From 56713da6483523251ae05225ea3e875e28dd0587 Mon Sep 17 00:00:00 2001
From: Aleksey Kulikov <skinny.mind@gmail.com>
Date: Sat, 4 Sep 2021 13:52:29 +0300
Subject: [PATCH] fix(tag): tag can point to any type of git object

---
 lib/src/bindings/tag.dart |  3 +++
 lib/src/tag.dart          | 21 +++++++++++++++++++--
 test/repository_test.dart |  2 +-
 test/tag_test.dart        |  4 ++--
 4 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/lib/src/bindings/tag.dart b/lib/src/bindings/tag.dart
index 63bdc57..1758d6d 100644
--- a/lib/src/bindings/tag.dart
+++ b/lib/src/bindings/tag.dart
@@ -34,6 +34,9 @@ Pointer<git_object> target(Pointer<git_tag> tag) {
   }
 }
 
+/// Get the type of a tag's tagged object.
+int targetType(Pointer<git_tag> tag) => libgit2.git_tag_target_type(tag);
+
 /// Get the id of a tag.
 Pointer<git_oid> id(Pointer<git_tag> tag) => libgit2.git_tag_id(tag);
 
diff --git a/lib/src/tag.dart b/lib/src/tag.dart
index f8bc9ac..8de67b1 100644
--- a/lib/src/tag.dart
+++ b/lib/src/tag.dart
@@ -1,5 +1,7 @@
 import 'dart:ffi';
 
+import 'package:libgit2dart/libgit2dart.dart';
+
 import 'bindings/libgit2_bindings.dart';
 import 'bindings/tag.dart' as bindings;
 import 'bindings/object.dart' as object_bindings;
@@ -73,12 +75,27 @@ class Tag {
     return Oid(result);
   }
 
-  /// Get the tagged object of a tag.
+  /// Get the tagged object (commit, tree, blob, tag) of a tag.
   ///
   /// This method performs a repository lookup for the given object and returns it.
   ///
+  /// Returned object should be explicitly downcasted to one of four of git object types.
+  ///
   /// Throws a [LibGit2Error] if error occured.
-  Commit get target => Commit(bindings.target(_tagPointer).cast());
+  Object get target {
+    final type = bindings.targetType(_tagPointer);
+    final object = bindings.target(_tagPointer);
+
+    if (type == GitObject.commit.value) {
+      return Commit(object.cast());
+    } else if (type == GitObject.tree.value) {
+      return Tree(object.cast());
+    } else if (type == GitObject.blob.value) {
+      return Blob(object.cast());
+    } else {
+      return Tag(object.cast());
+    }
+  }
 
   /// Get the id of a tag.
   Oid get id => Oid(bindings.id(_tagPointer));
diff --git a/test/repository_test.dart b/test/repository_test.dart
index e0d2e15..c7f1f2c 100644
--- a/test/repository_test.dart
+++ b/test/repository_test.dart
@@ -325,7 +325,7 @@ void main() {
 
         final newTag = repo[oid.sha] as Tag;
         final tagger = newTag.tagger;
-        final newTagTarget = newTag.target;
+        final newTagTarget = newTag.target as Commit;
 
         expect(newTag.id.sha, '131a5eb6b7a880b5096c550ee7351aeae7b95a42');
         expect(newTag.name, tagName);
diff --git a/test/tag_test.dart b/test/tag_test.dart
index 5751512..cdb1548 100644
--- a/test/tag_test.dart
+++ b/test/tag_test.dart
@@ -40,7 +40,7 @@ void main() {
         time: 1630599723,
         offset: 180,
       );
-      final target = tag.target;
+      final target = tag.target as Commit;
       final tagger = tag.tagger;
 
       expect(tag.id.sha, tagSHA);
@@ -74,7 +74,7 @@ void main() {
 
       final newTag = Tag.lookup(repo, oid.sha);
       final tagger = newTag.tagger;
-      final newTagTarget = newTag.target;
+      final newTagTarget = newTag.target as Commit;
 
       expect(newTag.id.sha, '131a5eb6b7a880b5096c550ee7351aeae7b95a42');
       expect(newTag.name, tagName);