import argparse
import logging
import sys
from jose import jws
from pathlib import Path

import json


def insert_sig_block (j):
    j['Signature'] = {
        'protected' : '',
        'signature' : ''
    }
    return j

if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument('-v', '--verbose', action='count', help='Verbose logging (can be specified multiple times)')
    parser.add_argument('--pretty', action="store_true", help='Pretty-print the JSON document before signing')
    parser.add_argument('-i', '--input', type=argparse.FileType('r'), default=sys.stdin, help="Path to input file (if absent, stdin is used)")
    args = parser.parse_args()

    match args.verbose:
        case v if v and v >= 2:
            logging.basicConfig(level=logging.DEBUG)
        case 1:
            logging.basicConfig(level=logging.INFO)
        case _:
            logging.basicConfig(level=logging.WARNING)

    logging.debug(f"Arguments: {args}")

    json_text = args.input.read()
    args.input.close()
    
    j = json.loads(json_text)
    j = insert_sig_block(j)
    
    indent = None
    if args.pretty:
        indent = '  '
    presigned_json_text = json.dumps(j, indent=indent)
    Path('presigned.json').write_text(presigned_json_text)
    presigned_json_bytes = presigned_json_text.encode('utf-8')
    
    signed = jws.sign(presigned_json_bytes, 'secret_key', algorithm="HS256")
    components = signed.split('.')

    j['Signature']['protected'] = components[0]
    j['Signature']['signature'] = components[2]

    signed_json_text = json.dumps(j, indent=indent)
    print(signed_json_text)