When printing timestamps on paper: use an absolute, context-free date format

Summary:
Ref T13573. Using the browser "Print" feature on pages produces "Thu, Aug 4, 12:22" timestamps which require context to interpret precisely (they don't have a year and don't have a timezone).

Instead, retain these timestamps in "screen" contexts but use "YYYY-MM-DD HH:MM:SS (UTC+X)" timestamps when printing.

Test Plan: Printed Maniphest tasks and other pages in Safari and Chrome using "?__print__=1" and "Print to PDF", saw absolute timestamps after this chagne in the printed documents.

Maniphest Tasks: T13573

Differential Revision: https://secure.phabricator.com/D21451

resources/celerity/map.php

@@ -9,7 +9,7 @@ return array(
   'names' => array(
     'conpherence.pkg.css' => '0e3cf785',
     'conpherence.pkg.js' => '020aebcf',
-    'core.pkg.css' => 'b13bef94',
+    'core.pkg.css' => 'bd937962',
     'core.pkg.js' => 'adc34883',
     'dark-console.pkg.js' => '187792c2',
     'differential.pkg.css' => '5c459f92',
@@ -113,7 +113,7 @@ return array(
     'rsrc/css/application/slowvote/slowvote.css' => '1694baed',
     'rsrc/css/application/tokens/tokens.css' => 'ce5a50bd',
     'rsrc/css/application/uiexample/example.css' => 'b4795059',
-    'rsrc/css/core/core.css' => '1b29ed61',
+    'rsrc/css/core/core.css' => 'b3ebd90d',
     'rsrc/css/core/remarkup.css' => '94c3d777',
     'rsrc/css/core/syntax.css' => '548567f6',
     'rsrc/css/core/z-index.css' => 'ac3bfcd4',
@@ -779,7 +779,7 @@ return array(
     'phabricator-busy' => '5202e831',
     'phabricator-chatlog-css' => 'abdc76ee',
     'phabricator-content-source-view-css' => 'cdf0d579',
-    'phabricator-core-css' => '1b29ed61',
+    'phabricator-core-css' => 'b3ebd90d',
     'phabricator-countdown-css' => 'bff8012f',
     'phabricator-darklog' => '3b869402',
     'phabricator-darkmessage' => '26cd4b73',

src/__phutil_library_map__.php

@@ -5959,9 +5959,11 @@ phutil_register_library_map(array(
     'celerity_get_resource_uri' => 'applications/celerity/api.php',
     'hsprintf' => 'infrastructure/markup/render.php',
     'javelin_tag' => 'infrastructure/javelin/markup.php',
+    'phabricator_absolute_datetime' => 'view/viewutils.php',
     'phabricator_date' => 'view/viewutils.php',
     'phabricator_datetime' => 'view/viewutils.php',
     'phabricator_datetimezone' => 'view/viewutils.php',
+    'phabricator_dual_datetime' => 'view/viewutils.php',
     'phabricator_form' => 'infrastructure/javelin/markup.php',
     'phabricator_format_local_time' => 'view/viewutils.php',
     'phabricator_relative_date' => 'view/viewutils.php',

src/applications/phriction/controller/PhrictionDocumentController.php

@@ -401,7 +401,7 @@ final class PhrictionDocumentController
 
     $view->addProperty(
       pht('Last Edited'),
-      phabricator_datetime($content->getDateCreated(), $viewer));
+      phabricator_dual_datetime($content->getDateCreated(), $viewer));
 
     return $view;
   }

src/infrastructure/javelin/markup.php

@@ -50,6 +50,23 @@ function javelin_tag(
     unset($attributes['aural']);
   }
 
+  if (isset($attributes['print'])) {
+    if ($attributes['print']) {
+      $class = idx($attributes, 'class', '');
+      $class = rtrim('print-only '.$class);
+      $attributes['class'] = $class;
+
+      // NOTE: Alternative print content is hidden from screen readers.
+      $attributes['aria-hidden'] = 'true';
+    } else {
+      $class = idx($attributes, 'class', '');
+      $class = rtrim('screen-only '.$class);
+      $attributes['class'] = $class;
+    }
+    unset($attributes['print']);
+  }
+
+
   return phutil_tag($tag, $attributes, $content);
 }
 

src/view/phui/PHUICurtainObjectRefView.php

@@ -46,7 +46,7 @@ final class PHUICurtainObjectRefView
 
     $epoch = $this->epoch;
     if ($epoch !== null) {
-      $epoch_view = phabricator_datetime($epoch, $viewer);
+      $epoch_view = phabricator_dual_datetime($epoch, $viewer);
 
       $epoch_cells = array();
 

src/view/phui/PHUIObjectItemView.php

@@ -192,7 +192,7 @@ final class PHUIObjectItemView extends AphrontTagView {
   }
 
   public function setEpoch($epoch) {
-    $date = phabricator_datetime($epoch, $this->getUser());
+    $date = phabricator_dual_datetime($epoch, $this->getUser());
     $this->addIcon('none', $date);
     return $this;
   }

src/view/phui/PHUITimelineEventView.php

@@ -591,7 +591,7 @@ final class PHUITimelineEventView extends AphrontView {
       }
 
       if ($date_created) {
-        $date = phabricator_datetime(
+        $date = phabricator_dual_datetime(
           $date_created,
           $this->getUser());
         if ($this->anchor) {
@@ -611,6 +611,7 @@ final class PHUITimelineEventView extends AphrontView {
               $date),
           );
         }
+
         $extra[] = $date;
       }
 

src/view/viewutils.php

@@ -38,6 +38,39 @@ function phabricator_time($epoch, $user) {
     $user->getUserSetting($time_key));
 }
 
+function phabricator_dual_datetime($epoch, $user) {
+  $screen_view = phabricator_datetime($epoch, $user);
+  $print_view = phabricator_absolute_datetime($epoch, $user);
+
+  $screen_tag = javelin_tag(
+    'span',
+    array(
+      'print' => false,
+    ),
+    $screen_view);
+
+  $print_tag = javelin_tag(
+    'span',
+    array(
+      'print' => true,
+    ),
+    $print_view);
+
+  return array(
+    $screen_tag,
+    $print_tag,
+  );
+}
+
+function phabricator_absolute_datetime($epoch, $user) {
+  $format = 'Y-m-d H:i:s (\\U\\T\\CP)';
+
+  $datetime = phabricator_format_local_time($epoch, $user, $format);
+  $datetime = preg_replace('/(UTC[+-])0?([^:]+)(:00)?/', '\\1\\2', $datetime);
+
+  return $datetime;
+}
+
 function phabricator_datetime($epoch, $user) {
   $time_key = PhabricatorTimeFormatSetting::SETTINGKEY;
   return phabricator_format_local_time(

webroot/rsrc/css/core/core.css

@@ -162,6 +162,33 @@ hr {
   opacity: 0.25;
 }
 
+.print-only {
+  display: none;
+}
+
+/* NOTE: These rules currently only work when applied to elements which
+   actually want "display: inline". There is no "display: auto". If there
+   is a future need to mix inline and block print elements, using
+   "display: initial" may be a reasonable approach. */
+
+.printable .print-only {
+  display: inline;
+}
+
+.printable .screen-only {
+  display: none;
+}
+
+@media print {
+  .screen-only {
+    display: none;
+  }
+
+  .print-only {
+    display: inline;
+  }
+}
+
 .routing-bar {
   position: fixed;
   top: 0;