Add a "Download Raw Diff" action to Differential

Summary: this lets people download diffs easily in case arc export, arc patch, etc isn't to their liking or whatever.

Test Plan: "Download Raw Diff" a few times with various things toggled in the "Revision Update History" widget

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T1294

Differential Revision: https://secure.phabricator.com/D2855

src/applications/differential/controller/DifferentialRevisionViewController.php

@@ -66,6 +66,22 @@ final class DifferentialRevisionViewController extends DifferentialController {
       $diff_vs = null;
     }
 
+    $arc_project = $target->loadArcanistProject();
+    $repository = ($arc_project ? $arc_project->loadRepository() : null);
+
+    list($changesets, $vs_map, $vs_changesets, $rendering_references) =
+      $this->loadChangesetsAndVsMap(
+        $target,
+        idx($diffs, $diff_vs),
+        $repository);
+
+    if ($request->getExists('download')) {
+      return $this->buildRawDiffResponse($changesets,
+                                         $vs_changesets,
+                                         $vs_map,
+                                         $repository);
+    }
+
     list($aux_fields, $props) = $this->loadAuxiliaryFieldsAndProperties(
       $revision,
       $target_manual,
@@ -75,14 +91,6 @@ final class DifferentialRevisionViewController extends DifferentialController {
         'arc:unit',
       ));
 
-    $arc_project = $target->loadArcanistProject();
-    $repository = ($arc_project ? $arc_project->loadRepository() : null);
-
-    list($changesets, $vs_map, $rendering_references) =
-      $this->loadChangesetsAndVsMap(
-        $target,
-        idx($diffs, $diff_vs),
-        $repository);
 
     $comments = $revision->loadComments();
     $comments = array_merge(
@@ -505,6 +513,13 @@ final class DifferentialRevisionViewController extends DifferentialController {
       );
     }
 
+    $request_uri = $this->getRequest()->getRequestURI();
+    $links[] = array(
+      'class' => 'action-download',
+      'name'  => 'Download Raw Diff',
+      'href'  => $request_uri->alter('download', 'true')
+    );
+
     return $links;
   }
 
@@ -643,39 +658,42 @@ final class DifferentialRevisionViewController extends DifferentialController {
     $changesets = mpull($changesets, null, 'getID');
 
     $refs          = array();
-    foreach ($changesets as $changeset) {
-      $refs[$changeset->getID()] = $changeset->getID();
-    }
-
     $vs_map        = array();
-    if ($diff_vs) {
     $vs_changesets = array();
+    if ($diff_vs) {
       $vs_id                  = $diff_vs->getID();
+      $vs_changesets_path_map = array();
       foreach (idx($changeset_groups, $vs_id, array()) as $changeset) {
         $path = $changeset->getAbsoluteRepositoryPath($repository, $diff_vs);
-        $vs_changesets[$path] = $changeset;
+        $vs_changesets_path_map[$path] = $changeset;
+        $vs_changesets[$changeset->getID()] = $changeset;
       }
       foreach ($changesets as $key => $changeset) {
-        $file = $changeset->getAbsoluteRepositoryPath($repository, $target);
+        $path = $changeset->getAbsoluteRepositoryPath($repository, $target);
-        if (isset($vs_changesets[$file])) {
+        if (isset($vs_changesets_path_map[$path])) {
-          $vs_map[$changeset->getID()] = $vs_changesets[$file]->getID();
+          $vs_map[$changeset->getID()] =
+            $vs_changesets_path_map[$path]->getID();
           $refs[$changeset->getID()] =
-            $changeset->getID().'/'.$vs_changesets[$file]->getID();
+            $changeset->getID().'/'.$vs_changesets_path_map[$path]->getID();
-          unset($vs_changesets[$file]);
+          unset($vs_changesets_path_map[$path]);
         } else {
           $refs[$changeset->getID()] = $changeset->getID();
         }
       }
-      foreach ($vs_changesets as $changeset) {
+      foreach ($vs_changesets_path_map as $path => $changeset) {
         $changesets[$changeset->getID()] = $changeset;
         $vs_map[$changeset->getID()]     = -1;
         $refs[$changeset->getID()]       = $changeset->getID().'/-1';
       }
+    } else {
+      foreach ($changesets as $changeset) {
+        $refs[$changeset->getID()] = $changeset->getID();
+      }
     }
 
     $changesets = msort($changesets, 'getSortKey');
 
-    return array($changesets, $vs_map, $refs);
+    return array($changesets, $vs_map, $vs_changesets, $refs);
   }
 
   private function loadAuxiliaryFieldsAndProperties(
@@ -834,4 +852,134 @@ final class DifferentialRevisionViewController extends DifferentialController {
       '</div>';
   }
 
+  /**
+   * Straight copy of the loadFileByPhid method in
+   * @{class:DifferentialReviewRequestMail}.
+   *
+   * This is because of the code similarity between the buildPatch method in
+   * @{class:DifferentialReviewRequestMail} and @{method:buildRawDiffResponse}
+   * in this class. Both of these methods end up using call_user_func and this
+   * piece of code is the lucky function.
+   *
+   * @return mixed (@{class:PhabricatorFile} if found, null if not)
+   */
+  public function loadFileByPHID($phid) {
+    $file = id(new PhabricatorFile())->loadOneWhere(
+      'phid = %s',
+      $phid);
+    if (!$file) {
+      return null;
+    }
+    return $file->loadFileData();
+  }
+
+  /**
+   * Note this code is somewhat similar to the buildPatch method in
+   * @{class:DifferentialReviewRequestMail}.
+   *
+   * @return @{class:AphrontRedirectResponse}
+   */
+  private function buildRawDiffResponse(
+    array $changesets,
+    array $vs_changesets,
+    array $vs_map,
+    PhabricatorRepository $repository = null) {
+
+    assert_instances_of($changesets,    'DifferentialChangeset');
+    assert_instances_of($vs_changesets, 'DifferentialChangeset');
+
+    $engine = new PhabricatorDifferenceEngine();
+    $generated_changesets = array();
+    foreach ($changesets as $changeset) {
+      $changeset->attachHunks($changeset->loadHunks());
+      $vs = idx($vs_map, $changeset->getID());
+      if ($vs) {
+        $choice = $vs_changeset = $vs_changesets[$vs];
+        $vs_changeset->attachHunks($vs_changeset->loadHunks());
+        $right = $vs_changeset->makeNewFile();
+      } else {
+        $choice = $changeset;
+        $right = $changeset->makeOldFile();
+      }
+      $left = $changeset->makeNewFile();
+
+      $synthetic = $engine->generateChangesetFromFileContent(
+        $left,
+        $right);
+
+      if (!$synthetic->getAffectedLineCount()) {
+        $filetype = $choice->getFileType();
+        if ($filetype == DifferentialChangeType::FILE_TEXT ||
+            $filetype == DifferentialChangeType::FILE_SYMLINK) {
+          continue;
+        }
+      }
+
+      $choice->attachHunks($synthetic->getHunks());
+
+      $generated_changesets[] = $choice;
+    }
+
+    $diff = new DifferentialDiff();
+    $diff->attachChangesets($generated_changesets);
+    $diff_dict = $diff->getDiffDict();
+
+    $changes = array();
+    foreach ($diff_dict['changes'] as $changedict) {
+      $changes[] = ArcanistDiffChange::newFromDictionary($changedict);
+    }
+    $bundle = ArcanistBundle::newFromChanges($changes);
+
+    $bundle->setLoadFileDataCallback(array($this, 'loadFileByPHID'));
+
+    $vcs = $repository ? $repository->getVersionControlSystem() : null;
+    switch ($vcs) {
+      case PhabricatorRepositoryType::REPOSITORY_TYPE_GIT:
+        $raw_diff = $bundle->toGitPatch();
+        break;
+      case PhabricatorRepositoryType::REPOSITORY_TYPE_SVN:
+      case PhabricatorRepositoryType::REPOSITORY_TYPE_MERCURIAL:
+      default:
+        $raw_diff = $bundle->toUnifiedDiff();
+        break;
+    }
+
+    $hash = PhabricatorHash::digest($raw_diff);
+
+    $file = id(new PhabricatorFile())->loadOneWhere(
+      'contentHash = %s LIMIT 1',
+      $hash);
+
+    if (!$file) {
+      $request_uri = $this->getRequest()->getRequestURI();
+
+      // this ends up being something like
+      //   D123.diff
+      // or the verbose
+      //   D123.vs123.id123.whitespaceignore-all.diff
+      // lame but nice to include these options
+      $file_name = ltrim($request_uri->getPath(), '/') . '.';
+      foreach ($request_uri->getQueryParams() as $key => $value) {
+        if ($key == 'download') {
+          continue;
+        }
+        $file_name .= $key . $value . '.';
+      }
+      $file_name .= 'diff';
+
+      // We're just caching the data; this is always safe.
+      $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
+
+      $file = PhabricatorFile::newFromFileData(
+        $raw_diff,
+        array(
+          'name' => $file_name,
+        ));
+
+      unset($unguarded);
+    }
+
+    return id(new AphrontRedirectResponse())->setURI($file->getBestURI());
+
+  }
 }