DEV: Remove OpenComposer mixin and refactor related logic (#23015)

The OpenComposer mixin comes from a time before we had a composer service. As well as being a general cleanup/refactor, this commit aims to removes interlinking between composer APIs and the discovery-related controllers which are being removed as part of #22622.

In summary, this commit:
- Removes OpenComposer mixin
- Adds and updates composer service APIs to support everything that `openComposer` did
- Updates consumers to call the composer service directly, instead of relying on the mixin (either directly, or via a route-action which bubbled up to some parent)
- Deprecates composer-related methods on `DiscourseRoute` and on the application route

app/assets/javascripts/discourse/app/components/card-container.hbs

@@ -7,7 +7,6 @@
   @showUser={{this.showUser}}
   @filterPosts={{this.filterPosts}}
   @composePrivateMessage={{route-action "composePrivateMessage"}}
-  @createNewMessageViaParams={{route-action "createNewMessageViaParams"}}
   role="dialog"
 />
 
@@ -15,5 +14,4 @@
   @topic={{this.topic.model}}
   @showUser={{this.showUser}}
   @showGroup={{this.showGroup}}
-  @createNewMessageViaParams={{route-action "createNewMessageViaParams"}}
 />

app/assets/javascripts/discourse/app/components/composer-action-title.hbs

@@ -2,8 +2,6 @@
   @composerModel={{this.model}}
   @replyOptions={{this.model.replyOptions}}
   @canWhisper={{this.canWhisper}}
-  @openComposer={{this.openComposer}}
-  @closeComposer={{this.closeComposer}}
   @action={{this.model.action}}
   @tabindex={{this.tabindex}}
   @topic={{this.model.topic}}

app/assets/javascripts/discourse/app/components/composer-container.hbs

@@ -46,8 +46,6 @@
             <div class="reply-details">
               <ComposerActionTitle
                 @model={{this.composer.model}}
-                @openComposer={{this.composer.openComposer}}
-                @closeComposer={{this.composer.closeComposer}}
                 @canWhisper={{this.composer.canWhisper}}
               />
 

app/assets/javascripts/discourse/app/components/group-card-contents.js

@@ -8,10 +8,12 @@ import discourseComputed from "discourse-common/utils/decorators";
 import { groupPath } from "discourse/lib/url";
 import { setting } from "discourse/lib/computed";
 import { modKeysPressed } from "discourse/lib/utilities";
+import { inject as service } from "@ember/service";
 
 const maxMembersToDisplay = 10;
 
 export default Component.extend(CardContentsBase, CleansUp, {
+  composer: service(),
   elementId: "group-card",
   mentionSelector: "a.mention-group",
   classNames: ["no-bg", "group-card"],
@@ -105,7 +107,7 @@ export default Component.extend(CardContentsBase, CleansUp, {
     },
 
     messageGroup() {
-      this.createNewMessageViaParams({
+      this.composer.openNewMessage({
         recipients: this.get("group.name"),
         hasGroups: true,
       });

app/assets/javascripts/discourse/app/controllers/discovery/topics.js

@@ -18,10 +18,10 @@ export default class TopicsController extends DiscoveryController.extend(
   DismissTopics
 ) {
   @service router;
+  @service composer;
   @controller discovery;
 
   period = null;
-  canCreateTopicOnCategory = null;
   selected = null;
   expandGloballyPinned = false;
   expandAllPinned = false;

app/assets/javascripts/discourse/app/controllers/group.js

@@ -22,6 +22,7 @@ export default Controller.extend({
   dialog: service(),
   currentUser: service(),
   router: service(),
+  composer: service(),
 
   counts: null,
   showing: "members",
@@ -130,7 +131,7 @@ export default Controller.extend({
 
   @action
   messageGroup() {
-    this.send("createNewMessageViaParams", {
+    this.composer.openNewMessage({
       recipients: this.get("model.name"),
       hasGroups: true,
     });

app/assets/javascripts/discourse/app/controllers/navigation/categories.js

@@ -1,6 +1,8 @@
 import NavigationDefaultController from "discourse/controllers/navigation/default";
 import { inject as controller } from "@ember/controller";
+import { inject as service } from "@ember/service";
 
 export default class NavigationCategoriesController extends NavigationDefaultController {
+  @service composer;
   @controller("discovery/categories") discoveryCategories;
 }

app/assets/javascripts/discourse/app/controllers/navigation/category.js

@@ -2,8 +2,11 @@ import NavigationDefaultController from "discourse/controllers/navigation/defaul
 import { calculateFilterMode } from "discourse/lib/filter-mode";
 import { dependentKeyCompat } from "@ember/object/compat";
 import { tracked } from "@glimmer/tracking";
+import { inject as service } from "@ember/service";
 
 export default class NavigationCategoryController extends NavigationDefaultController {
+  @service composer;
+
   @tracked category;
   @tracked filterType;
   @tracked noSubcategories;
@@ -16,4 +19,22 @@ export default class NavigationCategoryController extends NavigationDefaultContr
       noSubcategories: this.noSubcategories,
     });
   }
+
+  get createTopicTargetCategory() {
+    if (this.category?.canCreateTopic) {
+      return this.category;
+    }
+
+    if (this.siteSettings.default_subcategory_on_read_only_category) {
+      return this.category?.subcategoryWithCreateTopicPermission;
+    }
+  }
+
+  get enableCreateTopicButton() {
+    return !!this.createTopicTargetCategory;
+  }
+
+  get canCreateTopic() {
+    return this.currentUser?.can_create_topic;
+  }
 }

app/assets/javascripts/discourse/app/controllers/navigation/default.js

@@ -7,6 +7,7 @@ import { tracked } from "@glimmer/tracking";
 
 export default class NavigationDefaultController extends Controller {
   @service router;
+  @service composer;
   @controller discovery;
 
   @tracked category;

app/assets/javascripts/discourse/app/mixins/open-composer.js

@@ -1,77 +0,0 @@
-// This mixin allows a route to open the composer
-import Composer from "discourse/models/composer";
-import Mixin from "@ember/object/mixin";
-import { getOwner } from "discourse-common/lib/get-owner";
-
-export default Mixin.create({
-  openComposer(controller) {
-    let categoryId = controller.get("category.id");
-
-    if (
-      this.siteSettings.default_subcategory_on_read_only_category &&
-      !controller.canCreateTopicOnCategory
-    ) {
-      if (controller.canCreateTopicOnSubCategory) {
-        categoryId = controller.get("defaultSubcategory.id");
-      } else {
-        categoryId = this.siteSettings.default_composer_category;
-      }
-    }
-
-    if (
-      categoryId &&
-      !this.siteSettings.default_subcategory_on_read_only_category &&
-      controller.category.isUncategorizedCategory &&
-      !this.siteSettings.allow_uncategorized_topics
-    ) {
-      categoryId = null;
-    }
-
-    getOwner(this)
-      .lookup("service:composer")
-      .open({
-        prioritizedCategoryId: categoryId,
-        topicCategoryId: categoryId,
-        action: Composer.CREATE_TOPIC,
-        draftKey: controller.get("model.draft_key") || Composer.NEW_TOPIC_KEY,
-        draftSequence: controller.get("model.draft_sequence") || 0,
-      });
-  },
-
-  openComposerWithTopicParams(
-    controller,
-    topicTitle,
-    topicBody,
-    topicCategoryId,
-    topicTags
-  ) {
-    getOwner(this)
-      .lookup("service:composer")
-      .open({
-        action: Composer.CREATE_TOPIC,
-        topicTitle,
-        topicBody,
-        topicCategoryId,
-        topicTags,
-        draftKey: controller.get("model.draft_key") || Composer.NEW_TOPIC_KEY,
-        draftSequence: controller.get("model.draft_sequence"),
-      });
-  },
-
-  openComposerWithMessageParams({
-    recipients = "",
-    topicTitle = "",
-    topicBody = "",
-    hasGroups = false,
-  } = {}) {
-    getOwner(this).lookup("service:composer").open({
-      action: Composer.PRIVATE_MESSAGE,
-      recipients,
-      topicTitle,
-      topicBody,
-      archetypeId: "private_message",
-      draftKey: Composer.NEW_PRIVATE_MESSAGE_KEY,
-      hasGroups,
-    });
-  },
-});

app/assets/javascripts/discourse/app/models/category.js

@@ -345,6 +345,16 @@ const Category = RestModel.extend({
   isUncategorizedCategory(id) {
     return Category.isUncategorized(id);
   },
+
+  get canCreateTopic() {
+    return this.permission === PermissionType.FULL;
+  },
+
+  get subcategoryWithCreateTopicPermission() {
+    return this.subcategories?.find(
+      (subcategory) => subcategory.canCreateTopic
+    );
+  },
 });
 
 let _uncategorized;

app/assets/javascripts/discourse/app/routes/application.js

@@ -3,7 +3,6 @@ import Category from "discourse/models/category";
 import Composer from "discourse/models/composer";
 import DiscourseRoute from "discourse/routes/discourse";
 import I18n from "I18n";
-import OpenComposer from "discourse/mixins/open-composer";
 import { ajax } from "discourse/lib/ajax";
 import { findAll } from "discourse/models/login-method";
 import { getOwner } from "discourse-common/lib/get-owner";
@@ -17,6 +16,7 @@ import { action } from "@ember/object";
 import KeyboardShortcutsHelp from "discourse/components/modal/keyboard-shortcuts-help";
 import NotActivatedModal from "../components/modal/not-activated";
 import ForgotPassword from "discourse/components/modal/forgot-password";
+import deprecated from "discourse-common/lib/deprecated";
 
 function unlessReadOnly(method, message) {
   return function () {
@@ -38,7 +38,7 @@ function unlessStrictlyReadOnly(method, message) {
   };
 }
 
-const ApplicationRoute = DiscourseRoute.extend(OpenComposer, {
+const ApplicationRoute = DiscourseRoute.extend({
   siteTitle: setting("title"),
   shortSiteDescription: setting("short_site_description"),
   documentTitle: service(),
@@ -190,14 +190,17 @@ const ApplicationRoute = DiscourseRoute.extend(OpenComposer, {
       user.checkEmail();
     },
 
-    createNewTopicViaParams(title, body, category_id, tags) {
+    createNewTopicViaParams(title, body, categoryId, tags) {
-      this.openComposerWithTopicParams(
+      deprecated(
-        this.controllerFor("discovery/topics"),
+        "createNewTopicViaParam on the application route is deprecated. Use the composer service instead",
+        { id: "discourse.createNewTopicViaParams" }
+      );
+      getOwner(this).lookup("service:composer").openNewTopic({
         title,
         body,
-        category_id,
+        categoryId,
-        tags
+        tags,
-      );
+      });
     },
 
     createNewMessageViaParams({
@@ -206,10 +209,14 @@ const ApplicationRoute = DiscourseRoute.extend(OpenComposer, {
       topicBody = "",
       hasGroups = false,
     } = {}) {
-      this.openComposerWithMessageParams({
+      deprecated(
+        "createNewMessageViaParams on the application route is deprecated. Use the composer service instead",
+        { id: "discourse.createNewMessageViaParams" }
+      );
+      getOwner(this).lookup("service:composer").openNewMessage({
         recipients,
-        topicTitle,
+        title: topicTitle,
-        topicBody,
+        body: topicBody,
         hasGroups,
       });
     },

app/assets/javascripts/discourse/app/routes/build-category-route.js

@@ -13,7 +13,6 @@ import Category from "discourse/models/category";
 import CategoryList from "discourse/models/category-list";
 import DiscourseRoute from "discourse/routes/discourse";
 import I18n from "I18n";
-import PermissionType from "discourse/models/permission-type";
 import TopicList from "discourse/models/topic-list";
 import { action } from "@ember/object";
 import PreloadStore from "discourse/lib/preload-store";
@@ -152,33 +151,7 @@ class AbstractCategoryRoute extends DiscourseRoute {
 
   setupController(controller, model) {
     const topics = this.topics,
-      category = model.category,
+      category = model.category;
-      canCreateTopic = topics.get("can_create_topic");
-
-    let canCreateTopicOnCategory =
-      canCreateTopic && category.get("permission") === PermissionType.FULL;
-    let cannotCreateTopicOnCategory = !canCreateTopicOnCategory;
-    let defaultSubcategory;
-    let canCreateTopicOnSubCategory;
-
-    if (this.siteSettings.default_subcategory_on_read_only_category) {
-      cannotCreateTopicOnCategory = false;
-
-      if (!canCreateTopicOnCategory && category.subcategories) {
-        defaultSubcategory = category.subcategories.find((subcategory) => {
-          return subcategory.get("permission") === PermissionType.FULL;
-        });
-        canCreateTopicOnSubCategory = !!defaultSubcategory;
-      }
-    }
-
-    this.controllerFor("navigation/category").setProperties({
-      canCreateTopicOnCategory,
-      cannotCreateTopicOnCategory,
-      canCreateTopic,
-      canCreateTopicOnSubCategory,
-      defaultSubcategory,
-    });
 
     let topicOpts = {
       model: topics,
@@ -189,10 +162,6 @@ class AbstractCategoryRoute extends DiscourseRoute {
       selected: [],
       noSubcategories: this.routeConfig && !!this.routeConfig.no_subcategories,
       expandAllPinned: true,
-      canCreateTopic,
-      canCreateTopicOnCategory,
-      canCreateTopicOnSubCategory,
-      defaultSubcategory,
     };
 
     const p = category.get("params");

app/assets/javascripts/discourse/app/routes/discourse.js

@@ -1,9 +1,8 @@
-import Composer from "discourse/models/composer";
-import Draft from "discourse/models/draft";
 import Route from "@ember/routing/route";
 import { once } from "@ember/runloop";
 import { seenUser } from "discourse/lib/user-presence";
 import { getOwner } from "discourse-common/lib/get-owner";
+import deprecated from "discourse-common/lib/deprecated";
 
 const DiscourseRoute = Route.extend({
   showFooter: false,
@@ -54,24 +53,14 @@ const DiscourseRoute = Route.extend({
   },
 
   openTopicDraft() {
-    const composer = getOwner(this).lookup("service:composer");
+    deprecated(
-
+      "DiscourseRoute#openTopicDraft is deprecated. Inject the composer service and call openNewTopic instead",
-    if (
+      { id: "discourse.open-topic-draft" }
-      composer.get("model.action") === Composer.CREATE_TOPIC &&
+    );
-      composer.get("model.draftKey") === Composer.NEW_TOPIC_KEY
+    if (this.currentUser?.has_topic_draft) {
-    ) {
+      return getOwner(this)
-      composer.set("model.composeState", Composer.OPEN);
+        .lookup("service:composer")
-    } else {
+        .openNewTopic({ preferDraft: true });
-      Draft.get(Composer.NEW_TOPIC_KEY).then((data) => {
-        if (data.draft) {
-          composer.open({
-            action: Composer.CREATE_TOPIC,
-            draft: data.draft,
-            draftKey: Composer.NEW_TOPIC_KEY,
-            draftSequence: data.draft_sequence,
-          });
-        }
-      });
     }
   },
 

app/assets/javascripts/discourse/app/routes/discovery-categories.js

@@ -2,7 +2,6 @@ import CategoryList from "discourse/models/category-list";
 import DiscourseRoute from "discourse/routes/discourse";
 import EmberObject, { action } from "@ember/object";
 import I18n from "I18n";
-import OpenComposer from "discourse/mixins/open-composer";
 import PreloadStore from "discourse/lib/preload-store";
 import TopicList from "discourse/models/topic-list";
 import { ajax } from "discourse/lib/ajax";
@@ -13,9 +12,7 @@ import showModal from "discourse/lib/show-modal";
 import Session from "discourse/models/session";
 import { inject as service } from "@ember/service";
 
-export default class DiscoveryCategoriesRoute extends DiscourseRoute.extend(
+export default class DiscoveryCategoriesRoute extends DiscourseRoute {
-  OpenComposer
-) {
   @service router;
 
   renderTemplate() {
@@ -157,15 +154,6 @@ export default class DiscoveryCategoriesRoute extends DiscourseRoute.extend(
     showModal("reorder-categories");
   }
 
-  @action
-  createTopic() {
-    if (this.get("currentUser.has_topic_draft")) {
-      this.openTopicDraft();
-    } else {
-      this.openComposer(this.controllerFor("discovery/categories"));
-    }
-  }
-
   @action
   didTransition() {
     next(() => this.controllerFor("application").set("showFooter", true));

app/assets/javascripts/discourse/app/routes/discovery.js

@@ -1,5 +1,4 @@
 import DiscourseRoute from "discourse/routes/discourse";
-import OpenComposer from "discourse/mixins/open-composer";
 import User from "discourse/models/user";
 import { setTopicList } from "discourse/lib/topic-list-tracker";
 import { action } from "@ember/object";
@@ -9,9 +8,7 @@ import { resetCachedTopicList } from "discourse/lib/cached-topic-list";
   The parent route for all discovery routes.
   Handles the logic for showing the loading spinners.
 **/
-export default class DiscoveryRoute extends DiscourseRoute.extend(
+export default class DiscoveryRoute extends DiscourseRoute {
-  OpenComposer
-) {
   queryParams = {
     filter: { refreshModel: true },
   };
@@ -74,15 +71,6 @@ export default class DiscoveryRoute extends DiscourseRoute.extend(
     topic.clearPin();
   }
 
-  @action
-  createTopic() {
-    if (this.get("currentUser.has_topic_draft")) {
-      this.openTopicDraft();
-    } else {
-      this.openComposer(this.controllerFor("discovery/topics"));
-    }
-  }
-
   @action
   dismissReadTopics(dismissTopics) {
     const operationType = dismissTopics ? "topics" : "posts";

app/assets/javascripts/discourse/app/routes/new-message.js

@@ -7,6 +7,7 @@ import { inject as service } from "@ember/service";
 
 export default DiscourseRoute.extend({
   dialog: service(),
+  composer: service(),
 
   beforeModel(transition) {
     const params = transition.to.queryParams;
@@ -14,12 +15,12 @@ export default DiscourseRoute.extend({
     const groupName = params.groupname || params.group_name;
 
     if (this.currentUser) {
-      this.replaceWith("discovery.latest").then((e) => {
+      this.replaceWith("discovery.latest").then(() => {
         if (params.username) {
-          e.send("createNewMessageViaParams", {
+          this.composer.openNewMessage({
             recipients: params.username,
-            topicTitle: params.title,
+            title: params.title,
-            topicBody: params.body,
+            body: params.body,
           });
         } else if (groupName) {
           // send a message to a group
@@ -27,10 +28,10 @@ export default DiscourseRoute.extend({
             .then((result) => {
               if (result.messageable) {
                 next(() =>
-                  e.send("createNewMessageViaParams", {
+                  this.composer.openNewMessage({
                     recipients: groupName,
-                    topicTitle: params.title,
+                    title: params.title,
-                    topicBody: params.body,
+                    body: params.body,
                   })
                 );
               } else {
@@ -41,9 +42,9 @@ export default DiscourseRoute.extend({
             })
             .catch(() => this.dialog.alert(I18n.t("generic_error")));
         } else {
-          e.send("createNewMessageViaParams", {
+          this.composer.openNewMessage({
-            topicTitle: params.title,
+            title: params.title,
-            topicBody: params.body,
+            body: params.body,
           });
         }
       });

app/assets/javascripts/discourse/app/routes/new-topic.js

@@ -2,14 +2,58 @@ import Category from "discourse/models/category";
 import DiscourseRoute from "discourse/routes/discourse";
 import cookie from "discourse/lib/cookie";
 import { next } from "@ember/runloop";
+import { inject as service } from "@ember/service";
+
+export default class extends DiscourseRoute {
+  @service composer;
 
-export default DiscourseRoute.extend({
   beforeModel(transition) {
     if (this.currentUser) {
-      let category, categoryId;
+      const category = this.parseCategoryFromTransition(transition);
+
+      if (category) {
+        this.replaceWith("discovery.category", {
+          category,
+          id: category.id,
+        }).then(() => {
+          if (this.currentUser.can_create_topic) {
+            this.openComposer({ transition, category });
+          }
+        });
+      } else if (transition.from) {
+        // Navigation from another ember route
+        transition.abort();
+        this.openComposer({ transition });
+      } else {
+        this.replaceWith("discovery.latest").then(() => {
+          if (this.currentUser.can_create_topic) {
+            this.openComposer({ transition });
+          }
+        });
+      }
+    } else {
+      // User is not logged in
+      cookie("destination_url", window.location.href);
+      this.replaceWith("login");
+    }
+  }
+
+  openComposer({ transition, category }) {
+    next(() => {
+      this.composer.openNewTopic({
+        title: transition.to.queryParams.title,
+        body: transition.to.queryParams.body,
+        category,
+        tags: transition.to.queryParams.tags,
+      });
+    });
+  }
+
+  parseCategoryFromTransition(transition) {
+    let category;
 
     if (transition.to.queryParams.category_id) {
-        categoryId = transition.to.queryParams.category_id;
+      const categoryId = transition.to.queryParams.category_id;
       category = Category.findById(categoryId);
     } else if (transition.to.queryParams.category) {
       const splitCategory = transition.to.queryParams.category.split("/");
@@ -27,52 +71,10 @@ export default DiscourseRoute.extend({
           "slug"
         );
       }
-
-        if (category) {
-          categoryId = category.id;
     }
+    return category;
   }
 
-      if (category) {
-        let route = "discovery.category";
-        let params = { category, id: category.id };
-
-        this.replaceWith(route, params).then((e) => {
-          if (this.controllerFor("navigation/category").canCreateTopic) {
-            this._sendTransition(e, transition, categoryId);
-          }
-        });
-      } else {
-        if (transition.from) {
-          transition.abort();
-          this.send("createNewTopicViaParams");
-        } else {
-          this.replaceWith("discovery.latest").then((e) => {
-            if (this.controllerFor("navigation/default").canCreateTopic) {
-              this._sendTransition(e, transition);
-            }
-          });
-        }
-      }
-    } else {
-      // User is not logged in
-      cookie("destination_url", window.location.href);
-      this.replaceWith("login");
-    }
-  },
-
-  _sendTransition(event, transition, categoryId) {
-    next(() => {
-      event.send(
-        "createNewTopicViaParams",
-        transition.to.queryParams.title,
-        transition.to.queryParams.body,
-        categoryId,
-        transition.to.queryParams.tags
-      );
-    });
-  },
-
   _getCategory(mainCategory, subCategory, type) {
     let category;
     if (!subCategory) {
@@ -92,5 +94,5 @@ export default DiscourseRoute.extend({
     }
 
     return category;
-  },
+  }
-});
+}

app/assets/javascripts/discourse/app/services/composer.js

@@ -1,4 +1,9 @@
-import Composer, { SAVE_ICONS, SAVE_LABELS } from "discourse/models/composer";
+import Composer, {
+  CREATE_TOPIC,
+  NEW_TOPIC_KEY,
+  SAVE_ICONS,
+  SAVE_LABELS,
+} from "discourse/models/composer";
 import EmberObject, { action, computed } from "@ember/object";
 import { alias, and, or, reads } from "@ember/object/computed";
 import {
@@ -567,33 +572,6 @@ export default class ComposerService extends Service {
     this.close();
   }
 
-  @action
-  async openComposer(options, post, topic) {
-    await this.open(options);
-
-    let url = post?.url || topic?.url;
-    const topicTitle = topic?.title;
-
-    if (!url || !topicTitle) {
-      return;
-    }
-
-    url = `${location.protocol}//${location.host}${url}`;
-    const link = `[${escapeExpression(topicTitle)}](${url})`;
-    const continueDiscussion = I18n.t("post.continue_discussion", {
-      postLink: link,
-    });
-
-    const reply = this.get("model.reply");
-    if (reply?.includes(continueDiscussion)) {
-      return;
-    }
-
-    this.model.prependText(continueDiscussion, {
-      new_line: true,
-    });
-  }
-
   @action
   onPopupMenuAction(menuAction) {
     return (
@@ -1339,6 +1317,62 @@ export default class ComposerService extends Service {
     }
   }
 
+  async #openNewTopicDraft() {
+    if (
+      this.model?.action === Composer.CREATE_TOPIC &&
+      this.model?.draftKey === Composer.NEW_TOPIC_KEY
+    ) {
+      this.set("model.composeState", Composer.OPEN);
+    } else {
+      const data = await Draft.get(Composer.NEW_TOPIC_KEY);
+      if (data.draft) {
+        return this.open({
+          action: Composer.CREATE_TOPIC,
+          draft: data.draft,
+          draftKey: Composer.NEW_TOPIC_KEY,
+          draftSequence: data.draft_sequence,
+        });
+      }
+    }
+  }
+
+  @action
+  async openNewTopic({
+    title,
+    body,
+    category,
+    tags,
+    preferDraft = false,
+  } = {}) {
+    if (preferDraft && this.currentUser.has_topic_draft) {
+      return this.#openNewTopicDraft();
+    } else {
+      return this.open({
+        prioritizedCategoryId: category?.id,
+        topicCategoryId: category?.id,
+        topicTitle: title,
+        topicBody: body,
+        topicTags: tags,
+        action: CREATE_TOPIC,
+        draftKey: NEW_TOPIC_KEY,
+        draftSequence: 0,
+      });
+    }
+  }
+
+  @action
+  async openNewMessage({ title, body, recipients, hasGroups }) {
+    return this.open({
+      action: Composer.PRIVATE_MESSAGE,
+      recipients,
+      topicTitle: title,
+      topicBody: body,
+      archetypeId: "private_message",
+      draftKey: Composer.NEW_PRIVATE_MESSAGE_KEY,
+      hasGroups,
+    });
+  }
+
   // Given a potential instance and options, set the model for this composer.
   async _setModel(optionalComposerModel, opts) {
     this.set("linkLookup", null);
@@ -1406,6 +1440,12 @@ export default class ComposerService extends Service {
       this.model.set("reply", opts.topicBody);
     }
 
+    if (opts.prependText && !this.model.reply?.includes(opts.prependText)) {
+      this.model.prependText(opts.prependText, {
+        new_line: true,
+      });
+    }
+
     const defaultComposerHeight = this._getDefaultComposerHeight();
 
     this.set("model.composerHeight", defaultComposerHeight);

app/assets/javascripts/discourse/app/templates/discovery.hbs

@@ -3,7 +3,7 @@
   {{#unless this.viewingCategoriesList}}
     <CategoryReadOnlyBanner
       @category={{this.category}}
-      @readOnly={{this.navigationCategory.cannotCreateTopicOnCategory}}
+      @readOnly={{not this.navigationCategory.enableCreateTopicButton}}
     />
   {{/unless}}
 </div>

app/assets/javascripts/discourse/app/templates/discovery/topics.hbs

@@ -119,9 +119,12 @@
       @message={{this.footerMessage}}
     >
       {{#if this.latest}}
-        {{#if this.canCreateTopicOnCategory}}
+        {{#if this.category.canCreateTopic}}
           <DiscourseLinkedText
-            @action={{route-action "createTopic"}}
+            @action={{fn
+              this.composer.openNewTopic
+              (hash category=this.category preferDraft=true)
+            }}
             @text="topic.suggest_create_topic"
           />
         {{/if}}

app/assets/javascripts/discourse/app/templates/mobile/discovery/topics.hbs

@@ -76,9 +76,12 @@
       @message={{this.footerMessage}}
     >
       {{#if this.latest}}
-        {{#if this.canCreateTopicOnCategory}}
+        {{#if this.category.canCreateTopic}}
           <DiscourseLinkedText
-            @action={{route-action "createTopic"}}
+            @action={{fn
+              this.composer.openNewTopic
+              (hash category=this.category preferDraft=true)
+            }}
             @text="topic.suggest_create_topic"
           />
         {{/if}}

app/assets/javascripts/discourse/app/templates/navigation/categories.hbs

@@ -6,6 +6,6 @@
     @reorderCategories={{route-action "reorderCategories"}}
     @canCreateTopic={{this.canCreateTopic}}
     @hasDraft={{this.currentUser.has_topic_draft}}
-    @createTopic={{route-action "createTopic"}}
+    @createTopic={{fn this.composer.openNewTopic (hash preferDraft=true)}}
   />
 </DSection>

app/assets/javascripts/discourse/app/templates/navigation/category.hbs

@@ -23,8 +23,11 @@
     @filterMode={{this.filterMode}}
     @noSubcategories={{this.noSubcategories}}
     @canCreateTopic={{this.canCreateTopic}}
-    @createTopic={{route-action "createTopic"}}
+    @createTopic={{fn
-    @createTopicDisabled={{this.cannotCreateTopicOnCategory}}
+      this.composer.openNewTopic
+      (hash category=this.createTopicTargetCategory preferDraft=true)
+    }}
+    @createTopicDisabled={{not this.enableCreateTopicButton}}
     @hasDraft={{this.currentUser.has_topic_draft}}
     @editCategory={{route-action "editCategory" this.category}}
   />

app/assets/javascripts/discourse/app/templates/navigation/default.hbs

@@ -3,7 +3,7 @@
     @filterMode={{this.filterMode}}
     @canCreateTopic={{this.canCreateTopic}}
     @hasDraft={{this.currentUser.has_topic_draft}}
-    @createTopic={{route-action "createTopic"}}
+    @createTopic={{fn this.composer.openNewTopic (hash preferDraft=true)}}
     @skipCategoriesNavItem={{this.skipCategoriesNavItem}}
   />
 </DSection>

app/assets/javascripts/discourse/tests/fixtures/session-fixtures.js

@@ -14,6 +14,7 @@ export default {
       moderator: true,
       staff: true,
       can_create_group: true,
+      can_create_topic: true,
       title: "co-founder",
       reply_count: 859,
       topic_count: 36,

app/assets/javascripts/select-kit/addon/components/composer-actions.js

@@ -13,6 +13,7 @@ import { camelize } from "@ember/string";
 import { equal, gt } from "@ember/object/computed";
 import { isEmpty } from "@ember/utils";
 import { inject as service } from "@ember/service";
+import { escapeExpression } from "discourse/lib/utilities";
 
 // Component can get destroyed and lose state
 let _topicSnapshot = null;
@@ -27,6 +28,7 @@ export function _clearSnapshots() {
 
 export default DropdownSelectBoxComponent.extend({
   dialog: service(),
+  composer: service(),
   seq: 0,
   pluginApiIdentifiers: ["composer-actions"],
   classNames: ["composer-actions"],
@@ -234,14 +236,32 @@ export default DropdownSelectBoxComponent.extend({
     return items;
   },
 
+  _continuedFromText(post, topic) {
+    let url = post?.url || topic?.url;
+    const topicTitle = topic?.title;
+
+    if (!url || !topicTitle) {
+      return;
+    }
+
+    url = `${location.protocol}//${location.host}${url}`;
+    const link = `[${escapeExpression(topicTitle)}](${url})`;
+    return I18n.t("post.continue_discussion", {
+      postLink: link,
+    });
+  },
+
   _replyFromExisting(options, post, topic) {
-    this.closeComposer();
+    this.composer.closeComposer();
-    this.openComposer(options, post, topic);
+    this.composer.open({
+      ...options,
+      prependText: this._continuedFromText(post, topic),
+    });
   },
 
   _openComposer(options) {
-    this.closeComposer();
+    this.composer.closeComposer();
-    this.openComposer(options);
+    this.composer.open(options);
   },
 
   toggleWhisperSelected(options, model) {

spec/system/composer/default_to_subcategory_spec.rb

@@ -41,13 +41,9 @@ describe "Default to Subcategory when parent Category doesn't allow posting", ty
             end
           end
           describe "Category does not have subcategory" do
-            it "should have the 'New Topic' button enabled and default Subcategory set to latest default subcategory" do
+            it "should have the 'New Topic' button disabled" do
               category_page.visit(category_with_no_subcategory)
-              expect(category_page).to have_button("New Topic", disabled: false)
+              expect(category_page).to have_button("New Topic", disabled: true)
-              category_page.new_topic_button.click
-              select_kit =
-                PageObjects::Components::SelectKit.new("#reply-control.open .category-chooser")
-              expect(select_kit).to have_selected_value(default_latest_category.id)
             end
           end
         end
@@ -70,13 +66,9 @@ describe "Default to Subcategory when parent Category doesn't allow posting", ty
         end
         describe "Can't post on parent category" do
           describe "Category does not have subcategory" do
-            it "should have the 'New Topic' button enabled and default Subcategory not set" do
+            it "should have the 'New Topic' button disabled" do
               category_page.visit(category_with_no_subcategory)
-              expect(category_page).to have_button("New Topic", disabled: false)
+              expect(category_page).to have_button("New Topic", disabled: true)
-              category_page.new_topic_button.click
-              select_kit =
-                PageObjects::Components::SelectKit.new("#reply-control.open .category-chooser")
-              expect(select_kit).to have_selected_name("category…")
             end
           end
         end