FEATURE: Autolinking to category using hashtags.

app/assets/javascripts/discourse/components/category-group.js.es6

@@ -1,18 +1,19 @@
 import { categoryBadgeHTML } from 'discourse/helpers/category-link';
+import Category from 'discourse/models/category';
 
 export default Ember.Component.extend({
 
   _initializeAutocomplete: function() {
     const self = this,
           template = this.container.lookup('template:category-group-autocomplete.raw'),
-          regexp = new RegExp("href=['\"]" + Discourse.getURL('/c/') + "([^'\"]+)");
+          regexp = new RegExp(`href=['\"]${Discourse.getURL('/c/')}([^'\"]+)`);
 
     this.$('input').autocomplete({
       items: this.get('categories'),
       single: false,
       allowAny: false,
       dataSource(term){
-        return Discourse.Category.list().filter(function(category){
+        return Category.list().filter(function(category){
           const regex = new RegExp(term, "i");
           return category.get("name").match(regex) &&
             !_.contains(self.get('blacklist') || [], category) &&
@@ -22,7 +23,7 @@ export default Ember.Component.extend({
       onChangeItems(items) {
         const categories = _.map(items, function(link) {
           const slug = link.match(regexp)[1];
-          return Discourse.Category.findSingleBySlug(slug);
+          return Category.findSingleBySlug(slug);
         });
         Em.run.next(() => self.set("categories", categories));
       },

app/assets/javascripts/discourse/components/composer-editor.js.es6

@@ -1,6 +1,7 @@
 import userSearch from 'discourse/lib/user-search';
 import { default as computed, on } from 'ember-addons/ember-computed-decorators';
 import { linkSeenMentions, fetchUnseenMentions } from 'discourse/lib/link-mentions';
+import { linkSeenCategoryHashtags, fetchUnseenCategoryHashtags } from 'discourse/lib/link-category-hashtags';
 
 export default Ember.Component.extend({
   classNames: ['wmd-controls'],
@@ -111,13 +112,19 @@ export default Ember.Component.extend({
     $preview.scrollTop(desired + 50);
   },
 
-  _renderUnseen: function($preview, unseen) {
-    fetchUnseenMentions($preview, unseen, this.siteSettings).then(() => {
+  _renderUnseenMentions: function($preview, unseen) {
+    fetchUnseenMentions($preview, unseen).then(() => {
       linkSeenMentions($preview, this.siteSettings);
       this._warnMentionedGroups($preview);
     });
   },
 
+  _renderUnseenCategoryHashtags: function($preview, unseen) {
+    fetchUnseenCategoryHashtags(unseen).then(() => {
+      linkSeenCategoryHashtags($preview);
+    });
+  },
+
   _warnMentionedGroups($preview) {
     Ember.run.scheduleOnce('afterRender', () => {
       this._warnedMentions = this._warnedMentions || [];
@@ -386,11 +393,17 @@ export default Ember.Component.extend({
       // Paint mentions
       const unseen = linkSeenMentions($preview, this.siteSettings);
       if (unseen.length) {
-        Ember.run.debounce(this, this._renderUnseen, $preview, unseen, 500);
+        Ember.run.debounce(this, this._renderUnseenMentions, $preview, unseen, 500);
       }
 
       this._warnMentionedGroups($preview);
 
+      // Paint category hashtags
+      const unseenHashtags = linkSeenCategoryHashtags($preview);
+      if (unseenHashtags.length) {
+        Ember.run.debounce(this, this._renderUnseenCategoryHashtags, $preview, unseenHashtags, 500);
+      }
+
       const post = this.get('composer.post');
       let refresh = false;
 

app/assets/javascripts/discourse/components/d-editor.js.es6

@@ -2,6 +2,7 @@
 import loadScript from 'discourse/lib/load-script';
 import { default as computed, on, observes } from 'ember-addons/ember-computed-decorators';
 import { showSelector } from "discourse/lib/emoji/emoji-toolbar";
+import Category from 'discourse/models/category';
 
 // Our head can be a static string or a function that returns a string
 // based on input (like for numbered lists).
@@ -175,7 +176,11 @@ export default Ember.Component.extend({
 
   @on('didInsertElement')
   _startUp() {
-    this._applyEmojiAutocomplete();
+    const container = this.get('container'),
+          $editorInput = this.$('.d-editor-input');
+
+    this._applyEmojiAutocomplete(container, $editorInput);
+    this._applyCategoryHashtagAutocomplete(container, $editorInput);
 
     loadScript('defer/html-sanitizer-bundle').then(() => this.set('ready', true));
 
@@ -243,14 +248,52 @@ export default Ember.Component.extend({
     Ember.run.debounce(this, this._updatePreview, 30);
   },
 
-  _applyEmojiAutocomplete() {
+  _applyCategoryHashtagAutocomplete(container, $editorInput) {
+    const template = container.lookup('template:category-group-autocomplete.raw');
+
+    $editorInput.autocomplete({
+      template: template,
+      key: '#',
+      transformComplete(category) {
+        return category.get('slug');
+      },
+      dataSource(term) {
+        return Category.list().filter(category => {
+          const regexp = new RegExp(term, 'i');
+          return category.get('name').match(regexp);
+        });
+      },
+      triggerRule(textarea, opts) {
+        const result = Discourse.Utilities.caretRowCol(textarea);
+        const row = result.rowNum;
+        var col = result.colNum;
+        var 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;
+        }
+
+        if (col < 6) {
+          // Don't trigger autocomplete when ATX-style headers are used
+          return (line.slice(0, col) !== "#".repeat(col));
+        } else {
+          return true;
+        }
+      }
+    });
+  },
+
+  _applyEmojiAutocomplete(container, $editorInput) {
     if (!this.siteSettings.enable_emoji) { return; }
 
-    const container = this.container;
     const template = container.lookup('template:emoji-selector-autocomplete.raw');
     const self = this;
 
-    this.$('.d-editor-input').autocomplete({
+    $editorInput.autocomplete({
       template: template,
       key: ":",
 

app/assets/javascripts/discourse/dialects/category_hashtag_dialect.js

@@ -0,0 +1,23 @@
+/**
+  Supports Discourse's category hashtags (#category-slug) for automatically
+  generating a link to the category.
+**/
+Discourse.Dialect.inlineRegexp({
+  start: '#',
+  matcher: /^#([A-Za-z0-9][A-Za-z0-9\-]{0,40}[A-Za-z0-9])/,
+  spaceOrTagBoundary: true,
+
+  emitter: function(matches) {
+    var slug = matches[1],
+        hashtag = matches[0],
+        attributeClass = 'hashtag',
+        categoryHashtagLookup = this.dialect.options.categoryHashtagLookup,
+        result = categoryHashtagLookup && categoryHashtagLookup(slug);
+
+    if (result && result[0] === "category") {
+      return ['a', { class: attributeClass, href: result[1] }, hashtag];
+    } else {
+      return ['span', { class: attributeClass }, hashtag];
+    }
+  }
+});

app/assets/javascripts/discourse/lib/autocomplete.js.es6

@@ -282,6 +282,14 @@ export default function(options) {
     }, 50);
   });
 
+  const checkTriggerRule = (opts) => {
+    if (options.triggerRule) {
+      return options.triggerRule(me[0], opts);
+    } else {
+      return true;
+    }
+  };
+
   $(this).on('keypress.autocomplete', function(e) {
     var caretPosition, term;
 
@@ -289,7 +297,7 @@ export default function(options) {
     if (options.key && e.which === options.key.charCodeAt(0)) {
       caretPosition = Discourse.Utilities.caretPosition(me[0]);
       var prevChar = me.val().charAt(caretPosition - 1);
-      if (!prevChar || allowedLettersRegex.test(prevChar)) {
+      if (checkTriggerRule() && (!prevChar || allowedLettersRegex.test(prevChar))) {
         completeStart = completeEnd = caretPosition;
         updateAutoComplete(options.dataSource(""));
       }
@@ -343,7 +351,7 @@ export default function(options) {
         stopFound = prev === options.key;
         if (stopFound) {
           prev = me[0].value[c - 1];
-          if (!prev || allowedLettersRegex.test(prev)) {
+          if (checkTriggerRule({ backSpace: true }) && (!prev || allowedLettersRegex.test(prev))) {
             completeStart = c;
             caretPosition = completeEnd = initial;
             term = me[0].value.substring(c + 1, initial);

app/assets/javascripts/discourse/lib/link-category-hashtags.js.es6

@@ -0,0 +1,53 @@
+const validCategoryHashtags = {};
+const checkedCategoryHashtags = [];
+const testedKey = 'tested';
+const testedClass = `hashtag-${testedKey}`;
+
+function replaceSpan($elem, categorySlug, categoryLink) {
+  $elem.replaceWith(`<a href="${categoryLink}" class="hashtag">#${categorySlug}</a>`);
+}
+
+function updateFound($hashtags, categorySlugs) {
+  Ember.run.schedule('afterRender', () => {
+    $hashtags.each((index, hashtag) => {
+      const categorySlug = categorySlugs[index];
+      const link = validCategoryHashtags[categorySlug];
+      const $hashtag = $(hashtag);
+
+      if (link) {
+        replaceSpan($hashtag, categorySlug, link);
+      } else if (checkedCategoryHashtags.indexOf(categorySlug) !== -1) {
+        $hashtag.addClass(testedClass);
+      }
+    });
+  });
+};
+
+export function linkSeenCategoryHashtags($elem) {
+  const $hashtags = $(`span.hashtag:not(.${testedClass})`, $elem);
+  const unseen = [];
+
+  if ($hashtags.length) {
+    const categorySlugs = $hashtags.map((_, hashtag) => $(hashtag).text().substr(1));
+    if (categorySlugs.length) {
+      _.uniq(categorySlugs).forEach((categorySlug) => {
+        if (checkedCategoryHashtags.indexOf(categorySlug) === -1) {
+          unseen.push(categorySlug);
+        }
+      });
+    }
+    updateFound($hashtags, categorySlugs);
+  }
+
+  return unseen;
+};
+
+export function fetchUnseenCategoryHashtags(categorySlugs) {
+  return Discourse.ajax("/category_hashtags/check", { data: { category_slugs: categorySlugs } })
+    .then((response) => {
+      response.valid.forEach((category) => {
+        validCategoryHashtags[category.slug] = category.url;
+      });
+      checkedCategoryHashtags.push.apply(checkedCategoryHashtags, categorySlugs);
+    });
+}

app/assets/javascripts/discourse/lib/markdown.js

@@ -239,6 +239,7 @@ Discourse.Markdown.whiteListTag('a', 'class', 'attachment');
 Discourse.Markdown.whiteListTag('a', 'class', 'onebox');
 Discourse.Markdown.whiteListTag('a', 'class', 'mention');
 Discourse.Markdown.whiteListTag('a', 'class', 'mention-group');
+Discourse.Markdown.whiteListTag('a', 'class', 'hashtag');
 
 Discourse.Markdown.whiteListTag('a', 'target', '_blank');
 Discourse.Markdown.whiteListTag('a', 'rel', 'nofollow');
@@ -251,6 +252,7 @@ Discourse.Markdown.whiteListTag('div', 'class', 'title');
 Discourse.Markdown.whiteListTag('div', 'class', 'quote-controls');
 
 Discourse.Markdown.whiteListTag('span', 'class', 'mention');
+Discourse.Markdown.whiteListTag('span', 'class', 'hashtag');
 Discourse.Markdown.whiteListTag('aside', 'class', 'quote');
 Discourse.Markdown.whiteListTag('aside', 'data-*');
 

app/assets/javascripts/discourse/lib/utilities.js

@@ -143,6 +143,19 @@ Discourse.Utilities = {
     return String(text).trim();
   },
 
+  // Determine the row and col of the caret in an element
+  caretRowCol: function(el) {
+    var caretPosition = Discourse.Utilities.caretPosition(el);
+    var rows = el.value.slice(0, caretPosition).split("\n");
+    var rowNum = rows.length;
+
+    var colNum = caretPosition - rows.splice(0, rowNum - 1).reduce(function(sum, row) {
+      return sum + row.length + 1;
+    }, 0);
+
+    return { rowNum: rowNum, colNum: colNum};
+  },
+
   // Determine the position of the caret in an element
   caretPosition: function(el) {
     var r, rc, re;

app/assets/javascripts/discourse/routes/app-route-map.js.es6

@@ -42,6 +42,7 @@ export default function() {
     this.route('parentCategory', { path: '/c/:slug' });
     this.route('categoryNone', { path: '/c/:slug/none' });
     this.route('category', { path: '/c/:parentSlug/:slug' });
+    this.route('categoryWithID', { path: '/c/:parentSlug/:slug/:id' });
 
     // homepage
     this.route(Discourse.Utilities.defaultHomepage(), { path: '/' });

app/assets/javascripts/discourse/routes/discovery-category-with-id.js.es6

@@ -0,0 +1,11 @@
+import Category from 'discourse/models/category';
+
+export default Discourse.Route.extend({
+  model: function(params) {
+    return Category.findById(params.id);
+  },
+
+  redirect: function(model) {
+    this.transitionTo(`/c/${Category.slugFor(model)}`);
+  }
+});

app/controllers/category_hashtags_controller.rb

@@ -0,0 +1,14 @@
+class CategoryHashtagsController < ApplicationController
+  before_filter :ensure_logged_in
+
+  def check
+    category_slugs = params[:category_slugs]
+    category_slugs.each(&:downcase!)
+
+    valid_categories = Category.secured(guardian).where(slug: category_slugs).map do |category|
+      { slug: category.slug, url: category.url_with_id }
+    end.compact
+
+    render json: { valid: valid_categories }
+  end
+end

app/controllers/list_controller.rb

@@ -224,14 +224,22 @@ class ListController < ApplicationController
   def set_category
     slug_or_id = params.fetch(:category)
     parent_slug_or_id = params[:parent_category]
+    id = params[:id].to_i
 
     parent_category_id = nil
     if parent_slug_or_id.present?
       parent_category_id = Category.query_parent_category(parent_slug_or_id)
-      redirect_or_not_found and return if parent_category_id.blank?
+      redirect_or_not_found and return if parent_category_id.blank? && !id
     end
 
     @category = Category.query_category(slug_or_id, parent_category_id)
+
+    # Redirect if we have `/c/:parent_category/:category/:id`
+    if id
+      category = Category.find_by_id(id)
+      (redirect_to category.url, status: 301) && return if category
+    end
+
     redirect_or_not_found and return if !@category
 
     @description_meta = @category.description_text

app/models/category.rb

@@ -416,6 +416,10 @@ SQL
     url
   end
 
+  def url_with_id
+    self.parent_category ? "#{url}/#{self.id}" : "#{Discourse.base_uri}/c/#{self.id}-#{self.slug}"
+  end
+
   # If the name changes, try and update the category definition topic too if it's
   # an exact match
   def rename_category_definition

config/routes.rb

@@ -425,11 +425,12 @@ Discourse::Application.routes.draw do
   get "c/:parent_category/:category.rss" => "list#category_feed", format: :rss
   get "c/:category" => "list#category_latest"
   get "c/:category/none" => "list#category_none_latest"
-  get "c/:parent_category/:category" => "list#parent_category_category_latest"
+  get "c/:parent_category/:category/(:id)" => "list#parent_category_category_latest", constraints: { id: /\d+/ }
   get "c/:category/l/top" => "list#category_top", as: "category_top"
   get "c/:category/none/l/top" => "list#category_none_top", as: "category_none_top"
   get "c/:parent_category/:category/l/top" => "list#parent_category_category_top", as: "parent_category_category_top"
 
+  get "category_hashtags/check" => "category_hashtags#check"
 
   TopTopic.periods.each do |period|
     get "top/#{period}" => "list#top_#{period}"

lib/pretty_text.rb

@@ -48,6 +48,15 @@ module PrettyText
       end
     end
 
+    def category_hashtag_lookup(category_slug)
+      if category_slug
+        category = Category.find_by_slug(category_slug)
+        return ['category', category.url_with_id] if category
+      else
+        nil
+      end
+    end
+
     def get_topic_info(topic_id)
       return unless Fixnum === topic_id
       # TODO this only handles public topics, secured one do not get this
@@ -207,6 +216,7 @@ module PrettyText
       context.eval("Discourse.Emoji.applyCustomEmojis();")
 
       context.eval('opts["mentionLookup"] = function(u){return helpers.mention_lookup(u);}')
+      context.eval('opts["categoryHashtagLookup"] = function(c){return helpers.category_hashtag_lookup(c);}')
       context.eval('opts["lookupAvatar"] = function(p){return Discourse.Utilities.avatarImg({size: "tiny", avatarTemplate: helpers.avatar_template(p)});}')
       context.eval('opts["getTopicInfo"] = function(i){return helpers.get_topic_info(i)};')
       baked = context.eval('Discourse.Markdown.markdownConverter(opts).makeHtml(raw)')

spec/controllers/category_hashtags_controller_spec.rb

@@ -0,0 +1,46 @@
+require 'rails_helper'
+
+describe CategoryHashtagsController do
+  describe "check" do
+    describe "logged in" do
+      before do
+        log_in(:user)
+      end
+
+      it 'only returns the categories that are valid' do
+        category = Fabricate(:category)
+        xhr :get, :check, category_slugs: [category.slug, 'none']
+
+        expect(JSON.parse(response.body)).to eq(
+          { "valid" => [{ "slug" => category.slug, "url" => category.url_with_id }] }
+        )
+      end
+
+      it 'does not return restricted categories for a normal user' do
+        group = Fabricate(:group)
+        private_category = Fabricate(:private_category, group: group)
+        xhr :get, :check, category_slugs: [private_category.slug]
+
+        expect(JSON.parse(response.body)).to eq({ "valid" => [] })
+      end
+
+      it 'returns restricted categories for an admin' do
+        admin = log_in(:admin)
+        group = Fabricate(:group)
+        group.add(admin)
+        private_category = Fabricate(:private_category, group: group)
+        xhr :get, :check, category_slugs: [private_category.slug]
+
+        expect(JSON.parse(response.body)).to eq(
+          { "valid" => [{ "slug" => private_category.slug, "url" => private_category.url_with_id }] }
+        )
+      end
+    end
+
+    describe "not logged in" do
+      it 'raises an exception' do
+        expect { xhr :get, :check, category_slugs: [] }.to raise_error(Discourse::NotLoggedIn)
+      end
+    end
+  end
+end

spec/controllers/list_controller_spec.rb

@@ -83,6 +83,26 @@ describe ListController do
         it { is_expected.to respond_with(:success) }
       end
 
+      context 'with a link that has a parent slug, slug and id in its path' do
+        let(:child_category) { Fabricate(:category, parent_category: category) }
+
+        context "with valid slug" do
+          before do
+            xhr :get, :category_latest, parent_category: category.slug, category: child_category.slug, id: child_category.id
+          end
+
+          it { is_expected.to redirect_to(child_category.url) }
+        end
+
+        context "with invalid slug" do
+          before do
+            xhr :get, :category_latest, parent_category: 'random slug', category: 'random slug', id: child_category.id
+          end
+
+          it { is_expected.to redirect_to(child_category.url) }
+        end
+      end
+
       context 'another category exists with a number at the beginning of its name' do
         # One category has another category's id at the beginning of its name
         let!(:other_category) { Fabricate(:category, name: "#{category.id} name") }

spec/models/category_spec.rb

@@ -503,6 +503,22 @@ describe Category do
     end
   end
 
+  describe "#url_with_id" do
+    let(:category) { Fabricate(:category, name: 'cats') }
+
+    it "includes the id in the URL" do
+      expect(category.url_with_id).to eq("/c/#{category.id}-cats")
+    end
+
+    context "child category" do
+      let(:child_category) { Fabricate(:category, parent_category_id: category.id, name: 'dogs') }
+
+      it "includes the id in the URL" do
+        expect(child_category.url_with_id).to eq("/c/cats/dogs/#{child_category.id}")
+      end
+    end
+  end
+
   describe "uncategorized" do
     let(:cat) { Category.where(id: SiteSetting.uncategorized_category_id).first }
 

test/javascripts/lib/markdown-test.js.es6

@@ -289,6 +289,46 @@ test("Mentions", function() {
                 "it allows mentions within HTML tags");
 });
 
+test("Category hashtags", () => {
+  var alwaysTrue = { categoryHashtagLookup: (function() { return ["category", "http://test.discourse.org/category-hashtag"]; }) };
+
+  cookedOptions("Check out #category-hashtag", alwaysTrue,
+         "<p>Check out <a class=\"hashtag\" href=\"http://test.discourse.org/category-hashtag\">#category-hashtag</a></p>",
+         "it translates category hashtag into links");
+
+  cooked("Check out #category-hashtag",
+         "<p>Check out <span class=\"hashtag\">#category-hashtag</span></p>",
+         "it does not translate category hashtag into links if it is not a valid category hashtag");
+
+  cookedOptions("[#category-hashtag](http://www.test.com)", alwaysTrue,
+         "<p><a href=\"http://www.test.com\">#category-hashtag</a></p>",
+         "it does not translate category hashtag within links");
+
+  cooked("```\n# #category-hashtag\n```",
+         "<p><pre><code class=\"lang-auto\"># #category-hashtag</code></pre></p>",
+         "it does not translate category hashtags to links in code blocks");
+
+  cooked("># #category-hashtag\n",
+         "<blockquote><h1><span class=\"hashtag\">#category-hashtag</span></h1></blockquote>",
+         "it handles category hashtags in simple quotes");
+
+  cooked("# #category-hashtag",
+         "<h1><span class=\"hashtag\">#category-hashtag</span></h1>",
+         "it works within ATX-style headers");
+
+  cooked("don't `#category-hashtag`",
+         "<p>don't <code>#category-hashtag</code></p>",
+         "it does not mention in an inline code block");
+
+  cooked("test #hashtag1/#hashtag2",
+         "<p>test <span class=\"hashtag\">#hashtag1</span>/#hashtag2</p>",
+         "it does not convert category hashtag not bounded by spaces");
+
+  cooked("<small>#category-hashtag</small>",
+         "<p><small><span class=\"hashtag\">#category-hashtag</span></small></p>",
+         "it works between HTML tags");
+});
+
 
 test("Heading", function() {
   cooked("**Bold**\n----------", "<h2><strong>Bold</strong></h2>", "It will bold the heading");

test/javascripts/lib/utilities-test.js.es6

@@ -158,3 +158,27 @@ test("defaultHomepage", function() {
   Discourse.SiteSettings.top_menu = "latest|top|hot";
   equal(utils.defaultHomepage(), "latest", "default homepage is the first item in the top_menu site setting");
 });
+
+test("caretRowCol", () => {
+  var textarea = document.createElement('textarea');
+  const content = document.createTextNode("01234\n56789\n012345");
+  textarea.appendChild(content);
+  textarea.setAttribute('id', 'test');
+  document.body.appendChild(textarea);
+
+  const assertResult = (setCaretPos, expectedRowNum, expectedColNum) => {
+    Discourse.Utilities.setCaretPosition(textarea, setCaretPos);
+
+    const result = Discourse.Utilities.caretRowCol(textarea);
+    equal(result.rowNum, expectedRowNum, "returns the right row of the caret");
+    equal(result.colNum, expectedColNum,  "returns the right col of the caret");
+  };
+
+  assertResult(0, 1, 0);
+  assertResult(5, 1, 5);
+  assertResult(6, 2, 0);
+  assertResult(11, 2, 5);
+  assertResult(14, 3, 2);
+
+  document.body.removeChild(textarea);
+});