# -*- coding: utf-8 -*-
 
# Copyright (c) 2018  Michael Rasmussen <mir@datanom.net>
 
# This file is part of SecureMail.

# SecureMail is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# SecureMail is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with SecureMail.  If not, see <https://www.gnu.org/licenses/>.

from nacl.secret import SecretBox
from nacl.public import PrivateKey, Box
from nacl.utils import random
from nacl.encoding import HexEncoder
import nacl.hash

class Cryptonize:
    """
    Encrypt and decrypt objects
    """
    
    def symmetric_encrypt(self, key, plain):
        skey = self.sanitize_key(key)
        box = SecretBox(skey)
        cipher = box.encrypt(plain)
        box = None
        
        return cipher
        
    def symmetric_decrypt(self, key, cipher):
        skey = self.sanitize_key(key)
        box = SecretBox(skey)
        plain = box.decrypt(cipher)
        box = None
        
        return plain
        
    def asymmetric_encrypt(self, privkey, pubkey, plain):
        box = Box(privkey, pubkey)
        cipher = box.encrypt(plain)
        box = None
        
        return cipher
        
    def asymmetric_decrypt(self, privkey, pubkey, cipher):
        box = Box(privkey, pubkey)
        plain = box.decrypt(cipher)
        box = None
        
        return plain
        
    def get_random_key(self):
        return random(SecretBox.KEY_SIZE)
        
    def sanitize_key(self, key):
        if not isinstance(key, bytes):
            key = key.encode('utf-8')
        size = len(key)
        if size < SecretBox.KEY_SIZE:
            """We must pad"""
            pad = None
            for i in range(SecretBox.KEY_SIZE - size):
                if pad is None:
                    pad = b'\0'
                else:
                    pad += b'\0'
            newkey = key + pad
        else:
            newkey = key
        
                
        return newkey
        
    def get_key_pair(self):
        privkey = PrivateKey.generate()
        pubkey = privkey.public_key
        
        return (privkey, pubkey)

    def generate_hash(self, key):
        if not isinstance(key, bytes):
            key = key.encode('utf-8')
        HASHER = nacl.hash.sha512
        digest = HASHER(key, encoder=HexEncoder)

        return digest.decode()