import logging.config

logging.config.fileConfig('conf/logging.conf', disable_existing_loggers=False)  

import logging
import argparse
import os
import requests
import re
import json
import shutil
import tarfile

from docker import Client
from docker.errors import APIError
from tempfile import TemporaryFile, mkdtemp
from zipfile import ZipFile
from functools import partial
from datetime import datetime, timedelta
from threading import Event
from uuid import uuid4
from collections import defaultdict
from requests.exceptions import ConnectionError

from data import model
from workers.worker import Worker, WorkerUnhealthyException, JobException
from app import userfiles as user_files, build_logs, sentry, dockerfile_build_queue
from endpoints.notificationhelper import spawn_notification
from util.safetar import safe_extractall
from util.dockerfileparse import parse_dockerfile, ParsedDockerfile, serialize_dockerfile


logger = logging.getLogger(__name__)

TIMEOUT_PERIOD_MINUTES = 20
CACHE_EXPIRATION_PERIOD_HOURS = 24
NO_TAGS = ['<none>:<none>']
RESERVATION_TIME = (TIMEOUT_PERIOD_MINUTES + 5) * 60

def matches_system_error(status_str):
  """ Returns true if the given status string matches a known system error in the
      Docker builder.
  """
  KNOWN_MATCHES = ['lxc-start: invalid', 'lxc-start: failed to', 'lxc-start: Permission denied']

  for match in KNOWN_MATCHES:
    # 4 because we might have a Unix control code at the start.
    found = status_str.find(match[0:len(match) + 4])
    if found >= 0 and found <= 4: 
      return True

  return False


class StatusWrapper(object):
  def __init__(self, build_uuid):
    self._uuid = build_uuid
    self._status = {
      'total_commands': None,
      'current_command': None,
      'push_completion': 0.0,
      'pull_completion': 0.0,
    }

    self.__exit__(None, None, None)

  def __enter__(self):
    return self._status

  def __exit__(self, exc_type, value, traceback):
    build_logs.set_status(self._uuid, self._status)


class _IncompleteJsonError(Exception):
  def __init__(self, start_from):
    self.start_from = start_from


class _StreamingJSONDecoder(json.JSONDecoder):
  FLAGS = re.VERBOSE | re.MULTILINE | re.DOTALL
  WHITESPACE = re.compile(r'[ \t\n\r]*', FLAGS)

  def decode(self, s, _w=WHITESPACE.match):
    """Return the Python representation of ``s`` (a ``str`` or ``unicode``
    instance containing a JSON document)

    """
    start_from = 0
    while start_from < len(s):
      try:
        obj, end = self.raw_decode(s[start_from:], idx=_w(s[start_from:], 0).end())
      except ValueError:
        raise _IncompleteJsonError(start_from)
      end = _w(s[start_from:], end).end()
      start_from += end
      yield obj


class StreamingDockerClient(Client):
  def _stream_helper(self, response):
    """Generator for data coming from a chunked-encoded HTTP response."""
    content_buf = ''
    for content in response.iter_content(chunk_size=256):
      content_buf += content
      try:
        for val in json.loads(content_buf, cls=_StreamingJSONDecoder):
          yield val
        content_buf = ''
      except _IncompleteJsonError as exc:
        content_buf = content_buf[exc.start_from:]


class DockerfileBuildContext(object):
  def __init__(self, build_context_dir, dockerfile_subdir, repo, tag_names,
               push_token, build_uuid, cache_size_gb, pull_credentials=None):
    self._build_dir = build_context_dir
    self._dockerfile_subdir = dockerfile_subdir
    self._repo = repo
    self._tag_names = tag_names
    self._push_token = push_token
    self._status = StatusWrapper(build_uuid)
    self._build_logger = partial(build_logs.append_log_message, build_uuid)
    self._pull_credentials = pull_credentials
    self._cache_size_gb = cache_size_gb

    # Note: We have two different clients here because we (potentially) login
    # with both, but with different credentials that we do not want shared between
    # the build and push operations.
    self._push_cl = StreamingDockerClient(timeout=1200)
    self._build_cl = StreamingDockerClient(timeout=1200)

    dockerfile_path = os.path.join(self._build_dir, dockerfile_subdir,
                                   'Dockerfile')
    if not os.path.exists(dockerfile_path):
      raise RuntimeError('Build job did not contain a Dockerfile.')

    # Compute the number of steps
    with open(dockerfile_path, 'r') as dockerfileobj:
      self._parsed_dockerfile = parse_dockerfile(dockerfileobj.read())

    self.__inject_quay_repo_env(self._parsed_dockerfile, repo)
    self._num_steps = len(self._parsed_dockerfile.commands)

    with open(dockerfile_path, 'w') as dockerfileobj:
      dockerfileobj.write(serialize_dockerfile(self._parsed_dockerfile))

    logger.debug('Will build and push to repo %s with tags named: %s', self._repo,
                 self._tag_names)

  def __enter__(self):
    try:
      self.__cleanup_containers()
      self.__cleanup_images()
      self.__prune_cache()
    except APIError:
      sentry.client.captureException()
      message = 'Docker installation is no longer healthy.'
      logger.exception(message)
      raise WorkerUnhealthyException(message)

    return self

  def __exit__(self, exc_type, value, traceback):
    shutil.rmtree(self._build_dir)

    try:
      self.__cleanup_containers()
    except APIError:
      sentry.client.captureException()
      message = 'Docker installation is no longer healthy.'
      logger.exception(message)
      raise WorkerUnhealthyException(message)

  @staticmethod
  def __inject_quay_repo_env(parsed_dockerfile, quay_reponame):
    env_command = {
      'command': 'ENV',
      'parameters': 'QUAY_REPOSITORY %s' % quay_reponame
    }
    for index, command in reversed(list(enumerate(parsed_dockerfile.commands))):
      if command['command'] == 'FROM':
        new_command_index = index + 1
        logger.debug('Injecting env command at dockerfile index: %s', new_command_index)
        parsed_dockerfile.commands.insert(new_command_index, env_command)
        break

  @staticmethod
  def __total_completion(statuses, total_images):
    percentage_with_sizes = float(len(statuses.values()))/total_images
    sent_bytes = sum([status['current'] for status in statuses.values()])
    total_bytes = sum([status['total'] for status in statuses.values()])
    return float(sent_bytes)/total_bytes*percentage_with_sizes

  @staticmethod
  def __monitor_completion(status_stream, required_message, status_updater, status_completion_key,
                           num_images=0):
    images = {}
    for status in status_stream:
      logger.debug('%s: %s', status_completion_key, status)
      if 'status' in status:
        status_msg = status['status']

        if status_msg == required_message:
          if 'progressDetail' in status and 'id' in status:
            image_id = status['id']
            detail = status['progressDetail']

            if 'current' in detail and 'total' in detail:
              images[image_id] = detail
              with status_updater as status_update:
                status_update[status_completion_key] = \
                  DockerfileBuildContext.__total_completion(images, max(len(images), num_images))

      elif 'errorDetail' in status:
        message = 'Error pushing image.'
        if 'message' in status['errorDetail']:
          message = str(status['errorDetail']['message'])

        raise RuntimeError(message)

  def pull(self):
    # Login with the specified credentials (if any).
    if self._pull_credentials:
      logger.debug('Logging in with pull credentials: %s@%s',
                   self._pull_credentials['username'], self._pull_credentials['registry'])
      
      self._build_logger('Pulling base image: %s' % image_and_tag, log_data = {
        'phasestep': 'login',
        'username': self._pull_credentials['username'],
        'registry': self._pull_credentials['registry']
      })

      self._build_cl.login(self._pull_credentials['username'], self._pull_credentials['password'],
                           registry=self._pull_credentials['registry'], reauth=True)

    # Pull the image, in case it was updated since the last build
    image_and_tag_tuple = self._parsed_dockerfile.get_image_and_tag()
    if image_and_tag_tuple is None or image_and_tag_tuple[0] is None:
      self._build_logger('Missing FROM command in Dockerfile', build_logs.ERROR)
      raise JobException('Missing FROM command in Dockerfile')

    image_and_tag = ':'.join(image_and_tag_tuple)

    self._build_logger('Pulling base image: %s' % image_and_tag, log_data = {
      'phasestep': 'pull',
      'repo_url': image_and_tag
    })

    pull_status = self._build_cl.pull(image_and_tag, stream=True)

    self.__monitor_completion(pull_status, 'Downloading', self._status, 'pull_completion')

  def build(self, reservation_extension_method):
    # Start the build itself.
    logger.debug('Starting build.')

    with self._status as status:
      status['total_commands'] = self._num_steps

    logger.debug('Building to tags named: %s', self._tag_names)
    context_path = os.path.join(self._build_dir, self._dockerfile_subdir)

    logger.debug('Final context path: %s exists: %s', context_path,
                 os.path.exists(context_path))

    build_status = self._build_cl.build(path=context_path, stream=True)

    current_step = 0
    built_image = None
    for status in build_status:
      fully_unwrapped = ""
      if isinstance(status, dict):
        keys_to_extract = ['error', 'status', 'stream']
        for key in keys_to_extract:
          if key in status:
            fully_unwrapped = status[key]
            break
        
        if not fully_unwrapped:
          logger.debug('Status dict did not have any extractable keys and was: %s', status)
      elif isinstance(status, basestring):
        fully_unwrapped = status

      status_str = str(fully_unwrapped.encode('utf-8'))

      # Check for system errors when building.
      if matches_system_error(status_str):
        raise WorkerUnhealthyException(status_str)        

      logger.debug('Status: %s', status_str)
      step_increment = re.search(r'Step ([0-9]+) :', status_str)
      if step_increment:
        self._build_logger(status_str, build_logs.COMMAND)
        current_step = int(step_increment.group(1))
        logger.debug('Step now: %s/%s', current_step, self._num_steps)
        with self._status as status_update:
          status_update['current_command'] = current_step

          # Tell the queue that we're making progress every time we advance a step
          reservation_extension_method(RESERVATION_TIME)
        continue
      else:
        self._build_logger(status_str)

      complete = re.match(r'Successfully built ([a-z0-9]+)$', status_str)
      if complete:
        built_image = complete.group(1)
        logger.debug('Final image ID is: %s', built_image)
        continue

    # Get the image count
    if not built_image:
      return

    return built_image

  def push(self, built_image):
    # Login to the registry
    host = re.match(r'([a-z0-9.:]+)/.+/.+$', self._repo)
    if not host:
      raise RuntimeError('Invalid repo name: %s' % self._repo)

    for protocol in ['https', 'http']:
      registry_endpoint = '%s://%s/v1/' % (protocol, host.group(1))
      logger.debug('Attempting login to registry: %s', registry_endpoint)

      try:
        self._push_cl.login('$token', self._push_token, registry=registry_endpoint)
        break
      except APIError:
        pass  # Probably the wrong protocol

    for tag in self._tag_names:
      logger.debug('Tagging image %s as %s:%s', built_image, self._repo, tag)
      self._push_cl.tag(built_image, self._repo, tag)

    history = json.loads(self._push_cl.history(built_image))
    num_images = len(history)

    logger.debug('Pushing to repo %s', self._repo)
    resp = self._push_cl.push(self._repo, stream=True)
    self.__monitor_completion(resp, 'Pushing', self._status, 'push_completion', num_images)

  def __cleanup_containers(self):
    # First clean up any containers that might be holding the images
    for running in self._build_cl.containers(quiet=True):
      logger.debug('Killing container: %s', running['Id'])
      self._build_cl.kill(running['Id'])

    # Next, remove all of the containers (which should all now be killed)
    for container in self._build_cl.containers(all=True, quiet=True):
      logger.debug('Removing container: %s', container['Id'])
      self._build_cl.remove_container(container['Id'])

  def __cleanup_images(self):
    """ Remove tags on internal nodes, and remove images older than the expiratino time. """
    ids_to_images, ids_to_children = self.__compute_image_graph()

    # Untag all internal nodes, which are usually the base images
    for internal_id in ids_to_children.keys():
      internal = ids_to_images[internal_id]
      if internal['RepoTags'] != NO_TAGS:
        for tag_name in internal['RepoTags']:
          self._build_cl.remove_image(tag_name)

    # Make sure all of the leaves have gibberish tags, and remove those older than our expiration
    leaves = set(ids_to_images.keys()) - set(ids_to_children.keys())
    now = datetime.now()
    for leaf_id in leaves:
      leaf = ids_to_images[leaf_id]

      created = datetime.fromtimestamp(leaf['Created'])
      expiration = created + timedelta(hours=CACHE_EXPIRATION_PERIOD_HOURS)
      if expiration > now:
        # Assign a new tag as a uuid to preserve this image
        new_tag = str(uuid4())
        self._build_cl.tag(leaf['Id'], new_tag)

      # Remove all of the existing tags
      if leaf['RepoTags'] != NO_TAGS:
        for tag_name in leaf['RepoTags']:
          self._build_cl.remove_image(tag_name)

  def __prune_cache(self):
    """ Remove the oldest leaf image until the cache size is the desired size. """

    logger.debug('Pruning cache to size(gb): %s', self._cache_size_gb)
    while self.__compute_cache_size_gb() > self._cache_size_gb:
      logger.debug('Locating the oldest image in the cache to prune.')
      # Find the oldest tagged image and remove it
      oldest_creation_time = datetime.max
      oldest_image = None
      for image in self._build_cl.images():
        created = datetime.fromtimestamp(image['Created'])
        if created < oldest_creation_time:
          oldest_creation_time = created
          oldest_image = image

      logger.debug('Removing oldest image from cache: %s', oldest_image['Id'])
      # Remove all tags on the oldest image
      if oldest_image['RepoTags'] == NO_TAGS:
        # Remove the image id directly since there are no tags
        self._build_cl.remove_image(oldest_image['Id'])
      else:
        # Remove all tags
        for tag_name in oldest_image['RepoTags']:
          self._build_cl.remove_image(tag_name)

  def __compute_cache_size_gb(self):
    all_images = self._build_cl.images(all=True)
    size_in_bytes = sum([img['Size'] for img in all_images])
    size_in_gb = float(size_in_bytes)/1024/1024/1024
    logger.debug('Computed cache size(gb) of: %s', size_in_gb)
    return size_in_gb

  def __compute_image_graph(self):
    all_images = self._build_cl.images(all=True)

    ids_to_images = {}
    ids_to_children = defaultdict(list)
    for image in all_images:
      if image['ParentId'] != '':
        ids_to_children[image['ParentId']].append(image)
      ids_to_images[image['Id']] = image

    return (ids_to_images, ids_to_children)


class DockerfileBuildWorker(Worker):
  def __init__(self, cache_size_gb, *vargs, **kwargs):
    super(DockerfileBuildWorker, self).__init__(*vargs, **kwargs)

    self._mime_processors = {
      'application/zip': DockerfileBuildWorker.__prepare_zip,
      'application/x-zip-compressed': DockerfileBuildWorker.__prepare_zip,
      'text/plain': DockerfileBuildWorker.__prepare_dockerfile,
      'application/octet-stream': DockerfileBuildWorker.__prepare_dockerfile,
      'application/x-tar': DockerfileBuildWorker.__prepare_tarball,
      'application/gzip': DockerfileBuildWorker.__prepare_tarball,
      'application/x-gzip': DockerfileBuildWorker.__prepare_tarball,
    }

    self._timeout = Event()
    self._cache_size_gb = cache_size_gb

  @staticmethod
  def __prepare_zip(request_file):
    build_dir = mkdtemp(prefix='docker-build-')

    # Save the zip file to temp somewhere
    with TemporaryFile() as zip_file:
      zip_file.write(request_file.content)
      to_extract = ZipFile(zip_file)
      to_extract.extractall(build_dir)

    return build_dir

  @staticmethod
  def __prepare_dockerfile(request_file):
    build_dir = mkdtemp(prefix='docker-build-')
    dockerfile_path = os.path.join(build_dir, "Dockerfile")
    with open(dockerfile_path, 'w') as dockerfile:
      dockerfile.write(request_file.content)

    return build_dir

  @staticmethod
  def __prepare_tarball(request_file):
    build_dir = mkdtemp(prefix='docker-build-')

    # Save the zip file to temp somewhere
    with tarfile.open(mode='r|*', fileobj=request_file.raw) as tar_stream:
      safe_extractall(tar_stream, build_dir)

    return build_dir

  def watchdog(self):
    logger.debug('Running build watchdog code.')

    try:
      docker_cl = Client()
    
      # Iterate the running containers and kill ones that have been running more than 20 minutes
      for container in docker_cl.containers():
        start_time = datetime.fromtimestamp(container['Created'])
        running_time = datetime.now() - start_time
        if running_time > timedelta(minutes=TIMEOUT_PERIOD_MINUTES):
          logger.warning('Container has been running too long: %s with command: %s',
                         container['Id'], container['Command'])
          docker_cl.kill(container['Id'])
          self._timeout.set()
    except ConnectionError as exc:
      raise WorkerUnhealthyException(exc.message)

  def process_queue_item(self, job_details):
    self._timeout.clear()

    # Make sure we have more information for debugging problems
    sentry.client.user_context(job_details)

    repository_build = model.get_repository_build(job_details['namespace'],
                                                  job_details['repository'],
                                                  job_details['build_uuid'])

    pull_credentials = job_details.get('pull_credentials', None)

    job_config = json.loads(repository_build.job_config)

    resource_url = user_files.get_file_url(repository_build.resource_key)
    tag_names = job_config['docker_tags']
    build_subdir = job_config['build_subdir']
    repo = job_config['repository']

    access_token = repository_build.access_token.code

    log_appender = partial(build_logs.append_log_message,
                           repository_build.uuid)

    log_appender('initializing', build_logs.PHASE)

    start_msg = ('Starting job with resource url: %s repo: %s' % (resource_url,
                                                                  repo))
    logger.debug(start_msg)

    docker_resource = requests.get(resource_url, stream=True)
    c_type = docker_resource.headers['content-type']

    if ';' in c_type:
      c_type = c_type.split(';')[0]

    filetype_msg = ('Request to build type: %s with repo: %s and tags: %s' %
                    (c_type, repo, tag_names))
    logger.info(filetype_msg)
    log_appender(filetype_msg)

    # Spawn a notification that the build has started.
    event_data = {
      'build_id': repository_build.uuid,
      'build_name': repository_build.display_name,
      'docker_tags': tag_names,
      'trigger_id': repository_build.trigger.uuid,
      'trigger_kind': repository_build.trigger.service.name
    }

    spawn_notification(repository_build.repository, 'build_start', event_data,
                       subpage='build?current=%s' % repository_build.uuid,
                       pathargs=['build', repository_build.uuid])


    # Setup a handler for spawning failure messages.
    def spawn_failure(message, event_data):
      event_data['error_message'] = message
      spawn_notification(repository_build.repository, 'build_failure', event_data,
                         subpage='build?current=%s' % repository_build.uuid,
                         pathargs=['build', repository_build.uuid])

    if c_type not in self._mime_processors:
      log_appender('error', build_logs.PHASE)
      repository_build.phase = 'error'
      repository_build.save()
      message = 'Unknown mime-type: %s' % c_type
      log_appender(message, build_logs.ERROR)
      spawn_failure(message, event_data)
      raise JobException(message)

    # Try to build the build directory package from the buildpack.
    log_appender('unpacking', build_logs.PHASE)
    repository_build.phase = 'unpacking'
    repository_build.save()

    build_dir = None
    try:
      build_dir = self._mime_processors[c_type](docker_resource)
    except Exception as ex:
      cur_message = ex.message or 'Error while unpacking build package'
      log_appender(cur_message, build_logs.ERROR)
      spawn_failure(cur_message, event_data)
      raise JobException(cur_message)      

    # Start the build process.
    try:
      with DockerfileBuildContext(build_dir, build_subdir, repo, tag_names, access_token,
                                  repository_build.uuid, self._cache_size_gb,
                                  pull_credentials) as build_ctxt:
        log_appender('pulling', build_logs.PHASE)
        repository_build.phase = 'pulling'
        repository_build.save()
        build_ctxt.pull()

        self.extend_processing(RESERVATION_TIME)

        log_appender('building', build_logs.PHASE)
        repository_build.phase = 'building'
        repository_build.save()
        built_image = build_ctxt.build(self.extend_processing)

        if not built_image:
          log_appender('error', build_logs.PHASE)
          repository_build.phase = 'error'
          repository_build.save()

          message = 'Unable to build dockerfile.'
          if self._timeout.is_set():
            message = 'Build step was terminated after %s minutes.' % TIMEOUT_PERIOD_MINUTES

          log_appender(message, build_logs.ERROR)
          raise JobException(message)

        self.extend_processing(RESERVATION_TIME)

        log_appender('pushing', build_logs.PHASE)
        repository_build.phase = 'pushing'
        repository_build.save()

        build_ctxt.push(built_image)

        log_appender('complete', build_logs.PHASE)
        repository_build.phase = 'complete'
        repository_build.save()

        # Spawn a notification that the build has completed.
        spawn_notification(repository_build.repository, 'build_success', event_data,
                       subpage='build?current=%s' % repository_build.uuid,
                       pathargs=['build', repository_build.uuid])

    except WorkerUnhealthyException as exc:
      # Spawn a notification that the build has failed.
      spawn_failure(exc.message, event_data)
      
      # Raise the exception to the queue.
      raise exc

    except JobException as exc:
      # Spawn a notification that the build has failed.
      spawn_failure(exc.message, event_data)

      # Raise the exception to the queue.
      raise exc

    except ConnectionError as exc:
      # A connection exception means the worker has become unhealthy (Docker is down)
      # so we re-raise as that exception.
      log_appender('Docker daemon has gone away. Will retry shortly.', build_logs.ERROR)
      raise WorkerUnhealthyException(exc.message)

    except Exception as exc:
      # Spawn a notification that the build has failed.
      spawn_failure(exc.message, event_data)

      # Write the error to the logs.
      sentry.client.captureException()
      log_appender('error', build_logs.PHASE)
      logger.exception('Exception when processing request.')
      repository_build.phase = 'error'
      repository_build.save()
      log_appender(str(exc), build_logs.ERROR)

      # Raise the exception to the queue.
      raise JobException(str(exc))


desc = 'Worker daemon to monitor dockerfile build'
parser = argparse.ArgumentParser(description=desc)
parser.add_argument('--cachegb', default=20, type=float,
                    help='Maximum cache size in gigabytes.')
args = parser.parse_args()

worker = DockerfileBuildWorker(args.cachegb, dockerfile_build_queue,
                               reservation_seconds=RESERVATION_TIME)
worker.start(start_status_server_port=8000)