# License?

"""A U1DB implementation for using Object Stores as its persistence layer."""

import os
import string
import random
#import cStringIO
import hmac

import util


class Soledad(object):

    PREFIX        = os.environ['HOME']  + '/.config/leap/soledad'
    SECRET_PATH   = PREFIX + '/secret.gpg'
    GNUPG_HOME    = PREFIX + '/gnupg'
    SECRET_LENGTH = 50

    def __init__(self, user_email, gpghome=None):
        self._user_email = user_email
        if not os.path.isdir(self.PREFIX):
            os.makedirs(self.PREFIX)
        if not gpghome:
            gpghome = self.GNUPG_HOME
        self._gpg = util.GPGWrapper(gpghome=gpghome)
        # load/generate OpenPGP keypair
        if not self._has_openpgp_keypair():
            self._gen_openpgp_keypair()
        self._load_openpgp_keypair()
        # load/generate secret
        if not self._has_secret():
            self._gen_secret()
        self._load_secret()


    #-------------------------------------------------------------------------
    # Management of secret for symmetric encryption
    #-------------------------------------------------------------------------

    def _has_secret(self):
        """
        Verify if secret already exists in a local encrypted file.
        """
        if os.path.isfile(self.SECRET_PATH):
            return True
        return False

    def _load_secret(self):
        """
        Load secret from local encrypted file.
        """
        try:
            with open(self.SECRET_PATH) as f:
               self._secret = str(self._gpg.decrypt(f.read()))
        except IOError as e:
           raise IOError('Failed to open secret file %s.' % self.SECRET_PATH)

    def _gen_secret(self):
        """
        Generate secret for symmetric encryption and store it in a local encrypted file.
        """
        self._secret = ''.join(random.choice(string.ascii_uppercase + string.digits) for x in range(self.SECRET_LENGTH))
        ciphertext = self._gpg.encrypt(self._secret, self._fingerprint, self._fingerprint)
        f = open(self.SECRET_PATH, 'w')
        f.write(str(ciphertext))
        f.close()

    #-------------------------------------------------------------------------
    # Management of OpenPGP keypair
    #-------------------------------------------------------------------------

    def _has_openpgp_keypair(self):
        """
        Verify if a keypair exists for this user.
        """
        # TODO: verify if private key exists.
        try:
            self._gpg.find_key(self._user_email)
            return True
        except LookupError:
            return False

    def _gen_openpgp_keypair(self):
        """
        Generate a keypair for this user.
        """
        params = self._gpg.gen_key_input(
          key_type='RSA',
          key_length=4096,
          name_real=self._user_email,
          name_email=self._user_email,
          name_comment='Generated by LEAP Soledad.')
        self._gpg.gen_key(params)

    def _load_openpgp_keypair(self):
        """
        Load the fingerprint for this user's keypair.
        """
        self._fingerprint = self._gpg.find_key(self._user_email)['fingerprint']

    def publish_pubkey(self, keyserver):
        """
        Publish OpenPGP public key to a keyserver.
        """
        pass

    #-------------------------------------------------------------------------
    # Data encryption and decription
    #-------------------------------------------------------------------------

    def encrypt(self, data, sign=None, passphrase=None, symmetric=False):
        """
        Encrypt data.
        """
        return str(self._gpg.encrypt(data, self._fingerprint, sign=sign,
                                     passphrase=passphrase, symmetric=symmetric))

    def encrypt_symmetric(self, doc_id, data, sign=None):
        """
        Symmetrically encrypt data using this user's secret.
        """
        h = hmac.new(self._secret, doc_id).hexdigest()
        return self.encrypt(data, sign=sign, passphrase=h, symmetric=True)

    def decrypt(self, data, passphrase=None, symmetric=False):
        """
        Decrypt data.
        """
        return str(self._gpg.decrypt(data, passphrase=passphrase))

    def decrypt_symmetric(self, doc_id, data):
        """
        Symmetrically decrypt data using this user's secret.
        """
        h = hmac.new(self._secret, doc_id).hexdigest()
        return self.decrypt(data, passphrase=h)

    #-------------------------------------------------------------------------
    # Document storage, retrieval and sync
    #-------------------------------------------------------------------------
    
    def put(self, doc_id, data):
        """
        Store a document.
        """
        pass

    def get(self, doc_id):
        """
        Retrieve a document.
        """
        pass

    def sync(self):
        """
        Synchronize with LEAP server.
        """
        pass


__all__ = ['util']