narrow';
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import { hasMessageEverBeenInStream, hasMessageEverHadTopic } from './messageSelectors';
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/**
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* Navigate to the given narrow.
@@ -21,6 +32,171 @@ export const doNarrow =
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NavigationService.dispatch(navigateToChat(narrow));
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};
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/**
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* Narrow to a /near/ link, possibly after reinterpreting it for a message move.
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*
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* It feels quite broken when a link is clearly meant to get you to a
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* specific message, but tapping it brings you to a narrow where the message
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* *used* to be but isn't anymore because it was moved to a new stream or
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* topic. This was #5306.
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*
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* This action, when it can, recognizes when that's about to happen and
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* instead narrows you to the message's current stream/topic.
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*
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* To do so, it obviously needs to know the message's current stream/topic.
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* If those can't be gotten from Redux, we ask the server. If the server
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* can't help us (gives an error), we can't help the user, so we won't
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* follow a move in that case.
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*
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* N.B.: Gives a bad experience when the request takes a long time. We
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* should fix that; see TODOs.
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*/
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const doNarrowNearLink =
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(narrow: Narrow, nearOperand: number): ThunkAction<Promise<void>> =>
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async (dispatch, getState) => {
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const state = getState();
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const auth = getAuth(state);
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const messages = getMessages(state);
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const zulipFeatureLevel = getZulipFeatureLevel(state);
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const allowEditHistory = getRealm(state).allowEditHistory;
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/**
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* Narrow to the /near/ link without reinterpreting it for a message move.
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*
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* Use this when the link is meant to find the specific message
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* identified by nearOperand, and:
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* - nearOperand refers to a message that wasn't moved outside the
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* narrow specified by the link, or
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* - nearOperand *might* refer to a message that was moved, but we don't
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* know; we've tried and failed to find out.
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*
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* Or, use this to insist on the traditional meaning of "near" before
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* the message-move feature: take the narrow's stream/topic/etc.
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* literally, and open to the message "nearest" the given ID (sent
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* around the same time), even if the message with that ID isn't
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* actually in the narrow [1].
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*
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* User docs on moving messages:
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* https://zulip.com/help/move-content-to-another-stream
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* https://zulip.com/help/move-content-to-another-topic
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*
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* [1] Tim points out, at
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* https://chat.zulip.org/#narrow/stream/101-design/topic/redirects.20from.20near.20links/near/1343095 :
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* "[…] useful for situations where you might replace an existing
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* search for `stream: 1/topic: 1/near: 15` with
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* `stream: 2/topic: 2/near: 15` in order to view what was happening
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* in another conversation at the same time as an existing
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* conversation."
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*/
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const noMove = () => {
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dispatch(doNarrow(narrow, nearOperand));
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};
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const streamIdOperand =
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isStreamNarrow(narrow) || isTopicNarrow(narrow) ? streamIdOfNarrow(narrow) : null;
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const topicOperand = isTopicNarrow(narrow) ? topicOfNarrow(narrow) : null;
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if (streamIdOperand === null && topicOperand === null) {
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// Message moves only happen by changing the stream and/or topic.
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noMove();
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return;
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}
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// Grab the message and see if it was moved, so we can follow the move
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// if so.
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// Try to get it from our local data to avoid a server round-trip…
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let message = messages.get(nearOperand);
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// …but if we have to, go and ask the server.
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// TODO: Give feedback when the server round trip takes longer than
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// expected.
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// TODO: Let the user cancel the request so we don't force a doNarrow
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// after they've given up on tapping the link, and perhaps forgotten
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// about it. Like any request, this might take well over a minute to
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// resolve, or never resolve.
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// TODO: When these are fixed, remove warning in jsdoc.
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if (!message) {
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// TODO(server-5.0): Simplify.
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if (zulipFeatureLevel < 120) {
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// api.getSingleMessage won't give us the message's stream and
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// topic; see there. Hopefully the message wasn't moved.
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noMove();
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return;
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}
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try {
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message = await api.getSingleMessage(
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auth,
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{ message_id: nearOperand },
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zulipFeatureLevel,
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allowEditHistory,
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);
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} catch {
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// Hopefully the message, if it exists or ever existed, wasn't moved.
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noMove();
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return;
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}
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}
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// The FL 120 condition on calling api.getSingleMessage should ensure
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// `message` isn't void.
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// TODO(server-5.0): Simplify away.
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if (!message) {
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logging.error('`message` from api.getSingleMessage unexpectedly falsy');
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noMove();
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return;
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}
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if (message.type === 'private') {
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// A PM could never have been moved.
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noMove();
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return;
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}
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if (
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(topicOperand === null || topicOperand === message.subject)
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&& (streamIdOperand === null || streamIdOperand === message.stream_id)
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) {
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// The message is still in the stream and/or topic in the link.
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noMove();
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return;
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}
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if (
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(topicOperand !== null && hasMessageEverHadTopic(message, topicOperand) === false)
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|| (streamIdOperand !== null && hasMessageEverBeenInStream(message, streamIdOperand) === false)
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) {
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// The message was never in the narrow specified by the link. That'd
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// be an odd link to put in a message…anyway, perhaps we're meant to
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// use the traditional meaning of "near"; see noMove's jsdoc
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// for what that is.
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noMove();
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return;
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}
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// If we couldn't access the edit history in the checks above, assume
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// the message was moved. It's the likeliest explanation why its topic
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// and/or stream don't match the narrow link.
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const { stream_id, subject } = message;
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// Reinterpret the link's narrow with the message's current stream
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// and/or topic.
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dispatch(
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doNarrow(
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caseNarrowDefault(
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narrow,
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{
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stream: () => streamNarrow(stream_id),
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topic: () => topicNarrow(stream_id, subject),
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},
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() => narrow,
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),
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nearOperand,
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),
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);
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};
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export const messageLinkPress =
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(href: string): ThunkAction<Promise<void>> =>
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async (dispatch, getState, { getGlobalSettings }) => {
@@ -43,7 +219,7 @@ export const messageLinkPress =
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return;
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}
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46-
dispatch(doNarrow(narrow, nearOperand));
222+
await dispatch(doNarrowNearLink(narrow, nearOperand));
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} else if (!isUrlOnRealm(href, auth.realm)) {
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openLinkWithUserPreference(href, getGlobalSettings());
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} else {

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