import os
import logging
import json
import base64

from requests import Request, Session

from util.config.provider.baseprovider import get_yaml, CannotWriteConfigException
from util.config.provider.fileprovider import FileConfigProvider

logger = logging.getLogger(__name__)

KUBERNETES_API_HOST = os.environ.get('KUBERNETES_SERVICE_HOST', '')
port = os.environ.get('KUBERNETES_SERVICE_PORT')
if port:
  KUBERNETES_API_HOST += ':' + port

SERVICE_ACCOUNT_TOKEN_PATH = '/var/run/secrets/kubernetes.io/serviceaccount/token'

QE_NAMESPACE = os.environ.get('QE_K8S_NAMESPACE', 'quay-enterprise')
QE_CONFIG_SECRET = os.environ.get('QE_K8S_CONFIG_SECRET', 'quay-enterprise-config-secret')

class KubernetesConfigProvider(FileConfigProvider):
  """ Implementation of the config provider that reads and writes configuration
      data from a Kubernetes Secret. """
  def __init__(self, config_volume, yaml_filename, py_filename):
    super(KubernetesConfigProvider, self).__init__(config_volume, yaml_filename, py_filename)

    self.yaml_filename = yaml_filename

    # Load the service account token from the local store.
    if not os.path.exists(SERVICE_ACCOUNT_TOKEN_PATH):
      raise Exception('Cannot load Kubernetes service account token')

    with open(SERVICE_ACCOUNT_TOKEN_PATH, 'r') as f:
      self._service_token = f.read()

    # Make sure the configuration volume exists.
    if not self.volume_exists():
      os.makedirs(config_volume)

  @property
  def provider_id(self):
    return 'k8s'

  def save_config(self, config_obj):
    self._update_secret_file(self.yaml_filename, get_yaml(config_obj))
    super(KubernetesConfigProvider, self).save_config(config_obj)

  def write_volume_file(self, filename, contents):
    super(KubernetesConfigProvider, self).write_volume_file(filename, contents)

    try:
      self._update_secret_file(filename, contents)
    except IOError as ioe:
      raise CannotWriteConfigException(str(ioe))

  def save_volume_file(self, filename, flask_file):
    filepath = super(KubernetesConfigProvider, self).save_volume_file(filename, flask_file)

    try:
      with open(filepath, 'r') as f:
        self._update_secret_file(filename, f.read())
    except IOError as ioe:
      raise CannotWriteConfigException(str(ioe))

  def _assert_success(self, response):
    if response.status_code != 200:
      logger.error('Kubernetes API call failed with response: %s => %s', response.status_code,
                   response.text)
      raise CannotWriteConfigException('Kubernetes API call failed: %s' % response.text)

  def _update_secret_file(self, filename, value):
    # Check first that the namespace for Quay Enterprise exists. If it does not, report that
    # as an error, as it seems to be a common issue.
    namespace_url = 'namespaces/%s' % (QE_NAMESPACE)
    response = self._execute_k8s_api('GET', namespace_url)
    if response.status_code != 200:
      msg = 'A Kubernetes namespace with name `%s` must be created to save config' % QE_NAMESPACE
      raise CannotWriteConfigException(msg)

    # Save the secret to the namespace.
    secret_data = {}
    secret_data[filename] = base64.b64encode(value)

    data = {
      "kind": "Secret",
      "apiVersion": "v1",
      "metadata": {
        "name": QE_CONFIG_SECRET
      },
      "data": secret_data
    }

    secret_url = 'namespaces/%s/secrets/%s' % (QE_NAMESPACE, QE_CONFIG_SECRET)
    secret = self._lookup_secret()
    if not secret:
      self._assert_success(self._execute_k8s_api('POST', secret_url, data))
      return

    if not 'data' in secret:
      secret['data'] = {}

    secret['data'][filename] = base64.b64encode(value)
    self._assert_success(self._execute_k8s_api('PUT', secret_url, secret))


  def _lookup_secret(self):
    secret_url = 'namespaces/%s/secrets/%s' % (QE_NAMESPACE, QE_CONFIG_SECRET)
    response = self._execute_k8s_api('GET', secret_url)
    if response.status_code != 200:
      return None

    return json.loads(response.text)

  def _execute_k8s_api(self, method, relative_url, data=None):
    headers = {
      'Authorization': 'Bearer ' + self._service_token
    }

    if data:
      headers['Content-Type'] = 'application/json'

    data = json.dumps(data) if data else None
    session = Session()
    url = 'https://%s/api/v1/%s' % (KUBERNETES_API_HOST, relative_url)

    request = Request(method, url, data=data, headers=headers)
    return session.send(request.prepare(), verify=False, timeout=2)