FEATURE: Generic hashtag autocomplete part 1 (#18592)

This commit adds a new `/hashtag/search` endpoint and both
relevant JS and ruby plugin APIs to handle plugins adding their
own data sources and priority orders for types of things to search
when `#` is pressed.

A `context` param is added to `setupHashtagAutocomplete` which
a corresponding chat PR https://github.com/discourse/discourse-chat/pull/1302
will now use.

The UI calls `registerHashtagSearchParam` for each context that will
require a `#` search (e.g. the topic composer), for each type of record that
the context needs to search for, as well as a priority order for that type. Core
uses this call to add the `category` and `tag` data sources to the topic composer.

The `register_hashtag_data_source` ruby plugin API call is for plugins to
add a new data source for the hashtag searching endpoint, e.g. discourse-chat
may add a `channel` data source.

This functionality is hidden behind the `enable_experimental_hashtag_autocomplete`
flag, except for the change to `setupHashtagAutocomplete` since only core and
discourse-chat are using that function. Note this PR does **not** include required
changes for hashtag lookup or new styling.

app/assets/javascripts/discourse/app/components/d-editor.js

@@ -462,10 +462,15 @@ export default Component.extend(TextareaTextManipulation, {
   },
 
   _applyCategoryHashtagAutocomplete() {
-    setupHashtagAutocomplete(this._$textarea, this.siteSettings, (value) => {
-      this.set("value", value);
-      schedule("afterRender", this, this.focusTextArea);
-    });
+    setupHashtagAutocomplete(
+      "topic-composer",
+      this._$textarea,
+      this.siteSettings,
+      (value) => {
+        this.set("value", value);
+        schedule("afterRender", this, this.focusTextArea);
+      }
+    );
   },
 
   _applyEmojiAutocomplete($textarea) {

app/assets/javascripts/discourse/app/initializers/composer-hashtag-autocomplete.js

@@ -0,0 +1,16 @@
+import { withPluginApi } from "discourse/lib/plugin-api";
+
+export default {
+  name: "composer-hashtag-autocomplete",
+
+  initialize(container) {
+    const siteSettings = container.lookup("service:site-settings");
+
+    withPluginApi("1.4.0", (api) => {
+      if (siteSettings.enable_experimental_hashtag_autocomplete) {
+        api.registerHashtagSearchParam("category", "topic-composer", 100);
+        api.registerHashtagSearchParam("tag", "topic-composer", 50);
+      }
+    });
+  },
+};

app/assets/javascripts/discourse/app/lib/category-hashtags.js

@@ -1,9 +1,7 @@
+import { hashtagTriggerRule } from "discourse/lib/hashtag-autocomplete";
+import deprecated from "discourse-common/lib/deprecated";
+
 export const SEPARATOR = ":";
-import {
-  caretPosition,
-  caretRowCol,
-  inCodeBlock,
-} from "discourse/lib/utilities";
 
 export function replaceSpan($elem, categorySlug, categoryLink, type) {
   type = type ? ` data-type="${type}"` : "";
@@ -13,29 +11,12 @@ export function replaceSpan($elem, categorySlug, categoryLink, type) {
 }
 
 export function categoryHashtagTriggerRule(textarea, opts) {
-  const result = caretRowCol(textarea);
-  const row = result.rowNum;
-  let col = result.colNum;
-  let line = textarea.value.split("\n")[row - 1];
-
-  if (opts && opts.backSpace) {
-    col = col - 1;
-    line = line.slice(0, line.length - 1);
-
-    // Don't trigger autocomplete when backspacing into a `#category |` => `#category|`
-    if (/^#{1}\w+/.test(line)) {
-      return false;
+  deprecated(
+    "categoryHashtagTriggerRule is being replaced by hashtagTriggerRule and the new hashtag-autocomplete plugin APIs",
+    {
+      since: "2.9.0.beta10",
+      dropFrom: "3.0.0.beta1",
     }
-  }
-
-  // Don't trigger autocomplete when ATX-style headers are used
-  if (col < 6 && line.slice(0, col) === "#".repeat(col)) {
-    return false;
-  }
-
-  if (inCodeBlock(textarea.value, caretPosition(textarea))) {
-    return false;
-  }
-
-  return true;
+  );
+  return hashtagTriggerRule(textarea, opts);
 }

app/assets/javascripts/discourse/app/lib/hashtag-autocomplete.js

@@ -1,39 +1,81 @@
 import { findRawTemplate } from "discourse-common/lib/raw-templates";
-
-// TODO: (martin) Make a more generic version of these functions.
-import { categoryHashtagTriggerRule } from "discourse/lib/category-hashtags";
+import discourseLater from "discourse-common/lib/later";
+import { INPUT_DELAY, isTesting } from "discourse-common/config/environment";
+import { cancel } from "@ember/runloop";
+import { CANCELLED_STATUS } from "discourse/lib/autocomplete";
+import { ajax } from "discourse/lib/ajax";
+import discourseDebounce from "discourse-common/lib/debounce";
+import {
+  caretPosition,
+  caretRowCol,
+  inCodeBlock,
+} from "discourse/lib/utilities";
 import { search as searchCategoryTag } from "discourse/lib/category-tag-search";
 
 export function setupHashtagAutocomplete(
+  context,
   $textArea,
   siteSettings,
   afterComplete
 ) {
   if (siteSettings.enable_experimental_hashtag_autocomplete) {
-    _setupExperimental($textArea, siteSettings, afterComplete);
+    _setupExperimental(context, $textArea, siteSettings, afterComplete);
   } else {
     _setup($textArea, siteSettings, afterComplete);
   }
 }
 
-function _setupExperimental($textArea, siteSettings, afterComplete) {
+const contextBasedParams = {};
+
+export function registerHashtagSearchParam(param, context, priority) {
+  if (!contextBasedParams[context]) {
+    contextBasedParams[context] = {};
+  }
+  contextBasedParams[context][param] = priority;
+}
+
+export function hashtagTriggerRule(textarea, opts) {
+  const result = caretRowCol(textarea);
+  const row = result.rowNum;
+  let col = result.colNum;
+  let line = textarea.value.split("\n")[row - 1];
+
+  if (opts && opts.backSpace) {
+    col = col - 1;
+    line = line.slice(0, line.length - 1);
+
+    // Don't trigger autocomplete when backspacing into a `#category |` => `#category|`
+    if (/^#{1}\w+/.test(line)) {
+      return false;
+    }
+  }
+
+  // Don't trigger autocomplete when ATX-style headers are used
+  if (col < 6 && line.slice(0, col) === "#".repeat(col)) {
+    return false;
+  }
+
+  if (inCodeBlock(textarea.value, caretPosition(textarea))) {
+    return false;
+  }
+
+  return true;
+}
+
+function _setupExperimental(context, $textArea, siteSettings, afterComplete) {
   $textArea.autocomplete({
     template: findRawTemplate("hashtag-autocomplete"),
     key: "#",
     afterComplete,
     treatAsTextarea: $textArea[0].tagName === "INPUT",
-    transformComplete: (obj) => {
-      return obj.text;
-    },
+    transformComplete: (obj) => obj.ref,
     dataSource: (term) => {
       if (term.match(/\s/)) {
         return null;
       }
-      return searchCategoryTag(term, siteSettings);
-    },
-    triggerRule: (textarea, opts) => {
-      return categoryHashtagTriggerRule(textarea, opts);
+      return _searchGeneric(term, siteSettings, context);
     },
+    triggerRule: (textarea, opts) => hashtagTriggerRule(textarea, opts),
   });
 }
 
@@ -42,17 +84,78 @@ function _setup($textArea, siteSettings, afterComplete) {
     template: findRawTemplate("category-tag-autocomplete"),
     key: "#",
     afterComplete,
-    transformComplete: (obj) => {
-      return obj.text;
-    },
+    transformComplete: (obj) => obj.text,
     dataSource: (term) => {
       if (term.match(/\s/)) {
         return null;
       }
       return searchCategoryTag(term, siteSettings);
     },
-    triggerRule: (textarea, opts) => {
-      return categoryHashtagTriggerRule(textarea, opts);
-    },
+    triggerRule: (textarea, opts) => hashtagTriggerRule(textarea, opts),
   });
 }
+
+let searchCache = {};
+let searchCacheTime;
+let currentSearch;
+
+function _updateSearchCache(term, results) {
+  searchCache[term] = results;
+  searchCacheTime = new Date();
+  return results;
+}
+
+function _searchGeneric(term, siteSettings, context) {
+  if (currentSearch) {
+    currentSearch.abort();
+    currentSearch = null;
+  }
+  if (new Date() - searchCacheTime > 30000) {
+    searchCache = {};
+  }
+  const cached = searchCache[term];
+  if (cached) {
+    return cached;
+  }
+
+  return new Promise((resolve) => {
+    let timeoutPromise = isTesting()
+      ? null
+      : discourseLater(() => {
+          resolve(CANCELLED_STATUS);
+        }, 5000);
+
+    if (term === "") {
+      return resolve(CANCELLED_STATUS);
+    }
+
+    const debouncedSearch = (q, ctx, resultFunc) => {
+      discourseDebounce(this, _searchRequest, q, ctx, resultFunc, INPUT_DELAY);
+    };
+
+    debouncedSearch(term, context, (result) => {
+      cancel(timeoutPromise);
+      resolve(_updateSearchCache(term, result));
+    });
+  });
+}
+
+function _searchRequest(term, context, resultFunc) {
+  currentSearch = ajax("/hashtags/search.json", {
+    data: { term, order: _sortedContextParams(context) },
+  });
+  currentSearch
+    .then((r) => {
+      resultFunc(r.results || CANCELLED_STATUS);
+    })
+    .finally(() => {
+      currentSearch = null;
+    });
+  return currentSearch;
+}
+
+function _sortedContextParams(context) {
+  return Object.entries(contextBasedParams[context])
+    .sort((a, b) => b[1] - a[1])
+    .map((item) => item[0]);
+}

app/assets/javascripts/discourse/app/lib/plugin-api.js

@@ -104,6 +104,7 @@ import DiscourseURL from "discourse/lib/url";
 import { registerNotificationTypeRenderer } from "discourse/lib/notification-types-manager";
 import { registerUserMenuTab } from "discourse/lib/user-menu/tab";
 import { registerModelTransformer } from "discourse/lib/model-transformers";
+import { registerHashtagSearchParam } from "discourse/lib/hashtag-autocomplete";
 
 // If you add any methods to the API ensure you bump up the version number
 // based on Semantic Versioning 2.0.0. Please update the changelog at
@@ -1981,6 +1982,35 @@ class PluginApi {
   registerModelTransformer(modelName, transformer) {
     registerModelTransformer(modelName, transformer);
   }
+
+  /**
+   * EXPERIMENTAL. Do not use.
+   *
+   * When initiating a search inside the composer or other designated inputs
+   * with the `#` key, we search records based on params registered with
+   * this function, and order them by type using the priority here. Since
+   * there can be many different inputs that use `#` and some may need to
+   * weight different types higher in priority, we also require a context
+   * parameter.
+   *
+   * For example, the topic composer may wish to search for categories
+   * and tags, with categories appearing first in the results. The usage
+   * looks like this:
+   *
+   * api.registerHashtagSearchParam("category", "topic-composer", 100);
+   * api.registerHashtagSearchParam("tag", "topic-composer", 50);
+   *
+   * Additional types of records used for the hashtag search results
+   * can be registered via the #register_hashtag_data_source plugin API
+   * method.
+   *
+   * @param {string} param - The type of record to be fetched.
+   * @param {string} context - Where the hashtag search is being initiated using `#`
+   * @param {number} priority - Used for ordering types of records. Priority order is descending.
+   */
+  registerHashtagSearchParam(param, context, priority) {
+    registerHashtagSearchParam(param, context, priority);
+  }
 }
 
 // from http://stackoverflow.com/questions/6832596/how-to-compare-software-version-number-using-js-only-number

app/assets/javascripts/discourse/app/templates/hashtag-autocomplete.hbr

@@ -1,12 +1,8 @@
 <div class='autocomplete hashtag-autocomplete'>
   <ul>
     {{#each options as |option|}}
-      <li>
-        {{#if option.model}}
-          <a href>{{category-link option.model allowUncategorized="true" link="false"}}</a>
-        {{else}}
-          <a href>{{d-icon 'tag'}}{{option.name}} x {{option.count}}</a>
-        {{/if}}
+      <li class="hashtag-autocomplete__option">
+        <a class="hashtag-autocomplete__link" href>{{d-icon option.icon}}<span class="hashtag-autocomplete__text">{{option.text}}</span></a>
       </li>
     {{/each}}
   </ul>

app/assets/stylesheets/common/base/tagging.scss

@@ -191,7 +191,7 @@ header .discourse-tag {
   }
 }
 
-.autocomplete {
+.autocomplete.ac-category-or-tag {
   a {
     color: var(--primary-medium);
   }
@@ -203,6 +203,24 @@ header .discourse-tag {
   }
 }
 
+.hashtag-autocomplete {
+  .hashtag-autocomplete__option {
+    .hashtag-autocomplete__link {
+      align-items: center;
+      color: var(--primary-medium);
+      display: flex;
+
+      .d-icon {
+        padding-right: 0.5em;
+      }
+
+      .hashtag-autocomplete__text {
+        flex: 1;
+      }
+    }
+  }
+}
+
 .tags-admin-menu {
   margin-top: 20px;
   ul {

app/controllers/hashtags_controller.rb

@@ -3,46 +3,18 @@
 class HashtagsController < ApplicationController
   requires_login
 
-  HASHTAGS_PER_REQUEST = 20
-
   def show
     raise Discourse::InvalidParameters.new(:slugs) if !params[:slugs].is_a?(Array)
+    render json: HashtagAutocompleteService.new(guardian).lookup(params[:slugs])
+  end
 
-    all_slugs = []
-    tag_slugs = []
+  def search
+    params.require(:term)
+    params.require(:order)
+    raise Discourse::InvalidParameters.new(:order) if !params[:order].is_a?(Array)
 
-    params[:slugs][0..HASHTAGS_PER_REQUEST].each do |slug|
-      if slug.end_with?(PrettyText::Helpers::TAG_HASHTAG_POSTFIX)
-        tag_slugs << slug.chomp(PrettyText::Helpers::TAG_HASHTAG_POSTFIX)
-      else
-        all_slugs << slug
-      end
-    end
+    results = HashtagAutocompleteService.new(guardian).search(params[:term], params[:order])
 
-    # Try to resolve hashtags as categories first
-    category_slugs_and_ids = all_slugs.map { |slug| [slug, Category.query_from_hashtag_slug(slug)&.id] }.to_h
-    category_ids_and_urls = Category
-      .secured(guardian)
-      .select(:id, :slug, :parent_category_id) # fields required for generating category URL
-      .where(id: category_slugs_and_ids.values)
-      .map { |c| [c.id, c.url] }
-      .to_h
-    categories_hashtags = {}
-    category_slugs_and_ids.each do |slug, id|
-      if category_url = category_ids_and_urls[id]
-        categories_hashtags[slug] = category_url
-      end
-    end
-
-    # Resolve remaining hashtags as tags
-    tag_hashtags = {}
-    if SiteSetting.tagging_enabled
-      tag_slugs += (all_slugs - categories_hashtags.keys)
-      DiscourseTagging.filter_visible(Tag.where_name(tag_slugs), guardian).each do |tag|
-        tag_hashtags[tag.name] = tag.full_url
-      end
-    end
-
-    render json: { categories: categories_hashtags, tags: tag_hashtags }
+    render json: success_json.merge(results: results)
   end
 end

app/services/hashtag_autocomplete_service.rb

@@ -0,0 +1,192 @@
+# frozen_string_literal: true
+
+class HashtagAutocompleteService
+  HASHTAGS_PER_REQUEST = 20
+
+  attr_reader :guardian
+  cattr_reader :data_sources
+
+  def self.register_data_source(type, &block)
+    @@data_sources[type] = block
+  end
+
+  def self.clear_data_sources
+    @@data_sources = {}
+
+    register_data_source("category") do |guardian, term, limit|
+      guardian_categories = Site.new(guardian).categories
+
+      guardian_categories
+        .select { |category| category[:name].downcase.include?(term) }
+        .take(limit)
+        .map do |category|
+          HashtagItem.new.tap do |item|
+            item.text = category[:name]
+            item.slug = category[:slug]
+
+            # Single-level category heirarchy should be enough to distinguish between
+            # categories here.
+            item.ref =
+              if category[:parent_category_id]
+                parent_category =
+                  guardian_categories.find { |c| c[:id] === category[:parent_category_id] }
+                category[:slug] if !parent_category
+
+                parent_slug = parent_category[:slug]
+                "#{parent_slug}:#{category[:slug]}"
+              else
+                category[:slug]
+              end
+            item.icon = "folder"
+          end
+        end
+    end
+
+    register_data_source("tag") do |guardian, term, limit|
+      if SiteSetting.tagging_enabled
+        tags_with_counts, _ =
+          DiscourseTagging.filter_allowed_tags(
+            guardian,
+            term: term,
+            with_context: true,
+            limit: limit,
+            for_input: true,
+          )
+        TagsController
+          .tag_counts_json(tags_with_counts)
+          .take(limit)
+          .map do |tag|
+            HashtagItem.new.tap do |item|
+              item.text = "#{tag[:name]} x #{tag[:count]}"
+              item.slug = tag[:name]
+              item.icon = "tag"
+            end
+          end
+      else
+        []
+      end
+    end
+  end
+
+  clear_data_sources
+
+  class HashtagItem
+    # The text to display in the UI autocomplete menu for the item.
+    attr_accessor :text
+
+    # Canonical slug for the item. Different from the ref, which can
+    # have the type as a suffix to distinguish between conflicts.
+    attr_accessor :slug
+
+    # The icon to display in the UI autocomplete menu for the item.
+    attr_accessor :icon
+
+    # Distinguishes between different entities e.g. tag, category.
+    attr_accessor :type
+
+    # Inserted into the textbox when an autocomplete item is selected,
+    # and must be unique so it can be used for lookups via the #lookup
+    # method above.
+    attr_accessor :ref
+  end
+
+  def initialize(guardian)
+    @guardian = guardian
+  end
+
+  def lookup(slugs)
+    raise Discourse::InvalidParameters.new(:slugs) if !slugs.is_a?(Array)
+
+    all_slugs = []
+    tag_slugs = []
+
+    slugs[0..HashtagAutocompleteService::HASHTAGS_PER_REQUEST].each do |slug|
+      if slug.end_with?(PrettyText::Helpers::TAG_HASHTAG_POSTFIX)
+        tag_slugs << slug.chomp(PrettyText::Helpers::TAG_HASHTAG_POSTFIX)
+      else
+        all_slugs << slug
+      end
+    end
+
+    # Try to resolve hashtags as categories first
+    category_slugs_and_ids =
+      all_slugs.map { |slug| [slug, Category.query_from_hashtag_slug(slug)&.id] }.to_h
+    category_ids_and_urls =
+      Category
+        .secured(guardian)
+        .select(:id, :slug, :parent_category_id) # fields required for generating category URL
+        .where(id: category_slugs_and_ids.values)
+        .map { |c| [c.id, c.url] }
+        .to_h
+    categories_hashtags = {}
+    category_slugs_and_ids.each do |slug, id|
+      if category_url = category_ids_and_urls[id]
+        categories_hashtags[slug] = category_url
+      end
+    end
+
+    # Resolve remaining hashtags as tags
+    tag_hashtags = {}
+    if SiteSetting.tagging_enabled
+      tag_slugs += (all_slugs - categories_hashtags.keys)
+      DiscourseTagging
+        .filter_visible(Tag.where_name(tag_slugs), guardian)
+        .each { |tag| tag_hashtags[tag.name] = tag.full_url }
+    end
+
+    { categories: categories_hashtags, tags: tag_hashtags }
+  end
+
+  def search(term, types_in_priority_order, limit = 5)
+    raise Discourse::InvalidParameters.new(:order) if !types_in_priority_order.is_a?(Array)
+
+    results = []
+    slugs_by_type = {}
+    term = term.downcase
+    types_in_priority_order =
+      types_in_priority_order.select { |type| @@data_sources.keys.include?(type) }
+
+    types_in_priority_order.each do |type|
+      data = @@data_sources[type].call(guardian, term, limit - results.length)
+      next if data.empty?
+
+      all_data_items_valid = data.all? do |item|
+        item.kind_of?(HashtagItem) && item.slug.present? && item.text.present?
+      end
+      next if !all_data_items_valid
+
+      data.each do |item|
+        item.type = type
+        item.ref = item.ref || item.slug
+      end
+      slugs_by_type[type] = data.map(&:slug)
+
+      results.concat(data)
+
+      break if results.length >= limit
+    end
+
+    # Any items that are _not_ the top-ranked type (which could possibly not be
+    # the same as the first item in the types_in_priority_order if there was
+    # no data for that type) that have conflicting slugs with other items for
+    # other types need to have a ::type suffix added to their ref.
+    #
+    # This will be used for the lookup method above if one of these items is
+    # chosen in the UI, otherwise there is no way to determine whether a hashtag is
+    # for a category or a tag etc.
+    #
+    # For example, if there is a category with the slug #general and a tag
+    # with the slug #general, then the tag will have its ref changed to #general::tag
+    top_ranked_type = slugs_by_type.keys.first
+    results.each do |hashtag_item|
+      next if hashtag_item.type == top_ranked_type
+
+      other_slugs = results.reject { |r| r.type === hashtag_item.type }.map(&:slug)
+      if other_slugs.include?(hashtag_item.slug)
+        hashtag_item.ref = "#{hashtag_item.slug}::#{hashtag_item.type}"
+      end
+    end
+
+    results.take(limit)
+  end
+end

config/routes.rb

@@ -771,6 +771,7 @@ Discourse::Application.routes.draw do
     end
 
     get "hashtags" => "hashtags#show"
+    get "hashtags/search" => "hashtags#search"
 
     TopTopic.periods.each do |period|
       get "top/#{period}.rss", to: redirect("top.rss?period=#{period}", status: 301)

lib/plugin/instance.rb

@@ -1086,6 +1086,16 @@ class Plugin::Instance
     About.add_plugin_stat_group(plugin_stat_group_name, show_in_ui: show_in_ui, &block)
   end
 
+  # Registers a new record type to be searched via the HashtagAutocompleteService and the
+  # /hashtags/search endpoint. The data returned by the block must be an array
+  # with each item an instance of HashtagAutocompleteService::HashtagItem.
+  #
+  # See also registerHashtagSearchParam in the plugin JS API, otherwise the
+  # clientside hashtag search code will use the new type registered here.
+  def register_hashtag_data_source(type, &block)
+    HashtagAutocompleteService.register_data_source(type, &block)
+  end
+
   protected
 
   def self.js_path

spec/rails_helper.rb

@@ -155,6 +155,9 @@ module TestSetup
     # Make sure the default Post and Topic bookmarkables are registered
     Bookmark.reset_bookmarkables
 
+    # Make sure only the default category and tag hashtag data sources are registered.
+    HashtagAutocompleteService.clear_data_sources
+
     OmniAuth.config.test_mode = false
   end
 end

spec/services/hashtag_autocomplete_service_spec.rb

@@ -0,0 +1,133 @@
+# frozen_string_literal: true
+
+RSpec.describe HashtagAutocompleteService do
+  fab!(:user) { Fabricate(:user) }
+  fab!(:category1) { Fabricate(:category, name: "Book Club", slug: "book-club") }
+  fab!(:tag1) { Fabricate(:tag, name: "great-books") }
+  let(:guardian) { Guardian.new(user) }
+
+  subject { described_class.new(guardian) }
+
+  before { Site.clear_cache }
+
+  def register_bookmark_data_source
+    HashtagAutocompleteService.register_data_source("bookmark") do |guardian_scoped, term, limit|
+      guardian_scoped
+        .user
+        .bookmarks
+        .where("name ILIKE ?", "%#{term}%")
+        .limit(limit)
+        .map do |bm|
+          HashtagAutocompleteService::HashtagItem.new.tap do |item|
+            item.text = bm.name
+            item.slug = bm.name.gsub(" ", "-")
+            item.icon = "bookmark"
+          end
+        end
+    end
+  end
+
+  describe "#search" do
+    it "returns search results for tags and categories by default" do
+      expect(subject.search("book", %w[category tag]).map(&:text)).to eq(
+        ["Book Club", "great-books x 0"],
+      )
+    end
+
+    it "respects the types_in_priority_order param" do
+      expect(subject.search("book", %w[tag category]).map(&:text)).to eq(
+        ["great-books x 0", "Book Club"],
+      )
+    end
+
+    it "respects the limit param" do
+      expect(subject.search("book", %w[tag category], 1).map(&:text)).to eq(["great-books x 0"])
+    end
+
+    it "includes the tag count" do
+      tag1.update!(topic_count: 78)
+      expect(subject.search("book", %w[tag category], 1).map(&:text)).to eq(["great-books x 78"])
+    end
+
+    it "does case-insensitive search" do
+      expect(subject.search("book", %w[category tag]).map(&:text)).to eq(
+        ["Book Club", "great-books x 0"],
+      )
+      expect(subject.search("bOOk", %w[category tag]).map(&:text)).to eq(
+        ["Book Club", "great-books x 0"],
+      )
+    end
+
+    it "does not include categories the user cannot access" do
+      category1.update!(read_restricted: true)
+      expect(subject.search("book", %w[tag category]).map(&:text)).to eq(["great-books x 0"])
+    end
+
+    it "does not include tags the user cannot access" do
+      Fabricate(:tag_group, permissions: { "staff" => 1 }, tag_names: ["great-books"])
+      expect(subject.search("book", %w[tag]).map(&:text)).to be_empty
+    end
+
+    it "does not search other data sources if the limit is reached by earlier type data sources" do
+      Site.any_instance.expects(:categories).never
+      subject.search("book", %w[tag category], 1)
+    end
+
+    it "includes other data sources" do
+      Fabricate(:bookmark, user: user, name: "read review of this fantasy book")
+      Fabricate(:bookmark, user: user, name: "cool rock song")
+      guardian.user.reload
+
+      HashtagAutocompleteService.register_data_source("bookmark") do |guardian_scoped, term, limit|
+        guardian_scoped
+          .user
+          .bookmarks
+          .where("name ILIKE ?", "%#{term}%")
+          .limit(limit)
+          .map do |bm|
+            HashtagAutocompleteService::HashtagItem.new.tap do |item|
+              item.text = bm.name
+              item.slug = bm.name.dasherize
+              item.icon = "bookmark"
+            end
+          end
+      end
+
+      expect(subject.search("book", %w[category tag bookmark]).map(&:text)).to eq(
+        ["Book Club", "great-books x 0", "read review of this fantasy book"],
+      )
+    end
+
+    it "handles refs for categories that have a parent" do
+      parent = Fabricate(:category, name: "Hobbies", slug: "hobbies")
+      category1.update!(parent_category: parent)
+      expect(subject.search("book", %w[category tag]).map(&:ref)).to eq(
+        %w[hobbies:book-club great-books],
+      )
+    end
+
+    it "appends type suffixes for the ref on conflicting slugs on items that are not the top priority type" do
+      Fabricate(:tag, name: "book-club")
+      expect(subject.search("book", %w[category tag]).map(&:ref)).to eq(
+        %w[book-club great-books book-club::tag],
+      )
+
+      Fabricate(:bookmark, user: user, name: "book club")
+      guardian.user.reload
+
+      register_bookmark_data_source
+
+      expect(subject.search("book", %w[category tag bookmark]).map(&:ref)).to eq(
+        %w[book-club great-books book-club::tag book-club::bookmark],
+      )
+    end
+
+    context "when not tagging_enabled" do
+      before { SiteSetting.tagging_enabled = false }
+
+      it "does not return any tags" do
+        expect(subject.search("book", %w[category tag]).map(&:text)).to eq(["Book Club"])
+      end
+    end
+  end
+end