from fastapi import APIRouter, Depends, HTTPException
from pydantic import BaseModel, Field
from typing import List, Optional
from pyroute2 import IPRoute, NDB

router = APIRouter()

# Globals for lazy initialization
ip: IPRoute | None = None
ndb: NDB | None = None

# ------------------------------
# Pydantic models
# ------------------------------

class InterfaceAddress(BaseModel):
    """
    Represents an IP address assigned to a network interface.
    """
    family: str = Field(..., description="IP family: 'ipv4' or 'ipv6'.")
    address: str = Field(..., description="The IP address assigned to the interface.")
    prefixlen: int = Field(..., description="Subnet prefix length (e.g., 24 for 255.255.255.0).")


class InterfaceInfo(BaseModel):
    """
    Represents a network interface with all its properties.
    """
    ifindex: int = Field(..., description="Interface index (unique identifier assigned by the kernel).")
    name: str = Field(..., description="Interface name (e.g., 'eth0', 'enp38s0').")
    state: str = Field(..., description="Operational state (e.g., 'UP', 'DOWN', 'UNKNOWN').")
    mac: Optional[str] = Field(None, description="MAC address of the interface, if applicable.")
    mtu: int = Field(..., description="Maximum Transmission Unit for the interface.")
    flags: List[str] = Field(..., description="List of interface flags (e.g., ['BROADCAST', 'MULTICAST']).")
    addresses: List[InterfaceAddress] = Field(..., description="List of IP addresses assigned to the interface.")

class RouteInfo(BaseModel):
    """
    Represents a single routing table entry.
    """

    dst: Optional[str] = Field(
        None, description="Destination network in CIDR notation (e.g., '192.168.1.0/24'). None means default route."
    )

    gateway: Optional[str] = Field(
        None, description="Next-hop gateway IP address for this route. None if the route is directly connected."
    )

    prefsrc: Optional[str] = Field(
        None, description="Preferred source IP to use when sending packets via this route."
    )

    oif: Optional[int] = Field(
        None, description="Output interface index (ifindex) for this route. Can be used to look up the interface name."
    )

    ifname: Optional[str] = Field(
        None, description="Name of the interface corresponding to `oif` (e.g., 'eth0')."
    )

    table: int = Field(
        ..., description="Routing table ID (e.g., 254 = main, 255 = local)."
    )

    proto: Optional[int] = Field(
        None,
        description="Protocol of the route (numeric Linux codes, e.g., 2=kernel, 16=static)."
    )

    scope: Optional[int] = Field(
        None,
        description="Scope of the route: 0=global, 253=link, 254=host, 255=nowhere."
    )

    type: Optional[int] = Field(
        None,
        description="Type of the route (numeric code): 1=unicast, 2=local, 3=broadcast, 5=multicast."
    )

class BridgeInterfaceInfo(BaseModel):
    """
    Represents a network interface which is a member of an bridge.
    """
    ifindex: int = Field(..., description="Interface index of a bridge member")
    ifname: str = Field(..., description="Interface name of a bridge member")
    state: Optional[str] = Field(None, description="Operational state of the interface")
    mtu: Optional[int] = Field(None, description="MTU of the interface")

class BridgeInfo(BaseModel):
    """
    Represents a network bridge interface with all its properties.
    """
    ifindex: int = Field(..., description="Interface index of the bridge")
    ifname: str = Field(..., description="Bridge interface name")
    state: Optional[str] = Field(None, description="Operational state of the bridge")
    mtu: Optional[int] = Field(None, description="MTU of the bridge")
    stp_state: Optional[int] = Field(None, description="STP (Spanning Tree Protocol) state of the bridge")
    members: List[BridgeInterfaceInfo] = Field(default_factory=list, description="List of member interfaces of the bridge")

class BridgeCreateRequest(BaseModel):
    name: str
    interfaces: List[str]


class BridgeRemoveRequest(BaseModel):
    name: str
# ------------------------------
# Lazy Init Functions
# ------------------------------

def init_network_api():
    global ip, ndb
    if ip is None:
        ip = IPRoute()
    if ndb is None:
        ndb = NDB()

def shutdown_network_api():
    global ip, ndb
    if ip:
        ip.close()
        ip = None
    if ndb:
        ndb.close()
        ndb = None

def get_iproute():
    if ip is None:
        init_network_api()
    return ip

def get_ndb():
    if ndb is None:
        init_network_api()
    return ndb

# ------------------------------
# Utility functions
# ------------------------------

def parse_addresses(addrs):
    res = []
    for a in addrs:
        family = "ipv4" if a.get("family") == 2 else "ipv6"
        res.append(
            InterfaceAddress(
                family=family,
                address=a.get("address"),
                prefixlen=a.get("prefixlen"),
            )
        )
    return res

def parse_flags(flags_int: int) -> list[str]:
    """
    Converts the integer flags from pyroute2 to human-readable list of strings.
    """
    flags_map = {
        0x1: "UP",
        0x2: "BROADCAST",
        0x4: "DEBUG",
        0x8: "LOOPBACK",
        0x10: "POINTOPOINT",
        0x20: "NOTRAILERS",
        0x40: "RUNNING",
        0x80: "NOARP",
        0x100: "PROMISC",
        0x200: "ALLMULTI",
        0x400: "MASTER",
        0x800: "SLAVE",
        0x1000: "MULTICAST",
        0x2000: "PORTSEL",
        0x4000: "AUTOMEDIA",
        0x8000: "DYNAMIC",
        0x10000: "LOWER_UP",
        0x20000: "DORMANT",
        0x40000: "ECHO",
    }
    result = []
    for bit, name in flags_map.items():
        if flags_int & bit:
            result.append(name)
    return result

def iface_index(name: str, ip: IPRoute) -> int:
    idx = ip.link_lookup(ifname=name)
    if not idx:
        raise HTTPException(status_code=404, detail=f"Interface {name} not found")
    return idx[0]


def bridge_exists(name: str, ip: IPRoute) -> bool:
    return bool(ip.link_lookup(ifname=name))


# ------------------------------
# Endpoints
# ------------------------------

@router.get("/interfaces", response_model=List[InterfaceInfo])
def get_interfaces(ip: IPRoute = Depends(get_iproute)):
    result = []
    links = ip.get_links()
    addresses = ip.get_addr()

    addr_map = {}
    for a in addresses:
        ifindex = a.get("index")
        addr_map.setdefault(ifindex, []).append(a)

    for link in links:
        attrs = dict(link["attrs"])
        ifindex = link["index"]
        addrs = addr_map.get(ifindex, [])

        result.append(
            InterfaceInfo(
                ifindex=ifindex,
                name=attrs.get("IFLA_IFNAME"),
                state=attrs.get("IFLA_OPERSTATE", "unknown"),
                mac=attrs.get("IFLA_ADDRESS"),
                mtu=attrs.get("IFLA_MTU"),
                flags=parse_flags(link.get("flags", 0)),
                addresses=parse_addresses(addrs),
            )
        )
    return result

@router.get("/routes", response_model=List[RouteInfo])
def get_routes(ip: IPRoute = Depends(get_iproute)):
    routes = []
    for r in ip.get_routes():
        attrs = dict(r["attrs"])
        dst = attrs.get("RTA_DST")
        gateway = attrs.get("RTA_GATEWAY")
        prefsrc = attrs.get("RTA_PREFSRC")
        oif = r.get("oif")
        ifname = None
        if oif is not None:
            # translate ifindex → name
            link = ip.get_links(oif)[0]
            ifname = dict(link["attrs"]).get("IFLA_IFNAME")

        routes.append(
            RouteInfo(
                dst=f"{dst}/{r.get('dst_len')}" if dst else None,
                gateway=gateway,
                prefsrc=prefsrc,
                oif=oif,
                ifname=ifname,
                table=r.get("table", 254),
                proto=r.get("proto"),
                scope=r.get("scope"),
                type=r.get("type"),
            )
        )
    return routes


@router.get("/links", response_model=List[InterfaceInfo])
def get_raw_links(ip: IPRoute = Depends(get_iproute)):
    """
    Returns all interfaces in a clean Pydantic format.
    This is similar to /interfaces but avoids additional processing if needed.
    """
    result = []
    links = ip.get_links()
    addresses = ip.get_addr()

    # group addresses by interface index
    addr_map = {}
    for a in addresses:
        ifindex = a.get("index")
        addr_map.setdefault(ifindex, []).append(a)

    for link in links:
        attrs = dict(link.get("attrs", []))  # convert list of tuples to dict
        ifindex = link["index"]
        addrs = addr_map.get(ifindex, [])

        result.append(
            InterfaceInfo(
                ifindex=ifindex,
                name=attrs.get("IFLA_IFNAME", "unknown"),
                state=attrs.get("IFLA_OPERSTATE", "unknown"),
                mac=attrs.get("IFLA_ADDRESS"),
                mtu=attrs.get("IFLA_MTU", 0),
                flags=[],  # latest pyroute2 removed ifi_flags, leave empty
                addresses=parse_addresses(addrs),
            )
        )

    return result

@router.get("/bridges", response_model=List[BridgeInfo])
def get_bridges():
    """
    Get all bridge interfaces on the system, including their member interfaces.
    Returns detailed information:
    - Bridge index, name, state, MTU
    - STP state
    - Member interfaces with index, name, state, and MTU
    """
    bridges_list: List[BridgeInfo] = []

    with NDB() as ndb:
        for br in ndb.interfaces:
            # Only bridges
            if getattr(br, "kind", None) == "bridge":
                members: List[BridgeInterfaceInfo] = []
                # Find member interfaces
                for iface in ndb.interfaces:
                    if getattr(iface, "master", None) == br.index:
                        members.append(
                            BridgeInterfaceInfo(
                                ifindex=iface.index,
                                ifname=iface.ifname,
                                state=getattr(iface, "operstate", None),
                                mtu=getattr(iface, "mtu", None)
                            )
                        )

                bridges_list.append(
                    BridgeInfo(
                        ifindex=br.index,
                        ifname=br.ifname,
                        state=getattr(br, "operstate", None),
                        mtu=getattr(br, "mtu", None),
                        stp_state=getattr(br, "stp_state", None),
                        members=members
                    )
                )

    return bridges_list

@router.get("/full-state")
def full_state(
    ip: IPRoute = Depends(get_iproute),
):
    """
    Returns the full network state:
    - Interfaces with IP addresses and flags
    - Routes
    - Bridges with member interfaces
    """
    return {
        "interfaces": get_interfaces(ip),
        "routes": get_routes(ip),
        "bridges": get_bridges(),  # uses NDB internally
    }

@router.post("/create")
def create_bridge(req: BridgeCreateRequest, ip: IPRoute = Depends(get_iproute)):
    if bridge_exists(req.name, ip):
        raise HTTPException(400, f"Bridge {req.name} already exists")

    # Bridge erzeugen
    ip.link("add", ifname=req.name, kind="bridge")
    br_idx = iface_index(req.name, ip)

    # Bridge konfigurieren
    # TODO Parameter anpassen (STP, etc.)
    ip.link("set", index=br_idx, kind="bridge", br_stp_state=0)
    ip.link("set", index=br_idx, state="up")

    # Interfaces hinzufügen + aktivieren
    for iface in req.interfaces:
        idx = iface_index(iface, ip)

        # interface hochfahren
        ip.link("set", index=idx, state="down")  # optional - sicherer
        ip.link("set", index=idx, state="up")

        # interface in die bridge hängen
        ip.link("set", index=idx, master=br_idx)

    return {
        "status": "ok",
        "bridge": req.name,
        "interfaces": req.interfaces
    }


@router.post("/remove")
def remove_bridge(req: BridgeRemoveRequest, ip: IPRoute = Depends(get_iproute)):
    if not bridge_exists(req.name, ip):
        raise HTTPException(404, f"Bridge {req.name} not found")

    br_idx = iface_index(req.name, ip)

    # Bridge runterfahren
    ip.link("set", index=br_idx, state="down")

    # Bridge löschen
    ip.link("del", index=br_idx)

    return {
        "status": "ok",
        "deleted": req.name
    }