"""Plugin: CIDR/subnet calculator."""

from __future__ import annotations

import ipaddress

from derp.plugin import command


@command("cidr", help="Subnet info: !cidr <network> | !cidr contains <net> <ip>")
async def cmd_cidr(bot, message):
    """Calculate subnet properties or check IP membership.

    !cidr 192.168.1.0/24
    !cidr contains 10.0.0.0/8 10.1.2.3
    """
    parts = message.text.split()
    if len(parts) < 2:
        await bot.reply(message, "Usage: !cidr <network> | !cidr contains <net> <ip>")
        return

    subcmd = parts[1].lower()

    if subcmd == "contains" and len(parts) >= 4:
        await _contains(bot, message, parts[2], parts[3])
    elif subcmd == "contains":
        await bot.reply(message, "Usage: !cidr contains <network> <ip>")
    else:
        await _info(bot, message, parts[1])


async def _info(bot, message, network_str: str) -> None:
    """Show subnet information."""
    try:
        net = ipaddress.ip_network(network_str, strict=False)
    except ValueError:
        await bot.reply(message, f"Invalid network: {network_str}")
        return

    if isinstance(net, ipaddress.IPv4Network):
        host_count = net.num_addresses - 2 if net.prefixlen < 31 else net.num_addresses
        parts = [
            f"net:{net.network_address}/{net.prefixlen}",
            f"range:{net[0]}-{net[-1]}",
            f"hosts:{host_count}",
            f"mask:{net.netmask}",
            f"wildcard:{net.hostmask}",
        ]
        if net.prefixlen < 31:
            parts.append(f"broadcast:{net.broadcast_address}")
    else:
        parts = [
            f"net:{net.network_address}/{net.prefixlen}",
            f"range:{net[0]}-{net[-1]}",
            f"hosts:{net.num_addresses}",
        ]

    await bot.reply(message, " | ".join(parts))


async def _contains(bot, message, network_str: str, ip_str: str) -> None:
    """Check if an IP belongs to a network."""
    try:
        net = ipaddress.ip_network(network_str, strict=False)
    except ValueError:
        await bot.reply(message, f"Invalid network: {network_str}")
        return

    try:
        addr = ipaddress.ip_address(ip_str)
    except ValueError:
        await bot.reply(message, f"Invalid IP: {ip_str}")
        return

    if addr in net:
        await bot.reply(message, f"{addr} is in {net}")
    else:
        await bot.reply(message, f"{addr} is NOT in {net}")