module MongoMapper
  module Plugins
    module DefaultScope
      
      module ClassMethods
        def find_one options = {}
          super default_scope_options.merge(options)
        end

        def find_many options = {}
          super default_scope_options.merge(options)
        end
        
        def count options={}
          super default_scope_options.merge(options)
        end
        
        def with_exclusive_scope options = {}, &block
          Thread.current['mm_with_exclusive_scope'].should! :be_nil
          
          before = Thread.current['mm_with_exclusive_scope']
          begin
            Thread.current['mm_with_exclusive_scope'] = options
            block.call if block
          ensure
            Thread.current['mm_with_exclusive_scope'] = before
          end
        end
        
        def with_scope options = {}, &block
          Thread.current['mm_with_exclusive_scope'].should! :be_nil
          
          before = Thread.current['mm_with_scope']
          begin
            options = before.merge options if before
            Thread.current['mm_with_scope'] = options
            block.call if block
          ensure
            Thread.current['mm_with_scope'] = before
          end
        end
        
        protected
          def default_scope options = nil, &block          
            options.should! :be_a, [NilClass, Hash]
            self.write_inheritable_attribute(:default_scope, (options || block))
          end
                  
        private
          def default_scope_options
            default_scope = self.read_inheritable_attribute(:default_scope)
            
            exclusive_options = Thread.current['mm_with_exclusive_scope']
            return exclusive_options if exclusive_options
            
            options = if default_scope
              if default_scope.respond_to? :call
                default_scope.call self
              else
                default_scope
              end
            else
              {}
            end
            
            if scope_options = Thread.current['mm_with_scope']
              options = options.merge scope_options
            end
            
            options
          end
      end
      
    end
  end
end