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import secrets

from cryptography import __version__
from cryptography.hazmat.primitives import padding
from cryptography.hazmat.primitives.ciphers.algorithms import AES, ARC4
from cryptography.hazmat.primitives.ciphers.base import Cipher
from cryptography.hazmat.primitives.ciphers.modes import CBC, ECB

from pypdf._crypt_providers._base import CryptBase

crypt_provider = ("cryptography", __version__)


class CryptRC4(CryptBase):
    def __init__(self, key: bytes) -> None:
        self.cipher = Cipher(ARC4(key), mode=None)

    def encrypt(self, data: bytes) -> bytes:
        encryptor = self.cipher.encryptor()
        return encryptor.update(data) + encryptor.finalize()

    def decrypt(self, data: bytes) -> bytes:
        decryptor = self.cipher.decryptor()
        return decryptor.update(data) + decryptor.finalize()


class CryptAES(CryptBase):
    def __init__(self, key: bytes) -> None:
        self.alg = AES(key)

    def encrypt(self, data: bytes) -> bytes:
        iv = secrets.token_bytes(16)
        pad = padding.PKCS7(128).padder()
        data = pad.update(data) + pad.finalize()

        cipher = Cipher(self.alg, CBC(iv))
        encryptor = cipher.encryptor()
        return iv + encryptor.update(data) + encryptor.finalize()

    def decrypt(self, data: bytes) -> bytes:
        iv = data[:16]
        data = data[16:]
        # for empty encrypted data
        if not data:
            return data

        # just for robustness, it does not happen under normal circumstances
        if len(data) % 16 != 0:
            pad = padding.PKCS7(128).padder()
            data = pad.update(data) + pad.finalize()

        cipher = Cipher(self.alg, CBC(iv))
        decryptor = cipher.decryptor()
        d = decryptor.update(data) + decryptor.finalize()
        return d[: -d[-1]]


def rc4_encrypt(key: bytes, data: bytes) -> bytes:
    encryptor = Cipher(ARC4(key), mode=None).encryptor()
    return encryptor.update(data) + encryptor.finalize()


def rc4_decrypt(key: bytes, data: bytes) -> bytes:
    decryptor = Cipher(ARC4(key), mode=None).decryptor()
    return decryptor.update(data) + decryptor.finalize()


def aes_ecb_encrypt(key: bytes, data: bytes) -> bytes:
    encryptor = Cipher(AES(key), mode=ECB()).encryptor()
    return encryptor.update(data) + encryptor.finalize()


def aes_ecb_decrypt(key: bytes, data: bytes) -> bytes:
    decryptor = Cipher(AES(key), mode=ECB()).decryptor()
    return decryptor.update(data) + decryptor.finalize()


def aes_cbc_encrypt(key: bytes, iv: bytes, data: bytes) -> bytes:
    encryptor = Cipher(AES(key), mode=CBC(iv)).encryptor()
    return encryptor.update(data) + encryptor.finalize()


def aes_cbc_decrypt(key: bytes, iv: bytes, data: bytes) -> bytes:
    decryptor = Cipher(AES(key), mode=CBC(iv)).decryptor()
    return decryptor.update(data) + decryptor.finalize()
