""" Defines a KernelManager that provides signals and slots.
"""

# System library imports.
from PyQt4 import QtCore
import zmq

# IPython imports.
from IPython.utils.traitlets import Type
from IPython.zmq.kernelmanager import KernelManager, SubSocketChannel, \
    XReqSocketChannel, RepSocketChannel
from util import MetaQObjectHasTraits

# When doing multiple inheritance from QtCore.QObject and other classes
# the calling of the parent __init__'s is a subtle issue:
# * QtCore.QObject does not call super so you can't use super and put
#   QObject first in the inheritance list.
# * QtCore.QObject.__init__ takes 1 argument, the parent. So if you are going
#   to use super, any class that comes before QObject must pass it something
#   reasonable.
# In summary, I don't think using super in these situations will work.
# Instead we will need to call the __init__ methods of both parents
# by hand.  Not pretty, but it works.

class QtSubSocketChannel(SubSocketChannel, QtCore.QObject):

    # Emitted when any message is received.
    message_received = QtCore.pyqtSignal(object)

    # Emitted when a message of type 'pyout' or 'stdout' is received.
    output_received = QtCore.pyqtSignal(object)

    # Emitted when a message of type 'pyerr' or 'stderr' is received.
    error_received = QtCore.pyqtSignal(object)

    #---------------------------------------------------------------------------
    # 'object' interface
    #---------------------------------------------------------------------------
    
    def __init__(self, *args, **kw):
        """ Reimplemented to ensure that QtCore.QObject is initialized first.
        """
        QtCore.QObject.__init__(self)
        SubSocketChannel.__init__(self, *args, **kw)

    #---------------------------------------------------------------------------
    # 'SubSocketChannel' interface
    #---------------------------------------------------------------------------
    
    def call_handlers(self, msg):
        """ Reimplemented to emit signals instead of making callbacks.
        """
        # Emit the generic signal.
        self.message_received.emit(msg)
        
        # Emit signals for specialized message types.
        msg_type = msg['msg_type']
        if msg_type in ('pyout', 'stdout'):
            self.output_received.emit(msg)
        elif msg_type in ('pyerr', 'stderr'):
            self.error_received.emit(msg)

    def flush(self):
        """ Reimplemented to ensure that signals are dispatched immediately.
        """
        super(QtSubSocketChannel, self).flush()
        QtCore.QCoreApplication.instance().processEvents()


class QtXReqSocketChannel(XReqSocketChannel, QtCore.QObject):

    # Emitted when any message is received.
    message_received = QtCore.pyqtSignal(object)

    # Emitted when a reply has been received for the corresponding request type.
    execute_reply = QtCore.pyqtSignal(object)
    complete_reply = QtCore.pyqtSignal(object)
    object_info_reply = QtCore.pyqtSignal(object)

    #---------------------------------------------------------------------------
    # 'object' interface
    #---------------------------------------------------------------------------
    
    def __init__(self, *args, **kw):
        """ Reimplemented to ensure that QtCore.QObject is initialized first.
        """
        QtCore.QObject.__init__(self)
        XReqSocketChannel.__init__(self, *args, **kw)

    #---------------------------------------------------------------------------
    # 'XReqSocketChannel' interface
    #---------------------------------------------------------------------------
    
    def call_handlers(self, msg):
        """ Reimplemented to emit signals instead of making callbacks.
        """
        # Emit the generic signal.
        self.message_received.emit(msg)
        
        # Emit signals for specialized message types.
        msg_type = msg['msg_type']
        signal = getattr(self, msg_type, None)
        if signal:
            signal.emit(msg)


class QtRepSocketChannel(RepSocketChannel, QtCore.QObject):

    # Emitted when any message is received.
    message_received = QtCore.pyqtSignal(object)

    # Emitted when an input request is received.
    input_requested = QtCore.pyqtSignal(object)

    #---------------------------------------------------------------------------
    # 'object' interface
    #---------------------------------------------------------------------------
    
    def __init__(self, *args, **kw):
        """ Reimplemented to ensure that QtCore.QObject is initialized first.
        """
        QtCore.QObject.__init__(self)
        RepSocketChannel.__init__(self, *args, **kw)

    #---------------------------------------------------------------------------
    # 'RepSocketChannel' interface
    #---------------------------------------------------------------------------

    def call_handlers(self, msg):
        """ Reimplemented to emit signals instead of making callbacks.
        """
        # Emit the generic signal.
        self.message_received.emit(msg)
        
        # Emit signals for specialized message types.
        msg_type = msg['msg_type']
        if msg_type == 'input_request':
            self.input_requested.emit(msg)

class QtKernelManager(KernelManager, QtCore.QObject):
    """ A KernelManager that provides signals and slots.
    """

    __metaclass__ = MetaQObjectHasTraits

    # Emitted when the kernel manager has started listening.
    started_channels = QtCore.pyqtSignal()

    # Emitted when the kernel manager has stopped listening.
    stopped_channels = QtCore.pyqtSignal()

    # Use Qt-specific channel classes that emit signals.
    sub_channel_class = Type(QtSubSocketChannel)
    xreq_channel_class = Type(QtXReqSocketChannel)
    rep_channel_class = Type(QtRepSocketChannel)

    def __init__(self, *args, **kw):
        QtCore.QObject.__init__(self)
        KernelManager.__init__(self, *args, **kw)

    #---------------------------------------------------------------------------
    # 'object' interface
    #---------------------------------------------------------------------------
    
    def __init__(self, *args, **kw):
        """ Reimplemented to ensure that QtCore.QObject is initialized first.
        """
        QtCore.QObject.__init__(self)
        KernelManager.__init__(self, *args, **kw)

    #---------------------------------------------------------------------------
    # 'KernelManager' interface
    #---------------------------------------------------------------------------
    
    def start_channels(self):
        """ Reimplemented to emit signal.
        """
        super(QtKernelManager, self).start_channels()
        self.started_channels.emit()

    def stop_channels(self):
        """ Reimplemented to emit signal.
        """ 
        super(QtKernelManager, self).stop_channels()
        self.stopped_channels.emit()