#!/usr/bin/env python3

import sys
import os
import geoip2.database
import ipaddress

# Constants
DB_PATH = "<%= node[:geoipupdate][:directory] %>/GeoLite2-Country.mmdb"

# Default region when continent doesn't match any in the dictionary
DEFAULT_REGION = "eu-central-1"

# Mapping of continents to AWS regions
CONTINENT_TO_AWS_REGION = {
    "NA": "us-west-2", # North America
    "OC": "us-west-2", # Oceania
    "SA": "us-west-2", # South America
}

# Global to store last known modification time and database reader
last_mod_time = None
reader = None

def is_valid_ip(ip_str):
    """Check if a string is a valid IPv4 or IPv6 address."""
    try:
        ipaddress.ip_address(ip_str)
        return True
    except ValueError:
        return False

def get_reader():
    """Get the geoip2 database reader. Reload if the DB file has changed."""
    global last_mod_time
    global reader

    if not os.path.exists(DB_PATH):
      return None  # Database file missing

    current_mod_time = os.path.getmtime(DB_PATH)

    # If file has changed or reader isn't initialized, reload it
    if reader is None or current_mod_time != last_mod_time:
        if reader:
            reader.close()  # Close the existing reader before reinitializing
        reader = geoip2.database.Reader(DB_PATH)
        last_mod_time = current_mod_time

    return reader

def get_continent_from_ip(ip_address):
    """Return the continent for a given IP address."""
    if not is_valid_ip(ip_address):
        return None
    reader = get_reader()
    if reader is None:
      return None  # No continent as DB is missing
    try:
        response = reader.country(ip_address)
        return response.continent.code
    except:
        return None  # Indicates invalid IP address or other issues

def determine_aws_region(continent_code):
    """Determine AWS region based on the continent code using a dictionary."""
    return CONTINENT_TO_AWS_REGION.get(continent_code, DEFAULT_REGION)

def main():
    """Main function to process IP addresses from stdin and return AWS regions."""
    for line in sys.stdin:
        ip_address = line.strip()

        continent_code = get_continent_from_ip(ip_address)
        aws_region = determine_aws_region(continent_code)

        sys.stdout.write(f"{aws_region}\n")
        sys.stdout.flush()

if __name__ == "__main__":
    main()