FIX: generates markdown from pasting link (#21241)

After removing `TextareaTextManipulation` from `ChatComposer` and using `TextareaInteractor` as a proxy, one function has been forgotten: `paste(event)` which is not available in glimmer components anymore, and even less avaiable now that the mixin is not tied to a component anymore but a real DOM node. As a solution we now add a manual paste event listener which will call `paste(event)`.

app/assets/javascripts/discourse/app/mixins/textarea-text-manipulation.js

@@ -402,10 +402,12 @@ export default Mixin.create({
       plainText = plainText.replace(/\r/g, "");
       const table = this.extractTable(plainText);
       if (table) {
-        this.appEvents.trigger(
-          `${this.composerEventPrefix}:insert-text`,
-          table
-        );
+        this.composerEventPrefix
+          ? this.appEvents.trigger(
+              `${this.composerEventPrefix}:insert-text`,
+              table
+            )
+          : this.insertText(table);
         handled = true;
       }
     }
@@ -457,10 +459,12 @@ export default Mixin.create({
         }
 
         if (isComposer) {
-          this.appEvents.trigger(
-            `${this.composerEventPrefix}:insert-text`,
-            markdown
-          );
+          this.composerEventPrefix
+            ? this.appEvents.trigger(
+                `${this.composerEventPrefix}:insert-text`,
+                markdown
+              )
+            : this.insertText(markdown);
           handled = true;
         }
       }

plugins/chat/assets/javascripts/discourse/lib/textarea-interactor.js

@@ -3,6 +3,7 @@ import TextareaTextManipulation from "discourse/mixins/textarea-text-manipulatio
 import { next, schedule } from "@ember/runloop";
 import { setOwner } from "@ember/application";
 import { inject as service } from "@ember/service";
+import { registerDestructor } from "@ember/destroyable";
 
 // This class sole purpose is to provide a way to interact with the textarea
 // using the existing TextareaTextManipulation mixin without using it directly
@@ -12,6 +13,7 @@ export default class TextareaInteractor extends EmberObject.extend(
 ) {
   @service capabilities;
   @service site;
+  @service siteSettings;
 
   constructor(owner, textarea) {
     super(...arguments);
@@ -20,6 +22,18 @@ export default class TextareaInteractor extends EmberObject.extend(
     this._textarea = textarea;
     this.element = this._textarea;
     this.ready = true;
+    this.composerFocusSelector = ".chat-composer__input";
+
+    this.init(); // mixin init wouldn't be called otherwise
+    this.composerEventPrefix = null; // we don't need app events
+
+    // paste is using old native ember events defined on composer
+    this.textarea.addEventListener("paste", this.paste);
+    registerDestructor(this, (instance) => instance.teardown());
+  }
+
+  teardown() {
+    this.textarea.removeEventListener("paste", this.paste);
   }
 
   set value(value) {

plugins/chat/spec/system/chat_composer_spec.rb

@@ -262,4 +262,35 @@ RSpec.describe "Chat composer", type: :system, js: true do
       expect(find(".chat-composer__input").value).to eq("bb")
     end
   end
+
+  context "when pasting link over selected text" do
+    before do
+      channel_1.add(current_user)
+      sign_in(current_user)
+    end
+
+    it "outputs a markdown link" do
+      modifier = /darwin/i =~ RbConfig::CONFIG["host_os"] ? :command : :control
+      select_text = <<-JS
+        const element = document.querySelector(arguments[0]);
+        element.focus();
+        element.setSelectionRange(0, element.value.length)
+      JS
+
+      chat.visit_channel(channel_1)
+
+      find("body").send_keys("https://www.discourse.org")
+      page.execute_script(select_text, ".chat-composer__input")
+
+      page.send_keys [modifier, "c"]
+      page.send_keys [:backspace]
+
+      find("body").send_keys("discourse")
+      page.execute_script(select_text, ".chat-composer__input")
+
+      page.send_keys [modifier, "v"]
+
+      expect(find(".chat-composer__input").value).to eq("[discourse](https://www.discourse.org)")
+    end
+  end
 end