import logging
import json
import base64
import datetime

from requests import Request, Session

from config_app.config_util.k8sconfig import KubernetesConfig

logger = logging.getLogger(__name__)

QE_DEPLOYMENT_LABEL = 'quay-enterprise-component'

class KubernetesAccessorSingleton(object):
    """ Singleton allowing access to kubernetes operations """
    _instance = None

    def __init__(self, kube_config=None):
      self.kube_config = kube_config
      if kube_config is None:
        self.kube_config = KubernetesConfig.from_env()

      KubernetesAccessorSingleton._instance = self

    @classmethod
    def get_instance(cls, kube_config=None):
      """
      Singleton getter implementation, returns the instance if one exists, otherwise creates the
      instance and ties it to the class.
      :return: KubernetesAccessorSingleton
      """
      if cls._instance is None:
        return cls(kube_config)

      return cls._instance

    def save_file_as_secret(self, name, file_path):
        with open(file_path) as f:
            value = f.read()
            self._update_secret_file(name, value)

    def get_qe_deployments(self):
      """"
      Returns all deployments matching the label selector provided in the KubeConfig
      """
      deployment_selector_url = 'namespaces/%s/deployments?labelSelector=%s%%3D%s' % (
        self.kube_config.qe_namespace, QE_DEPLOYMENT_LABEL, self.kube_config.qe_deployment_selector
      )

      response = self._execute_k8s_api('GET', deployment_selector_url, api_prefix='apis/extensions/v1beta1')
      if response.status_code != 200:
        return None
      return json.loads(response.text)

    def cycle_qe_deployments(self, deployment_names):
      """"
      Triggers a rollout of all desired deployments in the qe namespace
      """

      for name in deployment_names:
        logger.debug('Cycling deployment %s', name)
        deployment_url = 'namespaces/%s/deployments/%s' % (self.kube_config.qe_namespace, name)

        # There is currently no command to simply rolling restart all the pods: https://github.com/kubernetes/kubernetes/issues/13488
        # Instead, we modify the template of the deployment with a dummy env variable to trigger a cycle of the pods
        # (based off this comment: https://github.com/kubernetes/kubernetes/issues/13488#issuecomment-240393845)
        self._assert_success(self._execute_k8s_api('PATCH', deployment_url, {
          'spec': {
            'template': {
              'spec': {
                'containers': [{
                  'name': 'quay-enterprise-app', 'env': [{
                    'name': 'RESTART_TIME',
                    'value': str(datetime.datetime.now())
                  }]
                }]
              }
            }
          }
        }, api_prefix='apis/extensions/v1beta1', content_type='application/strategic-merge-patch+json'))


    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 Exception('Kubernetes API call failed: %s' % response.text)

    def _update_secret_file(self, relative_file_path, value=None):
        if '/' in relative_file_path:
            raise Exception('Expected path from get_volume_path, but found slashes')

        # 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' % (self.kube_config.qe_namespace)
        response = self._execute_k8s_api('GET', namespace_url)
        if response.status_code // 100 != 2:
            msg = 'A Kubernetes namespace with name `%s` must be created to save config' % self.kube_config.qe_namespace
            raise Exception(msg)

        # Check if the secret exists. If not, then we create an empty secret and then update the file
        # inside.
        secret_url = 'namespaces/%s/secrets/%s' % (self.kube_config.qe_namespace, self.kube_config.qe_config_secret)
        secret = self._lookup_secret()
        if secret is None:
            self._assert_success(self._execute_k8s_api('POST', secret_url, {
                "kind": "Secret",
                "apiVersion": "v1",
                "metadata": {
                    "name": self.kube_config.qe_config_secret
                },
                "data": {}
            }))

        # Update the secret to reflect the file change.
        secret['data'] = secret.get('data', {})

        if value is not None:
            secret['data'][relative_file_path] = base64.b64encode(value)
        else:
            secret['data'].pop(relative_file_path)

        self._assert_success(self._execute_k8s_api('PUT', secret_url, secret))

    def _lookup_secret(self):
        secret_url = 'namespaces/%s/secrets/%s' % (self.kube_config.qe_namespace, self.kube_config.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, api_prefix='api/v1', content_type='application/json'):
        headers = {
            'Authorization': 'Bearer ' + self.kube_config.service_account_token
        }

        if data:
            headers['Content-Type'] = content_type

        data = json.dumps(data) if data else None
        session = Session()
        url = 'https://%s/%s/%s' % (self.kube_config.api_host, api_prefix, relative_url)

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