"""Central mapper for parent→child containment links.

Given a child model class and a parent model class, ``map_link`` returns
the field name on the child that should be set to connect it to its parent
in the NetBox object hierarchy (e.g. ``Interface.device``, ``IPAddress.assigned_object``).

This keeps the resolver free of per-node ``link`` boilerplate — the tree
author never specifies how children attach; the mapper knows.
"""

_LINK_MAP = {
    # ── DCIM: Device components → Device ─────────────────────
    ("dcim.consoleport", "dcim.device"): "device",
    ("dcim.consoleserverport", "dcim.device"): "device",
    ("dcim.powerport", "dcim.device"): "device",
    ("dcim.poweroutlet", "dcim.device"): "device",
    ("dcim.interface", "dcim.device"): "device",
    ("dcim.frontport", "dcim.device"): "device",
    ("dcim.rearport", "dcim.device"): "device",
    ("dcim.modulebay", "dcim.device"): "device",
    ("dcim.devicebay", "dcim.device"): "device",
    ("dcim.inventoryitem", "dcim.device"): "device",
    ("dcim.module", "dcim.device"): "device",
    ("dcim.virtualdevicecontext", "dcim.device"): "device",

    # ── DCIM: Components → Module ────────────────────────────
    ("dcim.consoleport", "dcim.module"): "module",
    ("dcim.consoleserverport", "dcim.module"): "module",
    ("dcim.powerport", "dcim.module"): "module",
    ("dcim.poweroutlet", "dcim.module"): "module",
    ("dcim.interface", "dcim.module"): "module",
    ("dcim.frontport", "dcim.module"): "module",
    ("dcim.rearport", "dcim.module"): "module",

    # ── DCIM: Hierarchical (self-referential) ───────────────
    ("dcim.interface", "dcim.interface"): "parent",
    ("dcim.modulebay", "dcim.modulebay"): "parent",
    ("dcim.inventoryitem", "dcim.inventoryitem"): "parent",
    ("dcim.devicerole", "dcim.devicerole"): "parent",
    ("dcim.platform", "dcim.platform"): "parent",
    ("dcim.region", "dcim.region"): "parent",
    ("dcim.sitegroup", "dcim.sitegroup"): "parent",
    ("dcim.location", "dcim.location"): "parent",

    # ── DCIM: Site hierarchy ─────────────────────────────────
    ("dcim.site", "dcim.region"): "region",
    ("dcim.site", "dcim.sitegroup"): "group",
    ("dcim.location", "dcim.site"): "site",

    # ── DCIM: Device placement ───────────────────────────────
    ("dcim.device", "dcim.site"): "site",
    ("dcim.device", "dcim.location"): "location",
    ("dcim.device", "dcim.rack"): "rack",
    ("dcim.device", "dcim.cluster"): "cluster",
    ("dcim.device", "dcim.virtualchassis"): "virtual_chassis",

    # ── DCIM: Rack ───────────────────────────────────────────
    ("dcim.rack", "dcim.site"): "site",
    ("dcim.rack", "dcim.location"): "location",
    ("dcim.rack", "dcim.rackgroup"): "group",
    ("dcim.rack", "dcim.rackrole"): "role",
    ("dcim.rack", "dcim.racktype"): "rack_type",
    ("dcim.rackreservation", "dcim.rack"): "rack",

    # ── DCIM: Power ──────────────────────────────────────────
    ("dcim.powerpanel", "dcim.site"): "site",
    ("dcim.powerpanel", "dcim.location"): "location",
    ("dcim.powerfeed", "dcim.powerpanel"): "power_panel",
    ("dcim.powerfeed", "dcim.rack"): "rack",

    # ── DCIM: Component inter-relations ──────────────────────
    ("dcim.poweroutlet", "dcim.powerport"): "power_port",
    ("dcim.frontport", "dcim.rearport"): "rear_port",

    # ── DCIM: Cables ─────────────────────────────────────────
    ("dcim.cable", "dcim.cablebundle"): "bundle",
    ("dcim.cabletermination", "dcim.cable"): "cable",

    # ── DCIM: GFK assignments ────────────────────────────────
    ("dcim.macaddress", "dcim.interface"): "assigned_object",
    ("dcim.macaddress", "virtualization.vminterface"): "assigned_object",

    # ── DCIM: InventoryItem ──────────────────────────────────
    ("dcim.inventoryitem", "dcim.inventoryitemrole"): "role",
    ("dcim.inventoryitem", "dcim.manufacturer"): "manufacturer",

    # ── DCIM: Type hierarchy ─────────────────────────────────
    ("dcim.devicetype", "dcim.manufacturer"): "manufacturer",
    ("dcim.moduletype", "dcim.manufacturer"): "manufacturer",
    ("dcim.platform", "dcim.manufacturer"): "manufacturer",

    # ── DCIM: Templates → DeviceType ─────────────────────────
    ("dcim.consoleporttemplate", "dcim.devicetype"): "device_type",
    ("dcim.consoleserverporttemplate", "dcim.devicetype"): "device_type",
    ("dcim.powerporttemplate", "dcim.devicetype"): "device_type",
    ("dcim.poweroutlettemplate", "dcim.devicetype"): "device_type",
    ("dcim.interfacetemplate", "dcim.devicetype"): "device_type",
    ("dcim.frontporttemplate", "dcim.devicetype"): "device_type",
    ("dcim.rearporttemplate", "dcim.devicetype"): "device_type",
    ("dcim.modulebaytemplate", "dcim.devicetype"): "device_type",
    ("dcim.devicebaytemplate", "dcim.devicetype"): "device_type",
    ("dcim.inventoryitemtemplate", "dcim.devicetype"): "device_type",

    # ── DCIM: Templates → ModuleType ─────────────────────────
    ("dcim.consoleporttemplate", "dcim.moduletype"): "module_type",
    ("dcim.consoleserverporttemplate", "dcim.moduletype"): "module_type",
    ("dcim.powerporttemplate", "dcim.moduletype"): "module_type",
    ("dcim.poweroutlettemplate", "dcim.moduletype"): "module_type",
    ("dcim.interfacetemplate", "dcim.moduletype"): "module_type",
    ("dcim.frontporttemplate", "dcim.moduletype"): "module_type",
    ("dcim.rearporttemplate", "dcim.moduletype"): "module_type",
    ("dcim.modulebaytemplate", "dcim.moduletype"): "module_type",

    # ── IPAM: IPAddress → Interface/VMInterface/FHRP (GFK) ───
    ("ipam.ipaddress", "dcim.interface"): "assigned_object",
    ("ipam.ipaddress", "virtualization.vminterface"): "assigned_object",
    ("ipam.ipaddress", "ipam.fhrpgroup"): "assigned_object",

    # ── IPAM: VLAN ───────────────────────────────────────────
    ("ipam.vlan", "ipam.vlangroup"): "group",
    ("ipam.vlan", "dcim.site"): "site",

    # ── IPAM: Prefix scope (GFK) ─────────────────────────────
    ("ipam.prefix", "dcim.site"): "scope",
    ("ipam.prefix", "dcim.location"): "scope",
    ("ipam.prefix", "dcim.region"): "scope",
    ("ipam.prefix", "dcim.sitegroup"): "scope",

    # ── IPAM: VLANGroup scope (GFK) ──────────────────────────
    ("ipam.vlangroup", "dcim.site"): "scope",
    ("ipam.vlangroup", "dcim.location"): "scope",
    ("ipam.vlangroup", "dcim.region"): "scope",
    ("ipam.vlangroup", "dcim.sitegroup"): "scope",

    # ── IPAM: FHRPGroupAssignment ────────────────────────────
    ("ipam.fhrpgroupassignment", "ipam.fhrpgroup"): "group",
    ("ipam.fhrpgroupassignment", "dcim.interface"): "interface",
    ("ipam.fhrpgroupassignment", "virtualization.vminterface"): "interface",

    # ── IPAM: Other ──────────────────────────────────────────
    ("ipam.aggregate", "ipam.rir"): "rir",
    ("ipam.asn", "ipam.rir"): "rir",
    ("ipam.asnrange", "ipam.rir"): "rir",
    ("ipam.vlantranslationrule", "ipam.vlantranslationpolicy"): "policy",

    # ── IPAM: Service (NetBox core ipam.Service) ─────────────
    ("ipam.service", "dcim.device"): "parent",
    ("ipam.service", "virtualization.virtualmachine"): "parent",

    # ── Virtualization ───────────────────────────────────────
    ("virtualization.vminterface", "virtualization.virtualmachine"): "virtual_machine",
    ("virtualization.vminterface", "virtualization.vminterface"): "parent",
    ("virtualization.virtualdisk", "virtualization.virtualmachine"): "virtual_machine",
    ("virtualization.virtualmachine", "virtualization.cluster"): "cluster",
    ("virtualization.virtualmachine", "dcim.site"): "site",
    ("virtualization.virtualmachine", "dcim.device"): "device",
    ("virtualization.cluster", "virtualization.clustergroup"): "group",
    ("virtualization.cluster", "virtualization.clustertype"): "type",
    ("virtualization.cluster", "dcim.site"): "scope",
    ("virtualization.cluster", "dcim.location"): "scope",
    ("virtualization.cluster", "dcim.region"): "scope",
    ("virtualization.cluster", "dcim.sitegroup"): "scope",
}


def _type_key(model):
    return f"{model._meta.app_label}.{model._meta.model_name}"


def map_link(child_model, parent_model):
    """Return the field name on *child_model* that links it to *parent_model*.

    Returns ``None`` when no containment relationship is known.
    """
    return _LINK_MAP.get((_type_key(child_model), _type_key(parent_model)))


def register_link(child_type, parent_type, field):
    """Register or override a containment link.

    *child_type* and *parent_type* are ``"app_label.model_name"`` strings.
    """
    _LINK_MAP[(child_type, parent_type)] = field