pm_list: Add search to direct message section.

Fixes #22113.

The search will only be visible when in the `more conversations`
view. Once we click `back to channels` and close the
`more conversations` view, the search will clear and the search
box will disappear.

We've chosen `pm_list_data.get_conversations` as the function
to which we will pass our search term. We could have technically
found the value of the filter element via JQuery in pm_list_data,
but pm_list_data does not handle any JQuery and we should keep
it that way.

`pm_list_data.get_list_info` also accepts the search_string so that
the info it returns in expanded view is accurate.

We've also added some code to `click_handlers` to make sure that
clicking the search input does not bring us into the DM narrow.

web/src/click_handlers.js

@@ -774,7 +774,13 @@ export function initialize() {
         e.preventDefault();
         e.stopPropagation();
 
+        if (!$(e.target).hasClass("direct-messages-list-filter")) {
+            // Avoiding having clicks on the filter input.
+            //
+            // TODO: Refactor to use more precise selectors for this
+            // click handler in general; this is a fragile pattern.
             window.location.hash = "narrow/is/dm";
+        }
     });
 
     // disable the draggability for left-sidebar components

web/src/pm_list.ts

@@ -39,8 +39,10 @@ export function close(): void {
 }
 
 export function _build_direct_messages_list(): vdom.Tag<PMNode> {
-    const conversations = pm_list_data.get_conversations();
-    const pm_list_info = pm_list_data.get_list_info(zoomed);
+    const $filter = $<HTMLInputElement>(".direct-messages-list-filter").expectOne();
+    const search_term = $filter.val()!;
+    const conversations = pm_list_data.get_conversations(search_term);
+    const pm_list_info = pm_list_data.get_list_info(zoomed, search_term);
     const conversations_to_be_shown = pm_list_info.conversations_to_be_shown;
     const more_conversations_unread_count = pm_list_info.more_conversations_unread_count;
 
@@ -55,6 +57,12 @@ export function _build_direct_messages_list(): vdom.Tag<PMNode> {
         );
     }
     const dom_ast = pm_list_dom.pm_ul(pm_list_nodes);
+
+    if (search_term === "") {
+        $("#clear-direct-messages-search-button").hide();
+    } else {
+        $("#clear-direct-messages-search-button").show();
+    }
     return dom_ast;
 }
 
@@ -197,16 +205,31 @@ function zoom_in(): void {
     $(".direct-messages-container").removeClass("zoom-out").addClass("zoom-in");
     $("#streams_list").hide();
     $(".left-sidebar .right-sidebar-items").hide();
+
+    const $filter = $(".direct-messages-list-filter").expectOne();
+    $filter.trigger("focus");
 }
 
 function zoom_out(): void {
     zoomed = false;
-    update_private_messages();
+    clear_search(true); // force rerender if the search is empty.
     $(".direct-messages-container").removeClass("zoom-in").addClass("zoom-out");
     $("#streams_list").show();
     $(".left-sidebar .right-sidebar-items").show();
 }
 
+export function clear_search(force_rerender = false): void {
+    const $filter = $(".direct-messages-list-filter").expectOne();
+    if ($filter.val() !== "") {
+        $filter.val("");
+        update_private_messages();
+    } else if (force_rerender) {
+        update_private_messages();
+    }
+}
+
+const throttled_update_private_message = _.throttle(update_private_messages, 50);
+
 export function initialize(): void {
     $(".direct-messages-container").on("click", "#show-more-direct-messages", (e) => {
         e.stopPropagation();
@@ -221,4 +244,18 @@ export function initialize(): void {
 
         zoom_out();
     });
+
+    $(".direct-messages-container").on("input", ".direct-messages-list-filter", (e) => {
+        e.stopPropagation();
+        e.preventDefault();
+
+        throttled_update_private_message();
+    });
+
+    $(".direct-messages-container").on("click", "#clear-direct-messages-search-button", (e) => {
+        e.stopPropagation();
+        e.preventDefault();
+
+        clear_search();
+    });
 }

web/src/pm_list_data.ts

@@ -48,7 +48,7 @@ type DisplayObject = {
     is_bot: boolean;
 };
 
-export function get_conversations(): DisplayObject[] {
+export function get_conversations(search_string = ""): DisplayObject[] {
     const conversations = pm_conversations.recent.get();
     const display_objects = [];
 
@@ -66,6 +66,16 @@ export function get_conversations(): DisplayObject[] {
 
     for (const conversation of conversations) {
         const user_ids_string = conversation.user_ids_string;
+
+        const users = people.get_users_from_ids(
+            people.user_ids_string_to_ids_array(user_ids_string),
+        );
+        if (!people.dm_matches_search_string(users, search_string)) {
+            // Skip adding the conversation to the display_objects array if it does
+            // not match the search_term.
+            continue;
+        }
+
         const reply_to = people.user_ids_string_to_emails_string(user_ids_string);
         assert(reply_to !== undefined);
         const recipients_string = people.get_recipients(user_ids_string);
@@ -110,11 +120,14 @@ export function get_conversations(): DisplayObject[] {
 }
 
 // Designed to closely match topic_list_data.get_list_info().
-export function get_list_info(zoomed: boolean): {
+export function get_list_info(
+    zoomed: boolean,
+    search_term = "",
+): {
     conversations_to_be_shown: DisplayObject[];
     more_conversations_unread_count: number;
 } {
-    const conversations = get_conversations();
+    const conversations = get_conversations(search_term);
 
     if (zoomed || conversations.length <= max_conversations_to_show) {
         return {

web/styles/left_sidebar.css

@@ -1130,6 +1130,13 @@ li.topic-list-item {
     }
 }
 
+/* Since direct-messages-sticky-header also has the `input-append`
+   class accompanying it. The display property of that class will
+   overwrite display: none if we don't have a more specific CSS
+   rule. It will also overwrite `display: none` even if `.zoom-out`
+   properties are declared after the `.input-append` properties since
+   the latter is more specific. */
+#direct-messages-sticky-header.zoom-out,
 .zoom-out {
     #topics_header {
         display: none;
@@ -1225,8 +1232,45 @@ li.topic-list-item {
            vertical centering. */
         line-height: 20px;
         white-space: nowrap;
+    }
 
-        .stream-list-filter {
+    &.hide_unread_counts {
+        .unread_count,
+        .unread_count.hide,
+        .masked_unread_count {
+            display: none;
+        }
+
+        /* When an empty unread count is hidden,
+           hide the masked unread count, too. */
+        .unread_count.hide + .masked_unread_count {
+            display: none;
+        }
+
+        .masked_unread_count {
+            display: block;
+            /* Hold space enough so single-digit
+               unreads don't shift on hover. */
+            margin: 0 3px;
+        }
+
+        &:hover {
+            .unread_count {
+                display: block;
+            }
+
+            .hide,
+            .masked_unread_count {
+                display: none;
+            }
+        }
+    }
+}
+
+.stream_search_section,
+.direct-messages-search-section {
+    .stream-list-filter,
+    .direct-messages-list-filter {
         /* Use the border-box model so flex
            can do its thing despite whatever
            padding and border we specify. */
@@ -1274,39 +1318,6 @@ li.topic-list-item {
     }
 }
 
-    &.hide_unread_counts {
-        .unread_count,
-        .unread_count.hide,
-        .masked_unread_count {
-            display: none;
-        }
-
-        /* When an empty unread count is hidden,
-           hide the masked unread count, too. */
-        .unread_count.hide + .masked_unread_count {
-            display: none;
-        }
-
-        .masked_unread_count {
-            display: block;
-            /* Hold space enough so single-digit
-               unreads don't shift on hover. */
-            margin: 0 3px;
-        }
-
-        &:hover {
-            .unread_count {
-                display: block;
-            }
-
-            .hide,
-            .masked_unread_count {
-                display: none;
-            }
-        }
-    }
-}
-
 /* Prepare an adjusted grid for the logged-out state,
    one that reassigns the vdots space to markers and
    controls. */
@@ -1415,6 +1426,13 @@ li.topic-list-item {
         }
     }
 
+    .direct-messages-search-section {
+        display: flex;
+        grid-column: row-content / markers-and-controls;
+        margin-top: 5px;
+        margin-bottom: 5px;
+    }
+
     .zoom-in-hide {
         display: none;
     }

web/templates/left_sidebar.hbs

@@ -155,6 +155,12 @@
         <a class="zoom-out-hide" id="hide-more-direct-messages">
             <span class="hide-more-direct-messages-text"> {{t 'back to channels' }}</span>
         </a>
+        <div class="zoom-out-hide direct-messages-search-section">
+            <input class="direct-messages-list-filter filter_text_input" type="text" autocomplete="off" placeholder="{{t 'Filter direct messages' }}" />
+            <button type="button" class="btn clear_search_button" id="clear-direct-messages-search-button">
+                <i class="fa fa-remove" aria-hidden="true"></i>
+            </button>
+        </div>
     </div>
     {{~!-- squash whitespace --~}}
     <div id="left_sidebar_scroll_container" class="scrolling_list" data-simplebar data-simplebar-tab-index="-1">

web/tests/pm_list_data.test.js

@@ -163,6 +163,19 @@ test("get_conversations", ({override}) => {
     set_pm_with_filter("iago@zulip.com");
     pm_data = pm_list_data.get_conversations();
     assert.deepEqual(pm_data, expected_data);
+
+    pm_data = pm_list_data.get_conversations("Ia");
+    assert.deepEqual(
+        pm_data,
+        expected_data.filter((item) => item.recipients === "Iago"),
+    );
+
+    // filter should work with email
+    pm_data = pm_list_data.get_conversations("me@zulip");
+    assert.deepEqual(
+        pm_data,
+        expected_data.filter((item) => item.recipients === "Me Myself"),
+    );
 });
 
 test("get_conversations bot", ({override}) => {