module RestChange

  ############### DATABASE ####################

# Changes the working-database to {name}

  def change_database name
    @classes = []
    @database = name
    ActiveOrient.database = name
  end

  ############# OBJECTS #################

=begin
  Convient update of the dataset by calling sql-patch

  The argument record can be specified as ActiveOrient::Model-instance or as rid-string( #0:0 )
  
  called from ModelRecord#update

  if the update was successful, the updated data are returned as Hash.

  First the cached object is retrieved
  Its modified by the parameters provided
  and then patched

  better would be: update the cached object and patch that. 
=end

  def update record, attributes , version=0   
    r = ActiveOrient::Model.autoload_object record.rid 
    return(false) unless r.is_a?(ActiveOrient::Model)
		raise "Cannot update the record, version-information missing. please reload ! " if version.nil?
    version = r.version if version.zero?
    result = patch_record(r.rid) do
      attributes.merge({'@version' => version, '@class' => r.class.ref_name })
    end
    # returns a new instance of ActiveOrient::Model and updates any reference on rid
    # It's assumed, that the version 
    # if the patch is not successfull no string is returned and thus no record is fetched
    # JSON.parse(result) if result.is_a?(String)
    if result.is_a?(String)
       JSON.parse(result) # return value
    else
      logger.error{ "REST::Update was not successfull" }
       nil   # returnvalue
    end
  end


=begin
Example:
  ORD.update_documents classname, set: {:symbol => 'TWR'}, where: {con_id: 340}

Replaces the symbol to TWR in each record where the con_id is 340

Both set and where take multiple attributes

Returns the JSON-Response.

# todo: clear the rid-cache 
=end

  def update_records o_class, set:{}, where: {}, remove: nil
		logger.progname = 'RestChange#UpdateRecords'
		count =  execute do 
			if set.present?
				"UPDATE #{classname(o_class)} SET #{generate_sql_list(set)} #{compose_where(where)}"
			elsif remove.present?
				"UPDATE #{classname(o_class)} remove #{remove} #{compose_where(where)}"
			end 
		end &.first
	rescue Exception => e
		logger.error{e.message}
		nil


	end

# Lazy Updating of the given Record.
# internal using while updating  records
  def patch_record rid	    # :nodoc:   (used by #update )
    logger.progname = 'RestChange#PatchRecord'
    content = yield
		if content.is_a? Hash
			begin
				ActiveOrient.db_pool.checkout do | conn |
					conn["/document/#{ActiveOrient.database}/#{rid}"].patch content.to_orient.to_json
				end
			rescue RestClient::Conflict => e  # (409)
				# most probably the server is busy. we  wait for a second  print an Error-Message and retry
				sleep(1)
				logger.error{ "RestClient::Error(409): Server is signaling a conflict ... retrying" }
				retry
			rescue RestClient::InternalServerError => e
				sentence=  JSON.parse( e.response)['errors'].last['content']
				logger.error{sentence}
				logger.error{ e.backtrace.map {|l| "  #{l}\n"}.join  }
				logger.error{e.message.to_s}
			end
		else
			logger.error{"PATCH FAILED: The Block must provide an Hash with properties to be updated"}
		end
	end
	alias patch_document patch_record


  #### EXPERIMENTAL ##########

=begin
  Used to add restriction or other properties to the Property of a Class.
  See http://orientdb.com/docs/2.1/SQL-Alter-Property.html
=end

  def alter_property o_class, property:, attribute: "DEFAULT", alteration:  # :nodoc: because untested
    logger.progname = 'RestChange#AlterProperty'
    begin
      attribute.to_s! unless attribute.is_a? String
      attribute.capitalize_first_letter
      case attribute
      when "LINKEDCLASS", "LINKEDTYPE", "NAME", "REGEX", "TYPE", "REGEX", "COLLATE", "CUSTOM"
        unless alteration.is_a? String
          logger.error{"#{alteration} should be a String."}
          return 0
        end
      when "MIN", "MAX"
        unless alteration.is_a? Integer
          logger.error{"#{alteration} should be an Integer."}
          return 0
        end
      when "MANDATORY", "NOTNULL", "READONLY"
        unless alteration.is_a? TrueClass or alteration.is_a? FalseClass
          logger.error{"#{alteration} should be an Integer."}
          return 0
        end
      when "DEFAULT"
      else
        logger.error{"Wrong attribute."}
        return 0
      end

			execute { "ALTER PROPERTY #{class_name(o_class)}.#{property} #{attribute} #{alteration}"}
    rescue Exception => e
      logger.error{e.message}
    end
  end


end