When inlines would disable a file shield in a diff, still apply the shield if all the comments are collapsed

Summary:
Ref T13515. We "shield" some changesets, including generated code and intradiffs with no intermediate changes.

These files don't get shielded if they have inline comments.

But, if the viewer has collapsed all the comments, we can shield the file again.

Test Plan:
- Created a change affecting files A and B, with three diffs:
- Touch A and B.
- Touch B only.
- Touch nothing.
- Added an inline to A and collapsed it.
- Viewed Diff 1 vs Diff 2:
- Saw A collapse with a note about inlines.
- Saw B changes, normally.
- Viewed Diff 2 vs Diff 3:
- Saw A collapse with a note about inlines.
- Saw B collapse normally.
- Uncollapsed the inline, viewed 1v2 and 2v3, saw A expand in both cases.

Maniphest Tasks: T13515

Differential Revision: https://secure.phabricator.com/D21136

src/applications/differential/parser/DifferentialChangesetParser.php

···
 
     $has_document_engine = ($engine_blocks !== null);
 
-    $shield = null;
-    if ($this->isTopLevel && !$this->comments && !$has_document_engine) {
+    // See T13515. Sometimes, we collapse file content by default: for
+    // example, if the file is marked as containing generated code.
+
+    // If a file has inline comments, that normally means we never collapse
+    // it. However, if the viewer has already collapsed all of the inlines,
+    // it's fine to collapse the file.
+
+    $expanded_comments = array();
+    foreach ($this->comments as $comment) {
+      if ($comment->isHidden()) {
+        continue;
+      }
+      $expanded_comments[] = $comment;
+    }
+
+    $collapsed_count = (count($this->comments) - count($expanded_comments));
+
+    $shield_raw = null;
+    $shield_text = null;
+    $shield_type = null;
+    if ($this->isTopLevel && !$expanded_comments && !$has_document_engine) {
       if ($this->isGenerated()) {
-        $shield = $renderer->renderShield(
-          pht(
-            'This file contains generated code, which does not normally '.
-            'need to be reviewed.'));
+        $shield_text = pht(
+          'This file contains generated code, which does not normally '.
+          'need to be reviewed.');
       } else if ($this->isMoveAway()) {
         // We put an empty shield on these files. Normally, they do not have
         // any diff content anyway. However, if they come through `arc`, they
···
         // We could show a message like "this file was moved", but we show
         // that as a change header anyway, so it would be redundant. Instead,
         // just render an empty shield to skip rendering the diff body.
-        $shield = '';
+        $shield_raw = '';
       } else if ($this->isUnchanged()) {
         $type = 'text';
         if (!$rows) {
···
           $type = 'none';
         }
 
+        $shield_type = $type;
+
         $type_add = DifferentialChangeType::TYPE_ADD;
         if ($this->changeset->getChangeType() == $type_add) {
           // Although the generic message is sort of accurate in a technical
           // sense, this more-tailored message is less confusing.
-          $shield = $renderer->renderShield(
-            pht('This is an empty file.'),
-            $type);
+          $shield_text = pht('This is an empty file.');
         } else {
-          $shield = $renderer->renderShield(
-            pht('The contents of this file were not changed.'),
-            $type);
+          $shield_text = pht('The contents of this file were not changed.');
         }
       } else if ($this->isDeleted()) {
-        $shield = $renderer->renderShield(
-          pht('This file was completely deleted.'));
+        $shield_text = pht('This file was completely deleted.');
       } else if ($this->changeset->getAffectedLineCount() > 2500) {
-        $shield = $renderer->renderShield(
+        $shield_text = pht(
+          'This file has a very large number of changes (%s lines).',
+          new PhutilNumber($this->changeset->getAffectedLineCount()));
+      }
+    }
+
+    $shield = null;
+    if ($shield_raw !== null) {
+      $shield = $shield_raw;
+    } else if ($shield_text !== null) {
+      if ($shield_type === null) {
+        $shield_type = 'default';
+      }
+
+      // If we have inlines and the shield would normally show the whole file,
+      // downgrade it to show only text around the inlines.
+      if ($collapsed_count) {
+        if ($shield_type === 'text') {
+          $shield_type = 'default';
+        }
+
+        $shield_text = array(
+          $shield_text,
+          ' ',
           pht(
-            'This file has a very large number of changes (%s lines).',
-            new PhutilNumber($this->changeset->getAffectedLineCount())));
+            'This file has %d collapsed inline comment(s).',
+            new PhutilNumber($collapsed_count)),
+        );
       }
+
+      $shield = $renderer->renderShield($shield_text, $shield_type);
     }
 
     if ($shield !== null) {