import sys

#: Dictionary of observers
_observers = {}

#: The current Navigator object.
navigator = None

#: The current application
application = None

#: The current project
project = None

#: The current workflow
workflow = None

#: A cfgparse/optparse options object.
options = None
        
def notify_observers(name):
    call = "%s_changed" % name
    for s in _observers.get(name, []):
        getattr(s, call)(getattr(sys.modules[__name__], name))

def _add_observer(name, observer):
    """Adds observer as an observer of the named object."""
    if not _observers.has_key(name):
        _observers[name] = []
    _observers[name].append(observer)
    
def _remove_observer(name, observer):
    """Removes observer as an observer of the named object."""
    if not _observers.has_key(name):
        return
    _observers.remove(observer)

def add_navigator_observer(observer):
    _add_observer('navigator', observer)

def add_project_observer(observer):
    _add_observer('project', observer)

def add_workflow_observer(observer):
    _add_observer('workflow', observer)

def add_application_observer(observer):
    _add_observer('application', observer)

def remove_navigator_observer(observer):
    _remove_observer('navigator', observer)

def remove_project_observer(observer):
    _remove_observer('project', observer)

def remove_workflow_observer(observer):
    _remove_observer('workflow', observer)

def remove_application_observer(observer):
    _remove_observer('application', observer)

def remove_options_observer(observer):
    _remove_observer('options', observer)

def set_navigator(nav):
    global navigator
    navigator = nav
    notify_observers('navigator')

def set_application(app):
    global application
    application = app
    notify_observers('application')

def set_project(p):
    global project
    project = p
    notify_observers('project')

def set_workflow(wf):
    global workflow
    workflow = wf
    notify_observers('workflow')

def set_options(opt):
    global options 
    options = opt
    notify_observers('options')