class TowerInfo:
    def __init__(self, netaddr, available_slots, status="active", appointments=None, pending_appointments=None):
        self.netaddr = netaddr
        self.available_slots = available_slots
        self.status = status

        if not appointments:
            self.appointments = {}
        else:
            self.appointments = appointments

        if not pending_appointments:
            self.pending_appointments = []
        else:
            self.pending_appointments = pending_appointments

    @classmethod
    def from_dict(cls, tower_data):
        netaddr = tower_data.get("netaddr")
        available_slots = tower_data.get("available_slots")
        status = tower_data.get("status")
        appointments = tower_data.get("appointments")
        pending_appointments = tower_data.get("pending_appointments")

        if any(v is None for v in [netaddr, available_slots, status, appointments, pending_appointments]):
            raise ValueError("Wrong appointment data, some fields are missing")

        return cls(netaddr, available_slots, status, appointments, pending_appointments)

    def to_dict(self):
        return self.__dict__

    def get_summary(self):
        return {
            "netaddr": self.netaddr,
            "status": self.status,
            "available_slots": self.available_slots,
            "pending_appointments": self.pending_appointments,
        }