import json
import funcy
from Crypto.Cipher import AES
from Crypto import Random


def decrypt(key_file, filename):
    with open(key_file, 'rb') as passFile:
        key = passFile.read()
    chunksize = 64 * 1024
    with open(filename, 'rb') as infile:
        file_size = int(infile.read(16))
        IV = infile.read(16)
        decryptor = AES.new(key, AES.MODE_CBC, IV)
        result_bytes = b''
        while True:
            chunk = infile.read(chunksize)
            if len(chunk) == 0:
                break
            result_bytes += decryptor.decrypt(chunk)

    result_bytes = result_bytes[:file_size]
    return result_bytes


def encrypt(parameters, key_file, filename):
    with open(key_file, 'rb') as passFile:
        key = passFile.read()
    chunksize = 64 * 1024
    object_to_encrypt = json.dumps(parameters)
    object_to_encrypt = object_to_encrypt.encode('UTF-8')
    output_file = filename
    filesize = str(len(object_to_encrypt)).zfill(16)
    IV = Random.new().read(16)
    encryptor = AES.new(key, AES.MODE_CBC, IV)
    with open(output_file, 'wb') as outfile:
        outfile.write(filesize.encode('UTF-8'))
        outfile.write(IV)
        for chunk in funcy.chunks(chunksize, object_to_encrypt):
            if len(chunk) == 0:
                break
            elif len(chunk) % 16 != 0:
                chunk += b' ' * (16 - (len(chunk) % 16))

            outfile.write(encryptor.encrypt(chunk))