# Copyright 2016 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Manages logic for service accounts."""

import io
import json
import os

from googlecloudsdk.core import config
from googlecloudsdk.core import exceptions
from googlecloudsdk.core import log
from oauth2client import service_account


class Error(exceptions.Error):
  """Errors raised by this module."""


class UnsupportedCredentialsType(Error):
  """Raised when given type credentials cannot be created."""


class BadCredentialFileException(Error):
  """Raised when file cannot be read."""


class BadCredentialJsonFileException(Error):
  """Raised when file cannot be read."""


def CredentialsFromAdcFile(filename):
  """Load credentials from given service account json file."""
  try:
    with open(filename) as f:
      json_key = json.load(f)
  except (EnvironmentError, ValueError) as e:
    raise BadCredentialFileException('Could not read json file {0}: {1}'
                                     .format(filename, e))

  return CredentialsFromAdcDict(json_key)


def CredentialsFromAdcDict(json_key):
  """Creates credentials object from a dict of application default creds."""
  if 'client_email' not in json_key:
    raise BadCredentialJsonFileException(
        'The .json key file is not in a valid format.')

  creds = service_account.ServiceAccountCredentials.from_json_keyfile_dict(
      json_key, scopes=config.CLOUDSDK_SCOPES)
  # User agent needs to be set separately, see
  # https://github.com/google/oauth2client/issues/445
  # pylint: disable=protected-access
  creds.user_agent = creds._user_agent = config.CLOUDSDK_USER_AGENT
  return creds


def CredentialsFromP12File(filename, account, password=None):
  """Create p12 service account credentials from given file."""

  try:
    with open(filename, 'rb') as f:
      private_key = f.read()
  except EnvironmentError as e:
    raise BadCredentialFileException('Could not read file {0}'.format(e))

  return CredentialsFromP12Key(private_key, account, password)


def CredentialsFromP12Key(private_key, account, password=None):
  """Creates creadentials object from given private key and account name."""
  log.warning('.p12 service account keys are not recomended unless it is '
              'necessary for backwards compatability. Please switch to '
              'a newer .json service account key for this account.')

  try:
    cred = service_account.ServiceAccountCredentials.from_p12_keyfile_buffer(
        service_account_email=account,
        file_buffer=io.BytesIO(private_key),
        private_key_password=password,
        scopes=config.CLOUDSDK_SCOPES)
  except NotImplementedError:
    if not os.environ.get('CLOUDSDK_PYTHON_SITEPACKAGES'):
      raise UnsupportedCredentialsType(
          ('PyOpenSSL is not available. If you have already installed '
           'PyOpenSSL, you will need to enable site packages by '
           'setting the environment variable CLOUDSDK_PYTHON_SITEPACKAGES '
           'to 1. If that does not work, see '
           'https://developers.google.com/cloud/sdk/crypto for details '
           'or consider using .json private key instead.'))
    else:
      raise UnsupportedCredentialsType(
          ('PyOpenSSL is not available. See '
           'https://developers.google.com/cloud/sdk/crypto for details '
           'or consider using .json private key instead.'))

  # pylint: disable=protected-access
  cred.user_agent = cred._user_agent = config.CLOUDSDK_USER_AGENT

  return cred
