1 files changed, 116 insertions, 0 deletions
diff --git a/app/services/merge_requests/add_context_service.rb b/app/services/merge_requests/add_context_service.rb
new file mode 100644
index 00000000000..bb82fa23468
--- /dev/null
+++ b/app/services/merge_requests/add_context_service.rb
@@ -0,0 +1,116 @@
+# frozen_string_literal: true
+
+module MergeRequests
+  class AddContextService < MergeRequests::BaseService
+    def execute
+      return error("You are not allowed to access the requested resource", 403) unless current_user&.can?(:update_merge_request, merge_request)
+      return error("Context commits: #{duplicates} are already created", 400) unless duplicates.empty?
+      return error("One or more context commits' sha is not valid.", 400) if commits.size != commit_ids.size
+
+      context_commit_ids = []
+      MergeRequestContextCommit.transaction do
+        context_commit_ids = MergeRequestContextCommit.bulk_insert(context_commit_rows, return_ids: true)
+        MergeRequestContextCommitDiffFile.bulk_insert(diff_rows(context_commit_ids))
+      end
+
+      commits
+    end
+
+    private
+
+    def raw_repository
+      project.repository.raw_repository
+    end
+
+    def merge_request
+      params[:merge_request]
+    end
+
+    def commit_ids
+      params[:commits]
+    end
+
+    def commits
+      project.repository.commits_by(oids: commit_ids)
+    end
+
+    def context_commit_rows
+      @context_commit_rows ||= build_context_commit_rows(merge_request.id, commits)
+    end
+
+    def diff_rows(context_commit_ids)
+      @diff_rows ||= build_diff_rows(raw_repository, commits, context_commit_ids)
+    end
+
+    def encode_in_base64?(diff_text)
+      (diff_text.encoding == Encoding::BINARY && !diff_text.ascii_only?) ||
+        diff_text.include?("\0")
+    end
+
+    def duplicates
+      existing_oids = merge_request.merge_request_context_commits.map { |commit| commit.sha.to_s }
+      duplicate_oids = existing_oids.select do |existing_oid|
+        commit_ids.select { |commit_id| existing_oid.start_with?(commit_id) }.count > 0
+      end
+
+      duplicate_oids
+    end
+
+    def build_context_commit_rows(merge_request_id, commits)
+      commits.map.with_index do |commit, index|
+        # generate context commit information for given commit
+        commit_hash = commit.to_hash.except(:parent_ids)
+        sha = Gitlab::Database::ShaAttribute.serialize(commit_hash.delete(:id))
+        commit_hash.merge(
+          merge_request_id: merge_request_id,
+          relative_order: index,
+          sha: sha,
+          authored_date: Gitlab::Database.sanitize_timestamp(commit_hash[:authored_date]),
+          committed_date: Gitlab::Database.sanitize_timestamp(commit_hash[:committed_date])
+        )
+      end
+    end
+
+    def build_diff_rows(raw_repository, commits, context_commit_ids)
+      diff_rows = []
+      diff_order = 0
+
+      commits.flat_map.with_index do |commit, index|
+        commit_hash = commit.to_hash.except(:parent_ids)
+        sha = Gitlab::Database::ShaAttribute.serialize(commit_hash.delete(:id))
+        # generate context commit diff information for given commit
+        diffs = commit.diffs
+
+        compare = Gitlab::Git::Compare.new(
+          raw_repository,
+          diffs.diff_refs.start_sha,
+          diffs.diff_refs.head_sha
+        )
+        compare.diffs.map do |diff|
+          diff_hash = diff.to_hash.merge(
+            sha: sha,
+            binary: false,
+            merge_request_context_commit_id: context_commit_ids[index],
+            relative_order: diff_order
+          )
+
+          # Compatibility with old diffs created with Psych.
+          diff_hash.tap do |hash|
+            diff_text = hash[:diff]
+
+            if encode_in_base64?(diff_text)
+              hash[:binary] = true
+              hash[:diff] = [diff_text].pack('m0')
+            end
+          end
+
+          # Increase order for commit so when present the diffs we can use it to keep order
+          diff_order += 1
+          diff_rows << diff_hash
+        end
+      end
+
+      diff_rows
+    end
+  end
+end