#===========================================================================================
#  _____ _____ _   _    _    __  __  ___  ____ _____ _____ ____ _   _ 
# |_   _| ____| \ | |  / \  |  \/  |/ _ \|  _ \_   _| ____/ ___| | | |
#   | | |  _| |  \| | / _ \ | |\/| | | | | |_) || | |  _|| |   | |_| |
#   | | | |___| |\  |/ ___ \| |  | | |_| |  _ < | | | |__| |___|  _  |
#   |_| |_____|_| \_/_/   \_\_|  |_|\___/|_| \_\|_| |_____\____|_| |_|
#
#    RSA Client Keys Manager V1 (Python 3.6)
#
#   Sources: 
#    https://nitratine.net/blog/post/asymmetric-encryption-and-decryption-in-python/
#    https://stackoverflow.com/questions/8933237/how-to-find-if-directory-exists-in-python 
#    https://stackoverflow.com/questions/273192/how-can-i-safely-create-a-nested-directory 
#
#===========================================================================================

# Basic cryptography tools 
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.asymmetric import rsa

# To format created key obj into text to be used/exported 
from cryptography.hazmat.primitives import serialization 

# To get user home directory 
from pathlib import Path

# Home made RSA Keys lib 
from utils.rsa_tenamortech_utils import * 

def check_for_existing_keys():
    keys_dir_path = Path.home() / '.auth_server_test' / 'client' 
    private_key_path = keys_dir_path / 'id_rsa'
    public_key_path = keys_dir_path / 'id_rsa.pub'

    # =========================================================
    # Private key file exists ? Load it
    # --- Public key file exists ? Load it
    # --- No Public key file ? Generate it from the Private
    # No Private key file ? Generate both keys (save as well) 
    # =========================================================

    if(private_key_path.exists()):
        print('Find private key from file [ OK ]')
        # Load private key from file
        print('Load private key from file [ ... ]')
        with open(str(private_key_path), "rb") as key_file:
            private_key = serialization.load_pem_private_key(
                key_file.read(),
                password=None,
                backend=default_backend()
            )
        print('Load private key from file [ OK ]')
        if(public_key_path.exists()):
            print('Find public key from file [ OK ]')
            # Load public key from file 
            print('Load public key from file [ ... ]')
            with open(str(public_key_path), "rb") as key_file:
                public_key = serialization.load_pem_public_key(
                    key_file.read(),
                    backend=default_backend()
                )
            print('Load public key from file [ OK ]')
            # Return keys 
            return (private_key,public_key)
        else:
            print('Find public key from file [ FAIL ]')
            print('Generating public key from private key [ ... ]')
            public_key = generate_public_key(1,private_key)
            print('Generating public key from private key [ OK ]')
            return (private_key,public_key)
    else:
        print('Find private key from file [ FAIL ]')
        print('New keys will be generated')
        return generate_keys(1) 
check_for_existing_keys()