Add mute relationship and user methods

app/models/relationships/mute.rb

@@ -0,0 +1,4 @@
+# frozen_string_literal: true
+
+class Relationships::Mute < Relationship
+end

app/models/user.rb

@@ -4,6 +4,7 @@ class User < ApplicationRecord
   include User::Relationship
   include User::Relationship::Follow
   include User::Relationship::Block
+  include User::Relationship::Mute
   include User::AnswerMethods
   include User::BanMethods
   include User::InboxMethods

app/models/user/relationship/mute.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+require "errors"
+
+class User
+  module Relationship
+    module Mute
+      extend ActiveSupport::Concern
+
+      included do
+        has_many :active_mute_relationships, class_name:  "Relationships::Mute",
+                                               foreign_key: "source_id",
+                                               dependent:   :destroy
+        has_many :passive_mute_relationships, class_name:  "Relationships::Mute",
+                                                foreign_key: "target_id",
+                                                dependent:   :destroy
+        has_many :muted_users, through: :active_mute_relationships, source: :target
+        has_many :muted_by_users,  through: :passive_mute_relationships, source: :source
+      end
+
+      def mute(target_user)
+        raise Errors::MutingSelf if target_user == self
+
+        create_relationship(active_mute_relationships, target_user)
+      end
+
+      def unmute(target_user)
+        destroy_relationship(active_mute_relationships, target_user)
+      end
+
+      def muting?(target_user)
+        relationship_active?(muted_users, target_user)
+      end
+    end
+  end
+end

lib/errors.rb

@@ -119,4 +119,7 @@ module Errors
     end
   end
   # endregion
+
+  class MutingSelf < SelfAction
+  end
 end