Prepare cherry-pick and revert for migration to Gitaly

3 files changed, 89 insertions, 4 deletions

diff --git a/lib/gitlab/git/commit.rb b/lib/gitlab/git/commit.rb
index 1f370686186..1957c254c28 100644
--- a/lib/gitlab/git/commit.rb
+++ b/lib/gitlab/git/commit.rb
@@ -413,6 +413,10 @@ module Gitlab
                            end
       end
 
+      def merge_commit?
+        parent_ids.size > 1
+      end
+
       private
 
       def init_from_hash(hash)
diff --git a/lib/gitlab/git/operation_service.rb b/lib/gitlab/git/operation_service.rb
index dcdec818f5e..6f054ed3c6c 100644
--- a/lib/gitlab/git/operation_service.rb
+++ b/lib/gitlab/git/operation_service.rb
@@ -15,9 +15,7 @@ module Gitlab
         end
 
         # Refactoring aid
-        unless new_repository.is_a?(Gitlab::Git::Repository)
-          raise "expected a Gitlab::Git::Repository, got #{new_repository}"
-        end
+        Gitlab::Git.check_namespace!(new_repository)
 
         @repository = new_repository
       end
diff --git a/lib/gitlab/git/repository.rb b/lib/gitlab/git/repository.rb
index 18210bcab4e..4b000bd31e2 100644
--- a/lib/gitlab/git/repository.rb
+++ b/lib/gitlab/git/repository.rb
@@ -19,6 +19,7 @@ module Gitlab
       InvalidRef = Class.new(StandardError)
       GitError = Class.new(StandardError)
       DeleteBranchError = Class.new(StandardError)
+      CreateTreeError = Class.new(StandardError)
 
       class << self
         # Unlike `new`, `create` takes the storage path, not the storage name
@@ -684,6 +685,88 @@ module Gitlab
         nil
       end
 
+      def revert(user:, commit:, branch_name:, message:, start_branch_name:, start_repository:)
+        OperationService.new(user, self).with_branch(
+          branch_name,
+          start_branch_name: start_branch_name,
+          start_repository: start_repository
+        ) do |start_commit|
+
+          Gitlab::Git.check_namespace!(commit, start_repository)
+
+          revert_tree_id = check_revert_content(commit, start_commit.sha)
+          raise CreateTreeError unless revert_tree_id
+
+          committer = user_to_committer(user)
+
+          create_commit(message: message,
+                        author: committer,
+                        committer: committer,
+                        tree: revert_tree_id,
+                        parents: [start_commit.sha])
+        end
+      end
+
+      def check_revert_content(target_commit, source_sha)
+        args = [target_commit.sha, source_sha]
+        args << { mainline: 1 } if target_commit.merge_commit?
+
+        revert_index = rugged.revert_commit(*args)
+        return false if revert_index.conflicts?
+
+        tree_id = revert_index.write_tree(rugged)
+        return false unless diff_exists?(source_sha, tree_id)
+
+        tree_id
+      end
+
+      def cherry_pick(user:, commit:, branch_name:, message:, start_branch_name:, start_repository:)
+        OperationService.new(user, self).with_branch(
+          branch_name,
+          start_branch_name: start_branch_name,
+          start_repository: start_repository
+        ) do |start_commit|
+
+          Gitlab::Git.check_namespace!(commit, start_repository)
+
+          cherry_pick_tree_id = check_cherry_pick_content(commit, start_commit.sha)
+          raise CreateTreeError unless cherry_pick_tree_id
+
+          committer = user_to_committer(user)
+
+          create_commit(message: message,
+                        author: {
+                            email: commit.author_email,
+                            name: commit.author_name,
+                            time: commit.authored_date
+                        },
+                        committer: committer,
+                        tree: cherry_pick_tree_id,
+                        parents: [start_commit.sha])
+        end
+      end
+
+      def check_cherry_pick_content(target_commit, source_sha)
+        args = [target_commit.sha, source_sha]
+        args << 1 if target_commit.merge_commit?
+
+        cherry_pick_index = rugged.cherrypick_commit(*args)
+        return false if cherry_pick_index.conflicts?
+
+        tree_id = cherry_pick_index.write_tree(rugged)
+        return false unless diff_exists?(source_sha, tree_id)
+
+        tree_id
+      end
+
+      def diff_exists?(sha1, sha2)
+        rugged.diff(sha1, sha2).size > 0
+      end
+
+      def user_to_committer(user)
+        Gitlab::Git.committer_hash(email: user.email, name: user.name)
+      end
+
       def create_commit(params = {})
         params[:message].delete!("\r")
 
@@ -835,7 +918,7 @@ module Gitlab
       end
 
       def with_repo_branch_commit(start_repository, start_branch_name)
-        raise "expected Gitlab::Git::Repository, got #{start_repository}" unless start_repository.is_a?(Gitlab::Git::Repository)
+        Gitlab::Git.check_namespace!(start_repository)
 
         return yield nil if start_repository.empty_repo?