from __future__ import unicode_literals

from .channel import Channel


class Message(object):
    """
    Represents a message sent over a Channel.

    The message content is a dict called .content, while
    reply_channel is an optional extra attribute representing a channel
    to use to reply to this message's end user, if that makes sense.
    """

    class Requeue(Exception):
        """
        Raise this while processing a message to requeue it back onto the
        channel. Useful if you're manually ensuring partial ordering, etc.
        """
        pass

    def __init__(self, content, channel, channel_layer, reply_channel=None):
        self.content = content
        self.channel = channel
        self.channel_layer = channel_layer
        if reply_channel:
            self.reply_channel = Channel(reply_channel, channel_layer=self.channel_layer)