import netaddr


class Singleton(type):
    _instances = {}

    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
        return cls._instances[cls]


class Container(object):
    def __init__(self):
        self.instances = dict()

    def add(self, instance_id, instance):
        if instance_id in self.instances:
            raise Exception()
        self.instances[instance_id] = instance

    def get(self, instance_id):
        if instance_id not in self.instances:
            return instance_id
        return self.instances[instance_id]


class AssignedObjectContainer(Container):
    # AssignedObjectContainer is the parent class
    # which is with the shared function of Devices/VMs Container

    def all(self):
        return self.instances.values()

    def getDNSServer(self):
        for instance in self.instances.values():
            if "dns" in list(map(str, instance.services)):
                return instance

    def getDHCPServer(self):
        for instance in self.instances.values():
            if "tftp" in list(map(str, instance.services)):
                return instance

    def getNTPServer(self):
        for instance in self.instances.values():
            if "ntp" in list(map(str, instance.services)):
                return instance

    def getRouters(self):
        """ Get a list of Devices/VMs which type is Router """

        ret = list()
        for instance in self.instances.values():
            if instance.role == "router":
                ret.append(instance)

        return ret

    def getRouterIPforPrefix(self, prefix):
        """ Get the first found IP address of exist routers as string """

        for router in self.getRouters():
            for interface in router.interfaces.values():

                # The mgmt-only interface will not act as gateway
                if interface["mgmtOnly"]:
                    continue

                for address in interface["addresses"]:
                    if netaddr.IPNetwork(address).ip in netaddr.IPNetwork(
                        prefix.subnet
                    ):
                        return str(netaddr.IPNetwork(address).ip)


class DeviceContainer(AssignedObjectContainer, metaclass=Singleton):
    # DeviceContainer holds all devices fetch from Netbox, device_id as key
    pass


class VirtualMachineContainer(AssignedObjectContainer, metaclass=Singleton):
    # DeviceContainer holds all devices fetch from Netbox, vm_id as key
    pass


class PrefixContainer(Container, metaclass=Singleton):
    # PrefixContainer holds all prefixes fetch from Netbox, prefix(str) as key

    def get(self, instance_id, name_segments=1):
        return super().get(instance_id)

    def all(self):
        return self.instances.values()

    def all_reserved_ips(self, ip_addr=""):
        ret = list()

        for prefix in self.instances.values():
            if ip_addr and netaddr.IPNetwork(ip_addr).ip in netaddr.IPNetwork(
                prefix.subnet
            ):
                if prefix.reserved_ips:
                    return list(prefix.reserved_ips.values())
            else:
                if prefix.reserved_ips:
                    ret.extend(list(prefix.reserved_ips.values()))

        return ret


class ServiceInfoContainer(Container, metaclass=Singleton):
    # ServiceInfoContainer holds hosts DNS/DHCP information in Tenant networks

    def __init__(self):
        super().__init__()
        self.initialized = False

    def all(self):
        return self.instances.items()

    def initialize(self):
        if self.initialized:
            return

        deviceContainer = DeviceContainer()
        vmContainer = VirtualMachineContainer()
        prefixContainer = PrefixContainer()

        for prefix in prefixContainer.all():

            subnet = netaddr.IPNetwork(prefix.subnet)
            domain = prefix.data.description or ""

            if not domain:
                continue

            # If prefix has set the Router IP, use this value as defualt,
            # otherwise find router in this subnet and get its IP address
            routes = (
                prefix.routes
                or deviceContainer.getRouterIPforPrefix(prefix)
                or vmContainer.getRouterIPforPrefix(prefix)
                or ""
            )

            self.instances[prefix.data.description] = {
                "domain": domain,
                "subnet": prefix.subnet,
                "router": routes,
                "dhcprange": prefix.dhcp_range or "",
                "hosts": dict(),
                "dnsServer": None,
                "ntpServer": None,
                "dhcpServer": None,
            }

            # Find the service IP address for this network
            serviceMap = {
                "dnsServer": deviceContainer.getDNSServer()
                or vmContainer.getDNSServer(),
                "ntpServer": deviceContainer.getNTPServer()
                or vmContainer.getNTPServer(),
                "dhcpServer": deviceContainer.getDHCPServer()
                or vmContainer.getDHCPServer(),
            }

            # Loop through the device's IP, and set IP to dataset
            for service, device in serviceMap.items():
                for interface in device.interfaces.values():
                    for address in interface["addresses"]:
                        address = netaddr.IPNetwork(address).ip
                        if address in subnet:
                            self.instances[domain][service] = {
                                "name": device.name,
                                "address": str(address),
                            }
                        else:
                            for neighbor in prefix.neighbor:
                                neighborSubnet = netaddr.IPNetwork(neighbor.subnet)
                                if address in neighborSubnet:
                                    self.instances[domain][service] = {
                                        "name": device.name,
                                        "address": str(address),
                                    }
                                    break

            # A dict to check if the device exists in this domain (prefix)
            deviceInDomain = dict()

            # Gather all Devices/VMs in this tenant, build IP/Hostname map
            for device in list(deviceContainer.all()) + list(vmContainer.all()):

                # Iterate the interface owned by device
                for intfName, interface in device.interfaces.items():

                    # Iterate the address with each interface
                    for address in interface["addresses"]:

                        # Extract the IP address from interface's IP (w/o netmask)
                        address = netaddr.IPNetwork(address).ip

                        # Only record the IP address in current subnet,
                        # Skip if the mac_address is blank
                        if address in subnet:

                            # deviceInDomain store the interface information like:
                            # {"mgmtserver1": {
                            #     "non-mgmt-counter": 1,
                            #     "interface": {
                            #         "bmc": {
                            #             "mgmtOnly": True,
                            #             "macaddr": "ca:fe:ba:be:00:00",
                            #             "ipaddr": [IPAddress("10.32.4.1")]
                            #         }
                            #         "eno1": {
                            #             "mgmtOnly": False,
                            #             "macaddr": "ca:fe:ba:be:11:11",
                            #             "ipaddr": [IPAddress("10.32.4.129"), IPAddress("10.32.4.130")]
                            #         }
                            #    }
                            #  "mgmtswitch1": ...
                            # }

                            deviceInDomain.setdefault(device.name, dict())
                            deviceInDomain[device.name].setdefault(
                                "non-mgmt-counter", 0
                            )
                            deviceInDomain[device.name].setdefault("interfaces", dict())

                            # Set up a interface structure in deviceInDomain[device.name]
                            deviceInDomain[device.name]["interfaces"].setdefault(
                                intfName, dict()
                            )
                            interfaceDict = deviceInDomain[device.name]["interfaces"][
                                intfName
                            ]
                            interfaceDict.setdefault("mgmtOnly", False)

                            # Use interface["mac_address"] as the default value, but if the mac_address
                            #  is None, that means we are dealing with a virtual interfaces
                            #  so we can get the linked interface's mac_address instead

                            interfaceDict.setdefault(
                                "mac_address", interface["mac_address"] or
                                device.interfaces[interface["instance"].label]["mac_address"]
                            )
                            interfaceDict.setdefault("ip_addresses", list())
                            interfaceDict["ip_addresses"].append(address)

                            # If the interface is mgmtOnly, set the attribute to True
                            # Otherwise, increase the non-mgmt-counter, the counter uses to
                            #  find out how many interfaces of this device has IPs on subnet
                            if interface["mgmtOnly"]:
                                interfaceDict["mgmtOnly"] = True
                            else:
                                deviceInDomain[device.name]["non-mgmt-counter"] += 1

            for deviceName, data in deviceInDomain.items():

                nonMgmtCounter = data["non-mgmt-counter"]
                for intfName, interface in data["interfaces"].items():

                    # If current interface doesn't have mac address set, skip
                    if not interface["mac_address"]:
                        continue

                    # In the default situation, hostname is deviceName
                    hostname_list = [deviceName]

                    # If the condition is -
                    #  1. multiple interfaces show on this subnet
                    #  2. the interface is a management-only interface
                    # then add interface name into hostname
                    if nonMgmtCounter > 1 or interface["mgmtOnly"]:
                        hostname_list.append(intfName)

                    # Iterate the IP address owns by current interface,
                    # if the interface has multiple IP addresses,
                    # add last digit to hostname for identifiability
                    for address in interface["ip_addresses"]:
                        hostname = hostname_list.copy()
                        if len(interface["ip_addresses"]) > 1:
                            hostname.append(str(address.words[-1]))

                        self.instances[domain]["hosts"][str(address)] = {
                            "hostname": "-".join(hostname),
                            "macaddr": interface["mac_address"].lower(),
                        }

        self.initialized = True