Write edges for commit reverts

Summary:
Ref T1751. When a commit reverts another commit:

  - Add an edge linking them;
  - Show the edge in Diffusion.

Next steps are:

  - If the reverted commit is associated with a Differential revision, leave a comment;
  - Also leave a comment on the commit (no API yet);
  - Also trigger an audit by the original commit's author.

Test Plan: Used `scripts/repository/reparse.php --message ...` to parse commits with revert language. Verified they appear correctly in Diffusion, and update Differential.

Reviewers: btrahan, epriestley

Reviewed By: btrahan, epriestley

Subscribers: Korvin, epriestley, cburroughs, joshuaspence, sascha-egerer, aran

Maniphest Tasks: T4896, T1751

Differential Revision: https://secure.phabricator.com/D5846

src/__phutil_library_map__.php

@@ -474,6 +474,8 @@ phutil_register_library_map(array(
     'DiffusionCommitRef' => 'applications/diffusion/data/DiffusionCommitRef.php',
     'DiffusionCommitRemarkupRule' => 'applications/diffusion/remarkup/DiffusionCommitRemarkupRule.php',
     'DiffusionCommitRemarkupRuleTestCase' => 'applications/diffusion/remarkup/__tests__/DiffusionCommitRemarkupRuleTestCase.php',
+    'DiffusionCommitRevertedByCommitEdgeType' => 'applications/diffusion/edge/DiffusionCommitRevertedByCommitEdgeType.php',
+    'DiffusionCommitRevertsCommitEdgeType' => 'applications/diffusion/edge/DiffusionCommitRevertsCommitEdgeType.php',
     'DiffusionCommitTagsController' => 'applications/diffusion/controller/DiffusionCommitTagsController.php',
     'DiffusionConduitAPIMethod' => 'applications/diffusion/conduit/DiffusionConduitAPIMethod.php',
     'DiffusionController' => 'applications/diffusion/controller/DiffusionController.php',
@@ -3536,6 +3538,8 @@ phutil_register_library_map(array(
     'DiffusionCommitRef' => 'Phobject',
     'DiffusionCommitRemarkupRule' => 'PhabricatorObjectRemarkupRule',
     'DiffusionCommitRemarkupRuleTestCase' => 'PhabricatorTestCase',
+    'DiffusionCommitRevertedByCommitEdgeType' => 'PhabricatorEdgeType',
+    'DiffusionCommitRevertsCommitEdgeType' => 'PhabricatorEdgeType',
     'DiffusionCommitTagsController' => 'DiffusionController',
     'DiffusionConduitAPIMethod' => 'ConduitAPIMethod',
     'DiffusionController' => 'PhabricatorController',

src/applications/diffusion/controller/DiffusionCommitController.php

@@ -419,6 +419,8 @@ final class DiffusionCommitController extends DiffusionController {
       ->withEdgeTypes(array(
         DiffusionCommitHasTaskEdgeType::EDGECONST,
         DiffusionCommitHasRevisionEdgeType::EDGECONST,
+        DiffusionCommitRevertsCommitEdgeType::EDGECONST,
+        DiffusionCommitRevertedByCommitEdgeType::EDGECONST,
       ));
 
     $edges = $edge_query->execute();
@@ -428,6 +430,11 @@ final class DiffusionCommitController extends DiffusionController {
     $revision_phid = key(
       $edges[$commit_phid][DiffusionCommitHasRevisionEdgeType::EDGECONST]);
 
+    $reverts_phids = array_keys(
+      $edges[$commit_phid][DiffusionCommitRevertsCommitEdgeType::EDGECONST]);
+    $reverted_by_phids = array_keys(
+      $edges[$commit_phid][DiffusionCommitRevertedByCommitEdgeType::EDGECONST]);
+
     $phids = $edge_query->getDestinationPHIDs(array($commit_phid));
 
     if ($data->getCommitDetail('authorPHID')) {
@@ -615,6 +622,17 @@ final class DiffusionCommitController extends DiffusionController {
       $props['References'] = $refs;
     }
 
+    if ($reverts_phids) {
+      $this->loadHandles($reverts_phids);
+      $props[pht('Reverts')] = $this->renderHandlesForPHIDs($reverts_phids);
+    }
+
+    if ($reverted_by_phids) {
+      $this->loadHandles($reverted_by_phids);
+      $props[pht('Reverted By')] = $this->renderHandlesForPHIDs(
+        $reverted_by_phids);
+    }
+
     if ($task_phids) {
       $task_list = array();
       foreach ($task_phids as $phid) {

src/applications/diffusion/edge/DiffusionCommitRevertedByCommitEdgeType.php

@@ -0,0 +1,16 @@
+<?php
+
+final class DiffusionCommitRevertedByCommitEdgeType
+  extends PhabricatorEdgeType {
+
+  const EDGECONST = 56;
+
+  public function getInverseEdgeConstant() {
+    return DiffusionCommitRevertsCommitEdgeType::EDGECONST;
+  }
+
+  public function shouldWriteInverseTransactions() {
+    return true;
+  }
+
+}

src/applications/diffusion/edge/DiffusionCommitRevertsCommitEdgeType.php

@@ -0,0 +1,19 @@
+<?php
+
+final class DiffusionCommitRevertsCommitEdgeType extends PhabricatorEdgeType {
+
+  const EDGECONST = 55;
+
+  public function getInverseEdgeConstant() {
+    return DiffusionCommitRevertedByCommitEdgeType::EDGECONST;
+  }
+
+  public function shouldWriteInverseTransactions() {
+    return true;
+  }
+
+  public function shouldPreventCycles() {
+    return true;
+  }
+
+}

src/applications/repository/worker/commitmessageparser/PhabricatorRepositoryCommitMessageParserWorker.php

@@ -102,6 +102,35 @@ abstract class PhabricatorRepositoryCommitMessageParserWorker
 
     $conn_w = id(new DifferentialRevision())->establishConnection('w');
 
+    $reverts_refs = id(new DifferentialCustomFieldRevertsParser())
+      ->parseCorpus($message);
+    $reverts = array_mergev(ipull($reverts_refs, 'monograms'));
+
+    if ($reverts) {
+      $reverted_commits = id(new DiffusionCommitQuery())
+        ->setViewer($actor)
+        ->withIdentifiers($reverts)
+        ->execute();
+      $reverted_commit_phids = mpull($reverted_commits, 'getPHID', 'getPHID');
+
+      // NOTE: Skip any write attempts if a user cleverly implies a commit
+      // reverts itself.
+      unset($reverted_commit_phids[$commit->getPHID()]);
+
+      $editor = new PhabricatorEdgeEditor();
+      foreach ($reverted_commit_phids as $commit_phid) {
+        try {
+          $editor->addEdge(
+            $commit->getPHID(),
+            DiffusionCommitRevertsCommitEdgeType::EDGECONST,
+            $commit_phid);
+        } catch (PhabricatorEdgeCycleException $ex) {
+          continue;
+        }
+      }
+      $editor->save();
+    }
+
     // NOTE: The `differential_commit` table has a unique ID on `commitPHID`,
     // preventing more than one revision from being associated with a commit.
     // Generally this is good and desirable, but with the advent of hash