Add a component for picking the time to send a job

Users need to pick a time in the next 24hrs, or send a file immediately.

Rationale for this is a bit lost in time-before-holiday, but generally:

‘Now’ and ‘later’ as the inital choices makes it really clear what
this feature is about conceptually.

The choice of times is absolute, eg ‘1pm’ not ‘in 3 hours’

app/assets/javascripts/radioSelect.js

@@ -0,0 +1,92 @@
+(function(Modules) {
+
+  "use strict";
+
+  var render = ($options, $button) => (
+    filterOptionVisibility($options) && setButtonState($options, $button)
+  );
+
+  var filterOptionVisibility = $options => $options
+    .removeClass('js-visible')
+    .filter(
+      (index, element) => (index === 0 || $(element).has(':checked').length)
+    )
+    .addClass('js-visible');
+
+  var setButtonState = ($options, $button) => $button
+    .addClass('js-visible')
+    .prop(
+      'value',
+      $options.has(':checked').find('input').attr('id') === $options.eq(0).find('input').attr('id') ?
+        'Later' : 'Choose a different time'
+    );
+
+  // Workaround because GOV.UK SelectionButtons doesn’t deselect in this case
+  var deselectUnchecked = $options => $options
+    .filter(
+      (index, element) => $(element).not(':has(:checked)')
+    ).removeClass('selected');
+
+  var refocus = $element => setTimeout(
+    () => $element.blur().trigger('focus'),
+    10
+  );
+
+  var renderIfComponentLosesFocus = ($options, $button, $focused) => () =>
+    ($focused.attr('type') !== 'radio') &&
+    render($options, $button) &&
+    refocus($focused); // Make sure that window scrolls to focused element
+
+  Modules.RadioSelect = function() {
+
+    this.start = function(component) {
+
+      let $component = $(component);
+      let $options = $('label', $component);
+
+      $component.append(
+        $button = $('<input type="button" value="Later" class="tertiary-button" />')
+      );
+
+      $button.on('click', () =>
+        $options.addClass('js-visible').has(':checked').focus() &&
+        $button.removeClass('js-visible')
+      );
+
+      $component.on('keydown', 'input[type=radio]', function() {
+
+        // intercept keypresses which aren’t enter or space
+        if (event.which !== 13 && event.which !== 32) {
+          setTimeout(
+            renderIfComponentLosesFocus($options, $button, $(document.activeElement)),
+            200
+          );
+          return true;
+        }
+
+        event.preventDefault();
+
+        render($options, $button);
+        refocus($(this));
+
+      });
+
+      $component.on('click', 'input[type=radio]', function(event) {
+
+        deselectUnchecked($options);
+
+        // stop click being triggered by keyboard events
+        if (!event.pageX) return true;
+
+        render($options, $button);
+        refocus($(this));
+
+      });
+
+      render($options, $button);
+
+    };
+
+  };
+
+})(window.GOVUK.Modules);