DEV: adds sendChatMessage client API (#21783)

Usage:

```
api.sendChatMessage(channelId, message, { threadId: 6 });
```

plugins/chat/assets/javascripts/discourse/lib/chat-composer-buttons.js

@@ -114,12 +114,12 @@ export function chatComposerButtons(composer, position, context) {
 
       if (isFunction(button.action)) {
         result.action = () => {
-          button.action.apply(composer);
+          button.action.apply(composer, [context]);
         };
       } else {
         const actionName = button.action;
         result.action = () => {
-          composer[actionName]();
+          composer[actionName](context);
         };
       }
 

plugins/chat/assets/javascripts/discourse/pre-initializers/chat-plugin-api.js

@@ -91,6 +91,26 @@ import { addChatDrawerStateCallback } from "discourse/plugins/chat/discourse/ser
  * });
  */
 
+/**
+ * Send a chat message, message or uploads must be provided
+ *
+ * @memberof PluginApi
+ * @instance
+ * @function sendChatMessage
+ * @param {number} channelId - The id of the channel
+ * @param {Object} options
+ * @param {string} [options.message] - The content of the message to send
+ * @param {string} [options.uploads] - A list of uploads to send
+ * @param {number} [options.threadId] - The thread id where the message should be sent
+ *
+ * @example
+ *
+ * api.sendChatMessage(
+ *   1,
+ *  { message: "Hello world", threadId: 2 }
+ * );
+ */
+
 export default {
   name: "chat-plugin-api",
   after: "inject-discourse-objects",
@@ -122,6 +142,20 @@ export default {
           },
         });
       }
+
+      if (!apiPrototype.hasOwnProperty("sendChatMessage")) {
+        Object.defineProperty(apiPrototype, "sendChatMessage", {
+          async value(channelId, options = {}) {
+            return this.container
+              .lookup("service:chat-api")
+              .sendMessage(channelId, {
+                thread_id: options.threadId,
+                message: options.message,
+                uploads: options.uploads,
+              });
+          },
+        });
+      }
     });
   },
 

plugins/chat/assets/javascripts/discourse/services/chat-api.js

@@ -170,6 +170,8 @@ export default class ChatApi extends Service {
    * @param {string} data.cooked - The cooked content of the message.
    * @param {number} [data.in_reply_to_id] - The ID of the replied-to message.
    * @param {number} [data.staged_id] - The staged ID of the message before it was persisted.
+   * @param {number} [data.thread_id] - The ID of the thread where this message should be posted.
+   * @param {number} [data.staged_thread_id] - The staged ID of the thread before it was persisted.
    * @param {Array.<number>} [data.upload_ids] - Array of upload ids linked to the message.
    * @returns {Promise}
    */

plugins/chat/test/javascripts/unit/utility/plugin-api-test.js

@@ -0,0 +1,23 @@
+import { module, test } from "qunit";
+import { withPluginApi } from "discourse/lib/plugin-api";
+import { setupTest } from "ember-qunit";
+import pretender from "discourse/tests/helpers/create-pretender";
+
+module("Chat | Unit | Utility | plugin-api", function (hooks) {
+  setupTest(hooks);
+
+  test("#sendChatMessage", async function (assert) {
+    const done = assert.async();
+
+    pretender.post("/chat/1", (request) => {
+      assert.strictEqual(request.url, "/chat/1");
+      assert.strictEqual(request.requestBody, "thread_id=2&message=hello");
+      done();
+      return [200, {}, {}];
+    });
+
+    withPluginApi("1.1.0", async (api) => {
+      await api.sendChatMessage(1, { message: "hello", threadId: 2 });
+    });
+  });
+});