No submit if no photo is selected

app/assets/javascripts/archive-uploader.js

@@ -1,15 +1,24 @@
-const profileFileBtn = document.getElementById("profile-file-btn");
-
+const checkProfileUploadButton = function() {
+  let photoFiles = $("#profile-file-btn")[0].files;
+  let profileFiles = $("#photos-file-btn")[0].files;
+  if ((photoFiles.size + profileFiles.size) === 0) {
+    $("#upload_profile_files").attr("disabled", "disabled");
+  } else {
+    $("#upload_profile_files").removeAttr("disabled");
+  }
+};
+const profileFileButton = document.getElementById("profile-file-btn");
 const profileFileChosen = document.getElementById("profile-file-chosen");
 
-profileFileBtn.addEventListener("change", function() {
+const photosFileButton = document.getElementById("photos-file-btn");
+const photosFileChosen = document.getElementById("photos-file-chosen");
+
+profileFileButton.addEventListener("change", function() {
   profileFileChosen.textContent = this.files[0].name;
+  checkProfileUploadButton();
 });
 
-const photosFileBtn = document.getElementById("photos-file-btn");
-
-const photosFileChosen = document.getElementById("photos-file-chosen");
-
-photosFileBtn.addEventListener("change", function() {
+photosFileButton.addEventListener("change", function() {
   photosFileChosen.textContent = this.files[0].name;
+  checkProfileUploadButton();
 });

app/views/users/_import_account_modal.haml

@@ -57,6 +57,9 @@
               .clearfix
                 .btn.btn-default{data: {dismiss: "modal"}}
                   = t("users.import_modal.cancel")
-                = f.submit t("users.import_modal.start_import"), class: "btn btn-primary.pull-right", id: "change_email_preferences"
+                = f.submit t("users.import_modal.start_import"),
+                class: "btn btn-primary.pull-right",
+                id: "upload_profile_files",
+                disabled: true
 
 = javascript_include_tag "archive-uploader"