# Author: Trevor Perrin
# See the LICENSE file for legal information regarding use of this file.

"""Factory functions for asymmetric cryptography.
@sort: generateRSAKey, parsePEMKey, parseAsPublicKey
"""

from .compat import *

from .rsakey import RSAKey
from .python_rsakey import Python_RSAKey
from tlslite.utils import cryptomath

if cryptomath.m2cryptoLoaded:
    from .openssl_rsakey import OpenSSL_RSAKey

if cryptomath.pycryptoLoaded:
    from .pycrypto_rsakey import PyCrypto_RSAKey

# **************************************************************************
# Factory Functions for RSA Keys
# **************************************************************************

def generateRSAKey(bits, implementations=["openssl", "python"]):
    """Generate an RSA key with the specified bit length.

    @type bits: int
    @param bits: Desired bit length of the new key's modulus.

    @rtype: L{tlslite.utils.rsakey.RSAKey}
    @return: A new RSA private key.
    """
    for implementation in implementations:
        if implementation == "openssl" and cryptomath.m2cryptoLoaded:
            return OpenSSL_RSAKey.generate(bits)
        elif implementation == "python":
            return Python_RSAKey.generate(bits)
    raise ValueError("No acceptable implementations")

#Parse as an OpenSSL or Python key
def parsePEMKey(s, private=False, public=False, passwordCallback=None,
                implementations=["openssl", "python"]):
    """Parse a PEM-format key.

    The PEM format is used by OpenSSL and other tools.  The
    format is typically used to store both the public and private
    components of a key.  For example::

       -----BEGIN RSA PRIVATE KEY-----
        MIICXQIBAAKBgQDYscuoMzsGmW0pAYsmyHltxB2TdwHS0dImfjCMfaSDkfLdZY5+
        dOWORVns9etWnr194mSGA1F0Pls/VJW8+cX9+3vtJV8zSdANPYUoQf0TP7VlJxkH
        dSRkUbEoz5bAAs/+970uos7n7iXQIni+3erUTdYEk2iWnMBjTljfgbK/dQIDAQAB
        AoGAJHoJZk75aKr7DSQNYIHuruOMdv5ZeDuJvKERWxTrVJqE32/xBKh42/IgqRrc
        esBN9ZregRCd7YtxoL+EVUNWaJNVx2mNmezEznrc9zhcYUrgeaVdFO2yBF1889zO
        gCOVwrO8uDgeyj6IKa25H6c1N13ih/o7ZzEgWbGG+ylU1yECQQDv4ZSJ4EjSh/Fl
        aHdz3wbBa/HKGTjC8iRy476Cyg2Fm8MZUe9Yy3udOrb5ZnS2MTpIXt5AF3h2TfYV
        VoFXIorjAkEA50FcJmzT8sNMrPaV8vn+9W2Lu4U7C+K/O2g1iXMaZms5PC5zV5aV
        CKXZWUX1fq2RaOzlbQrpgiolhXpeh8FjxwJBAOFHzSQfSsTNfttp3KUpU0LbiVvv
        i+spVSnA0O4rq79KpVNmK44Mq67hsW1P11QzrzTAQ6GVaUBRv0YS061td1kCQHnP
        wtN2tboFR6lABkJDjxoGRvlSt4SOPr7zKGgrWjeiuTZLHXSAnCY+/hr5L9Q3ZwXG
        6x6iBdgLjVIe4BZQNtcCQQDXGv/gWinCNTN3MPWfTW/RGzuMYVmyBFais0/VrgdH
        h1dLpztmpQqfyH/zrBXQ9qL/zR4ojS6XYneO/U18WpEe
        -----END RSA PRIVATE KEY-----

    To generate a key like this with OpenSSL, run::

        openssl genrsa 2048 > key.pem

    This format also supports password-encrypted private keys.  TLS
    Lite can only handle password-encrypted private keys when OpenSSL
    and M2Crypto are installed.  In this case, passwordCallback will be
    invoked to query the user for the password.

    @type s: str
    @param s: A string containing a PEM-encoded public or private key.

    @type private: bool
    @param private: If True, a L{SyntaxError} will be raised if the
    private key component is not present.

    @type public: bool
    @param public: If True, the private key component (if present) will
    be discarded, so this function will always return a public key.

    @type passwordCallback: callable
    @param passwordCallback: This function will be called, with no
    arguments, if the PEM-encoded private key is password-encrypted.
    The callback should return the password string.  If the password is
    incorrect, SyntaxError will be raised.  If no callback is passed
    and the key is password-encrypted, a prompt will be displayed at
    the console.

    @rtype: L{tlslite.utils.RSAKey.RSAKey}
    @return: An RSA key.

    @raise SyntaxError: If the key is not properly formatted.
    """
    for implementation in implementations:
        if implementation == "openssl" and cryptomath.m2cryptoLoaded:
            key = OpenSSL_RSAKey.parse(s, passwordCallback)
            break
        elif implementation == "python":
            key = Python_RSAKey.parsePEM(s)
            break
    else:
        raise ValueError("No acceptable implementations")

    return _parseKeyHelper(key, private, public)


def _parseKeyHelper(key, private, public):
    if private:
        if not key.hasPrivateKey():
            raise SyntaxError("Not a private key!")

    if public:
        return _createPublicKey(key)

    if private:
        if hasattr(key, "d"):
            return _createPrivateKey(key)
        else:
            return key

    return key

def parseAsPublicKey(s):
    """Parse a PEM-formatted public key.

    @type s: str
    @param s: A string containing a PEM-encoded public or private key.

    @rtype: L{tlslite.utils.rsakey.RSAKey}
    @return: An RSA public key.

    @raise SyntaxError: If the key is not properly formatted.
    """
    return parsePEMKey(s, public=True)

def parsePrivateKey(s):
    """Parse a PEM-formatted private key.

    @type s: str
    @param s: A string containing a PEM-encoded private key.

    @rtype: L{tlslite.utils.rsakey.RSAKey}
    @return: An RSA private key.

    @raise SyntaxError: If the key is not properly formatted.
    """
    return parsePEMKey(s, private=True)

def _createPublicKey(key):
    """
    Create a new public key.  Discard any private component,
    and return the most efficient key possible.
    """
    if not isinstance(key, RSAKey):
        raise AssertionError()
    return _createPublicRSAKey(key.n, key.e)

def _createPrivateKey(key):
    """
    Create a new private key.  Return the most efficient key possible.
    """
    if not isinstance(key, RSAKey):
        raise AssertionError()
    if not key.hasPrivateKey():
        raise AssertionError()
    return _createPrivateRSAKey(key.n, key.e, key.d, key.p, key.q, key.dP,
                                key.dQ, key.qInv)

def _createPublicRSAKey(n, e, implementations = ["openssl", "pycrypto",
                                                "python"]):
    for implementation in implementations:
        if implementation == "openssl" and cryptomath.m2cryptoLoaded:
            return OpenSSL_RSAKey(n, e)
        elif implementation == "pycrypto" and cryptomath.pycryptoLoaded:
            return PyCrypto_RSAKey(n, e)
        elif implementation == "python":
            return Python_RSAKey(n, e)
    raise ValueError("No acceptable implementations")

def _createPrivateRSAKey(n, e, d, p, q, dP, dQ, qInv,
                        implementations = ["pycrypto", "python"]):
    for implementation in implementations:
        if implementation == "pycrypto" and cryptomath.pycryptoLoaded:
            return PyCrypto_RSAKey(n, e, d, p, q, dP, dQ, qInv)
        elif implementation == "python":
            return Python_RSAKey(n, e, d, p, q, dP, dQ, qInv)
    raise ValueError("No acceptable implementations")
