goimport os, sys
import base64, string
import json, requests

from pyasn1.codec.der.decoder import decode
from pyasn1.codec.der.encoder import encode
from pyasn1_modules import rfc2315
from argparse import ArgumentParser
from requests.auth import HTTPBasicAuth

def envelop(binFile, pkcs7String, outFile):
	with open(binFile,'rb') as f:
		encryptedBinary = f.read()
		f.closed

	# remove the -----BEGIN PKCS7----- header/footer
	j = pkcs7String[pkcs7String.find('\n')+1:pkcs7String.rfind('\n')]
	j = "".join(j)
	base64_img_bytes = j.encode('utf-8')
	env_der = base64.decodebytes(base64_img_bytes)
	
	# merge files and then compare
	content, rest = decode(env_der, asn1Spec=rfc2315.ContentInfo())
	assert content['contentType'] == rfc2315.envelopedData

	myenvelope, rest = decode(content['content'], asn1Spec=rfc2315.EnvelopedData())

	encr = rfc2315.EncryptedContentInfo()
	encr['contentType'] = myenvelope['encryptedContentInfo']['contentType']
	encr['contentEncryptionAlgorithm'] = myenvelope['encryptedContentInfo']['contentEncryptionAlgorithm']
	encr['encryptedContent'] = memoryview(encryptedBinary)

	myenvelope['encryptedContentInfo'] = encr

	newcontent = rfc2315.ContentInfo()
	newcontent['contentType'] = rfc2315.envelopedData
	newcontent['content'] = encode(myenvelope)

	envelope_buffer = memoryview(encode(newcontent))

	with open(outFile,'wb') as f:
		f.write(envelope_buffer)
		f.closed

if __name__ == "__main__":
	parser = ArgumentParser(description='This script is used to create a digital envelope from the raw recording. Example: python envelop-pkcs7.py -binFile abc00000001.mp3.bin -output abc00000001.mp3.bin.pkcs7')
	parser.add_argument("-binFile", action='store', dest="binFile", type=str, required=True, help='File path to the bin file downloaded')
	parser.add_argument("-jsonFile", action='store', dest="jsonFile", type=str, required=True, help='File path to the json file downloaded')
	parser.add_argument("-output", action='store', dest="outFile", type=str, required=True, help='File path to save the digital envelope bin file')

	args = parser.parse_args()

	pkcs7String = ""

	try:

		with open(args.jsonFile) as f:
  			data = json.load(f)
		pkcs7String = data['mediaFiles'][0]["pkcs7"]
		print(pkcs7String)

	except:
		print("Reading PKCS7 failed")
		sys.exit()

	if pkcs7String:
		envelop(args.binFile, pkcs7String, args.outFile)
		print("Done!")
	else:
		print("PKCS7 key not found in JSON file.")