Add Block relationship type

app/models/relationships/block.rb

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

app/models/user.rb

@@ -1,6 +1,7 @@
 class User < ApplicationRecord
   include User::Relationship
   include User::Relationship::Follow
+  include User::Relationship::Block
   include User::AnswerMethods
   include User::InboxMethods
   include User::QuestionMethods

app/models/user/relationship/block.rb

@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+require 'errors'
+
+class User
+  module Relationship
+    module Block
+      extend ActiveSupport::Concern
+
+      included do
+        has_many :active_block_relationships, class_name:  "Relationships::Block",
+                                              foreign_key: "source_id",
+                                              dependent:   :destroy
+        has_many :passive_block_relationships, class_name:  "Relationships::Block",
+                                               foreign_key: "target_id",
+                                               dependent:   :destroy
+        has_many :blocked_users,    through: :active_block_relationships, source: :target
+        has_many :blocked_by_users, through: :passive_block_relationships, source: :source
+      end
+
+      # Block an user
+      def block(target_user)
+        raise Errors::BlockingSelf if target_user == self
+
+        unfollow(target_user) if following?(target_user)
+        target_user.unfollow(self) if target_user.following?(self)
+        target_user.inboxes.where(question: { user_id: id }).destroy_all
+        inboxes.where(question: { user_id: target_user.id, author_is_anonymous: false }).destroy_all
+        ListMember.where(list: { user_id: target_user.id }, user_id: id).destroy_all
+        create_relationship(active_block_relationships, target_user)
+      end
+
+      # Unblock an user
+      def unblock(target_user)
+        destroy_relationship(active_block_relationships, target_user)
+      end
+
+      # Is <tt>self</tt> blocking <tt>target_user</tt>?
+      def blocking?(target_user)
+        relationship_active?(blocked_users, target_user)
+      end
+    end
+  end
+end

app/models/user/relationship/follow.rb

@@ -21,6 +21,8 @@ class User
       # Follow an user
       def follow(target_user)
         raise Errors::FollowingSelf if target_user == self
+        raise Errors::FollowingOtherBlockedSelf if target_user.blocked_by?(self)
+        raise Errors::FollowingSelfBlockedOther if blocked_by?(target_user)
 
         create_relationship(active_follow_relationships, target_user)
       end

lib/errors.rb

@@ -42,4 +42,36 @@ module Errors
 
   class UserNotFound < NotFound
   end
+
+  # region User Blocking
+  class Blocked < Forbidden
+  end
+
+  class OtherBlockedSelf < Blocked
+  end
+
+  class BlockingSelf < SelfAction
+  end
+
+  class AskingOtherBlockedSelf < OtherBlockedSelf
+  end
+
+  class FollowingOtherBlockedSelf < OtherBlockedSelf
+  end
+
+  class SelfBlockedOther < Blocked
+  end
+
+  class AskingSelfBlockedOther < SelfBlockedOther
+  end
+
+  class FollowingSelfBlockedOther < SelfBlockedOther
+  end
+
+  class AnsweringOtherBlockedSelf < OtherBlockedSelf
+  end
+
+  class AnsweringSelfBlockedOther < SelfBlockedOther
+  end
+  # endregion
 end