import sys, traceback, threading

EXIT_SUCCESS=0
EXIT_ERROR=1

def info(message):
    # print info to sys.stderr because it isn’t really output, just debug information
    print("INFO: "+str(message), file=sys.stderr)
    traceback.print_stack()

def warn(message, is_exception=False):
    print("WARNING: "+str(message), file=sys.stderr)
    if is_exception:
        traceback.print_exc()
    else:
        traceback.print_stack()

def error(message, is_exception=True, handle_gracefully=True):
    print("ERROR: "+str(message), file=sys.stderr)
    if is_exception:
        traceback.print_exc()
    else:
        traceback.print_stack()
    if handle_gracefully:
        pass
    else:
        sys.exit(EXIT_ERROR)

# easy way to communicate across events
#TODO: make thread safe
class Communication:
    def __init__(self):
        self.lock = threading.Lock()
        self.__messages = {}

    # send a message tagged with name and containing content, adds to the beginning of the list of messages with the same tag by default, a function to run as an additional action can be provided
    def send(self, name, content, reverse_order=True, additional_action=None):
        self.lock.acquire()
        if name in self.__messages:
            if reverse_order:
                self.__messages[name] = [content] + self.__messages[name]
            else:
                self.__messages[name] = self.__messages[name] + [content]
        else:
            self.__messages[name] = [content]
        if additional_action == None:
            pass
        else:
            additional_action()
        self.lock.release()

    # get the content of the first message tagged with name, removes the returned message by default
    def get(self, name, remove=True):
        self.lock.acquire()
        if name in self.__messages and len(self.__messages[name])>0:
            if remove:
                content = self.__messages[name].pop(0)
                if len(self.__messages[name])==0:
                    del self.__messages[name]
                self.lock.release()
                return content
            else:
                self.lock.release()
                return self.__messages[name][0]
        else:
            self.lock.release()
            return None

    # get the contents for all messages tagged with name
    def get_all(self, name, clear=False):
        self.lock.acquire()
        if name in self.__messages and len(self.__messages[name])>0:
            contents = self.__messages[name]
            if clear:
                del self.__messages[name]
            self.lock.release()
            return contents
        else:
            self.lock.release()
            return None

    # deletes all messages tagged with name
    def clear(self, name):
        self.lock.acquire()
        if name in self.__messages:
            del self.__messages[name]
        self.lock.release()

    def __del__(self):
        if len(self.__messages)>0:
            warn("__messages not empty upon destruction of Communication object:\n"+str(self.__messages))