import logging

from peewee import JOIN_LEFT_OUTER, fn
from datetime import timedelta, datetime

from data.model import (DataModelException, tag, db_transaction, storage, image, permission,
                        _basequery, config)
from data.database import (Repository, Namespace, RepositoryTag, Star, Image, ImageStorage, User,
                           Visibility, RepositoryPermission, TupleSelector, RepositoryActionCount,
                           Role, RepositoryAuthorizedEmail, TagManifest, DerivedStorageForImage,
                           db_for_update, get_epoch_timestamp, db_random_func)


logger = logging.getLogger(__name__)


def get_public_repo_visibility():
  return _basequery.get_public_repo_visibility()


def create_repository(namespace, name, creating_user, visibility='private'):
  private = Visibility.get(name=visibility)
  namespace_user = User.get(username=namespace)
  repo = Repository.create(name=name, visibility=private, namespace_user=namespace_user)
  admin = Role.get(name='admin')

  if creating_user and not creating_user.organization:
    RepositoryPermission.create(user=creating_user, repository=repo, role=admin)

    if creating_user.username != namespace:
      # Permission prototypes only work for orgs
      permission.apply_default_permissions(repo, creating_user)
  return repo


def get_repository(namespace_name, repository_name):
  try:
    return _basequery.get_existing_repository(namespace_name, repository_name)
  except Repository.DoesNotExist:
    return None


def _purge_all_repository_tags(namespace_name, repository_name):
  """ Immediately purge all repository tags without respecting the lifeline procedure """
  try:
    repo = _basequery.get_existing_repository(namespace_name, repository_name)
  except Repository.DoesNotExist:
    raise DataModelException('Invalid repository \'%s/%s\'' %
                             (namespace_name, repository_name))

  # Delete all manifests.
  repo_tags = list(RepositoryTag.select().where(RepositoryTag.repository == repo.id))
  if not repo_tags:
    return

  TagManifest.delete().where(TagManifest.tag << repo_tags).execute()

  # Delete all tags.
  RepositoryTag.delete().where(RepositoryTag.repository == repo.id).execute()


def purge_repository(namespace_name, repository_name):
  # Delete all tags to allow gc to reclaim storage
  _purge_all_repository_tags(namespace_name, repository_name)

  # Gc to remove the images and storage
  garbage_collect_repository(namespace_name, repository_name)

  # Delete the rest of the repository metadata
  fetched = _basequery.get_existing_repository(namespace_name, repository_name)
  fetched.delete_instance(recursive=True, delete_nullable=False)


def find_repository_with_garbage():
  epoch_timestamp = get_epoch_timestamp()

  try:
    candidates = (RepositoryTag
                  .select(RepositoryTag.repository)
                  .join(Repository)
                  .join(Namespace, on=(Repository.namespace_user == Namespace.id))
                  .where(~(RepositoryTag.lifetime_end_ts >> None),
                         (RepositoryTag.lifetime_end_ts <=
                          (epoch_timestamp - Namespace.removed_tag_expiration_s)))
                  .limit(500)
                  .distinct()
                  .alias('candidates'))

    found = (RepositoryTag
             .select(candidates.c.repository_id)
             .from_(candidates)
             .order_by(db_random_func())
             .get())

    if found is None:
      return

    return Repository.get(Repository.id == found.repository_id)
  except RepositoryTag.DoesNotExist:
    return None
  except Repository.DoesNotExist:
    return None


def garbage_collect_repository(namespace_name, repository_name):
  repo = get_repository(namespace_name, repository_name)
  if repo is not None:
    garbage_collect_repo(repo)


def garbage_collect_repo(repo):
  logger.debug('Garbage collecting repository %s', repo.id)

  storage_id_whitelist = set()
  tag.garbage_collect_tags(repo)

  with db_transaction():
    # Get a list of all images used by tags in the repository
    tagged_images = (Image
                     .select(Image.id, Image.ancestors)
                     .join(RepositoryTag)
                     .where(Image.repository == repo))

    def gen_referenced_ancestors():
      for tagged_image in tagged_images:
        # The ancestor list is in the format '/1/2/3/', extract just the ids
        ancestor_id_strings = tagged_image.ancestors.split('/')[1:-1]
        for img_id_str in ancestor_id_strings:
          yield int(img_id_str)
        yield tagged_image.id

    referenced_ancestors = set(gen_referenced_ancestors())

    # We desire two pieces of information from the database from the following
    # query: all of the image ids which are associated with this repository,
    # and the storages which are associated with those images. In order to
    # fetch just this information, and bypass all of the peewee model parsing
    # code, which is overkill for just two fields, we use a tuple query, and
    # feed that directly to the dictionary tuple constructor which takes an
    # iterable of tuples containing [(k, v), (k, v), ...]
    all_repo_images = Image.select(Image.id, Image.storage).where(Image.repository == repo).tuples()
    images_to_storages = dict(all_repo_images)
    to_remove = list(set(images_to_storages.keys()).difference(referenced_ancestors))

    if len(to_remove) > 0:
      logger.info('Cleaning up unreferenced images: %s', to_remove)
      storage_id_whitelist = {images_to_storages[to_remove_id] for to_remove_id in to_remove}

      # Lookup any derived images for the images to remove.
      derived = DerivedStorageForImage.select().where(
        DerivedStorageForImage.source_image << to_remove)

      has_derived = False
      for derived_image in derived:
        has_derived = True
        storage_id_whitelist.add(derived_image.derivative_id)

      # Delete any derived images and the images themselves.
      if has_derived:
        DerivedStorageForImage.delete().where(
          DerivedStorageForImage.source_image << to_remove).execute()

      Image.delete().where(Image.id << to_remove).execute()

  if len(to_remove) > 0:
    logger.info('Garbage collecting storage for images: %s', to_remove)
    storage.garbage_collect_storage(storage_id_whitelist)


def star_repository(user, repository):
  """ Stars a repository. """
  star = Star.create(user=user.id, repository=repository.id)
  star.save()


def unstar_repository(user, repository):
  """ Unstars a repository. """
  try:
    (Star
     .delete()
     .where(Star.repository == repository.id, Star.user == user.id)
     .execute())
  except Star.DoesNotExist:
    raise DataModelException('Star not found.')


def get_user_starred_repositories(user):
  """ Retrieves all of the repositories a user has starred. """
  query = (Repository
           .select(Repository, User, Visibility)
           .join(Star)
           .switch(Repository)
           .join(User)
           .switch(Repository)
           .join(Visibility)
           .where(Star.user == user))

  return query


def repository_is_starred(user, repository):
  """ Determines whether a user has starred a repository or not. """
  try:
    (Star
     .select()
     .where(Star.repository == repository.id, Star.user == user.id)
     .get())
    return True
  except Star.DoesNotExist:
    return False


def get_when_last_modified(repository_ids):
  if not repository_ids:
    return {}

  tuples = (RepositoryTag
            .select(RepositoryTag.repository, fn.Max(RepositoryTag.lifetime_start_ts))
            .where(RepositoryTag.repository << repository_ids)
            .group_by(RepositoryTag.repository)
            .tuples())

  last_modified_map = {}
  for record in tuples:
    last_modified_map[record[0]] = record[1]

  return last_modified_map


def get_action_counts(repository_ids):
  if not repository_ids:
    return {}

  # Filter the join to recent entries only.
  last_week = datetime.now() - timedelta(weeks=1)
  tuples = (RepositoryActionCount
            .select(RepositoryActionCount.repository, fn.Sum(RepositoryActionCount.count))
            .where(RepositoryActionCount.repository << repository_ids)
            .where(RepositoryActionCount.date >= last_week)
            .group_by(RepositoryActionCount.repository)
            .tuples())

  action_count_map = {}
  for record in tuples:
    action_count_map[record[0]] = record[1]

  return action_count_map


def get_visible_repositories(username, namespace=None, include_public=False):
  """ Returns the repositories visible to the given user (if any).
  """
  if not include_public and not username:
    return []

  query = (Repository
           .select(Repository.name, Repository.id.alias('id'), Repository.description, Namespace.username,
                   Repository.visibility)
           .distinct()
           .switch(Repository)
           .join(Namespace, on=(Repository.namespace_user == Namespace.id))
           .switch(Repository)
           .join(RepositoryPermission, JOIN_LEFT_OUTER))

  query = _basequery.filter_to_repos_for_user(query, username, namespace, include_public)
  return query


def get_sorted_matching_repositories(prefix, only_public, checker, limit=10):
  """ Returns repositories matching the given prefix string and passing the given checker
      function.
  """
  last_week = datetime.now() - timedelta(weeks=1)
  results = []
  existing_ids = []

  def get_search_results(search_clause, with_count=False):
    if len(results) >= limit:
      return

    select_items = [Repository, Namespace]
    if with_count:
      select_items.append(fn.Sum(RepositoryActionCount.count).alias('count'))

    query = (Repository
             .select(*select_items)
             .join(Namespace, on=(Namespace.id == Repository.namespace_user))
             .switch(Repository)
             .where(search_clause)
             .group_by(Repository.id, Namespace.id))

    if only_public:
      query = query.where(Repository.visibility == _basequery.get_public_repo_visibility())

    if existing_ids:
      query = query.where(~(Repository.id << existing_ids))

    if with_count:
      query = (query
               .switch(Repository)
               .join(RepositoryActionCount)
               .where(RepositoryActionCount.date >= last_week)
               .order_by(fn.Sum(RepositoryActionCount.count).desc()))

    for result in query:
      if len(results) >= limit:
        return results

      # Note: We compare IDs here, instead of objects, because calling .visibility on the
      # Repository will kick off a new SQL query to retrieve that visibility enum value. We don't
      # join the visibility table in SQL, as well, because it is ungodly slow in MySQL :-/
      result.is_public = result.visibility_id == _basequery.get_public_repo_visibility().id
      result.count = result.count if with_count else 0

      if not checker(result):
        continue

      results.append(result)
      existing_ids.append(result.id)

  # For performance reasons, we conduct the repo name and repo namespace searches on their
  # own. This also affords us the ability to give higher precedence to repository names matching
  # over namespaces, which is semantically correct.
  get_search_results(_basequery.prefix_search(Repository.name, prefix), with_count=True)
  get_search_results(_basequery.prefix_search(Repository.name, prefix), with_count=False)

  get_search_results(_basequery.prefix_search(Namespace.username, prefix), with_count=True)
  get_search_results(_basequery.prefix_search(Namespace.username, prefix), with_count=False)

  return results


def lookup_repository(repo_id):
  try:
    return Repository.get(Repository.id == repo_id)
  except Repository.DoesNotExist:
    return None


def is_repository_public(repository):
  return repository.visibility == _basequery.get_public_repo_visibility()


def repository_is_public(namespace_name, repository_name):
  try:
    (Repository
     .select()
     .join(Namespace, on=(Repository.namespace_user == Namespace.id))
     .switch(Repository)
     .join(Visibility)
     .where(Namespace.username == namespace_name, Repository.name == repository_name,
            Visibility.name == 'public')
     .get())
    return True
  except Repository.DoesNotExist:
    return False


def set_repository_visibility(repo, visibility):
  visibility_obj = Visibility.get(name=visibility)
  if not visibility_obj:
    return

  repo.visibility = visibility_obj
  repo.save()


def get_email_authorized_for_repo(namespace, repository, email):
  try:
    return (RepositoryAuthorizedEmail
            .select(RepositoryAuthorizedEmail, Repository, Namespace)
            .join(Repository)
            .join(Namespace, on=(Repository.namespace_user == Namespace.id))
            .where(Namespace.username == namespace, Repository.name == repository,
                   RepositoryAuthorizedEmail.email == email)
            .get())
  except RepositoryAuthorizedEmail.DoesNotExist:
    return None


def create_email_authorization_for_repo(namespace_name, repository_name, email):
  try:
    repo = _basequery.get_existing_repository(namespace_name, repository_name)
  except Repository.DoesNotExist:
    raise DataModelException('Invalid repository %s/%s' %
                             (namespace_name, repository_name))

  return RepositoryAuthorizedEmail.create(repository=repo, email=email, confirmed=False)


def confirm_email_authorization_for_repo(code):
  try:
    found = (RepositoryAuthorizedEmail
             .select(RepositoryAuthorizedEmail, Repository, Namespace)
             .join(Repository)
             .join(Namespace, on=(Repository.namespace_user == Namespace.id))
             .where(RepositoryAuthorizedEmail.code == code)
             .get())
  except RepositoryAuthorizedEmail.DoesNotExist:
    raise DataModelException('Invalid confirmation code.')

  found.confirmed = True
  found.save()

  return found