#!/usr/bin/env python3
 
import sys
import re
import urllib.request
import urllib.parse
 
 
def fetch_prefixes(keyword: str) -> list[str]:
    url = (
        "https://bgp.he.net/search?"
        + urllib.parse.urlencode({"search[search]": keyword, "commit": "Search"})
    )
 
    req = urllib.request.Request(
        url,
        headers={"User-Agent": "Mozilla/5.0 (compatible; bgp-search/1.0)"},
    )
 
    with urllib.request.urlopen(req, timeout=15) as resp:
        html = resp.read().decode("utf-8", errors="replace")
 
    prefixes = re.findall(
        r'href="/net/([^"]+)"',
        html,
    )
 
    return sorted(set(prefixes))
 
 
def main():
    if len(sys.argv) < 2:
        print("Use: python3 bgp_search.py <key_word>", file=sys.stderr)
        print("For example: python3 bgp_search.py ozon", file=sys.stderr)
        sys.exit(1)
 
    keyword = sys.argv[1]
    prefixes = fetch_prefixes(keyword)
 
    if not prefixes:
        print(f"Network for '{keyword}' not found.", file=sys.stderr)
        sys.exit(0)
 
    for prefix in prefixes:
        print(prefix)
 
 
if __name__ == "__main__":
    main()