DEV: API allow post actions to optionally provide visual feedback

post action feedback is the mechanism in which we provide visual feedback
to the user when a post action is clicked, in cases where the action is a
background (hidden to user) for example: copying text to the clipboard

Core uses this to share post links, but other plugins (for example: AI) use
this to share post transcripts via the clipboard.

This adds a proper plugin API to consume this functionality

`addPostMenuButton` can provide a builder that specified a function as the action. 

This function will be called with an object that has both the current post and a method for showing feedback.

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

@@ -144,7 +144,7 @@ import { modifySelectKit } from "select-kit/mixins/plugin-api";
 // docs/CHANGELOG-JAVASCRIPT-PLUGIN-API.md whenever you change the version
 // using the format described at https://keepachangelog.com/en/1.0.0/.
 
-export const PLUGIN_API_VERSION = "1.21.0";
+export const PLUGIN_API_VERSION = "1.22.0";
 
 // This helper prevents us from applying the same `modifyClass` over and over in test mode.
 function canModify(klass, type, resolverName, changes) {
@@ -594,7 +594,33 @@ class PluginApi {
    *     position: 'first'  // can be `first`, `last` or `second-last-hidden`
    *   };
    * });
+   *
    * ```
+   *
+   * action: may be a string or a function. If it is a string, a wiget action
+   * will be triggered. If it is function, the function will be called.
+   *
+   * function will recieve a single argument:
+   *  {
+   *    post:
+   *    showFeedback:
+   *  }
+   *
+   *  showFeedback can be called to issue a visual feedback on button press.
+   *  It gets a single argument with a localization key.
+   *
+   *  Example:
+   *
+   *  api.addPostMenuButton('coffee', () => {
+   *    return {
+   *      action: ({ post, showFeedback }) => {
+   *        drinkCoffee(post);
+   *        showFeedback('discourse_plugin.coffee.drink');
+   *      },
+   *      icon: 'coffee',
+   *      className: 'hot-coffee',
+   *    }
+   *  }
    **/
   addPostMenuButton(name, callback) {
     apiExtraButtons[name] = callback;

app/assets/javascripts/discourse/app/lib/post-action-feedback.js

@@ -0,0 +1,90 @@
+import { SVG_NAMESPACE } from "discourse-common/lib/icon-library";
+import I18n from "discourse-i18n";
+
+export default function postActionFeedback({
+  postId,
+  actionClass,
+  messageKey,
+  actionCallback,
+  errorCallback,
+}) {
+  if (recentlyCopied(postId, actionClass)) {
+    return;
+  }
+
+  const maybePromise = actionCallback();
+
+  if (maybePromise && maybePromise.then) {
+    maybePromise
+      .then(() => {
+        showAlert(postId, actionClass, messageKey);
+      })
+      .catch(() => {
+        if (errorCallback) {
+          errorCallback();
+        }
+      });
+  } else {
+    showAlert(postId, actionClass, messageKey);
+  }
+}
+
+export function recentlyCopied(postId, actionClass) {
+  return document.querySelector(
+    `article[data-post-id='${postId}'] .${actionClass} .${actionClass}-checkmark`
+  );
+}
+
+export function showAlert(postId, actionClass, messageKey) {
+  const postSelector = `article[data-post-id='${postId}']`;
+  const actionBtn = document.querySelector(`${postSelector} .${actionClass}`);
+
+  actionBtn?.classList.add("post-action-feedback-button");
+
+  createAlert(I18n.t(messageKey), postId, actionBtn);
+  createCheckmark(actionBtn, actionClass, postId);
+  styleBtn(actionBtn);
+}
+
+function createAlert(message, postId, actionBtn) {
+  if (!actionBtn) {
+    return;
+  }
+
+  let alertDiv = document.createElement("div");
+  alertDiv.className = "post-action-feedback-alert -success";
+  alertDiv.textContent = message;
+
+  actionBtn.appendChild(alertDiv);
+
+  setTimeout(() => alertDiv.classList.add("slide-out"), 1000);
+  setTimeout(() => removeElement(alertDiv), 2500);
+}
+
+function createCheckmark(btn, actionClass, postId) {
+  const svgId = `svg_${actionClass}_${postId}`;
+  const checkmark = makeCheckmarkSvg(postId, actionClass, svgId);
+  btn.appendChild(checkmark.content);
+
+  setTimeout(() => checkmark.classList.remove("is-visible"), 3000);
+  setTimeout(() => removeElement(document.getElementById(svgId)), 3500);
+}
+
+function styleBtn(btn) {
+  btn.classList.add("is-copied");
+  setTimeout(() => btn.classList.remove("is-copied"), 3200);
+}
+
+function makeCheckmarkSvg(postId, actionClass, svgId) {
+  const svgElement = document.createElement("template");
+  svgElement.innerHTML = `
+      <svg class="${actionClass}-checkmark post-action-feedback-svg is-visible" id="${svgId}" xmlns="${SVG_NAMESPACE}" viewBox="0 0 52 52">
+        <path class="checkmark__check" fill="none" d="M13 26 l10 10 20 -20"/>
+      </svg>
+    `;
+  return svgElement;
+}
+
+function removeElement(element) {
+  element?.parentNode?.removeChild(element);
+}

app/assets/javascripts/discourse/app/widgets/post-menu.js

@@ -5,6 +5,7 @@ import { h } from "virtual-dom";
 import AdminPostMenu from "discourse/components/admin-post-menu";
 import DeleteTopicDisallowedModal from "discourse/components/modal/delete-topic-disallowed";
 import { formattedReminderTime } from "discourse/lib/bookmark";
+import { recentlyCopied, showAlert } from "discourse/lib/post-action-feedback";
 import {
   NO_REMINDER_ICON,
   WITH_REMINDER_ICON,
@@ -653,8 +654,36 @@ export default createWidget("post-menu", {
         if (buttonAttrs) {
           const { position, beforeButton, afterButton } = buttonAttrs;
           delete buttonAttrs.position;
+          let button;
+
+          if (typeof buttonAttrs.action === "function") {
+            const original = buttonAttrs.action;
+            const self = this;
+
+            buttonAttrs.action = async function (post) {
+              let showFeedback = null;
+
+              if (buttonAttrs.className) {
+                showFeedback = (messageKey) => {
+                  showAlert(post.id, buttonAttrs.className, messageKey);
+                };
+              }
+
+              const postAttrs = {
+                post,
+                showFeedback,
+              };
+
+              if (
+                !buttonAttrs.className ||
+                !recentlyCopied(post.id, buttonAttrs.actionClass)
+              ) {
+                self.sendWidgetAction(original, postAttrs);
+              }
+            };
+          }
 
-          let button = this.attach(this.settings.buttonType, buttonAttrs);
+          button = this.attach(this.settings.buttonType, buttonAttrs);
 
           const content = [];
           if (beforeButton) {

app/assets/javascripts/discourse/app/widgets/post.js

@@ -4,11 +4,8 @@ import { h } from "virtual-dom";
 import ShareTopicModal from "discourse/components/modal/share-topic";
 import { dateNode } from "discourse/helpers/node";
 import autoGroupFlairForUser from "discourse/lib/avatar-flair";
-import {
-  recentlyCopiedPostLink,
-  showCopyPostLinkAlert,
-} from "discourse/lib/copy-post-link";
 import { relativeAgeMediumSpan } from "discourse/lib/formatter";
+import postActionFeedback from "discourse/lib/post-action-feedback";
 import { nativeShare } from "discourse/lib/pwa-utils";
 import {
   prioritizeNameFallback,
@@ -654,29 +651,22 @@ createWidget("post-contents", {
     }
 
     const post = this.findAncestorModel();
-    const postUrl = post.shareUrl;
     const postId = post.id;
 
-    // Do nothing if the user just copied the link.
-    if (recentlyCopiedPostLink(postId)) {
-      return;
-    }
-
-    const shareUrl = new URL(postUrl, window.origin).toString();
+    let actionCallback = () => clipboardCopy(post.shareUrl);
 
     // Can't use clipboard in JS tests.
     if (isTesting()) {
-      return showCopyPostLinkAlert(postId);
+      actionCallback = () => {};
     }
 
-    clipboardCopy(shareUrl)
-      .then(() => {
-        showCopyPostLinkAlert(postId);
-      })
-      .catch(() => {
-        // If the clipboard copy fails for some reason, may as well show the old modal.
-        this.share();
-      });
+    postActionFeedback({
+      postId,
+      actionClass: "post-action-menu__copy-link",
+      messageKey: "post.controls.link_copied",
+      actionCallback: () => actionCallback,
+      errorCallback: () => this.share(),
+    });
   },
 
   init() {

app/assets/javascripts/discourse/app/widgets/widget.js

@@ -330,11 +330,17 @@ export default class Widget {
 
     const view = this._findView();
     if (view) {
-      const method = view.get(name);
-      if (!method) {
-        // eslint-disable-next-line no-console
-        console.warn(`${name} not found`);
-        return;
+      let method;
+
+      if (typeof name === "function") {
+        method = name;
+      } else {
+        method = view.get(name);
+        if (!method) {
+          // eslint-disable-next-line no-console
+          console.warn(`${name} not found`);
+          return;
+        }
       }
 
       if (typeof method === "string") {

app/assets/javascripts/discourse/tests/integration/components/widgets/post-menu-test.js

@@ -1,4 +1,4 @@
-import { render } from "@ember/test-helpers";
+import { click, render } from "@ember/test-helpers";
 import { hbs } from "ember-cli-htmlbars";
 import { module, test } from "qunit";
 import { h } from "virtual-dom";
@@ -38,6 +38,48 @@ module("Integration | Component | Widget | post-menu", function (hooks) {
     );
   });
 
+  test("add extra button with feedback", async function (assert) {
+    this.set("args", {});
+
+    let testPost = null;
+
+    withPluginApi("0.14.0", (api) => {
+      api.addPostMenuButton("coffee", () => {
+        return {
+          action: ({ post, showFeedback }) => {
+            testPost = post;
+            showFeedback("coffee.drink");
+          },
+          icon: "coffee",
+          className: "hot-coffee",
+          title: "coffee.title",
+          position: "first",
+          actionParam: { id: 123 }, // hack for testing
+        };
+      });
+    });
+
+    await render(hbs`
+       <article data-post-id="123">
+          <MountWidget @widget="post-menu" @args={{this.args}} />
+       </article>`);
+
+    await click(".hot-coffee");
+
+    assert.strictEqual(123, testPost.id, "callback was called with post");
+    assert.strictEqual(
+      count(".post-action-feedback-button"),
+      1,
+      "It renders feedback"
+    );
+
+    assert.strictEqual(
+      count(".actions .extra-buttons .hot-coffee"),
+      1,
+      "It renders extra button"
+    );
+  });
+
   test("removes button based on callback", async function (assert) {
     this.set("args", { canCreatePost: true, canRemoveReply: true });