FIX: validates import theme form (#6513)

app/assets/javascripts/admin/controllers/modals/admin-import-theme.js.es6

@@ -1,7 +1,10 @@
 import ModalFunctionality from "discourse/mixins/modal-functionality";
 import { ajax } from "discourse/lib/ajax";
 import { popupAjaxError } from "discourse/lib/ajax-error";
-import { observes } from "ember-addons/ember-computed-decorators";
+import {
+  default as computed,
+  observes
+} from "ember-addons/ember-computed-decorators";
 
 export default Ember.Controller.extend(ModalFunctionality, {
   local: Ember.computed.equal("selection", "local"),
@@ -11,8 +14,14 @@ export default Ember.Controller.extend(ModalFunctionality, {
   loading: false,
   keyGenUrl: "/admin/themes/generate_key_pair",
   importUrl: "/admin/themes/import",
-
   checkPrivate: Ember.computed.match("uploadUrl", /^git/),
+  localFile: null,
+  uploadUrl: null,
+
+  @computed("loading", "remote", "uploadUrl", "local", "localFile")
+  importDisabled(isLoading, isRemote, uploadUrl, isLocal, localFile) {
+    return isLoading || (isRemote && !uploadUrl) || (isLocal && !localFile);
+  },
 
   @observes("privateChecked")
   privateWasChecked() {
@@ -32,6 +41,10 @@ export default Ember.Controller.extend(ModalFunctionality, {
   },
 
   actions: {
+    uploadLocaleFile() {
+      this.set("localFile", $("#file-input")[0].files[0]);
+    },
+
     importTheme() {
       let options = {
         type: "POST"
@@ -41,7 +54,7 @@ export default Ember.Controller.extend(ModalFunctionality, {
         options.processData = false;
         options.contentType = false;
         options.data = new FormData();
-        options.data.append("theme", $("#file-input")[0].files[0]);
+        options.data.append("theme", this.get("localFile"));
       } else {
         options.data = {
           remote: this.get("uploadUrl"),

app/assets/javascripts/admin/templates/modal/admin-import-theme.hbs

@@ -4,7 +4,7 @@
     <label class="radio" for="local">{{i18n 'upload_selector.from_my_computer'}}</label>
     {{#if local}}
       <div class="inputs">
-        <input type="file" id="file-input" accept='.dcstyle.json,application/json'><br>
+        <input onchange={{action "uploadLocaleFile"}} type="file" id="file-input" accept='.dcstyle.json,application/json'><br>
         <span class="description">{{i18n 'admin.customize.theme.import_file_tip'}}</span>
       </div>
     {{/if}}
@@ -44,6 +44,6 @@
 {{/d-modal-body}}
 
 <div class="modal-footer">
-  {{d-button action="importTheme" disabled=loading class='btn btn-primary' icon='upload' label='admin.customize.import'}}
+  {{d-button action="importTheme" disabled=importDisabled class='btn btn-primary' icon='upload' label='admin.customize.import'}}
   {{d-modal-cancel close=(action "closeModal")}}
 </div>