#!/usr/bin/env python3
"""
mchip.cc Tag Writer fuer USB-NFC-Reader (ACR122U etc.) via nfcpy.

Flow:  Tag auflegen -> UID lesen -> GET /api/chip?uid=... -> NDEF-URL schreiben

Setup (Windows):
  pip install nfcpy requests
  ACR122U: libusb-Treiber via Zadig installieren (einmalig)

Usage: python write_chip.py --user USERNAME --key API_KEY [--base https://mchip.cc]
   Der API-Key wird auf /chips fuer 1 Stunde freigeschaltet ("Enable API").
"""

import argparse
import requests
import nfc
import nfc.ndef

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument('--user', required=True, help='mchip.cc username')
    ap.add_argument('--key', required=True, help='Writer API key (enabled on /chips)')
    ap.add_argument('--mchip', default=None, help='M-Chip id/slug to activate the chip for')
    ap.add_argument('--base', default='https://mtag.cc')
    ap.add_argument('--url-mode', choices=['token', 'virtual', 'uid'], default='token',
                    help='token=write random public_id hash (default), virtual=mint UID-free token per tag, uid=write raw hardware UID')
    ap.add_argument('--lock', action='store_true',
                    help='Set permanent read-only lock bit after writing (IRREVERSIBLE!)')
    args = ap.parse_args()
    base, key, user = args.base.rstrip('/'), args.key, args.user
    extra = {'mchip': args.mchip} if args.mchip else {}
    extra['url_mode'] = 'uid' if args.url_mode == 'uid' else 'token'

    mode_info = 'WITH permanent Lock-Bit (--lock)' if args.lock else 'without Lock-Bit (re-writable)'
    print(f'Hold a tag to the reader (url-mode={args.url_mode}, {mode_info}; Ctrl+C to quit).')
    with nfc.ContactlessFrontend('usb') as clf:
        while True:
            tag = clf.connect(rdwr={'on-connect': lambda t: False,
                                    'beep-on-connect': False})
            if tag is None:
                continue
            uid = 'virtual' if args.url_mode == 'virtual' else tag.identifier.hex().upper()
            print('Tag:', uid if uid != 'virtual' else f'UID-free (hw={tag.identifier.hex().upper()})')

            try:
                r = requests.get(f'{base}/api/chip',
                                 params={'user': user, 'key': key, 'uid': uid, **extra}, timeout=10)
            except requests.RequestException as e:
                print('lookup failed:', e); continue
            if r.status_code == 401:
                print('  API disabled/invalid — enable the key on /chips'); continue
            if r.status_code not in (200,):
                print('  error:', r.json().get('error')); continue
            data = r.json()
            print('  status:', data['status'])
            url = data['url']
            print('  writing:', url)

            if not tag.ndef or not tag.ndef.is_writeable:
                print('  tag not NDEF-writeable'); continue
            tag.ndef.message = nfc.ndef.Message(nfc.ndef.UriRecord(url))
            if args.lock:
                tag.ndef.is_writeable = False
                print('  OK — tag written + LOCKED (permanent read-only).')
            else:
                print('  OK — tag written (re-writable).')

if __name__ == '__main__':
    main()