from sqlmodel import select
import libvirt

from openec2.libvirt import LibvirtSingleton
from openec2.db import DatabaseDep
from openec2.db.ipam import IPAMEntry
from openec2.utils.ip import ipv4_to_int, int_to_ipv4


def _libvirt_host_update(instance_id: str, mac: str, ipv4: str) -> str:
    return f"<host name='{instance_id}' mac='{mac}' ip='{ipv4}' />"


def add_instance_dhcp_mapping(instance_id: str, mac: str, ipv4: str, db: DatabaseDep):
    """
    Adds a DHCP entry for the network to give the instance a static
    private IPv4 address.
    """
    entry = IPAMEntry(
        ipv4_addr_raw=ipv4_to_int(ipv4),
        instance_id=instance_id,
        # TODO
        vpc_id="default",
    )
    db.add(entry)

    # Tell libvirt about this mapping
    conn = LibvirtSingleton.of().connection
    conn.networkLookupByName("default").update(
        libvirt.VIR_NETWORK_UPDATE_COMMAND_ADD_LAST,
        libvirt.VIR_NETWORK_SECTION_IP_DHCP_HOST,
        0,
        _libvirt_host_update(instance_id, mac, ipv4),
        flags=libvirt.VIR_NETWORK_UPDATE_AFFECT_LIVE,
    )

def remove_instance_dhcp_mapping(instance_id: str, mac: str ,ipv4: str, db: DatabaseDep):
    i = ipv4_to_int(ipv4)
    entry = db.exec(select(IPAMEntry).where(IPAMEntry.ipv4_addr_raw == i, IPAMEntry.instance_id == instance_id)).first()
    db.delete(entry)

    # Tell libvirt about this mapping
    conn = LibvirtSingleton.of().connection
    conn.networkLookupByName("default").update(
        libvirt.VIR_NETWORK_UPDATE_COMMAND_DELETE,
        libvirt.VIR_NETWORK_SECTION_IP_DHCP_HOST,
        0,
        _libvirt_host_update(instance_id, mac, ipv4),
        flags=libvirt.VIR_NETWORK_UPDATE_AFFECT_LIVE,
    )

def is_ipv4_available(ipv4: str, db: DatabaseDep) -> bool:
    i = ipv4_to_int(ipv4)
    return db.exec(select(IPAMEntry).where(IPAMEntry.ipv4_addr_raw == i)).first() is None

def get_available_ipv4(db: DatabaseDep) -> str:
    entries = db.exec(select(IPAMEntry)).all()
    # TODO: Use the VPC's subnet
    max_ip = max(e.ipv4_addr_raw for e in entries) if entries else ipv4_to_int("192.168.122.2")
    # TODO: Check if we're still inside the subnet
    return int_to_ipv4(max_ip + 1)