import logging
import os
import uuid
import threading
import boto.ec2
import requests
import cachetools
import trollius
import datetime
import release
import socket
import hashlib

from jinja2 import FileSystemLoader, Environment
from trollius import coroutine, From, Return, get_event_loop
from functools import partial

from buildman.asyncutil import AsyncWrapper
from container_cloud_config import CloudConfigContext
from app import metric_queue, app
from util.metrics.metricqueue import duration_collector_async


logger = logging.getLogger(__name__)


ONE_HOUR = 60*60

_TAG_RETRY_COUNT = 3 # Number of times to retry adding tags.
_TAG_RETRY_SLEEP = 2 # Number of seconds to wait between tag retries.

ENV = Environment(loader=FileSystemLoader('buildman/templates'))
TEMPLATE = ENV.get_template('cloudconfig.yaml')
CloudConfigContext().populate_jinja_environment(ENV)

class ExecutorException(Exception):
  """ Exception raised when there is a problem starting or stopping a builder.
  """
  pass


class BuilderExecutor(object):
  def __init__(self, executor_config, manager_hostname):
    """ Interface which can be plugged into the EphemeralNodeManager to provide a strategy for
        starting and stopping builders.
    """
    self.executor_config = executor_config
    self.manager_hostname = manager_hostname

    default_websocket_scheme = 'wss' if app.config['PREFERRED_URL_SCHEME'] == 'https' else 'ws'
    self.websocket_scheme = executor_config.get("WEBSOCKET_SCHEME", default_websocket_scheme)

  @property
  def name(self):
    """ Name returns the unique name for this executor. """
    return self.executor_config.get('NAME') or self.__class__.__name__

  @coroutine
  def start_builder(self, realm, token, build_uuid):
    """ Create a builder with the specified config. Returns a unique id which can be used to manage
        the builder.
    """
    raise NotImplementedError

  @coroutine
  def stop_builder(self, builder_id):
    """ Stop a builder which is currently running.
    """
    raise NotImplementedError

  def allowed_for_namespace(self, namespace):
    """ Returns true if this executor can be used for builds in the given namespace. """

    # Check for an explicit namespace whitelist.
    namespace_whitelist = self.executor_config.get('NAMESPACE_WHITELIST')
    if namespace_whitelist is not None and namespace in namespace_whitelist:
      return True

    # Check for a staged rollout percentage. If found, we hash the namespace and, if it is found
    # in the first X% of the character space, we allow this executor to be used.
    staged_rollout = self.executor_config.get('STAGED_ROLLOUT')
    if staged_rollout is not None:
      bucket = int(hashlib.sha256(namespace).hexdigest()[-2:], 16)
      return bucket < (256 * staged_rollout)

    # If there are no restrictions in place, we are free to use this executor.
    return staged_rollout is None and namespace_whitelist is None

  @property
  def minimum_retry_threshold(self):
    """ Returns the minimum number of retries required for this executor to be used or 0 if
        none. """
    return self.executor_config.get('MINIMUM_RETRY_THRESHOLD', 0)

  def generate_cloud_config(self, realm, token, coreos_channel, manager_hostname,
                            quay_username=None, quay_password=None):
    if quay_username is None:
      quay_username = self.executor_config['QUAY_USERNAME']

    if quay_password is None:
      quay_password = self.executor_config['QUAY_PASSWORD']

    return TEMPLATE.render(
        realm=realm,
        token=token,
        quay_username=quay_username,
        quay_password=quay_password,
        manager_hostname=manager_hostname,
        websocket_scheme=self.websocket_scheme,
        coreos_channel=coreos_channel,
        worker_tag=self.executor_config['WORKER_TAG'],
        logentries_token=self.executor_config.get('LOGENTRIES_TOKEN', None),
        volume_size=self.executor_config.get('VOLUME_SIZE', '42G'),
    )


class EC2Executor(BuilderExecutor):
  """ Implementation of BuilderExecutor which uses libcloud to start machines on a variety of cloud
      providers.
  """
  COREOS_STACK_URL = 'http://%s.release.core-os.net/amd64-usr/current/coreos_production_ami_hvm.txt'

  def __init__(self, *args, **kwargs):
    self._loop = get_event_loop()
    super(EC2Executor, self).__init__(*args, **kwargs)

  def _get_conn(self):
    """ Creates an ec2 connection which can be used to manage instances.
    """
    return AsyncWrapper(boto.ec2.connect_to_region(
      self.executor_config['EC2_REGION'],
      aws_access_key_id=self.executor_config['AWS_ACCESS_KEY'],
      aws_secret_access_key=self.executor_config['AWS_SECRET_KEY'],
    ))

  @classmethod
  @cachetools.ttl_cache(ttl=ONE_HOUR)
  def _get_coreos_ami(cls, ec2_region, coreos_channel):
    """ Retrieve the CoreOS AMI id from the canonical listing.
    """
    stack_list_string = requests.get(EC2Executor.COREOS_STACK_URL % coreos_channel).text
    stack_amis = dict([stack.split('=') for stack in stack_list_string.split('|')])
    return stack_amis[ec2_region]

  @coroutine
  @duration_collector_async(metric_queue.builder_time_to_start, ['ec2'])
  def start_builder(self, realm, token, build_uuid):
    region = self.executor_config['EC2_REGION']
    channel = self.executor_config.get('COREOS_CHANNEL', 'stable')

    coreos_ami = self.executor_config.get('COREOS_AMI', None)
    if coreos_ami is None:
      get_ami_callable = partial(self._get_coreos_ami, region, channel)
      coreos_ami = yield From(self._loop.run_in_executor(None, get_ami_callable))

    user_data = self.generate_cloud_config(realm, token, channel, self.manager_hostname)
    logger.debug('Generated cloud config for build %s: %s', build_uuid, user_data)

    ec2_conn = self._get_conn()

    ssd_root_ebs = boto.ec2.blockdevicemapping.BlockDeviceType(
      size=int(self.executor_config.get('BLOCK_DEVICE_SIZE', 48)),
      volume_type='gp2',
      delete_on_termination=True,
    )
    block_devices = boto.ec2.blockdevicemapping.BlockDeviceMapping()
    block_devices['/dev/xvda'] = ssd_root_ebs

    interfaces = None
    if self.executor_config.get('EC2_VPC_SUBNET_ID', None) is not None:
      interface = boto.ec2.networkinterface.NetworkInterfaceSpecification(
        subnet_id=self.executor_config['EC2_VPC_SUBNET_ID'],
        groups=self.executor_config['EC2_SECURITY_GROUP_IDS'],
        associate_public_ip_address=True,
      )
      interfaces = boto.ec2.networkinterface.NetworkInterfaceCollection(interface)

    try:
      reservation = yield From(ec2_conn.run_instances(
        coreos_ami,
        instance_type=self.executor_config['EC2_INSTANCE_TYPE'],
        key_name=self.executor_config.get('EC2_KEY_NAME', None),
        user_data=user_data,
        instance_initiated_shutdown_behavior='terminate',
        block_device_map=block_devices,
        network_interfaces=interfaces,
      ))
    except boto.exception.EC2ResponseError as ec2e:
      logger.exception('Unable to spawn builder instance')
      metric_queue.put_deprecated('EC2BuildStartFailure', 1, unit='Count')
      metric_queue.ephemeral_build_worker_failure.Inc(labelvalues=[build_uuid])
      raise ec2e

    if not reservation.instances:
      raise ExecutorException('Unable to spawn builder instance.')
    elif len(reservation.instances) != 1:
      raise ExecutorException('EC2 started wrong number of instances!')

    launched = AsyncWrapper(reservation.instances[0])

    # Sleep a few seconds to wait for AWS to spawn the instance.
    yield From(trollius.sleep(_TAG_RETRY_SLEEP))

    # Tag the instance with its metadata.
    for i in range(0, _TAG_RETRY_COUNT):
      try:
        yield From(launched.add_tags({
          'Name': 'Quay Ephemeral Builder',
          'Realm': realm,
          'Token': token,
          'BuildUUID': build_uuid,
        }))
      except boto.exception.EC2ResponseError as ec2e:
        if ec2e.error_code == 'InvalidInstanceID.NotFound':
          if i < _TAG_RETRY_COUNT - 1:
            logger.warning('Failed to write EC2 tags for instance %s for build %s (attempt #%s)',
                           launched.id, build_uuid, i)
            yield From(trollius.sleep(_TAG_RETRY_SLEEP))
            continue

          raise ExecutorException('Unable to find builder instance.')

        logger.exception('Failed to write EC2 tags (attempt #%s)', i)

    logger.debug('Machine with ID %s started for build %s', launched.id, build_uuid)
    raise Return(launched.id)

  @coroutine
  def stop_builder(self, builder_id):
    try:
      ec2_conn = self._get_conn()
      terminated_instances = yield From(ec2_conn.terminate_instances([builder_id]))
    except boto.exception.EC2ResponseError as ec2e:
      if ec2e.error_code == 'InvalidInstanceID.NotFound':
        logger.debug('Instance %s already terminated', builder_id)
        return

      logger.exception('Exception when trying to terminate instance %s', builder_id)
      raise

    if builder_id not in [si.id for si in terminated_instances]:
      raise ExecutorException('Unable to terminate instance: %s' % builder_id)


class PopenExecutor(BuilderExecutor):
  """ Implementation of BuilderExecutor which uses Popen to fork a quay-builder process.
  """
  def __init__(self, executor_config, manager_hostname):
    self._jobs = {}

    super(PopenExecutor, self).__init__(executor_config, manager_hostname)

  """ Executor which uses Popen to fork a quay-builder process.
  """
  @coroutine
  @duration_collector_async(metric_queue.builder_time_to_start, ['fork'])
  def start_builder(self, realm, token, build_uuid):
    # Now start a machine for this job, adding the machine id to the etcd information
    logger.debug('Forking process for build')
    import subprocess

    ws_host = os.environ.get("BUILDMAN_WS_HOST", "localhost")
    ws_port = os.environ.get("BUILDMAN_WS_PORT", "8787")
    builder_env = {
      'TOKEN': token,
      'REALM': realm,
      'ENDPOINT': 'ws://%s:%s' % (ws_host, ws_port),
      'DOCKER_TLS_VERIFY': os.environ.get('DOCKER_TLS_VERIFY', ''),
      'DOCKER_CERT_PATH': os.environ.get('DOCKER_CERT_PATH', ''),
      'DOCKER_HOST': os.environ.get('DOCKER_HOST', ''),
    }

    logpipe = LogPipe(logging.INFO)
    spawned = subprocess.Popen('/Users/jake/bin/quay-builder', stdout=logpipe, stderr=logpipe,
                               env=builder_env)

    builder_id = str(uuid.uuid4())
    self._jobs[builder_id] = (spawned, logpipe)
    logger.debug('Builder spawned with id: %s', builder_id)
    raise Return(builder_id)

  @coroutine
  def stop_builder(self, builder_id):
    if builder_id not in self._jobs:
      raise ExecutorException('Builder id not being tracked by executor.')

    logger.debug('Killing builder with id: %s', builder_id)
    spawned, logpipe = self._jobs[builder_id]

    if spawned.poll() is None:
      spawned.kill()
    logpipe.close()


class KubernetesExecutor(BuilderExecutor):
  """ Executes build jobs by creating Kubernetes jobs which run a qemu-kvm virtual
      machine in a pod """
  def __init__(self, *args, **kwargs):
    super(KubernetesExecutor, self).__init__(*args, **kwargs)
    self._loop = get_event_loop()
    self.namespace = self.executor_config.get('BUILDER_NAMESPACE', 'builder')
    self.image = self.executor_config.get('BUILDER_VM_CONTAINER_IMAGE',
                                          'quay.io/quay/quay-builder-qemu-coreos:stable')

  @coroutine
  def _request(self, method, path, **kwargs):
    request_options = dict(kwargs)

    tls_cert = self.executor_config.get('K8S_API_TLS_CERT')
    tls_key = self.executor_config.get('K8S_API_TLS_KEY')
    tls_ca = self.executor_config.get('K8S_API_TLS_CA')

    if 'timeout' not in request_options:
      request_options['timeout'] = self.executor_config.get("K8S_API_TIMEOUT", 20)

    if tls_cert and tls_key:
      scheme = 'https'
      request_options['cert'] = (tls_cert, tls_key)
      if tls_ca:
        request_options['verify'] = tls_ca
    else:
      scheme = 'http'

    server = self.executor_config.get('K8S_API_SERVER', 'localhost:8080')
    url = '%s://%s%s' % (scheme, server, path)

    logger.debug('Executor config: %s', self.executor_config)
    logger.debug('Kubernetes request: %s %s: %s', method, url, request_options)
    res = requests.request(method, url, **request_options)
    logger.debug('Kubernetes response: %s: %s', res.status_code, res.text)
    raise Return(res)

  def _jobs_path(self):
    return '/apis/batch/v1/namespaces/%s/jobs' % self.namespace

  def _job_path(self, build_uuid):
    return '%s/%s' % (self._jobs_path(), build_uuid)

  def _job_resource(self, build_uuid, user_data, coreos_channel='stable'):
    vm_memory_limit = self.executor_config.get('VM_MEMORY_LIMIT', '4G')
    vm_volume_size = self.executor_config.get('VOLUME_SIZE', '32G')

    # Minimum acceptable free resources for this container to "fit" in a quota
    # These may be lower than the aboslute limits if the cluster is knowingly
    # oversubscribed by some amount.
    container_requests = {
      'memory' : self.executor_config.get('CONTAINER_MEMORY_REQUEST', '3968Mi'),
    }

    release_sha = release.GIT_HEAD or 'none'
    if ' ' in release_sha:
      release_sha = 'HEAD'

    return {
      'apiVersion': 'batch/v1',
      'kind': 'Job',
      'metadata': {
        'namespace': self.namespace,
        'generateName': build_uuid + '-',
        'labels': {
          'build': build_uuid,
          'time': datetime.datetime.now().strftime('%Y-%m-%d-%H'),
          'manager': socket.gethostname(),
          'quay-sha': release_sha,
        },
      },
      'spec' : {
        'activeDeadlineSeconds': self.executor_config.get('MAXIMUM_JOB_TIME', 7200),
        'template': {
          'metadata': {
            'labels': {
              'build': build_uuid,
              'time': datetime.datetime.now().strftime('%Y-%m-%d-%H'),
              'manager': socket.gethostname(),
              'quay-sha': release_sha,
            },
          },
          'spec': {
            # This volume is a hack to mask the token for the namespace's
            # default service account, which is placed in a file mounted under
            # `/var/run/secrets/kubernetes.io/serviceaccount` in all pods.
            # There's currently no other way to just disable the service
            # account at either the pod or namespace level.
            #
            #   https://github.com/kubernetes/kubernetes/issues/16779
            #
            'volumes': [
              {
                'name': 'secrets-mask',
                'emptyDir': {
                  'medium': 'Memory',
                },
              },
            ],
            'containers': [
              {
                'name': 'builder',
                'imagePullPolicy': 'Always',
                'image': self.image,
                'securityContext': {'privileged': True},
                'env': [
                  {'name': 'USERDATA', 'value': user_data},
                  {'name': 'VM_MEMORY', 'value': vm_memory_limit},
                  {'name': 'VM_VOLUME_SIZE', 'value': vm_volume_size},
                ],
                'resources': {
                  'requests': container_requests,
                },
                'volumeMounts': [
                  {
                    'name': 'secrets-mask',
                    'mountPath': '/var/run/secrets/kubernetes.io/serviceaccount',
                  },
                ],
              },
            ],
            'imagePullSecrets': [{'name': 'builder'}],
            'restartPolicy': 'Never',
            'dnsPolicy': 'Default',
          },
        },
      },
    }

  @coroutine
  @duration_collector_async(metric_queue.builder_time_to_start, ['k8s'])
  def start_builder(self, realm, token, build_uuid):
    # generate resource
    channel = self.executor_config.get('COREOS_CHANNEL', 'stable')
    user_data = self.generate_cloud_config(realm, token, channel, self.manager_hostname)
    resource = self._job_resource(build_uuid, user_data, channel)
    logger.debug('Generated kubernetes resource:\n%s', resource)

    # schedule
    create_job = yield From(self._request('POST', self._jobs_path(), json=resource))
    if int(create_job.status_code / 100) != 2:
      raise ExecutorException('Failed to create job: %s: %s: %s' %
                              (build_uuid, create_job.status_code, create_job.text))

    job = create_job.json()
    raise Return(job['metadata']['name'])

  @coroutine
  def stop_builder(self, builder_id):
    pods_path = '/api/v1/namespaces/%s/pods' % self.namespace

    # Delete the job itself.
    try:
      yield From(self._request('DELETE', self._job_path(builder_id)))
    except:
      logger.exception('Failed to send delete job call for job %s', builder_id)

    # Delete the pod(s) for the job.
    selectorString = "job-name=%s" % builder_id
    try:
      yield From(self._request('DELETE', pods_path, params=dict(labelSelector=selectorString)))
    except:
      logger.exception("Failed to send delete pod call for job %s", builder_id)


class LogPipe(threading.Thread):
  """ Adapted from http://codereview.stackexchange.com/a/17959
  """
  def __init__(self, level):
    """Setup the object with a logger and a loglevel
    and start the thread
    """
    threading.Thread.__init__(self)
    self.daemon = False
    self.level = level
    self.fd_read, self.fd_write = os.pipe()
    self.pipe_reader = os.fdopen(self.fd_read)
    self.start()

  def fileno(self):
    """Return the write file descriptor of the pipe
    """
    return self.fd_write

  def run(self):
    """Run the thread, logging everything.
    """
    for line in iter(self.pipe_reader.readline, ''):
      logging.log(self.level, line.strip('\n'))

    self.pipe_reader.close()

  def close(self):
    """Close the write end of the pipe.
    """
    os.close(self.fd_write)