import time;
now = time.time;

debug_mode = False;

def debug_print(message):
    if debug_mode:
        print "[TimedCollection]: %s" % (message);

class TimedObject:
    def __init__(self, obj, lifetime):
        self.obj = obj;
        self.timestamp = now();
        self.lifetime = lifetime;
        self.expire_flag = False;

    def __str__(self):
        return str(self.obj);

    def expired(self):
        if self.expire_flag:
            return True;

        current_time = now();
        if current_time - self.timestamp > self.lifetime:
            self.expire_flag = True;
            return True;

        return False;

    def get_object(self):
        return self.obj;

class TimedCollection:
    DEFAULT_LIFETIME = 5.0; # seconds

    def __init__(self, lifetime=DEFAULT_LIFETIME):
        self.objs = [];
        self.lifetime = lifetime;

    def __delitem__(self, item):
        self.remove(item);

    def __len__(self):
        return len(self.objs);

    def set_lifetime(self, lifetime):
        debug_print("Lifetime=%f" % (lifetime));
        self.lifetime = lifetime;

    def add(self, obj, lifetime=None):
        if lifetime == None:
            lifetime = self.lifetime;

        debug_print("Added %s (lifetime=%f)" % (str(obj), lifetime));
        self.objs.append(TimedObject(obj, lifetime));

    def remove(self, obj):
        debug_print("Removing %s" % (str(obj)));
        index = self.index_of(obj);
        if index < 0:
            return False;

        del self.objs[index];
        return True;

    def index_of(self, obj):
        for n in xrange(0, len(self.objs)):
            if self.objs[n] == obj:
                return n;

        return -1;

    def clear(self):
        debug_print("Cleared");
        del self.objs;
        self.objs = [];

    def update(self):
        remove_list = [];
        for item in self.objs:
            if item.expired():
                remove_list.append(item);

        for item in remove_list:
            assert self.remove(item);


if __name__ == '__main__':
    # Run tests.
    debug_mode = False;

    col = TimedCollection();
    col.set_lifetime(5.0);
    col.add("hi");
    col.add("how are you?", 7.5);
    col.add("what's up?", 9.0);

    seconds_passed = 0;
    while len(col) != 0:
        time.sleep(1.0);
        col.update();
        seconds_passed += 1;
        assert seconds_passed < 15;

    debug_print("Testing successful.");