"""
.. module::glue.message

"""

from __future__ import absolute_import, division, print_function

__all__ = ['Message', 'ErrorMessage', 'SubsetMessage', 'SubsetCreateMessage',
           'SubsetUpdateMessage', 'SubsetDeleteMessage', 'DataMessage',
           'DataAddComponentMessage', 'DataUpdateMessage',
           'DataCollectionMessage', 'DataCollectionActiveChange',
           'DataCollectionActiveDataChange', 'DataCollectionAddMessage',
           'DataCollectionDeleteMessage']


class Message(object):

    """
    Base class for messages that the hub handles.

    Each message represents a specific kind of event. After clients
    register to a hub, the subscribe to specific message classes, and
    will only receive those kinds of messages.

    The message class family is hierarchical, and a client subscribing
    to a message class implicitly subscribes to all of its subclasses.

    :attr sender: The object which sent the message
    :attr tag: An optional string describing the message
    """

    def __init__(self, sender, tag=None):
        """Create a new message

        :param sender: The object sending the message
        :param tag: An optional string describing the message
        """
        self.sender = sender
        self.tag = tag

    def __str__(self):
        return '%s: %s\n\t Sent from: %s' % (type(self).__name__,
                                             self.tag or '',
                                             self.sender)


class ErrorMessage(Message):

    """ Used to send general purpose error messages """
    pass


class SubsetMessage(Message):

    """
    A general message issued by a subset.

    """

    def __init__(self, sender, tag=None):
        from glue.core.subset import Subset
        if (not isinstance(sender, Subset)):
            raise TypeError("Sender must be a subset: %s"
                            % type(sender))
        Message.__init__(self, sender, tag=tag)
        self.subset = self.sender


class SubsetCreateMessage(SubsetMessage):

    """
    A message that a subset issues when its state changes
    """
    pass


class SubsetUpdateMessage(SubsetMessage):

    """
    A message that a subset issues when its state changes.
    """

    def __init__(self, sender, attribute=None, tag=None):
        """
        :param attribute: An optional label of what attribute has changed
        """
        SubsetMessage.__init__(self, sender, tag=tag)
        self.attribute = attribute

    def __str__(self):
        result = super(SubsetUpdateMessage, self).__str__()
        result += "\n\t Updated %s" % self.attribute
        return result


class SubsetDeleteMessage(SubsetMessage):

    """
    A message that a subset issues when it is deleted
    """
    pass


class DataMessage(Message):

    """
    The base class for messages that data objects issue
    """

    def __init__(self, sender, tag=None):
        from glue.core.data import Data
        if (not isinstance(sender, Data)):
            raise TypeError("Sender must be a data instance: %s"
                            % type(sender))
        Message.__init__(self, sender, tag=tag)
        self.data = self.sender


class DataAddComponentMessage(DataMessage):

    def __init__(self, sender, component_id, tag=None):
        super(DataAddComponentMessage, self).__init__(sender, tag=tag)
        self.component_id = component_id


class ComponentsChangedMessage(DataMessage):
    pass


class ComponentReplacedMessage(ComponentsChangedMessage):

    def __init__(self, sender, old_component, new_component, tag=None):
        super(ComponentReplacedMessage, self).__init__(sender, old_component)
        self.old = old_component
        self.new = new_component


class DataUpdateMessage(DataMessage):

    def __init__(self, sender, attribute, tag=None):
        super(DataUpdateMessage, self).__init__(sender, tag=tag)
        self.attribute = attribute


class NumericalDataChangedMessage(DataMessage):
    pass


class DataCollectionMessage(Message):

    def __init__(self, sender, tag=None):
        from glue.core.data_collection import DataCollection
        if (not isinstance(sender, DataCollection)):
            raise TypeError("Sender must be a DataCollection instance: %s"
                            % type(sender))
        Message.__init__(self, sender, tag=tag)


class DataCollectionActiveChange(DataCollectionMessage):
    pass


class DataCollectionActiveDataChange(DataCollectionMessage):
    pass


class DataCollectionAddMessage(DataCollectionMessage):

    def __init__(self, sender, data, tag=None):
        DataCollectionMessage.__init__(self, sender, tag=tag)
        self.data = data


class DataCollectionDeleteMessage(DataCollectionMessage):

    def __init__(self, sender, data, tag=None):
        DataCollectionMessage.__init__(self, sender, tag=tag)
        self.data = data


class SettingsChangeMessage(Message):
    """
    Indicates that some of the application-wide settings have changed

    Parameters
    ----------
    settings : iterable
        An iterable of the settings that have changed.
    """

    def __init__(self, sender, settings, tag=None):
        super(SettingsChangeMessage, self).__init__(sender=sender, tag=tag)
        self.settings = settings