""" Various decorators for endpoint and API handlers. """

import os
import logging

from functools import wraps
from flask import abort, request, make_response

import features

from app import app, ip_resolver, model_cache
from auth.auth_context import get_authenticated_context, get_authenticated_user
from data.database import RepositoryState
from data.model.repository import get_repository, get_repository_state
from data.model.repo_mirror import get_mirroring_robot, get_mirror
from data.registry_model import registry_model
from data.readreplica import ReadOnlyModeException
from util.names import parse_namespace_repository, ImplicitLibraryNamespaceNotAllowed
from util.http import abort
from util.request import get_request_ip

logger = logging.getLogger(__name__)


def parse_repository_name(include_tag=False,
                          ns_kwarg_name='namespace_name',
                          repo_kwarg_name='repo_name',
                          tag_kwarg_name='tag_name',
                          incoming_repo_kwarg='repository'):
  """ Decorator which parses the repository name found in the incoming_repo_kwarg argument,
      and applies its pieces to the decorated function.
  """
  def inner(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
      try:
        repo_name_components = parse_namespace_repository(kwargs[incoming_repo_kwarg],
                                                          app.config['LIBRARY_NAMESPACE'],
                                                          include_tag=include_tag,
                                                          allow_library=features.LIBRARY_SUPPORT)
      except ImplicitLibraryNamespaceNotAllowed:
        abort(400, message='A namespace must be specified explicitly')

      del kwargs[incoming_repo_kwarg]
      kwargs[ns_kwarg_name] = repo_name_components[0]
      kwargs[repo_kwarg_name] = repo_name_components[1]
      if include_tag:
        kwargs[tag_kwarg_name] = repo_name_components[2]
      return func(*args, **kwargs)
    return wrapper
  return inner


def param_required(param_name, allow_body=False):
  """ Marks a route as requiring a parameter with the given name to exist in the request's arguments
      or (if allow_body=True) in its body values. If the parameter is not present, the request will
      fail with a 400.
  """
  def wrapper(wrapped):
    @wraps(wrapped)
    def decorated(*args, **kwargs):
      if param_name not in request.args:
        if not allow_body or param_name not in request.values:
          abort(400, message='Required param: %s' % param_name)
      return wrapped(*args, **kwargs)
    return decorated
  return wrapper


def readonly_call_allowed(func):
  """ Marks a method as allowing for invocation when the registry is in a read only state.
      Only necessary on non-GET methods.
  """
  func.__readonly_call_allowed = True
  return func


def anon_allowed(func):
  """ Marks a method to allow anonymous access where it would otherwise be disallowed. """
  func.__anon_allowed = True
  return func


def anon_protect(func):
  """ Marks a method as requiring some form of valid user auth before it can be executed. """
  func.__anon_protected = True
  return check_anon_protection(func)


def check_anon_protection(func):
  """ Validates a method as requiring some form of valid user auth before it can be executed. """

  @wraps(func)
  def wrapper(*args, **kwargs):
    # Skip if anonymous access is allowed.
    if features.ANONYMOUS_ACCESS or '__anon_allowed' in dir(func):
      return func(*args, **kwargs)

    # Check for validated context. If none exists, fail with a 401.
    if get_authenticated_context() and not get_authenticated_context().is_anonymous:
      return func(*args, **kwargs)

    abort(401, message='Anonymous access is not allowed')

  return wrapper


def check_readonly(func):
  """ Validates that a non-GET method is not invoked when the registry is in read-only mode,
      unless explicitly marked as being allowed.
  """

  @wraps(func)
  def wrapper(*args, **kwargs):
    # Skip if a GET method.
    if request.method == 'GET':
      return func(*args, **kwargs)

    # Skip if not in read only mode.
    if app.config.get('REGISTRY_STATE', 'normal') != 'readonly':
      return func(*args, **kwargs)

    # Skip if readonly access is allowed.
    if hasattr(func, '__readonly_call_allowed'):
      return func(*args, **kwargs)

    raise ReadOnlyModeException()
  return wrapper


def route_show_if(value):
  """ Adds/shows the decorated route if the given value is True. """

  def decorator(f):
    @wraps(f)
    def decorated_function(*args, **kwargs):
      if not value:
        abort(404)

      return f(*args, **kwargs)
    return decorated_function
  return decorator


def require_xhr_from_browser(func):
  """ Requires that API GET calls made from browsers are made via XHR, in order to prevent
      reflected text attacks.
  """

  @wraps(func)
  def wrapper(*args, **kwargs):
    if app.config.get('BROWSER_API_CALLS_XHR_ONLY', False):
      if request.method == 'GET' and request.user_agent.browser:
        has_xhr_header = request.headers.get('X-Requested-With') == 'XMLHttpRequest'
        if not has_xhr_header and not app.config.get('DEBUGGING') == True:
          logger.warning('Disallowed possible RTA to URL %s with user agent %s',
                         request.path, request.user_agent)
          abort(400, message='API calls must be invoked with an X-Requested-With header ' +
                'if called from a browser')

    return func(*args, **kwargs)
  return wrapper


def check_region_blacklisted(error_class=None, namespace_name_kwarg=None):
  """ Decorator which checks if the incoming request is from a region geo IP blocked
      for the current namespace. The first argument to the wrapped function must be
      the namespace name.
  """
  def wrapper(wrapped):
    @wraps(wrapped)
    def decorated(*args, **kwargs):
      if namespace_name_kwarg:
        namespace_name = kwargs[namespace_name_kwarg]
      else:
        namespace_name = args[0]

      region_blacklist = registry_model.get_cached_namespace_region_blacklist(model_cache,
                                                                              namespace_name)
      if region_blacklist:
        # Resolve the IP information and block if on the namespace's blacklist.
        remote_ip = get_request_ip()
        resolved_ip_info = ip_resolver.resolve_ip(remote_ip)
        logger.debug('Resolved IP information for IP %s: %s', remote_ip, resolved_ip_info)

        if (resolved_ip_info and
            resolved_ip_info.country_iso_code and
            resolved_ip_info.country_iso_code in region_blacklist):
          if error_class:
            raise error_class()

          abort(403, 'Pulls of this data have been restricted geographically')

      return wrapped(*args, **kwargs)
    return decorated
  return wrapper


def check_repository_state(f):
  @wraps(f)
  def wrapper(namespace_name, repo_name, *args, **kwargs):
    """
    Conditionally allow changes depending on the Repository's state.
    NORMAL    -> Pass
    READ_ONLY -> Block all POST/PUT/DELETE
    MIRROR    -> Same as READ_ONLY, except treat the Mirroring Robot User as Normal
    """
    user = get_authenticated_user()
    if user is None:
      # NOTE: Remaining auth checks will be handled by subsequent decorators.
      return f(namespace_name, repo_name, *args, **kwargs)

    repository = get_repository(namespace_name, repo_name)
    if not repository:
      return f(namespace_name, repo_name, *args, **kwargs)

    if repository.state == RepositoryState.READ_ONLY:
      abort(405, '%s/%s is in read-only mode.' % (namespace_name, repo_name))

    if repository.state == RepositoryState.MIRROR:
      mirror = get_mirror(repository)
      robot = mirror.internal_robot if mirror is not None else None

      if mirror is None:
        abort(500, 'Repository %s/%s is set as a mirror but the Mirror configuration is missing.' % (
          namespace_name, repo_name))

      elif robot is None:
        abort(400, 'Repository %s/%s is configured for mirroring but no robot is assigned.' % (
          namespace_name, repo_name))

      elif user.id != robot.id:
        abort(405,
          'Repository %s/%s is a mirror. Mirrored repositories cannot be modified directly.' % (
            namespace_name, repo_name))

      elif user.id == robot.id:
        pass  # User is designated robot for this mirror repo.

      else:
        msg = (
          'An internal error has occurred while verifying repository %s/%s state. Please report '
          'this to an administrator.'
        ) % (namespace_name, repo_name)
        raise Exception(msg)

    return f(namespace_name, repo_name, *args, **kwargs)
  return wrapper