import logging
import hashlib
import json

from collections import defaultdict
from datetime import datetime
import dateutil.parser

from peewee import JOIN, IntegrityError, fn

from data.model import (DataModelException, db_transaction, _basequery, storage,
                        InvalidImageException)
from data.database import (Image, Repository, ImageStoragePlacement, Namespace, ImageStorage,
                           ImageStorageLocation, RepositoryPermission, DerivedStorageForImage,
                           ImageStorageTransformation, User)

from util.canonicaljson import canonicalize

logger = logging.getLogger(__name__)

def _namespace_id_for_username(username):
  try:
    return User.get(username=username).id
  except User.DoesNotExist:
    return None


def get_image_with_storage(docker_image_id, storage_uuid):
  """ Returns the image with the given docker image ID and storage uuid or None if none.
  """
  try:
    return (Image
            .select(Image, ImageStorage)
            .join(ImageStorage)
            .where(Image.docker_image_id == docker_image_id,
                   ImageStorage.uuid == storage_uuid)
            .get())
  except Image.DoesNotExist:
    return None


def get_parent_images(namespace_name, repository_name, image_obj):
  """ Returns a list of parent Image objects starting with the most recent parent
      and ending with the base layer. The images in this query will include the storage.
  """
  parents = image_obj.ancestors

  # Ancestors are in the format /<root>/<intermediate>/.../<parent>/, with each path section
  # containing the database Id of the image row.
  parent_db_ids = parents.strip('/').split('/')
  if parent_db_ids == ['']:
    return []

  def filter_to_parents(query):
    return query.where(Image.id << parent_db_ids)

  parents = _get_repository_images_and_storages(namespace_name, repository_name,
                                                filter_to_parents)
  id_to_image = {unicode(image.id): image for image in parents}
  try:
    return [id_to_image[parent_id] for parent_id in reversed(parent_db_ids)]
  except KeyError as ke:
    logger.exception('Could not find an expected parent image for image %s', image_obj.id)
    raise DataModelException('Unknown parent image')


def get_placements_for_images(images):
  """ Returns the placements for the given images, as a map from image storage ID to placements. """
  if not images:
    return {}

  query = (ImageStoragePlacement
           .select(ImageStoragePlacement, ImageStorageLocation, ImageStorage)
           .join(ImageStorageLocation)
           .switch(ImageStoragePlacement)
           .join(ImageStorage)
           .where(ImageStorage.id << [image.storage_id for image in images]))

  placement_map = defaultdict(list)
  for placement in query:
    placement_map[placement.storage.id].append(placement)

  return dict(placement_map)


def get_image_and_placements(namespace_name, repo_name, docker_image_id):
  """ Returns the repo image (with a storage object) and storage placements for the image
      or (None, None) if non found.
  """
  repo_image = get_repo_image_and_storage(namespace_name, repo_name, docker_image_id)
  if repo_image is None:
    return (None, None)

  query = (ImageStoragePlacement
           .select(ImageStoragePlacement, ImageStorageLocation)
           .join(ImageStorageLocation)
           .switch(ImageStoragePlacement)
           .join(ImageStorage)
           .where(ImageStorage.id == repo_image.storage_id))

  return repo_image, list(query)


def get_repo_image(namespace_name, repository_name, docker_image_id):
  """ Returns the repository image with the given Docker image ID or None if none.
      Does not include the storage object.
  """
  def limit_to_image_id(query):
    return query.where(Image.docker_image_id == docker_image_id).limit(1)

  query = _get_repository_images(namespace_name, repository_name, limit_to_image_id)
  try:
    return query.get()
  except Image.DoesNotExist:
    return None


def get_repo_image_and_storage(namespace_name, repository_name, docker_image_id):
  """ Returns the repository image with the given Docker image ID or None if none.
      Includes the storage object.
  """
  def limit_to_image_id(query):
    return query.where(Image.docker_image_id == docker_image_id)

  images = _get_repository_images_and_storages(namespace_name, repository_name, limit_to_image_id)
  if not images:
    return None

  return images[0]


def get_image_by_id(namespace_name, repository_name, docker_image_id):
  """ Returns the repository image with the given Docker image ID or raises if not found.
      Includes the storage object.
  """
  image = get_repo_image_and_storage(namespace_name, repository_name, docker_image_id)
  if not image:
    raise InvalidImageException('Unable to find image \'%s\' for repo \'%s/%s\'' %
                                (docker_image_id, namespace_name, repository_name))
  return image


def _get_repository_images_and_storages(namespace_name, repository_name, query_modifier):
  query = (Image
           .select(Image, ImageStorage)
           .join(ImageStorage)
           .switch(Image)
           .join(Repository)
           .join(Namespace, on=(Repository.namespace_user == Namespace.id))
           .where(Repository.name == repository_name, Namespace.username == namespace_name))

  query = query_modifier(query)
  return query


def _get_repository_images(namespace_name, repository_name, query_modifier):
  query = (Image
           .select()
           .join(Repository)
           .join(Namespace, on=(Repository.namespace_user == Namespace.id))
           .where(Repository.name == repository_name, Namespace.username == namespace_name))

  query = query_modifier(query)
  return query


def lookup_repository_images(repo, docker_image_ids):
  return (Image
          .select(Image, ImageStorage)
          .join(ImageStorage)
          .where(Image.repository == repo, Image.docker_image_id << docker_image_ids))


def get_repository_images_without_placements(repo_obj, with_ancestor=None):
  query = (Image
           .select(Image, ImageStorage)
           .join(ImageStorage)
           .where(Image.repository == repo_obj))

  if with_ancestor:
    ancestors_string = '%s%s/' % (with_ancestor.ancestors, with_ancestor.id)
    query = query.where((Image.ancestors ** (ancestors_string + '%')) |
                        (Image.id == with_ancestor.id))

  return query


def get_repository_images(namespace_name, repository_name):
  """ Returns all the repository images in the repository. Does not include storage objects. """
  return _get_repository_images(namespace_name, repository_name, lambda q: q)


def __translate_ancestry(old_ancestry, translations, repo_obj, username, preferred_location):
  if old_ancestry == '/':
    return '/'

  def translate_id(old_id, docker_image_id):
    logger.debug('Translating id: %s', old_id)
    if old_id not in translations:
      image_in_repo = find_create_or_link_image(docker_image_id, repo_obj, username, translations,
                                                preferred_location)
      translations[old_id] = image_in_repo.id
    return translations[old_id]

  # Select all the ancestor Docker IDs in a single query.
  old_ids = [int(id_str) for id_str in old_ancestry.split('/')[1:-1]]
  query = Image.select(Image.id, Image.docker_image_id).where(Image.id << old_ids)
  old_images = {i.id: i.docker_image_id for i in  query}

  # Translate the old images into new ones.
  new_ids = [str(translate_id(old_id, old_images[old_id])) for old_id in old_ids]
  return '/%s/' % '/'.join(new_ids)


def _find_or_link_image(existing_image, repo_obj, username, translations, preferred_location):
  with db_transaction():
    # Check for an existing image, under the transaction, to make sure it doesn't already exist.
    repo_image = get_repo_image(repo_obj.namespace_user.username, repo_obj.name,
                                existing_image.docker_image_id)
    if repo_image:
      return repo_image

    # Make sure the existing base image still exists.
    try:
      to_copy = Image.select().join(ImageStorage).where(Image.id == existing_image.id).get()

      msg = 'Linking image to existing storage with docker id: %s and uuid: %s'
      logger.debug(msg, existing_image.docker_image_id, to_copy.storage.uuid)

      new_image_ancestry = __translate_ancestry(to_copy.ancestors, translations, repo_obj,
                                                username, preferred_location)

      copied_storage = to_copy.storage

      translated_parent_id = None
      if new_image_ancestry != '/':
        translated_parent_id = int(new_image_ancestry.split('/')[-2])

      new_image = Image.create(docker_image_id=existing_image.docker_image_id,
                               repository=repo_obj,
                               storage=copied_storage,
                               ancestors=new_image_ancestry,
                               command=existing_image.command,
                               created=existing_image.created,
                               comment=existing_image.comment,
                               v1_json_metadata=existing_image.v1_json_metadata,
                               aggregate_size=existing_image.aggregate_size,
                               parent=translated_parent_id,
                               v1_checksum=existing_image.v1_checksum)


      logger.debug('Storing translation %s -> %s', existing_image.id, new_image.id)
      translations[existing_image.id] = new_image.id
      return new_image
    except Image.DoesNotExist:
      return None


def find_create_or_link_image(docker_image_id, repo_obj, username, translations,
                              preferred_location):

  # First check for the image existing in the repository. If found, we simply return it.
  repo_image = get_repo_image(repo_obj.namespace_user.username, repo_obj.name,
                              docker_image_id)
  if repo_image:
    return repo_image

  # We next check to see if there is an existing storage the new image can link to.
  existing_image_query = (Image
                          .select(Image, ImageStorage)
                          .distinct()
                          .join(ImageStorage)
                          .switch(Image)
                          .join(Repository)
                          .join(RepositoryPermission, JOIN.LEFT_OUTER)
                          .switch(Repository)
                          .join(Namespace, on=(Repository.namespace_user == Namespace.id))
                          .where(ImageStorage.uploading == False,
                                 Image.docker_image_id == docker_image_id))

  existing_image_query = _basequery.filter_to_repos_for_user(existing_image_query,
                                                             _namespace_id_for_username(username))

  # If there is an existing image, we try to translate its ancestry and copy its storage.
  new_image = None
  try:
    logger.debug('Looking up existing image for ID: %s', docker_image_id)
    existing_image = existing_image_query.get()

    logger.debug('Existing image %s found for ID: %s', existing_image.id, docker_image_id)
    new_image = _find_or_link_image(existing_image, repo_obj, username, translations,
                                    preferred_location)
    if new_image:
      return new_image
  except Image.DoesNotExist:
    logger.debug('No existing image found for ID: %s', docker_image_id)

  # Otherwise, create a new storage directly.
  with db_transaction():
    # Final check for an existing image, under the transaction.
    repo_image = get_repo_image(repo_obj.namespace_user.username, repo_obj.name,
                                docker_image_id)
    if repo_image:
      return repo_image

    logger.debug('Creating new storage for docker id: %s', docker_image_id)
    new_storage = storage.create_v1_storage(preferred_location)

    return Image.create(docker_image_id=docker_image_id,
                        repository=repo_obj, storage=new_storage,
                        ancestors='/')


def set_image_metadata(docker_image_id, namespace_name, repository_name, created_date_str, comment,
                       command, v1_json_metadata, parent=None):
  """ Sets metadata that is specific to how a binary piece of storage fits into the layer tree.
  """
  with db_transaction():
    try:
      fetched = (Image
                 .select(Image, ImageStorage)
                 .join(Repository)
                 .join(Namespace, on=(Repository.namespace_user == Namespace.id))
                 .switch(Image)
                 .join(ImageStorage)
                 .where(Repository.name == repository_name, Namespace.username == namespace_name,
                        Image.docker_image_id == docker_image_id)
                 .get())
    except Image.DoesNotExist:
      raise DataModelException('No image with specified id and repository')

    fetched.created = datetime.now()
    if created_date_str is not None:
      try:
        fetched.created = dateutil.parser.parse(created_date_str).replace(tzinfo=None)
      except:
        # parse raises different exceptions, so we cannot use a specific kind of handler here.
        pass

    # We cleanup any old checksum in case it's a retry after a fail
    fetched.v1_checksum = None
    fetched.comment = comment
    fetched.command = command
    fetched.v1_json_metadata = v1_json_metadata

    if parent:
      fetched.ancestors = '%s%s/' % (parent.ancestors, parent.id)
      fetched.parent = parent

    fetched.save()
    return fetched


def get_image(repo, docker_image_id):
  try:
    return (Image
            .select(Image, ImageStorage)
            .join(ImageStorage)
            .where(Image.docker_image_id == docker_image_id, Image.repository == repo)
            .get())
  except Image.DoesNotExist:
    return None


def get_image_by_db_id(id):
  try:
    return Image.get(id=id)
  except Image.DoesNotExist:
    return None


def synthesize_v1_image(repo, image_storage_id, storage_image_size, docker_image_id,
                        created_date_str, comment, command, v1_json_metadata, parent_image=None):
  """ Find an existing image with this docker image id, and if none exists, write one with the
      specified metadata.
  """
  ancestors = '/'
  if parent_image is not None:
    ancestors = '{0}{1}/'.format(parent_image.ancestors, parent_image.id)

  created = None
  if created_date_str is not None:
    try:
      created = dateutil.parser.parse(created_date_str).replace(tzinfo=None)
    except:
      # parse raises different exceptions, so we cannot use a specific kind of handler here.
      pass

  # Get the aggregate size for the image.
  aggregate_size = _basequery.calculate_image_aggregate_size(ancestors, storage_image_size,
                                                             parent_image)

  try:
    return Image.create(docker_image_id=docker_image_id, ancestors=ancestors, comment=comment,
                        command=command, v1_json_metadata=v1_json_metadata, created=created,
                        storage=image_storage_id, repository=repo, parent=parent_image,
                        aggregate_size=aggregate_size)
  except IntegrityError:
    return Image.get(docker_image_id=docker_image_id, repository=repo)


def ensure_image_locations(*names):
  with db_transaction():
    locations = ImageStorageLocation.select().where(ImageStorageLocation.name << names)

    insert_names = list(names)

    for location in locations:
      insert_names.remove(location.name)

    if not insert_names:
      return

    data = [{'name': name} for name in insert_names]
    ImageStorageLocation.insert_many(data).execute()


def get_max_id_for_sec_scan():
  """ Gets the maximum id for a clair sec scan """
  return Image.select(fn.Max(Image.id)).scalar()


def get_min_id_for_sec_scan(version):
  """ Gets the minimum id for a clair sec scan """
  return (Image
          .select(fn.Min(Image.id))
          .where(Image.security_indexed_engine < version)
          .scalar())


def total_image_count():
  """ Returns the total number of images in DB """
  return Image.select().count()


def get_image_pk_field():
  """ Returns the primary key for Image DB model """
  return Image.id


def get_images_eligible_for_scan(clair_version):
  """ Returns a query that gives all images eligible for a clair scan """
  return (get_image_with_storage_and_parent_base()
          .where(Image.security_indexed_engine < clair_version)
          .where(ImageStorage.uploading == False))


def get_image_with_storage_and_parent_base():
  Parent = Image.alias()
  ParentImageStorage = ImageStorage.alias()

  return (Image
          .select(Image, ImageStorage, Parent, ParentImageStorage)
          .join(ImageStorage)
          .switch(Image)
          .join(Parent, JOIN.LEFT_OUTER, on=(Image.parent == Parent.id))
          .join(ParentImageStorage, JOIN.LEFT_OUTER, on=(ParentImageStorage.id == Parent.storage)))


def set_secscan_status(image, indexed, version):
  return (Image
          .update(security_indexed=indexed, security_indexed_engine=version)
          .where(Image.id == image.id)
          .where((Image.security_indexed_engine != version) | (Image.security_indexed != indexed))
          .execute()) != 0


def _get_uniqueness_hash(varying_metadata):
  if not varying_metadata:
    return None

  return hashlib.sha256(json.dumps(canonicalize(varying_metadata))).hexdigest()


def find_or_create_derived_storage(source_image, transformation_name, preferred_location,
                                   varying_metadata=None):
  existing = find_derived_storage_for_image(source_image, transformation_name, varying_metadata)
  if existing is not None:
    return existing

  uniqueness_hash = _get_uniqueness_hash(varying_metadata)
  trans = ImageStorageTransformation.get(name=transformation_name)
  new_storage = storage.create_v1_storage(preferred_location)

  try:
    derived = DerivedStorageForImage.create(source_image=source_image, derivative=new_storage,
                                            transformation=trans, uniqueness_hash=uniqueness_hash)
  except IntegrityError:
    # Storage was created while this method executed. Just return the existing.
    ImageStoragePlacement.delete().where(ImageStoragePlacement.storage == new_storage).execute()
    new_storage.delete_instance()
    return find_derived_storage_for_image(source_image, transformation_name, varying_metadata)

  return derived


def find_derived_storage_for_image(source_image, transformation_name, varying_metadata=None):
  uniqueness_hash = _get_uniqueness_hash(varying_metadata)

  try:
    found = (DerivedStorageForImage
             .select(ImageStorage, DerivedStorageForImage)
             .join(ImageStorage)
             .switch(DerivedStorageForImage)
             .join(ImageStorageTransformation)
             .where(DerivedStorageForImage.source_image == source_image,
                    ImageStorageTransformation.name == transformation_name,
                    DerivedStorageForImage.uniqueness_hash == uniqueness_hash)
             .get())
    return found
  except DerivedStorageForImage.DoesNotExist:
    return None


def delete_derived_storage(derived_storage):
  derived_storage.derivative.delete_instance(recursive=True)