Adds ordering to projects contributors in API

Allows ordering in GET api/v4/projects/:project_id/repository/contributors
through `order_by` and `sort` params.
The available `order_by` options are: name|email|commits.
The available `sort` options are: asc|desc.

1 files changed, 14 insertions, 0 deletions

diff --git a/app/models/commit.rb b/app/models/commit.rb
index 307e4fcedfe..13c31111134 100644
--- a/app/models/commit.rb
+++ b/app/models/commit.rb
@@ -52,6 +52,20 @@ class Commit
       diffs.reduce(0) { |sum, d| sum + Gitlab::Git::Util.count_lines(d.diff) }
     end
 
+    def order_by(collection:, order_by:, sort:)
+      return collection unless %w[email name commits].include?(order_by)
+      return collection unless %w[asc desc].include?(sort)
+
+      collection.sort do |a, b|
+        operands = [a, b].tap { |o| o.reverse! if sort == 'desc' }
+
+        attr1, attr2 = operands.first.public_send(order_by), operands.second.public_send(order_by) # rubocop:disable PublicSend
+
+        # use case insensitive comparison for string values
+        order_by.in?(%w[email name]) ? attr1.casecmp(attr2) : attr1 <=> attr2
+      end
+    end
+
     # Truncate sha to 8 characters
     def truncate_sha(sha)
       sha[0..MIN_SHA_LENGTH]