2 files changed, 77 insertions, 0 deletions
diff --git a/app/finders/issuables/author_filter.rb b/app/finders/issuables/author_filter.rb
new file mode 100644
index 00000000000..ce68dbafb95
--- /dev/null
+++ b/app/finders/issuables/author_filter.rb
@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+module Issuables
+  class AuthorFilter < BaseFilter
+    def filter
+      filtered = by_author(issuables)
+      filtered = by_author_union(filtered)
+      by_negated_author(filtered)
+    end
+
+    private
+
+    def by_author(issuables)
+      if params[:author_id].present?
+        issuables.authored(params[:author_id])
+      elsif params[:author_username].present?
+        issuables.authored(User.by_username(params[:author_username]))
+      else
+        issuables
+      end
+    end
+
+    def by_author_union(issuables)
+      return issuables unless or_filters_enabled? && or_params&.fetch(:author_username).present?
+
+      issuables.authored(User.by_username(or_params[:author_username]))
+    end
+
+    def by_negated_author(issuables)
+      return issuables unless not_filters_enabled? && not_params.present?
+
+      if not_params[:author_id].present?
+        issuables.not_authored(not_params[:author_id])
+      elsif not_params[:author_username].present?
+        issuables.not_authored(User.by_username(not_params[:author_username]))
+      else
+        issuables
+      end
+    end
+  end
+end
diff --git a/app/finders/issuables/base_filter.rb b/app/finders/issuables/base_filter.rb
new file mode 100644
index 00000000000..641ae2568cc
--- /dev/null
+++ b/app/finders/issuables/base_filter.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module Issuables
+  class BaseFilter
+    attr_reader :issuables, :params
+
+    def initialize(issuables, params:, or_filters_enabled: false, not_filters_enabled: false)
+      @issuables = issuables
+      @params = params
+      @or_filters_enabled = or_filters_enabled
+      @not_filters_enabled = not_filters_enabled
+    end
+
+    def filter
+      raise NotImplementedError
+    end
+
+    private
+
+    def or_params
+      params[:or]
+    end
+
+    def not_params
+      params[:not]
+    end
+
+    def or_filters_enabled?
+      @or_filters_enabled
+    end
+
+    def not_filters_enabled?
+      @not_filters_enabled
+    end
+  end
+end