nodegit · implausible · Jan 29, 2019 · Jan 28, 2019 · Jan 28, 2019 · Jan 28, 2019
diff --git a/lib/commit.js b/lib/commit.js
@@ -1,4 +1,5 @@
 var events = require("events");
+var fp = require("lodash/fp");
 var NodeGit = require("../");
 var Commit = NodeGit.Commit;
 var LookupWrapper = NodeGit.Utils.lookupWrapper;
@@ -50,6 +51,130 @@ Commit.prototype.amend = function (
       });
 };
 
+/**
+ * Amend a commit with the given signature
+ * @async
+ * @param {String} updateRef
+ * @param {Signature} author
+ * @param {Signature} committer
+ * @param {String} messageEncoding
+ * @param {String} message
+ * @param {Tree|Oid} tree
+ * @param {String} signatureField
+ * @param {Function} onSignature
+ * @return {Oid}
+*/
+Commit.prototype.amendWithSignature = function(
+  updateRef,
+  author,
+  committer,
+  messageEncoding,
+  message,
+  tree,
+  signatureField,
+  onSignature
+) {
+    var repo = this.repo;
+    var parentOids = this.parents();
+    var _this = this;
+    var promises = [];
+
+    if (tree instanceof NodeGit.Oid) {
+      promises.push(repo.getTree(tree));
+    } else {
+      promises.push(Promise.resolve(tree));
+    }
+
+    parentOids.forEach(function (parentOid) {
+      promises.push(repo.getCommit(parentOid));
+    });
+
+    var treeObject;
+    var parents;
+    var commitContent;
+    var commitOid;
+    var commit;
+
+    var createCommitPromise = Promise.all(promises)
+      .then(function(results) {
+        treeObject = fp.head(results);
+        parents = fp.tail(results);
+        return _this.getTree();
+      })
+      .then(function(commitTreeResult) {
+        var commitTree = commitTreeResult;
+
+        var truthyArgs = fp.omitBy(
+          fp.isNil,
+          {
+            author,
+            committer,
+            messageEncoding,
+            message,
+            tree: treeObject
+          }
+        );
+
+        var commitFields = {
+          author: _this.author(),
+          committer: _this.committer(),
+          messageEncoding: _this.messageEncoding(),
+          message: _this.message(),
+          tree: commitTree
+        };
+
+        var {
+          author: resolvedAuthor,
+          committer: resolvedCommitter,
+          messageEncoding: resolvedMessageEncoding,
+          message: resolvedMessage,
+          tree: resolvedTree
+        } = fp.assign(
+          truthyArgs,
+          commitFields
+        );
+
+        return Commit.createBuffer(
+          repo,
+          resolvedAuthor,
+          resolvedCommitter,
+          resolvedMessageEncoding,
+          resolvedMessage,
+          resolvedTree,
+          parents.length,
+          parents
+        );
+      })
+      .then(function(commitContentResult) {
+        commitContent = commitContentResult + "\n";
+        return onSignature(commitContent);
+      })
+      .then(function(signature) {
+        return Commit.createWithSignature(
+          repo,
+          commitContent,
+          signature,
+          signatureField
+        );
+      });
+
+    if (!updateRef) {
+      return createCommitPromise;
+    }
+
+    return createCommitPromise.then(function(commitOidResult) {
+      commitOid = commitOidResult;
+      return repo.getCommit(commitOid);
+    }).then(function(commitResult) {
+      commit = commitResult;
+      return repo.getReference(updateRef);
+    }).then(function(ref) {
+      return ref.setTarget(commitOid, `commit (amend): ${commit.summary()}`);
+    }).then(function() {
+      return commitOid;
+    });
+};
+
 /**
  * Retrieve the commit time as a Date object.
  * @return {Date}

diff --git a/test/tests/commit.js b/test/tests/commit.js
@@ -450,6 +450,73 @@ describe("Commit", function() {
     });
   });
 
+
+  it("can amend commit with signature", function() {
+    const signature = "-----BEGIN PGP SIGNATURE-----\n" +
+    "\n" +
+    "iQJHBAEBCAAxFiEEKdxGpJ93wnkLaBKfURjJKedOfEMFAlxPKUYTHHN0ZXZla0Bh\n" +
+    "eG9zb2Z0LmNvbQAKCRBRGMkp5058Q3vcD/0Uf6P68g98Kbvsgjg/aidM1ujruXaw\n" +
+    "X5WSsCAw+wWGICOj0n+KBnmQruI4HSFz3zykEshuOpcBv1X/+huwDeB/hBqonCU8\n" +
+    "QdexCdWR70YbT1bufesUwV9v1qwE4WOmFxWXgwh55K0wDRkc0u2aLcwrJkIEEVfs\n" +
+    "HqZyFzU4kwbGekY/m7d1DsBhWyKEGW9/25WMYmjWOWOiaFjeBaHLlxiEM8KGnMLH\n" +
+    "wx37NuFuaABgi23AAcBGdeWy04TEuU4S51+bHM3RotrZ2cryW2lEbkkXodhIJcq0\n" +
+    "RgrStCbvR0ehnOPdYSiRbxK8JNLZuNjHlK2g7wVi+C83vwMQuhU4H6OlYHGVr664\n" +
+    "4YzL83FdIo7wiMOFd2OOMLlCfHgTun60FvjCs4WHjrwH1fQl287FRPLa/4olBSQP\n" +
+    "yUXJaZdxm4cB4L/1pmbb/J/XUiOio3MpaN3GFm2hZloUlag1uPDBtCxTl5odvj4a\n" +
+    "GOmTBWznXxF/zrKnQVSvv+EccNxYFc0VVjAxGgNqPzIxDAKtw1lE5pbBkFpFpNHz\n" +
+    "StmwZkP9QIJY4hJYQfM+pzHLe8xjexL+Kh/TrYXgY1m/4vJe0HJSsnRnaR8Yfqhh\n" +
+    "LReqo94VHRYXR0rZQv4py0D9TrWaI8xHLve6ewhLPNRzyaI9fNrinbcPYZZOWnRi\n" +
+    "ekgUBx+BX6nJOw==\n" +
+    "=4Hy5\n" +
+    "-----END PGP SIGNATURE-----";
+
+    function onSignature(dataToSign) {
+      return new Promise(function (resolve) {
+        return resolve(signature);
+      });
+    }
+
+    var repo;
+    var oid;
+    var commit;
+    var message;
+    var parents;
+
+    return NodeGit.Repository.open(reposPath)
+      .then(function(repoResult) {
+        repo = repoResult;
+        return repo.getHeadCommit();
+      })
+      .then(function(headCommit) {
+        message = headCommit.message().trim();
+        parents = headCommit.parents();
+
+        return headCommit.amendWithSignature(
+          null,
+          null,
+          null,
+          null,
+          null,
+          null,
+          "gpgsig",
+          onSignature
+        );
+      })
+      .then(function(oidResult) {
+        oid = oidResult;
+        return NodeGit.Commit.lookup(repo, oid);
+      })
+      .then(function(commitResult) {
+        commit = commitResult;
+        return commit.getSignature("gpgsig");
+      })
+      .then(function(signatureInfo) {
+        assert.equal(signatureInfo.signature, signature);
+        assert.equal(commit.message().trim(), message);
+        assert.deepEqual(commit.parents(), parents);
+      });
+  });
+
   it("has an owner", function() {
     var owner = this.commit.owner();
     assert.ok(owner instanceof Repository);