#!/usr/bin/env python3

import json
from pathlib import Path
import subprocess
import sys

upstream_config_file = Path(sys.argv[1]).resolve()
bird_config_file = Path(sys.argv[2]).resolve()

print("Loading upstream config from {}".format(upstream_config_file))
print("Deploying bird peering config file to {}".format(bird_config_file))
print("\n")
upstream_config = json.loads(upstream_config_file.read_text())

# collect tunnel interface names
tunnel_interface_names = []

# collect bird 2 peering directives
bird_config = ""

for peering in upstream_config:
    tunnel_interface_name = "peer{id}as{asn}".format(
        id=peering["peering-id"],
        asn=str(peering["remote-as"])[-4:],
    )
    print("Configuring {}".format(tunnel_interface_name))

    tunnel_interface_names.append(tunnel_interface_name)

    tunnel_config = """[Interface]
PrivateKey = {local_privatekey}
ListenPort = {local_endpoint_port}

[Peer]
PublicKey = {remote_publickey}
Endpoint = {remote_endpoint_addr}:{remote_endpoint_port}
AllowedIPs = fd00::/8, fe80::/10""".format(
        local_privatekey=peering["local-privatekey"],
        local_endpoint_port=peering["local-endpoint-port"],
        remote_publickey=peering["remote-publickey"],
        remote_endpoint_addr=peering["remote-endpoint-addr"],
        remote_endpoint_port=peering["remote-endpoint-port"],
    )

    tunnel_config_file = Path() / "{}.conf".format(tunnel_interface_name)
    tunnel_config_file.write_text(tunnel_config)


    r = subprocess.run(["ip", "address", "show", "dev", tunnel_interface_name], capture_output=True)
    if r.returncode != 0:
        subprocess.run(["ip", "link", "add", "dev", tunnel_interface_name, "type", "wireguard"], check=True)
        subprocess.run(["ip", "link", "set", "up", "dev", tunnel_interface_name], check=True)

    subprocess.run(["wg", "syncconf", tunnel_interface_name, tunnel_config_file], check=True)
    subprocess.run(["ip", "address", "change", "{}/128".format(peering["local-ip"]), "peer", "{}/128".format(peering["remote-ip"]), "dev", tunnel_interface_name], check=True)

    tunnel_config_file.unlink(missing_ok=True)

    bird_config += """
protocol bgp {tunnel_interface_name} from bgp_dn42 {{
    neighbor {remote_ip}%{tunnel_interface_name} as {remote_as};
}}
""".format(
    tunnel_interface_name=tunnel_interface_name,
    remote_ip=peering["remote-ip"],
    remote_as=peering["remote-as"],
)

# Writing generated bird config
bird_config_file.write_text(bird_config)

# remove all peer interfaces that are not supported
r = subprocess.run(["ip", "--json", "link", "show"], check=True, capture_output=True,text=True)
interfaces = json.loads(r.stdout)
for interface in interfaces:
    if interface["ifname"].startswith("peer") and interface["ifname"] not in tunnel_interface_names:
        print("Removing {}".format(interface["ifname"]))
        subprocess.run(["ip", "link", "delete", interface["ifname"]], check=True)