"""
YANG Path Constants for Arista EOS 4.35.0F

This module provides validated gNMI YANG paths for managing
Arista EVPN-VXLAN fabrics via gNMI.

Usage:
    from yang.paths import Interfaces, BGP, VXLAN

    # Get interface state path
    path = Interfaces.state("Ethernet1")

    # Get all BGP neighbors
    path = BGP.NEIGHBORS
"""

from dataclasses import dataclass

# =============================================================================
# Interfaces (OpenConfig)
# =============================================================================

class Interfaces:
    """OpenConfig interface paths."""

    # Base paths
    ROOT = "/interfaces/interface"

    @staticmethod
    def interface(name: str) -> str:
        """Get path for specific interface."""
        return f"/interfaces/interface[name={name}]"

    @staticmethod
    def config(name: str) -> str:
        """Get interface config path."""
        return f"/interfaces/interface[name={name}]/config"

    @staticmethod
    def state(name: str) -> str:
        """Get interface state path."""
        return f"/interfaces/interface[name={name}]/state"

    @staticmethod
    def oper_status(name: str) -> str:
        """Get interface operational status path."""
        return f"/interfaces/interface[name={name}]/state/oper-status"

    @staticmethod
    def admin_status(name: str) -> str:
        """Get interface admin status path."""
        return f"/interfaces/interface[name={name}]/state/admin-status"

    @staticmethod
    def counters(name: str) -> str:
        """Get interface counters path."""
        return f"/interfaces/interface[name={name}]/state/counters"


# =============================================================================
# Loopbacks (OpenConfig)
# =============================================================================

class Loopbacks:
    """Loopback interface paths."""

    @staticmethod
    def interface(index: int) -> str:
        """Get loopback interface path."""
        return f"/interfaces/interface[name=Loopback{index}]"

    @staticmethod
    def config(index: int) -> str:
        """Get loopback config path."""
        return f"/interfaces/interface[name=Loopback{index}]/config"

    # Common loopbacks
    LOOPBACK0 = "/interfaces/interface[name=Loopback0]"
    LOOPBACK1 = "/interfaces/interface[name=Loopback1]"  # VTEP source


# =============================================================================
# VLANs (OpenConfig)
# =============================================================================

class VLANs:
    """OpenConfig VLAN paths."""

    # Base path
    ROOT = "/network-instances/network-instance[name=default]/vlans/vlan"

    @staticmethod
    def vlan(vlan_id: int) -> str:
        """Get specific VLAN path."""
        return f"/network-instances/network-instance[name=default]/vlans/vlan[vlan-id={vlan_id}]"

    @staticmethod
    def config(vlan_id: int) -> str:
        """Get VLAN config path."""
        return f"/network-instances/network-instance[name=default]/vlans/vlan[vlan-id={vlan_id}]/config"

    @staticmethod
    def svi(vlan_id: int) -> str:
        """Get SVI interface path."""
        return f"/interfaces/interface[name=Vlan{vlan_id}]"


# =============================================================================
# BGP (OpenConfig)
# =============================================================================

class BGP:
    """OpenConfig BGP paths."""

    # Base path for BGP
    _BASE = "/network-instances/network-instance[name=default]/protocols/protocol[identifier=BGP][name=BGP]/bgp"

    # Global paths
    GLOBAL = f"{_BASE}/global"
    GLOBAL_CONFIG = f"{_BASE}/global/config"
    GLOBAL_STATE = f"{_BASE}/global/state"

    # Neighbors
    NEIGHBORS = f"{_BASE}/neighbors/neighbor"

    @staticmethod
    def neighbor(address: str) -> str:
        """Get specific neighbor path."""
        return f"{BGP._BASE}/neighbors/neighbor[neighbor-address={address}]"

    @staticmethod
    def neighbor_config(address: str) -> str:
        """Get neighbor config path."""
        return f"{BGP._BASE}/neighbors/neighbor[neighbor-address={address}]/config"

    @staticmethod
    def neighbor_state(address: str) -> str:
        """Get neighbor state path."""
        return f"{BGP._BASE}/neighbors/neighbor[neighbor-address={address}]/state"

    @staticmethod
    def neighbor_session_state(address: str) -> str:
        """Get neighbor session state path."""
        return f"{BGP._BASE}/neighbors/neighbor[neighbor-address={address}]/state/session-state"

    @staticmethod
    def neighbor_afi_safi(address: str, afi_safi: str) -> str:
        """
        Get neighbor AFI-SAFI path.

        Args:
            address: Neighbor IP address
            afi_safi: AFI-SAFI name (e.g., 'IPV4_UNICAST', 'L2VPN_EVPN')
        """
        return f"{BGP._BASE}/neighbors/neighbor[neighbor-address={address}]/afi-safis/afi-safi[afi-safi-name={afi_safi}]"


# AFI-SAFI constants
class AfiSafi:
    """BGP AFI-SAFI identifiers."""

    IPV4_UNICAST = "IPV4_UNICAST"
    IPV6_UNICAST = "IPV6_UNICAST"
    L2VPN_EVPN = "L2VPN_EVPN"


# =============================================================================
# VXLAN (Arista Experimental)
# =============================================================================

class VXLAN:
    """
    Arista VXLAN paths.

    Model: arista-exp-eos-vxlan (augments openconfig-interfaces)
    """

    # Base paths
    INTERFACE = "/interfaces/interface[name=Vxlan1]"
    ROOT = "/interfaces/interface[name=Vxlan1]/arista-vxlan"
    CONFIG = "/interfaces/interface[name=Vxlan1]/arista-vxlan/config"
    STATE = "/interfaces/interface[name=Vxlan1]/arista-vxlan/state"

    # Specific config leaves
    SOURCE_INTERFACE = "/interfaces/interface[name=Vxlan1]/arista-vxlan/config/src-ip-intf"
    UDP_PORT = "/interfaces/interface[name=Vxlan1]/arista-vxlan/config/udp-port"

    # VNI mappings
    VLAN_TO_VNIS = "/interfaces/interface[name=Vxlan1]/arista-vxlan/vlan-to-vnis"
    VRF_TO_VNIS = "/interfaces/interface[name=Vxlan1]/arista-vxlan/vrf-to-vnis"

    @staticmethod
    def vlan_to_vni(vlan_id: int) -> str:
        """Get specific VLAN-to-VNI mapping path."""
        return f"/interfaces/interface[name=Vxlan1]/arista-vxlan/vlan-to-vnis/vlan-to-vni[vlan={vlan_id}]"

    @staticmethod
    def vrf_to_vni(vrf_name: str) -> str:
        """Get specific VRF-to-VNI mapping path."""
        return f"/interfaces/interface[name=Vxlan1]/arista-vxlan/vrf-to-vnis/vrf-to-vni[vrf={vrf_name}]"


# =============================================================================
# MLAG (Arista Experimental)
# =============================================================================

class MLAG:
    """
    Arista MLAG paths.

    Model: arista-exp-eos-mlag

    WARNING: Only config is exposed via gNMI.
    State (peer status, role) requires eAPI.
    """

    ROOT = "/arista/eos/mlag"
    CONFIG = "/arista/eos/mlag/config"

    # Config fields (for reference)
    # - domain-id
    # - local-intf
    # - peer-address
    # - peer-link-intf
    # - dual-primary-action
    # - dual-primary-detection-delay
    # - heartbeat-peer-address


# =============================================================================
# EVPN (Arista Experimental)
# =============================================================================

class EVPN:
    """
    Arista EVPN paths.

    Model: arista-exp-eos-evpn

    WARNING: Only config is exposed via gNMI.
    Learned routes/MACs require eAPI.
    """

    ROOT = "/arista/eos/evpn"
    INSTANCES = "/arista/eos/evpn/evpn-instances"

    @staticmethod
    def instance(name: str) -> str:
        """Get specific EVPN instance path."""
        return f"/arista/eos/evpn/evpn-instances/evpn-instance[name={name}]"

    @staticmethod
    def instance_config(name: str) -> str:
        """Get EVPN instance config path."""
        return f"/arista/eos/evpn/evpn-instances/evpn-instance[name={name}]/config"

    @staticmethod
    def route_target(name: str) -> str:
        """Get EVPN instance route-target path."""
        return f"/arista/eos/evpn/evpn-instances/evpn-instance[name={name}]/route-target/config"


# =============================================================================
# Port-Channel / LAG (OpenConfig)
# =============================================================================

class PortChannel:
    """OpenConfig LAG/Port-Channel paths."""

    @staticmethod
    def interface(channel_id: int) -> str:
        """Get port-channel interface path."""
        return f"/interfaces/interface[name=Port-Channel{channel_id}]"

    @staticmethod
    def config(channel_id: int) -> str:
        """Get port-channel config path."""
        return f"/interfaces/interface[name=Port-Channel{channel_id}]/config"

    @staticmethod
    def aggregation(channel_id: int) -> str:
        """Get LAG aggregation config path."""
        return f"/interfaces/interface[name=Port-Channel{channel_id}]/aggregation/config"

    @staticmethod
    def aggregation_state(channel_id: int) -> str:
        """Get LAG aggregation state path."""
        return f"/interfaces/interface[name=Port-Channel{channel_id}]/aggregation/state"


# =============================================================================
# System (OpenConfig)
# =============================================================================

class System:
    """OpenConfig system paths."""

    ROOT = "/system"
    CONFIG = "/system/config"
    STATE = "/system/state"
    HOSTNAME = "/system/config/hostname"


# =============================================================================
# Subscription Helpers
# =============================================================================

@dataclass
class SubscriptionPath:
    """Helper for building subscription paths."""

    path: str
    mode: str = "on-change"  # on-change, sample, target-defined

    def __str__(self) -> str:
        return self.path


# Common subscription paths for fabric monitoring
class FabricSubscriptions:
    """Pre-defined subscription paths for fabric monitoring."""

    # Interface state changes
    INTERFACE_STATE = SubscriptionPath("/interfaces/interface/state")

    # BGP session state changes
    BGP_SESSIONS = SubscriptionPath(
        "/network-instances/network-instance[name=default]/protocols/protocol[identifier=BGP][name=BGP]/bgp/neighbors/neighbor/state/session-state"
    )

    # VXLAN VNI changes
    VXLAN_VNIS = SubscriptionPath(
        "/interfaces/interface[name=Vxlan1]/arista-vxlan/vlan-to-vnis"
    )

    @classmethod
    def all(cls) -> list[SubscriptionPath]:
        """Get all fabric subscription paths."""
        return [
            cls.INTERFACE_STATE,
            cls.BGP_SESSIONS,
            cls.VXLAN_VNIS,
        ]