left-sidebar: Add topic filter input in zoomed topic view.

Fixes: #18505.

frontend_tests/node_tests/topic_list_data.js

@@ -16,6 +16,10 @@ const narrow_state = mock_esm("../../static/js/narrow_state", {
     topic() {},
 });
 
+const topic_list = mock_esm("../../static/js/topic_list", {
+    get_topic_search_term() {},
+});
+
 const stream_data = zrequire("stream_data");
 const stream_topic_history = zrequire("stream_topic_history");
 const topic_list_data = zrequire("topic_list_data");
@@ -50,14 +54,16 @@ test("get_list_info w/real stream_topic_history", (override) => {
         num_possible_topics: 0,
     });
 
-    for (const i of _.range(7)) {
+    function add_topic_message(topic_name, message_id) {
-        const topic_name = "topic " + i;
         stream_topic_history.add_message({
             stream_id: general.stream_id,
             topic_name,
-            message_id: 1000 + i,
+            message_id,
         });
     }
+    for (const i of _.range(7)) {
+        add_topic_message("topic " + i, 1000 + i);
+    }
 
     override(narrow_state, "topic", () => "topic 6");
 
@@ -75,12 +81,24 @@ test("get_list_info w/real stream_topic_history", (override) => {
         url: "#narrow/stream/556-general/topic/topic.206",
     });
 
-    // If we zoom in, we'll show all 7 topics.
+    // If we zoom in, our results based on topic filter.
+    // If topic search input is empty, we show all 7 topics.
+
     const zoomed = true;
+    override(topic_list, "get_topic_search_term", () => "");
     list_info = get_list_info(zoomed);
     assert.equal(list_info.items.length, 7);
     assert.equal(list_info.more_topics_unreads, 0);
     assert.equal(list_info.num_possible_topics, 7);
+
+    add_topic_message("After Brooklyn", 1008);
+    add_topic_message("Catering", 1009);
+    // when topic search is open then we list topics based on search term.
+    override(topic_list, "get_topic_search_term", () => "b,c");
+    list_info = get_list_info(zoomed);
+    assert.equal(list_info.items.length, 2);
+    assert.equal(list_info.more_topics_unreads, 0);
+    assert.equal(list_info.num_possible_topics, 2);
 });
 
 test("get_list_info unreads", (override) => {

static/js/click_handlers.js

@@ -40,6 +40,7 @@ import * as settings_toggle from "./settings_toggle";
 import * as stream_edit from "./stream_edit";
 import * as stream_list from "./stream_list";
 import * as stream_popover from "./stream_popover";
+import * as topic_list from "./topic_list";
 import * as ui_util from "./ui_util";
 import * as unread_ops from "./unread_ops";
 import * as user_status_ui from "./user_status_ui";
@@ -694,6 +695,8 @@ export function initialize() {
 
     // LEFT SIDEBAR
 
+    $("body").on("click", "#clear_search_topic_button", topic_list.clear_topic_search);
+
     $(".streams_filter_icon").on("click", (e) => {
         e.stopPropagation();
         stream_list.toggle_filter_displayed(e);

static/js/topic_list.js

@@ -1,6 +1,7 @@
 import $ from "jquery";
 import _ from "lodash";
 
+import render_filter_topics from "../templates/filter_topics.hbs";
 import render_more_topics from "../templates/more_topics.hbs";
 import render_more_topics_spinner from "../templates/more_topics_spinner.hbs";
 import render_topic_list_item from "../templates/topic_list_item.hbs";
@@ -115,12 +116,24 @@ export function spinner_li() {
     };
 }
 
+function filter_topics_li() {
+    const eq = (other) => other.filter_topics;
+
+    return {
+        key: "filter",
+        filter_topics: true,
+        render: render_filter_topics,
+        eq,
+    };
+}
+
 export class TopicListWidget {
     prior_dom = undefined;
 
     constructor(parent_elem, my_stream_id) {
         this.parent_elem = parent_elem;
         this.my_stream_id = my_stream_id;
+        this.topic_search_text = "";
     }
 
     build_list(spinner) {
@@ -141,6 +154,10 @@ export class TopicListWidget {
             nodes.push(spinner_li());
         } else if (!is_showing_all_possible_topics) {
             nodes.push(more_li(more_topics_unreads));
+        } else if (zoomed) {
+            // In the zoomed topic view, we need to add the input
+            // for filtering through list of topics.
+            nodes.unshift(filter_topics_li());
         }
 
         const dom = vdom.ul({
@@ -159,7 +176,36 @@ export class TopicListWidget {
         return this.my_stream_id;
     }
 
+    update_topic_search_text(text) {
+        this.topic_search_text = text;
+    }
+
+    update_topic_search_input() {
+        const input = this.parent_elem.find("#filter-topic-input");
+        if (input.length) {
+            // Restore topic search text saved in remove()
+            // after the element was rerendered.
+            input.val(this.topic_search_text);
+            input.trigger("focus");
+
+            // setup event handlers.
+            const rebuild_list = () => this.build();
+            input.on("input", rebuild_list);
+        }
+    }
+
     remove() {
+        // If text was present in the topic search filter, we store
+        // the input value lazily before removing old elements.  This
+        // is a workaround for the quirk that the filter input is part
+        // of the region that we rerender.
+        const input = this.parent_elem.find("#filter-topic-input");
+        if (input.length) {
+            this.update_topic_search_text(input.val());
+        } else {
+            // Clear the topic search input when zooming out.
+            this.update_topic_search_text("");
+        }
         this.parent_elem.find(".topic-list").remove();
         this.prior_dom = undefined;
     }
@@ -170,6 +216,7 @@ export class TopicListWidget {
         const replace_content = (html) => {
             this.remove();
             this.parent_elem.append(html);
+            this.update_topic_search_input();
         };
 
         const find = () => this.parent_elem.find(".topic-list");
@@ -180,6 +227,25 @@ export class TopicListWidget {
     }
 }
 
+export function clear_topic_search(e) {
+    e.stopPropagation();
+    const input = $("#filter-topic-input");
+    if (input.length) {
+        input.val("");
+        input.trigger("blur");
+
+        // Since this changes the contents of the search input, we
+        // need to rerender the topic list.
+        const stream_ids = Array.from(active_widgets.keys());
+
+        const stream_id = stream_ids[0];
+        const widget = active_widgets.get(stream_id);
+        const parent_widget = widget.get_parent();
+
+        rebuild(parent_widget, stream_id);
+    }
+}
+
 export function active_stream_id() {
     const stream_ids = Array.from(active_widgets.keys());
 
@@ -255,6 +321,14 @@ export function zoom_in() {
     stream_topic_history_util.get_server_history(stream_id, on_success);
 }
 
+export function get_topic_search_term() {
+    const filter = $("#filter-topic-input");
+    if (filter.val() === undefined) {
+        return "";
+    }
+    return filter.val().trim();
+}
+
 export function initialize() {
     $("#stream_filters").on("click", ".topic-box", (e) => {
         if (e.metaKey || e.ctrlKey) {

static/js/topic_list_data.js

@@ -2,7 +2,9 @@ import * as hash_util from "./hash_util";
 import * as muting from "./muting";
 import * as narrow_state from "./narrow_state";
 import * as stream_topic_history from "./stream_topic_history";
+import * as topic_list from "./topic_list";
 import * as unread from "./unread";
+import * as util from "./util";
 
 const max_topics = 5;
 const max_topics_with_unread = 8;
@@ -17,7 +19,11 @@ export function get_list_info(stream_id, zoomed) {
         active_topic = active_topic.toLowerCase();
     }
 
-    const topic_names = stream_topic_history.get_recent_topic_names(stream_id);
+    let topic_names = stream_topic_history.get_recent_topic_names(stream_id);
+    if (zoomed) {
+        const search_term = topic_list.get_topic_search_term();
+        topic_names = util.filter_by_word_prefix_match(topic_names, search_term, (item) => item);
+    }
 
     const items = [];
 

static/styles/app_components.css

@@ -413,6 +413,12 @@ div.overlay {
         width: calc(100% - 34px);
         margin-left: 10px;
     }
+    .input-append .topic-list-filter {
+        /* Input width = 100% - 11px margin x2 - 6px padding x2 - 1px border x2. */
+        width: calc(100% - 36px);
+        margin-left: 11px;
+        margin-bottom: 5px;
+    }
 }
 
 .stream-selection-header-colorblock {

static/styles/left_sidebar.css

@@ -100,6 +100,15 @@ li.show-more-topics {
                 padding-right: 0;
                 padding-bottom: 2px;
                 padding-left: $topic_indent;
+
+                &.filter-topics {
+                    padding-bottom: 0;
+                }
+
+                .input-append.topic_search_section {
+                    margin-bottom: 3px;
+                    margin-left: 3px;
+                }
             }
         }
     }
@@ -515,6 +524,14 @@ li.expanded_private_message {
     width: 236px;
 }
 
+.topic-list-filter {
+    /* Input width = 100% - 30px right-margin - 6px right-padding */
+    /* To keep the right edge of input along with its borders inline with other
+       topic items we consider to subtract the space given for right margin of
+       other items, and right padding of input element.  */
+    width: calc(100% - 36px);
+}
+
 .zero_count {
     visibility: hidden;
 }

static/templates/filter_topics.hbs

@@ -0,0 +1,8 @@
+<li class="topic-list-item filter-topics">
+    <div class="input-append topic_search_section">
+        <input class="topic-list-filter home-page-input" id="filter-topic-input" type="text" autocomplete="off" placeholder="{{t 'Filter topics'}}" />
+        <button type="button" class="btn clear_search_button" id="clear_search_topic_button">
+            <i class="fa fa-remove" aria-hidden="true"></i>
+        </button>
+    </div>
+</li>