Add post status administration (#105)

app/workflows/ReorderWorkflow.rb

@@ -0,0 +1,68 @@
+class ReorderWorkflow
+  attr_accessor :entity_classname, :column_name
+  attr_accessor :entity_id, :src_index, :dst_index
+
+  # This workflow is used by entities which has a "order" column of sort
+  # Given:
+  #   entity_classname: the entity class name, e.g. PostStatus
+  #   column_name: the name of the db column that contains the order information, e.g. 'order'
+  #   entity_id: the id of the entity being reordered
+  #   src_index: the current order of the entity
+  #   dst_index = the new order of the entity
+  #
+  # The workflow reorders the record with id <entity_id> of entity <entity_classname>
+  # from <src_index> to <dst_index> using <column_name> as the db column that keeps the ordering
+  #
+  # Returns:
+  #   A collection of the reordered records, if successful
+  #   nil, if unsuccessful
+
+  def initialize(entity_classname: "", column_name: "", entity_id: "", src_index: "", dst_index: "")
+    @entity_classname = entity_classname
+    @column_name = column_name
+    @entity_id = entity_id
+    @src_index = src_index
+    @dst_index = dst_index
+  end
+
+  def run
+    convert_indexes_to_i
+    
+    if src_index == dst_index
+      return {}
+    end
+
+    lowest_index = src_index < dst_index ? src_index : dst_index
+    highest_index = src_index < dst_index ? dst_index : src_index
+    column_name_sanitized = ActiveRecord::Base.connection.quote_column_name(column_name)
+
+    entity_records = entity_classname.where("#{column_name_sanitized} BETWEEN #{lowest_index} AND #{highest_index}")
+
+    # reorder records
+    entity_records.each do |entity_record|
+      if entity_record.id == entity_id
+        entity_record[column_name] = dst_index
+      elsif src_index < dst_index
+        entity_record[column_name] -= 1
+      elsif src_index > dst_index
+        entity_record[column_name] += 1
+      end
+    end
+
+    # save all changes in a single transaction
+    entity_classname.transaction do
+      begin
+        entity_records.each(&:save!)
+
+        return entity_records
+      rescue
+        return nil
+      end
+    end
+  end
+
+  def convert_indexes_to_i
+    self.src_index = src_index.to_i
+    self.dst_index = dst_index.to_i
+  end
+end