#!/usr/bin/env python3
"""
IP utility functions for PIC — derive all container and virtual IPs from the
docker network subnet so that one ip_range setting drives everything.

The canonical source of IPs is the .env file at the project root.
docker-compose.yml uses ${VAR:-default} substitution to read from it.
"""

import ipaddress
import os
from typing import Dict, List, Optional

# Fixed host-number offsets within the subnet (e.g. 172.20.0.0/16 → 172.20.0.<offset>)
CONTAINER_OFFSETS: Dict[str, int] = {
    'caddy':        2,
    'dns':          3,
    'dhcp':         4,
    'ntp':          5,
    'mail':         6,
    'radicale':     7,
    'webdav':       8,
    'wireguard':    9,
    'api':          10,
    'webui':        11,
    'rainloop':     12,
    'filegator':    13,
    # Caddy virtual IPs — each service gets its own IP so Caddy can route by dst addr
    'vip_calendar': 21,
    'vip_files':    22,
    'vip_mail':     23,
    'vip_webdav':   24,
}

# Mapping from service key → docker-compose env var name (static containers only)
ENV_VAR_NAMES: Dict[str, str] = {
    'caddy':     'CADDY_IP',
    'dns':       'DNS_IP',
    'dhcp':      'DHCP_IP',
    'ntp':       'NTP_IP',
    'mail':      'MAIL_IP',
    'radicale':  'RADICALE_IP',
    'webdav':    'WEBDAV_IP',
    'wireguard': 'WG_IP',
    'api':       'API_IP',
    'webui':     'WEBUI_IP',
    'rainloop':  'RAINLOOP_IP',
    'filegator': 'FILEGATOR_IP',
}

# Default host-port bindings for each service
PORT_DEFAULTS: Dict[str, int] = {
    'dns_port':             53,
    'dhcp_port':            67,
    'ntp_port':             123,
    'mail_smtp_port':       25,
    'mail_submission_port': 587,
    'mail_imap_port':       993,
    'radicale_port':        5232,
    'webdav_port':          8080,
    'wg_port':              51820,
    'api_port':             3000,
    'webui_port':           8081,
    'rainloop_port':        8888,
    'filegator_port':       8082,
}

# Mapping from port key → docker-compose env var name
PORT_ENV_VAR_NAMES: Dict[str, str] = {
    'dns_port':             'DNS_PORT',
    'dhcp_port':            'DHCP_PORT',
    'ntp_port':             'NTP_PORT',
    'mail_smtp_port':       'MAIL_SMTP_PORT',
    'mail_submission_port': 'MAIL_SUBMISSION_PORT',
    'mail_imap_port':       'MAIL_IMAP_PORT',
    'radicale_port':        'RADICALE_PORT',
    'webdav_port':          'WEBDAV_PORT',
    'wg_port':              'WG_PORT',
    'api_port':             'API_PORT',
    'webui_port':           'WEBUI_PORT',
    'rainloop_port':        'RAINLOOP_PORT',
    'filegator_port':       'FILEGATOR_PORT',
}

# Mapping from port key → docker-compose service name(s) that must restart on port change
PORT_TO_CONTAINERS: Dict[str, List[str]] = {
    'dns_port':             ['dns'],
    'dhcp_port':            ['dhcp'],
    'ntp_port':             ['ntp'],
    'mail_smtp_port':       ['mail'],
    'mail_submission_port': ['mail'],
    'mail_imap_port':       ['mail'],
    'radicale_port':        ['radicale'],
    'webdav_port':          ['webdav'],
    'wg_port':              ['wireguard'],
    'api_port':             ['api'],
    'webui_port':           ['webui'],
    'rainloop_port':        ['rainloop'],
    'filegator_port':       ['filegator'],
}


def get_service_ips(ip_range: str) -> Dict[str, str]:
    """
    Derive all container and virtual IPs from the docker network subnet.

    Example: '172.20.0.0/16' → {'caddy': '172.20.0.2', 'dns': '172.20.0.3', ...}
    The offset of each service within the subnet is fixed (see CONTAINER_OFFSETS).
    """
    network = ipaddress.IPv4Network(ip_range, strict=False)
    base = int(network.network_address)
    return {
        name: str(ipaddress.IPv4Address(base + offset))
        for name, offset in CONTAINER_OFFSETS.items()
    }


def get_virtual_ips(ip_range: str) -> Dict[str, str]:
    """
    Return only the four Caddy virtual IPs keyed by service name.
    Used by firewall_manager to set per-service iptables rules.
    """
    ips = get_service_ips(ip_range)
    return {
        'calendar': ips['vip_calendar'],
        'files':    ips['vip_files'],
        'mail':     ips['vip_mail'],
        'webdav':   ips['vip_webdav'],
    }


def write_caddyfile(ip_range: str, cell_name: str, domain: str, path: str) -> bool:
    """
    Generate the Caddy reverse-proxy config from the current ip_range, cell_name, and domain.

    Must be called after any ip_range or domain change so Caddy routes correctly.
    Container-internal ports are fixed by docker-compose and never change.
    Returns True on success.
    """
    try:
        ips = get_service_ips(ip_range)
        caddy_ip      = ips['caddy']
        vip_calendar  = ips['vip_calendar']
        vip_files     = ips['vip_files']
        vip_mail      = ips['vip_mail']
        vip_webdav    = ips['vip_webdav']
        content = f"""\
{{
    auto_https off
}}

# Main cell domain — no service-IP restriction needed
http://{cell_name}.{domain}, http://{caddy_ip}:80 {{
    handle /api/* {{
        reverse_proxy cell-api:3000
    }}
    handle /calendar* {{
        reverse_proxy cell-radicale:5232
    }}
    handle /files* {{
        reverse_proxy cell-filegator:8080
    }}
    handle /webmail* {{
        reverse_proxy cell-rainloop:8888
    }}
    handle {{
        reverse_proxy cell-webui:80
    }}
}}

# Per-service virtual IPs — each gets its own IP so iptables can target them
http://calendar.{domain}, http://{vip_calendar}:80 {{
    reverse_proxy cell-radicale:5232
}}

http://files.{domain}, http://{vip_files}:80 {{
    reverse_proxy cell-filegator:8080
}}

http://mail.{domain}, http://webmail.{domain}, http://{vip_mail}:80 {{
    reverse_proxy cell-rainloop:8888
}}

http://webdav.{domain}, http://{vip_webdav}:80 {{
    reverse_proxy cell-webdav:80
}}

http://api.{domain} {{
    reverse_proxy cell-api:3000
}}

http://webui.{domain} {{
    reverse_proxy cell-webui:80
}}

# Catch-all for direct IP / localhost
:80 {{
    handle /api/* {{
        reverse_proxy cell-api:3000
    }}
    handle {{
        reverse_proxy cell-webui:80
    }}
}}
"""
        os.makedirs(os.path.dirname(os.path.abspath(path)), exist_ok=True)
        tmp = path + '.tmp'
        with open(tmp, 'w') as f:
            f.write(content)
            f.flush()
            os.fsync(f.fileno())
        os.replace(tmp, path)
        return True
    except Exception:
        return False


def write_env_file(ip_range: str, path: str, ports: Optional[Dict[str, int]] = None) -> bool:
    """
    Write (or overwrite) the docker-compose .env file with IPs and ports.

    docker-compose reads this file automatically at startup to substitute
    ${VAR:-default} placeholders in docker-compose.yml.  Call this at setup
    time and whenever ip_range or port values change.

    ports: override specific port defaults (keys from PORT_DEFAULTS).
    Returns True on success, False if the path is not writable.
    """
    try:
        ips = get_service_ips(ip_range)
        merged_ports = dict(PORT_DEFAULTS)
        if ports:
            merged_ports.update(ports)
        lines = [f'CELL_NETWORK={ip_range}\n']
        for svc, var in ENV_VAR_NAMES.items():
            lines.append(f'{var}={ips[svc]}\n')
        for key, var in PORT_ENV_VAR_NAMES.items():
            lines.append(f'{var}={merged_ports[key]}\n')
        os.makedirs(os.path.dirname(os.path.abspath(path)), exist_ok=True)
        content = ''.join(lines)
        # Write in-place (same inode) so Docker bind-mounted files see the update.
        # os.replace() changes the inode which breaks file bind-mounts inside containers.
        with open(path, 'w') as f:
            f.write(content)
            f.flush()
            os.fsync(f.fileno())
        return True
    except Exception:
        return False