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"""Implementation of MySQL Authentication Plugin."""

import hashlib
import struct

from typing import Optional

from .helpers import hexlify


def xor_string(hash1: bytes, hash2: bytes, hash_size: int) -> bytes:
    """Encrypt/Decrypt function used for password encryption in
    authentication, using a simple XOR.

    Args:
        hash1 (str): The first hash.
        hash2 (str): The second hash.

    Returns:
        str: A string with the xor applied.
    """
    xored = [h1 ^ h2 for (h1, h2) in zip(hash1, hash2)]
    return struct.pack(f"{hash_size}B", *xored)


class BaseAuthPlugin:
    """Base class for implementing the authentication plugins."""

    def __init__(self, username: Optional[str] = None, password: Optional[str] = None):
        self._username: Optional[str] = username
        self._password: Optional[str] = password

    def name(self) -> str:
        """Returns the plugin name.

        Returns:
            str: The plugin name.
        """
        raise NotImplementedError

    def auth_name(self) -> str:
        """Returns the authentication name.

        Returns:
            str: The authentication name.
        """
        raise NotImplementedError


class MySQL41AuthPlugin(BaseAuthPlugin):
    """Class implementing the MySQL Native Password authentication plugin."""

    def name(self) -> str:
        """Returns the plugin name.

        Returns:
            str: The plugin name.
        """
        return "MySQL 4.1 Authentication Plugin"

    def auth_name(self) -> str:
        """Returns the authentication name.

        Returns:
            str: The authentication name.
        """
        return "MYSQL41"

    def auth_data(self, data: bytes) -> str:
        """Hashing for MySQL 4.1 authentication.

        Args:
            data (bytes): The authentication data.

        Returns:
            str: The authentication response.
        """
        if self._password:
            password = (
                self._password.encode("utf-8")
                if isinstance(self._password, str)
                else self._password
            )
            hash1 = hashlib.sha1(password).digest()
            hash2 = hashlib.sha1(hash1).digest()
            xored = xor_string(hash1, hashlib.sha1(data + hash2).digest(), 20)
            return f"\0{self._username}\0*{hexlify(xored)}\0"
        return f"\0{self._username}\0"


class PlainAuthPlugin(BaseAuthPlugin):
    """Class implementing the MySQL Plain authentication plugin."""

    def name(self) -> str:
        """Returns the plugin name.

        Returns:
            str: The plugin name.
        """
        return "Plain Authentication Plugin"

    def auth_name(self) -> str:
        """Returns the authentication name.

        Returns:
            str: The authentication name.
        """
        return "PLAIN"

    def auth_data(self) -> str:
        """Returns the authentication data.

        Returns:
            str: The authentication data.
        """
        return f"\0{self._username}\0{self._password}"


class Sha256MemoryAuthPlugin(BaseAuthPlugin):
    """Class implementing the SHA256_MEMORY authentication plugin."""

    def name(self) -> str:
        """Returns the plugin name.

        Returns:
            str: The plugin name.
        """
        return "SHA256_MEMORY Authentication Plugin"

    def auth_name(self) -> str:
        """Returns the authentication name.

        Returns:
            str: The authentication name.
        """
        return "SHA256_MEMORY"

    def auth_data(self, data: bytes) -> str:
        """Hashing for SHA256_MEMORY authentication.

        The scramble is of the form:
            SHA256(SHA256(SHA256(PASSWORD)),NONCE) XOR SHA256(PASSWORD)

        Args:
            data (bytes): The authentication data.

        Returns:
            str: The authentication response.
        """
        password = (
            self._password.encode("utf-8")
            if isinstance(self._password, str)
            else self._password
        )
        hash1 = hashlib.sha256(password).digest()
        hash2 = hashlib.sha256(hashlib.sha256(hash1).digest() + data).digest()
        xored = xor_string(hash2, hash1, 32)
        return f"\0{self._username}\0{hexlify(xored)}"
