Add params validations and remove extra params support

Remove label_name and milestone_title params support
Add mutually_exclusive validation for author_id and author_username
Add mutually_exclusive validation for assignee_id and assignee_username
Add validation to allow single value for asignee_username on CE
Add separate issue_stats_params helper for statistics params and
reuse in issues_params.

3 files changed, 63 insertions, 19 deletions

diff --git a/lib/api/helpers/issues_helpers.rb b/lib/api/helpers/issues_helpers.rb
index 12bbc598532..fb791691069 100644
--- a/lib/api/helpers/issues_helpers.rb
+++ b/lib/api/helpers/issues_helpers.rb
@@ -24,7 +24,6 @@ module API
 
         args.delete(:id)
         args[:milestone_title] ||= args.delete(:milestone)
-        args[:milestone_title] ||= args.delete(:milestone_title)
         args[:label_name] ||= args.delete(:labels)
         args[:scope] = args[:scope].underscore if args[:scope]
 
@@ -35,10 +34,8 @@ module API
         # rubocop: disable CodeReuse/ActiveRecord
         finder = issue_finder(args)
         issues = finder.execute.with_api_entity_associations
-        order_by = declared_params[:sort].present? && %w(asc desc).include?(declared_params[:sort].downcase)
-        issues = issues.reorder(order_options_with_tie_breaker) if order_by
 
-        issues
+        issues.reorder(order_options_with_tie_breaker)
         # rubocop: enable CodeReuse/ActiveRecord
       end
 
diff --git a/lib/api/issues.rb b/lib/api/issues.rb
index 6977657e356..9fd2d959c22 100644
--- a/lib/api/issues.rb
+++ b/lib/api/issues.rb
@@ -19,15 +19,10 @@ module API
         end
       end
 
-      params :issues_params do
-        optional :labels, :label_name, type: Array[String], coerce_with: Validations::Types::LabelsList.coerce, desc: 'Comma-separated list of label names'
-        optional :with_labels_data, type: Boolean, desc: 'Return more label data than just lable title', default: false
+      params :issues_stats_params do
+        optional :labels, type: Array[String], coerce_with: Validations::Types::LabelsList.coerce, desc: 'Comma-separated list of label names'
         optional :milestone, type: String, desc: 'Milestone title'
-        optional :order_by, type: String, values: %w[created_at updated_at], default: 'created_at',
-                            desc: 'Return issues ordered by `created_at` or `updated_at` fields.'
-        optional :sort, type: String, default: 'desc',
-                        desc: 'Return issues sorted in `asc` or `desc` order.'
-        optional :milestone, :milestone_title, type: String, desc: 'Return issues for a specific milestone'
+        optional :milestone, type: String, desc: 'Return issues for a specific milestone'
         optional :iids, type: Array[Integer], desc: 'The IID array of issues'
         optional :search, type: String, desc: 'Search issues for text present in the title, description, or any combination of these'
         optional :in, type: String, desc: '`title`, `description`, or a string joining them with comma'
@@ -35,23 +30,39 @@ module API
         optional :created_before, type: DateTime, desc: 'Return issues created before the specified time'
         optional :updated_after, type: DateTime, desc: 'Return issues updated after the specified time'
         optional :updated_before, type: DateTime, desc: 'Return issues updated before the specified time'
+
         optional :author_id, type: Integer, desc: 'Return issues which are authored by the user with the given ID'
         optional :author_username, type: String, desc: 'Return issues which are authored by the user with the given username'
+        mutually_exclusive :author_id, :author_username
+
         optional :assignee_id, types: [Integer, String], integer_none_any: true,
                                desc: 'Return issues which are assigned to the user with the given ID'
-        optional :assignee_username, type: Array[String],
+        optional :assignee_username, type: Array[String], check_assignees_count: true,
+                                     coerce_with: Validations::CheckAssigneesCount.coerce,
                                      desc: 'Return issues which are assigned to the user with the given username'
+        mutually_exclusive :assignee_id, :assignee_username
+
         optional :scope, type: String, values: %w[created-by-me assigned-to-me created_by_me assigned_to_me all],
                          desc: 'Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`'
         optional :my_reaction_emoji, type: String, desc: 'Return issues reacted by the authenticated user by the given emoji'
         optional :confidential, type: Boolean, desc: 'Filter confidential or public issues'
-        optional :state, type: String, values: %w[opened closed all], default: 'all',
-                         desc: 'Return opened, closed, or all issues'
-        use :pagination
 
         use :issues_params_ee if Gitlab.ee?
       end
 
+      params :issues_params do
+        optional :with_labels_data, type: Boolean, desc: 'Return more label data than just lable title', default: false
+        optional :state, type: String, values: %w[opened closed all], default: 'all',
+                 desc: 'Return opened, closed, or all issues'
+        optional :order_by, type: String, values: %w[created_at updated_at], default: 'created_at',
+                 desc: 'Return issues ordered by `created_at` or `updated_at` fields.'
+        optional :sort, type: String, values: %w[asc desc], default: 'desc',
+                 desc: 'Return issues sorted in `asc` or `desc` order.'
+
+        use :issues_stats_params
+        use :pagination
+      end
+
       params :issue_params do
         optional :description, type: String, desc: 'The description of an issue'
         optional :assignee_ids, type: Array[Integer], desc: 'The array of user IDs to assign issue'
@@ -68,7 +79,7 @@ module API
 
     desc "Get currently authenticated user's issues statistics"
     params do
-      use :issues_params
+      use :issues_stats_params
       optional :scope, type: String, values: %w[created-by-me assigned-to-me created_by_me assigned_to_me all], default: 'created_by_me',
                        desc: 'Return issues for the given scope: `created_by_me`, `assigned_to_me` or `all`'
     end
@@ -131,7 +142,7 @@ module API
 
       desc 'Get statistics for the list of group issues'
       params do
-        use :issues_params
+        use :issues_stats_params
       end
       get ":id/issues_statistics" do
         group = find_group!(params[:id])
@@ -172,7 +183,7 @@ module API
 
       desc 'Get statistics for the list of project issues'
       params do
-        use :issues_params
+        use :issues_stats_params
       end
       get ":id/issues_statistics" do
         project = find_project!(params[:id])
diff --git a/lib/api/validations/check_assignees_count.rb b/lib/api/validations/check_assignees_count.rb
new file mode 100644
index 00000000000..e19c88e97b1
--- /dev/null
+++ b/lib/api/validations/check_assignees_count.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module API
+  module Validations
+    class CheckAssigneesCount < Grape::Validations::Base
+      def self.coerce
+        lambda do |value|
+          case value
+          when String
+            [value]
+          when Array
+            value
+          when CheckAssigneesCount
+            value
+          else
+            []
+          end
+        end
+      end
+
+      def validate_param!(attr_name, params)
+        unless param_allowed?(attr_name, params)
+          raise Grape::Exceptions::Validation,
+                params: [@scope.full_name(attr_name)],
+                message: "allows one value, but found #{params[attr_name].size}: #{params[attr_name].join(", ")}"
+        end
+      end
+
+      private
+
+      def param_allowed?(attr_name, params)
+        params[attr_name].size <= 1
+      end
+    end
+  end
+end