FEATURE: Support pasting a list of usernames into a PM

This allows you to paste multiple usernames into a PM's recipient list
at once. It supports usernames separated by spaces, commas, and new lines.

app/assets/javascripts/discourse/components/user-selector.js.es6

@@ -9,6 +9,25 @@ export default TextField.extend({
   autocapitalize: false,
   name: "user-selector",
 
+  init() {
+    this._super();
+    this._paste = e => {
+      let pastedText = "";
+      if (window.clipboardData && window.clipboardData.getData) {
+        // IE
+        pastedText = window.clipboardData.getData("Text");
+      } else if (e.clipboardData && e.clipboardData.getData) {
+        pastedText = e.clipboardData.getData("text/plain");
+      }
+
+      if (pastedText.length > 0) {
+        this.importText(pastedText);
+        e.preventDefault();
+        return false;
+      }
+    };
+  },
+
   @observes("usernames")
   _update() {
     if (this.canReceiveUpdates === "true") {
@@ -19,6 +38,7 @@ export default TextField.extend({
   @on("willDestroyElement")
   _destroyAutocompleteInstance() {
     $(this.element).autocomplete("destroy");
+    this.element.addEventListener("paste", this._paste);
   },
 
   @on("didInsertElement")
@@ -52,6 +72,8 @@ export default TextField.extend({
       return usernames;
     };
 
+    this.element.addEventListener("paste", this._paste);
+
     const userSelectorComponent = this;
 
     $(this.element)
@@ -128,6 +150,24 @@ export default TextField.extend({
       });
   },
 
+  importText(text) {
+    let usernames = [];
+    if ((this.usernames || "").length > 0) {
+      usernames = this.usernames.split(",");
+    }
+
+    (text || "").split(/[, \n]+/).forEach(val => {
+      val = val.replace(/^@+/, "").trim();
+      if (val.length > 0) {
+        usernames.push(val);
+      }
+    });
+    this.set("usernames", usernames.uniq().join(","));
+    if (this.canReceiveUpdates !== "true") {
+      this._createAutocompleteInstance({ updateData: true });
+    }
+  },
+
   // THIS IS A HUGE HACK TO SUPPORT CLEARING THE INPUT
   @observes("usernames")
   _clearInput() {

test/javascripts/components/user-selector-test.js.es6

@@ -0,0 +1,38 @@
+import componentTest from "helpers/component-test";
+
+moduleForComponent("user-selector", { integration: true });
+
+componentTest("pasting a list of usernames", {
+  template: `{{user-selector usernames=usernames class="test-selector"}}`,
+
+  beforeEach() {
+    this.set("usernames", "evil,trout");
+  },
+
+  test(assert) {
+    let element = find(".test-selector")[0];
+    let paste = text => {
+      let e = new Event("paste");
+      e.clipboardData = { getData: () => text };
+      element.dispatchEvent(e);
+    };
+
+    assert.equal(this.get("usernames"), "evil,trout");
+    paste("zip,zap,zoom");
+    assert.equal(this.get("usernames"), "evil,trout,zip,zap,zoom");
+    paste("evil,abc,abc,abc");
+    assert.equal(this.get("usernames"), "evil,trout,zip,zap,zoom,abc");
+
+    this.set("usernames", "");
+    paste("names with spaces");
+    assert.equal(this.get("usernames"), "names,with,spaces");
+
+    this.set("usernames", null);
+    paste("@eviltrout,@codinghorror sam");
+    assert.equal(this.get("usernames"), "eviltrout,codinghorror,sam");
+
+    this.set("usernames", null);
+    paste("eviltrout\nsam\ncodinghorror");
+    assert.equal(this.get("usernames"), "eviltrout,sam,codinghorror");
+  }
+});