text: const util = require('./util');
  const render_subscription = require('../templates/subscription.hbs');
  const render_subscription_settings = require('../templates/subscription_settings.hbs');
  const render_subscription_table_body = require('../templates/subscription_table_body.hbs');
  const render_subscriptions = require('../templates/subscriptions.hbs');
  
  exports.show_subs_pane = {
      nothing_selected: function () {
          $(".nothing-selected, #stream_settings_title").show();
          $("#add_new_stream_title, .settings, #stream-creation").hide();
      },
      settings: function () {
          $(".settings, #stream_settings_title").show();
          $("#add_new_stream_title, #stream-creation, .nothing-selected").hide();
      },
  };
  
  exports.check_button_for_sub = function (sub) {
      return $(".stream-row[data-stream-id='" + sub.stream_id + "'] .check");
  };
  
  exports.row_for_stream_id = function (stream_id) {
      return $(".stream-row[data-stream-id='" + stream_id + "']");
  };
  
  exports.settings_button_for_sub = function (sub) {
      // We don't do expectOne() here, because this button is only
      // visible if the user has that stream selected in the streams UI.
      return $(".subscription_settings[data-stream-id='" + sub.stream_id + "'] .subscribe-button");
  };
  
  function get_row_data(row) {
      const row_id = parseInt(row.attr('data-stream-id'), 10);
      if (row_id) {
          const row_object = stream_data.get_sub_by_id(row_id);
          return {
              id: row_id,
              object: row_object,
          };
      }
  }
  
  exports.get_active_data = function () {
      const active_row = $('div.stream-row.active');
      const valid_active_id = parseInt(active_row.attr('data-stream-id'), 10);
      const active_tab = $('.subscriptions-container').find('div.ind-tab.selected');
      return {
          row: active_row,
          id: valid_active_id,
          tab: active_tab,
      };
  };
  
  function get_hash_safe() {
      if (typeof window !== "undefined" && typeof window.location.hash === "string") {
          return window.location.hash.substr(1);
      }
  
      return "";
  }
  
  function selectText(element) {
      let range;
      let sel;
      if (window.getSelection) {
          sel = window.getSelection();
          range = document.createRange();
          range.selectNodeContents(element);
  
          sel.removeAllRanges();
          sel.addRange(range);
      } else if (document.body.createTextRange) {
          range = document.body.createTextRange();
          range.moveToElementText(element);
          range.select();
      }
  }
  
  function should_list_all_streams() {
      return !page_params.realm_is_zephyr_mirror_realm;
  }
  
  // this finds the stream that is actively open in the settings and focused in
  // the left side.
  exports.active_stream = function () {
      const hash_components = window.location.hash.substr(1).split(/\//);
  
      // if the string casted to a number is valid, and another component
      // after exists then it's a stream name/id pair.
      if (typeof parseFloat(hash_components[1]) === "number" && hash_components[2]) {
          return {
              id: parseFloat(hash_components[1]),
              name: hash_components[2],
          };
      }
  };
  
  exports.toggle_home = function (sub, status_element) {
      stream_muting.update_is_muted(sub, !sub.is_muted);
      stream_edit.set_stream_property(sub, 'is_muted', sub.is_muted, status_element);
  };
  
  exports.toggle_pin_to_top_stream = function (sub) {
      stream_edit.set_stream_property(sub, 'pin_to_top', !sub.pin_to_top);
  };
  
  let subscribed_only = true;
  
  exports.is_subscribed_stream_tab_active = function () {
      // Returns true if "Subscribed" tab in stream settings is open
      // otherwise false.
      return subscribed_only;
  };
  
  exports.update_stream_name = function (sub, new_name) {
      const old_name = sub.name;
  
      // Rename the stream internally.
      stream_data.rename_sub(sub, new_name);
      const stream_id = sub.stream_id;
  
      // Update the left sidebar.
      stream_list.rename_stream(sub, new_name);
  
      // Update the stream settings
      stream_edit.update_stream_name(sub, new_name);
  
      // Update the subscriptions page
      const sub_row = exports.row_for_stream_id(stream_id);
      sub_row.find(".stream-name").text(new_name);
  
      // Update the message feed.
      message_live_update.update_stream_name(stream_id, new_name);
  
      // Clear rendered typeahead cache
      typeahead_helper.clear_rendered_stream(stream_id);
  
      // Update compose_state if needed
      if (compose_state.stream_name() === old_name) {
          compose_state.stream_name(new_name);
      }
  
      // Update navbar if needed
      const filter = narrow_state.filter();
      if (filter && filter._sub && filter._sub.stream_id === sub.stream_id) {
          tab_bar.render_title_area();
      }
  };
  
  exports.update_stream_description = function (sub, description, rendered_description) {
      sub.description = description;
      sub.rendered_description = rendered_description.replace('<p>', '').replace('</p>', '');
  
      // Update stream row
      const sub_row = exports.row_for_stream_id(sub.stream_id);
      sub_row.find(".description").html(util.clean_user_content_links(sub.rendered_description));
  
      // Update stream settings
      stream_edit.update_stream_description(sub);
  
      // Update navbar if needed
      const filter = narrow_state.filter();
      if (filter && filter._sub && filter._sub.stream_id === sub.stream_id) {
          tab_bar.render_title_area();
      }
  };
  
  exports.update_stream_privacy = function (sub, values) {
      stream_data.update_stream_privacy(sub, values);
      stream_data.update_calculated_fields(sub);
  
      // Update UI elements
      stream_ui_updates.update_stream_privacy_type_icon(sub);
      stream_ui_updates.update_stream_subscription_type_text(sub);
      stream_ui_updates.update_change_stream_privacy_settings(sub);
      stream_ui_updates.update_settings_button_for_sub(sub);
      stream_ui_updates.update_subscribers_count(sub);
      stream_ui_updates.update_add_subscriptions_elements(sub);
      stream_list.redraw_stream_privacy(sub);
  
      // Update navbar if needed
      const filter = narrow_state.filter();
      if (filter && filter._sub && filter._sub.stream_id === sub.stream_id) {
          tab_bar.render_title_area();
      }
  };
  
  exports.update_stream_post_policy = function (sub, new_value) {
      stream_data.update_stream_post_policy(sub, new_value);
      stream_data.update_calculated_fields(sub);
  
      stream_ui_updates.update_stream_subscription_type_text(sub);
  };
  
  exports.update_message_retention_setting = function (sub, new_value) {
      stream_data.update_message_retention_setting(sub, new_value);
      stream_ui_updates.update_stream_subscription_type_text(sub);
  };
  
  exports.set_color = function (stream_id, color) {
      const sub = stream_data.get_sub_by_id(stream_id);
      stream_edit.set_stream_property(sub, 'color', color);
  };
  
  exports.rerender_subscriptions_settings = function (sub) {
      // This rerendes the subscriber data for a given sub object
      // where it might have already been rendered in the subscriptions UI.
      if (typeof sub === "undefined") {
          blueslip.error('Undefined sub passed to function rerender_subscriptions_settings');
          return;
      }
      stream_data.update_subscribers_count(sub);
      stream_ui_updates.update_subscribers_count(sub);
      stream_ui_updates.update_subscribers_list(sub);
  };
  
  exports.add_sub_to_table = function (sub) {
      if (exports.is_sub_already_present(sub)) {
          // If a stream is already listed/added in subscription modal,
          // display stream in `Subscribed` tab and return.
          // This can happen in some corner cases (which might
          // be backend bugs) where a realm adminsitrator is subscribed
          // to a private stream, in which case they might get two
          // stream-create events.
          stream_ui_updates.update_stream_row_in_settings_tab(sub);
          return;
      }
  
      const html = render_subscription(sub);
      const settings_html = render_subscription_settings(sub);
      if (stream_create.get_name() === sub.name) {
          ui.get_content_element($(".streams-list")).prepend(html);
          ui.reset_scrollbar($(".streams-list"));
      } else {
          ui.get_content_element($(".streams-list")).append(html);
      }
      ui.get_content_element($(".subscriptions .settings")).append($(settings_html));
  
      if (stream_create.get_name() === sub.name) {
          // This `stream_create.get_name()` check tells us whether the
          // stream was just created in this browser window; it's a hack
          // to work around the server_events code flow not having a
          // good way to associate with this request because the stream
          // ID isn't known yet.  These are appended to the top of the
          // list, so they are more visible.
          exports.row_for_stream_id(sub.stream_id).click();
          stream_create.reset_created_stream();
      }
  };
  
  exports.is_sub_already_present = function (sub) {
      // This checks if a stream is already listed the "Manage streams"
      // UI, by checking for its subscribe/unsubscribe checkmark button.
      const button = exports.check_button_for_sub(sub);
      if (button.length !== 0) {
          return true;
      }
      return false;
  };
  
  exports.remove_stream = function (stream_id) {
      // It is possible that row is empty when we deactivate a
      // stream, but we let jQuery silently handle that.
      const row = exports.row_for_stream_id(stream_id);
      row.remove();
      const sub = stream_data.get_sub_by_id(stream_id);
      if (stream_edit.is_sub_settings_active(sub)) {
          stream_edit.open_edit_panel_empty();
      }
  };
  
  exports.update_settings_for_subscribed = function (sub) {
      stream_ui_updates.update_add_subscriptions_elements(sub);
      $(".subscription_settings[data-stream-id='" + sub.stream_id + "'] #preview-stream-button").show();
  
      if (exports.is_sub_already_present(sub)) {
          stream_data.update_subscribers_count(sub);
          stream_ui_updates.update_stream_row_in_settings_tab(sub);
          stream_ui_updates.update_subscribers_count(sub, true);
          stream_ui_updates.update_check_button_for_sub(sub);
          stream_ui_updates.update_settings_button_for_sub(sub);
          stream_ui_updates.update_change_stream_privacy_settings(sub);
      } else {
          exports.add_sub_to_table(sub);
      }
  
      stream_ui_updates.update_subscribers_list(sub);
  
      // Display the swatch and subscription stream_settings
      stream_ui_updates.update_regular_sub_settings(sub);
  };
  
  exports.show_active_stream_in_left_panel = function () {
      const selected_row = get_hash_safe().split(/\//)[1];
  
      if (parseFloat(selected_row)) {
          const sub_row = exports.row_for_stream_id(selected_row);
          sub_row.addClass("active");
      }
  };
  
  exports.add_tooltips_to_left_panel = function () {
      for (const row of $("#subscriptions_table .stream-row")) {
          $(row).find('.sub-info-box [class$="-bar"] [class$="-count"]').tooltip({
              placement: 'left', animation: false,
          });
      }
  };
  
  exports.update_settings_for_unsubscribed = function (sub) {
      exports.rerender_subscriptions_settings(sub);
      stream_ui_updates.update_check_button_for_sub(sub);
      stream_ui_updates.update_settings_button_for_sub(sub);
      stream_ui_updates.update_regular_sub_settings(sub);
      stream_ui_updates.update_change_stream_privacy_settings(sub);
  
      stream_data.update_stream_email_address(sub, "");
      // If user unsubscribed from private stream then user cannot subscribe to
      // stream without invitation and cannot add subscribers to stream.
      if (!sub.should_display_subscription_button) {
          stream_ui_updates.update_add_subscriptions_elements(sub);
      }
      if (page_params.is_guest) {
          stream_edit.open_edit_panel_empty();
      }
  
      // Remove private streams from subscribed streams list.
      stream_ui_updates.update_stream_row_in_settings_tab(sub);
  };
  
  function triage_stream(query, sub) {
      if (query.subscribed_only) {
          // reject non-subscribed streams
          if (!sub.subscribed) {
              return 'rejected';
          }
      }
  
      const search_terms = search_util.get_search_terms(query.input);
  
      function match(attr) {
          const val = sub[attr];
  
          return search_util.vanilla_match({
              val: val,
              search_terms: search_terms,
          });
      }
  
      if (match('name')) {
          return 'name_match';
      }
  
      if (match('description')) {
          return 'desc_match';
      }
  
      return 'rejected';
  }
  
  function get_stream_id_buckets(stream_ids, query) {
      // When we simplify the settings UI, we can get
      // rid of the "others" bucket.
  
      const buckets = {
          name: [],
          desc: [],
          other: [],
      };
  
      for (const stream_id of stream_ids) {
          const sub = stream_data.get_sub_by_id(stream_id);
          const match_status = triage_stream(query, sub);
  
          if (match_status === 'name_match') {
              buckets.name.push(stream_id);
          } else if (match_status === 'desc_match') {
              buckets.desc.push(stream_id);
          } else {
              buckets.other.push(stream_id);
          }
      }
  
      stream_data.sort_for_stream_settings(buckets.name, query.sort_order);
      stream_data.sort_for_stream_settings(buckets.desc, query.sort_order);
  
      return buckets;
  }
  
  exports.populate_stream_settings_left_panel = function () {
      const sub_rows = stream_data.get_updated_unsorted_subs();
  
      const template_data = {
          subscriptions: sub_rows,
      };
  
      const finish = blueslip.start_timing('render_subscriptions');
      const html = render_subscriptions(template_data);
      finish();
  
      ui.get_content_element($('#subscriptions_table .streams-list')).html(html);
  };
  
  // query is now an object rather than a string.
  // Query { input: String, subscribed_only: Boolean, sort_order: String }
  exports.filter_table = function (query) {
      exports.show_active_stream_in_left_panel();
  
      function stream_id_for_row(row) {
          return parseInt($(row).attr('data-stream-id'), 10);
      }
  
      const widgets = new Map();
      const streams_list_scrolltop = ui.get_scroll_element($(".streams-list")).scrollTop();
  
      const stream_ids = [];
  
      for (const row of $("#subscriptions_table .stream-row")) {
          const stream_id = stream_id_for_row(row);
          stream_ids.push(stream_id);
      }
  
      const buckets = get_stream_id_buckets(stream_ids, query);
  
      // If we just re-built the DOM from scratch we wouldn't need
      // all this hidden/notdisplayed logic.
      const hidden_ids = new Set();
  
      for (const stream_id of buckets.other) {
          hidden_ids.add(stream_id);
      }
  
      for (const row of $("#subscriptions_table .stream-row")) {
          const stream_id = stream_id_for_row(row);
  
          // Below code goes away if we don't do sort-DOM-in-place.
          if (hidden_ids.has(stream_id)) {
              $(row).addClass('notdisplayed');
          } else {
              $(row).removeClass('notdisplayed');
          }
  
          widgets.set(stream_id, $(row).detach());
      }
  
      exports.add_tooltips_to_left_panel();
  
      ui.reset_scrollbar($("#subscription_overlay .streams-list"));
  
      const all_stream_ids = [
          ...buckets.name,
          ...buckets.desc,
          ...buckets.other,
      ];
  
      for (const stream_id of all_stream_ids) {
          ui.get_content_element($('#subscriptions_table .streams-list')).append(widgets.get(stream_id));
      }
  
      exports.maybe_reset_right_panel();
  
      // this puts the scrollTop back to what it was before the list was updated again.
      ui.get_scroll_element($(".streams-list")).scrollTop(streams_list_scrolltop);
  };
  
  let sort_order = "by-stream-name";
  
  exports.get_search_params = function () {
      const search_box = $("#stream_filter input[type='text']");
      const input = search_box.expectOne().val().trim();
      const params = {
          input: input,
          subscribed_only: subscribed_only,
          sort_order: sort_order,
      };
      return params;
  };
  
  exports.maybe_reset_right_panel = function () {
      if ($(".stream-row.active").hasClass("notdisplayed")) {
          $(".right .settings").hide();
          $(".nothing-selected").show();
          $(".stream-row.active").removeClass("active");
      }
  };
  
  exports.actually_filter_streams = function () {
      const search_params = exports.get_search_params();
      exports.filter_table(search_params);
  };
  
  const filter_streams = _.throttle(exports.actually_filter_streams, 50);
  
  // Make it explicit that our toggler is not created right away.
  exports.toggler = undefined;
  
  exports.switch_stream_tab = function (tab_name) {
      /*
          This switches the stream tab, but it doesn't update
          the toggler widget.  You may instead want to
          use `toggler.goto`.
      */
  
      if (tab_name === "all-streams") {
          subscribed_only = false;
      } else if (tab_name === "subscribed") {
          subscribed_only = true;
      }
  
      exports.actually_filter_streams();
      stream_edit.setup_subscriptions_tab_hash(tab_name);
  };
  
  exports.sort_toggler = undefined;
  exports.switch_stream_sort = function (tab_name) {
      if (tab_name === "by-stream-name"
          || tab_name === "by-subscriber-count"
          || tab_name === "by-weekly-traffic") {
          sort_order = tab_name;
      } else {
          sort_order = "by-stream-name";
      }
      exports.actually_filter_streams();
  };
  
  exports.setup_page = function (callback) {
      // We should strongly consider only setting up the page once,
      // but I am writing these comments write before a big release,
      // so it's too risky a change for now.
      //
      // The history behind setting up the page from scratch every
      // time we go into "Manage Streams" is that we used to have
      // some live-update issues, so being able to re-launch the
      // streams page is kind of a workaround for those bugs, since
      // we will re-populate the widget.
      //
      // For now, every time we go back into the widget we'll
      // continue the strategy that we re-render everything from scratch.
      // Also, we'll always go back to the "Subscribed" tab.
      function initialize_components() {
          // Sort by name by default when opening "Manage streams".
          sort_order = "by-stream-name";
          exports.sort_toggler = components.toggle({
              values: [
                  { label: `<i class="fa fa-sort-alpha-asc" title="${i18n.t("Sort by name")}"></i>`, key: "by-stream-name" },
                  { label: `<i class="fa fa-user-o" title="${i18n.t("Sort by number of subscribers")}"></i>`, key: "by-subscriber-count" },
                  { label: `<i class="fa fa-bar-chart" title="${i18n.t("Sort by estimated weekly traffic")}"></i>`, key: "by-weekly-traffic" },
              ],
              html_class: "stream_sorter_toggle",
              callback: function (value, key) {
                  exports.switch_stream_sort(key);
              },
          });
          $("#subscriptions_table .search-container").prepend(exports.sort_toggler.get());
  
          // Reset our internal state to reflect that we're initially in
          // the "Subscribed" tab if we're reopening "Manage streams".
          subscribed_only = true;
          exports.toggler = components.toggle({
              child_wants_focus: true,
              values: [
                  { label: i18n.t("Subscribed"), key: "subscribed" },
                  { label: i18n.t("All streams"), key: "all-streams" },
              ],
              callback: function (value, key) {
                  exports.switch_stream_tab(key);
              },
          });
  
          if (should_list_all_streams()) {
              const toggler_elem = exports.toggler.get();
              $("#subscriptions_table .search-container").prepend(toggler_elem);
          }
          if (page_params.is_guest) {
              exports.toggler.disable_tab('all-streams');
          }
  
          // show the "Stream settings" header by default.
          $(".display-type #stream_settings_title").show();
      }
  
      function populate_and_fill() {
  
          $('#subscriptions_table').empty();
  
          const template_data = {
              can_create_streams: page_params.can_create_streams,
              hide_all_streams: !should_list_all_streams(),
              max_name_length: page_params.stream_name_max_length,
              max_description_length: page_params.stream_description_max_length,
              is_admin: page_params.is_admin,
              stream_post_policy_values: stream_data.stream_post_policy_values,
              stream_post_policy: stream_data.stream_post_policy_values.everyone.code,
              zulip_plan_is_not_limited: page_params.zulip_plan_is_not_limited,
              realm_message_retention_setting:
                  stream_edit.get_display_text_for_realm_message_retention_setting,
              upgrade_text_for_wide_organization_logo:
                  page_params.upgrade_text_for_wide_organization_logo,
          };
  
          const rendered = render_subscription_table_body(template_data);
          $('#subscriptions_table').append(rendered);
  
          exports.populate_stream_settings_left_panel();
          initialize_components();
          exports.actually_filter_streams();
          stream_create.set_up_handlers();
  
          $("#stream_filter input[type='text']").on("input", function () {
              // Debounce filtering in case a user is typing quickly
              filter_streams();
          });
  
          $("#clear_search_stream_name").on("click", function () {
              $("#stream_filter input[type='text']").val("");
              filter_streams();
          });
  
          if (callback) {
              callback();
          }
      }
  
      populate_and_fill();
  
      if (!should_list_all_streams()) {
          $('.create_stream_button').val(i18n.t("Subscribe"));
      }
  };
  
  exports.switch_to_stream_row = function (stream_id) {
      const stream_row = exports.row_for_stream_id(stream_id);
  
      exports.get_active_data().row.removeClass("active");
      stream_row.addClass("active");
  
      scroll_util.scroll_element_into_container(stream_row, stream_row.parent());
  
      // It's dubious that we need this timeout any more.
      setTimeout(function () {
          if (stream_id === exports.get_active_data().id) {
              stream_row.click();
          }
      }, 100);
  };
  
  exports.change_state = function (section) {
      // if in #streams/new form.
      if (section === "new") {
          if (!page_params.is_guest) {
              exports.do_open_create_stream();
          } else {
              exports.toggler.goto('subscribed');
          }
          return;
      }
  
      if (section === "all") {
          exports.toggler.goto('all-streams');
          return;
      }
  
      if (section === "subscribed") {
          exports.toggler.goto('subscribed');
          return;
      }
  
      // if the section is a valid number.
      if (/\d+/.test(section)) {
          const stream_id = parseInt(section, 10);
          // Guest users can not access unsubscribed streams
          // So redirect guest users to 'subscribed' tab
          // for any unsubscribed stream settings hash
          if (page_params.is_guest && !stream_data.id_is_subscribed(stream_id)) {
              exports.toggler.goto('subscribed');
          } else {
              exports.switch_to_stream_row(stream_id);
          }
          return;
      }
  
      blueslip.warn('invalid section for streams: ' + section);
      exports.toggler.goto('subscribed');
  };
  
  exports.launch = function (section) {
      exports.setup_page(function () {
          overlays.open_overlay({
              name: 'subscriptions',
              overlay: $("#subscription_overlay"),
              on_close: function () {
                  hashchange.exit_overlay();
              },
          });
          exports.change_state(section);
      });
      if (!exports.get_active_data().id) {
          $('#search_stream_name').focus();
      }
  };
  
  exports.switch_rows = function (event) {
      const active_data = exports.get_active_data();
      let switch_row;
      if (window.location.hash === '#streams/new') {
          // Prevent switching stream rows when creating a new stream
          return false;
      } else if (!active_data.id || active_data.row.hasClass('notdisplayed')) {
          switch_row = $('div.stream-row:not(.notdisplayed)').first();
          if ($('#search_stream_name').is(":focus")) {
              $('#search_stream_name').blur();
          }
      } else {
          if (event === 'up_arrow') {
              switch_row = active_data.row.prevAll().not('.notdisplayed').first();
          } else if (event === 'down_arrow') {
              switch_row = active_data.row.nextAll().not('.notdisplayed').first();
          }
          if ($('#search_stream_name').is(":focus")) {
              // remove focus from Filter streams input instead of switching rows
              // if Filter streams input is focused
              return $('#search_stream_name').blur();
          }
      }
  
      const row_data = get_row_data(switch_row);
      if (row_data) {
          const stream_id = row_data.id;
          exports.switch_to_stream_row(stream_id);
      } else if (event === 'up_arrow' && !row_data) {
          $('#search_stream_name').focus();
      }
      return true;
  };
  
  exports.keyboard_sub = function () {
      const active_data = exports.get_active_data();
      const row_data = get_row_data(active_data.row);
      if (row_data) {
          exports.sub_or_unsub(row_data.object);
          if (row_data.object.subscribed && active_data.tab.text() === 'Subscribed') {
              active_data.row.addClass('notdisplayed');
              active_data.row.removeClass('active');
          }
      }
  };
  
  exports.toggle_view = function (event) {
      const active_data = exports.get_active_data();
  
      if (event === 'right_arrow' && active_data.tab.text() === 'Subscribed') {
          exports.toggler.goto('all-streams');
      } else if (event === 'left_arrow' && active_data.tab.text() === 'All streams') {
          exports.toggler.goto('subscribed');
      }
  };
  
  exports.view_stream = function () {
      const active_data = exports.get_active_data();
      const row_data = get_row_data(active_data.row);
      if (row_data) {
          const stream_narrow_hash = '#narrow/stream/' + hash_util.encode_stream_name(row_data.object.name);
          hashchange.go_to_location(stream_narrow_hash);
      }
  };
  
  /* For the given stream_row, remove the tick and replace by a spinner. */
  function display_subscribe_toggle_spinner(stream_row) {
      /* Prevent sending multiple requests by removing the button class. */
      $(stream_row).removeClass("sub_unsub_button");
  
      /* Hide the tick. */
      const tick = $(stream_row).find("svg");
      tick.addClass("hide");
  
      /* Add a spinner to show the request is in process. */
      const spinner = $(stream_row).find(".sub_unsub_status").expectOne();
      spinner.show();
      loading.make_indicator(spinner);
  }
  
  /* For the given stream_row, add the tick and delete the spinner. */
  function hide_subscribe_toggle_spinner(stream_row) {
      /* Re-enable the button to handle requests. */
      $(stream_row).addClass("sub_unsub_button");
  
      /* Show the tick. */
      const tick = $(stream_row).find("svg");
      tick.removeClass("hide");
  
      /* Destroy the spinner. */
      const spinner = $(stream_row).find(".sub_unsub_status").expectOne();
      loading.destroy_indicator(spinner);
  }
  
  function ajaxSubscribe(stream, color, stream_row) {
      // Subscribe yourself to a single stream.
      let true_stream_name;
  
      if (stream_row !== undefined) {
          display_subscribe_toggle_spinner(stream_row);
      }
      return channel.post({
          url: "/json/users/me/subscriptions",
          data: {subscriptions: JSON.stringify([{name: stream, color: color}]) },
          success: function (resp, statusText, xhr) {
              if (overlays.streams_open()) {
                  $("#create_stream_name").val("");
              }
  
              const res = JSON.parse(xhr.responseText);
              if (!$.isEmptyObject(res.already_subscribed)) {
                  // Display the canonical stream capitalization.
                  true_stream_name = res.already_subscribed[people.my_current_email()][0];
                  ui_report.success(i18n.t("Already subscribed to __stream__", {stream: true_stream_name}),
                                    $(".stream_change_property_info"));
              }
              // The rest of the work is done via the subscribe event we will get
  
              if (stream_row !== undefined) {
                  hide_subscribe_toggle_spinner(stream_row);
              }
          },
          error: function (xhr) {
              if (stream_row !== undefined) {
                  hide_subscribe_toggle_spinner(stream_row);
              }
              ui_report.error(i18n.t("Error adding subscription"), xhr,
                              $(".stream_change_property_info"));
          },
      });
  }
  
  function ajaxUnsubscribe(sub, stream_row) {
      // TODO: use stream_id when backend supports it
      if (stream_row !== undefined) {
          display_subscribe_toggle_spinner(stream_row);
      }
      return channel.del({
          url: "/json/users/me/subscriptions",
          data: {subscriptions: JSON.stringify([sub.name]) },
          success: function () {
              $(".stream_change_property_info").hide();
              // The rest of the work is done via the unsubscribe event we will get
  
              if (stream_row !== undefined) {
                  hide_subscribe_toggle_spinner(stream_row);
              }
          },
          error: function (xhr) {
              if (stream_row !== undefined) {
                  hide_subscribe_toggle_spinner(stream_row);
              }
              ui_report.error(i18n.t("Error removing subscription"), xhr,
                              $(".stream_change_property_info"));
          },
      });
  }
  
  exports.do_open_create_stream = function () {
      // Only call this directly for hash changes.
      // Prefer open_create_stream().
  
      const stream = $.trim($("#search_stream_name").val());
  
      if (!should_list_all_streams()) {
          // Realms that don't allow listing streams should simply be subscribed to.
          stream_create.set_name(stream);
          ajaxSubscribe($("#search_stream_name").val());
          return;
      }
  
      stream_create.new_stream_clicked(stream);
  };
  
  exports.open_create_stream = function () {
      exports.do_open_create_stream();
      hashchange.update_browser_history('#streams/new');
  };
  
  
  exports.sub_or_unsub = function (sub, stream_row) {
      if (sub.subscribed) {
          ajaxUnsubscribe(sub, stream_row);
      } else {
          ajaxSubscribe(sub.name, sub.color, stream_row);
      }
  };
  
  
  exports.initialize = function () {
      $("#subscriptions_table").on("click", ".create_stream_button", function (e) {
          e.preventDefault();
          exports.open_create_stream();
      });
  
      $(".subscriptions").on("click", "[data-dismiss]", function (e) {
          e.preventDefault();
          // we want to make sure that the click is not just a simulated
          // click; this fixes an issue where hitting "enter" would
          // trigger this code path due to bootstrap magic.
          if (e.clientY !== 0) {
              exports.show_subs_pane.nothing_selected();
          }
      });
  
      $("body").on("mouseover", ".subscribed-button", function (e) {
          $(e.target).addClass("btn-danger").text(i18n.t("Unsubscribe"));
      }).on("mouseout", ".subscribed-button", function (e) {
          $(e.target).removeClass("btn-danger").text(i18n.t("Subscribed"));
      });
  
      $("#subscriptions_table").on("click", ".email-address", function () {
          selectText(this);
      });
  
      $('.empty_feed_sub_unsub').click(function (e) {
          e.preventDefault();
  
          $('#subscription-status').hide();
          const stream_name = narrow_state.stream();
          if (stream_name === undefined) {
              return;
          }
          const sub = stream_data.get_sub(stream_name);
          exports.sub_or_unsub(sub);
  
          $('.empty_feed_notice').hide();
          $('#empty_narrow_message').show();
      });
  
      $("#subscriptions_table").on("click", ".stream-row, .create_stream_button", function () {
          $(".right").addClass("show");
          $(".subscriptions-header").addClass("slide-left");
      });
  
      $("#subscriptions_table").on("click", ".fa-chevron-left", function () {
          $(".right").removeClass("show");
          $(".subscriptions-header").removeClass("slide-left");
      });
  
      (function defocus_sub_settings() {
          const sel = ".search-container, .streams-list, .subscriptions-header";
  
          $("#subscriptions_table").on("click", sel, function (e) {
              if ($(e.target).is(sel)) {
                  stream_edit.open_edit_panel_empty();
              }
          });
      }());
  
  };
  
  window.subs = exports;
  