from __future__ import absolute_import

import types

from struct import pack

from vertica_python.vertica.messages import *

class Message(object):

    @classmethod
    def _message_id(cls, message_id):
        instance_message_id = message_id

        def message_id(self):
            return instance_message_id
        setattr(cls, 'message_id', types.MethodType(message_id, cls))

    def message_string(self, msg):

        if isinstance(msg, list):
            msg = ''.join(msg)

        if hasattr(msg, 'bytesize'):
            bytesize = msg.bytesize + 4
        else:
            bytesize = len(msg) + 4

        message_size = pack('!I', bytesize)
        if self.message_id() is not None:
            msg_with_size = "{0}{1}{2}".format(self.message_id(), message_size, msg)
        else:
            msg_with_size = "{0}{1}".format(message_size, msg)

        return msg_with_size


class BackendMessage(Message):
    MessageIdMap = {}

    @classmethod
    def factory(cls, type, data):
        klass = cls.MessageIdMap[type]
        if klass is not None:
            return klass(data)
        else:
            return messages.Unknown(type, data)

    @classmethod
    def _message_id(cls, message_id):
        super(BackendMessage, cls)
        cls.MessageIdMap[message_id] = cls


class FrontendMessage(Message):
    def to_bytes(self):
        return self.message_string('')