
"""StateData module: contains StateData class"""

from direct.showbase.DirectObject import *

from direct.directnotify import DirectNotifyGlobal

class StateData(DirectObject):
    """
    A StateData is a base class for a single state within a Finite
    State Machine (ClassicFSM).
    """

    notify = DirectNotifyGlobal.directNotify.newCategory('StateData')

    def __init__(self, doneEvent):
        self.doneEvent = doneEvent
        self.doneStatus = None
        self.isLoaded = 0
        self.isEntered = 0
    
    def enter(self):
        """
        Enters the StateData.  This makes it active in whatever sense
        this applies.  Returns true if this is a change (i.e. it was
        not previously entered), or false if this is the same (i.e. it
        was already entered).
        """
        if self.isEntered:
            return 0
        if not self.isLoaded:
            self.notify.warning("entered StateData before it was loaded")
            self.load()
        self.isEntered = 1
        StateData.notify.debug('enter()')
        return 1

    def exit(self):
        """
        Exits the StateData.  Returns true if this is a change
        (i.e. it was previously entered), or false if this is the same
        (i.e. it was already exited).
        """
        if not self.isEntered:
            return 0
        self.isEntered = 0
        StateData.notify.debug('exit()')
        return 1

    def load(self):
        """
        Loads the StateData.  This loads whatever assets are needed
        from disk, and otherwise prepares the StateData for being
        entered, without actually entering it.  Returns true if this
        is a change (i.e. it was not already loaded), or false if this
        is the same (i.e. it was previously loaded).
        """
        if self.isLoaded:
            return 0
        self.isLoaded = 1
        StateData.notify.debug('load()')
        return 1

    def unload(self):
        """
        Unloads the StateData.  This frees whatever assets were loaded
        by load(), and generally makes the memory usage for this thing
        be as small as possible.  Some StateData-derived classes can
        load and unload repeatedly; others are useless once they have
        been unloaded.
        """
        if not self.isLoaded:
            return 0
        if self.isEntered:
            self.notify.warning("unloaded StateData before it was exited")
            self.exit()
        self.isLoaded = 0
        StateData.notify.debug('unload()')
        return 1

    def getDoneStatus(self):
        """
        The done status of a state data may be anything.  It is common
        practice to return a Python dictionary or a string; the default
        value is None.
        """
        return self.doneStatus
