import logging
import re

from collections import namedtuple
from cachetools import lru_cache
from flask import request, jsonify

import features
from app import app, userevents, instance_keys
from auth.auth_context import get_authenticated_context, get_authenticated_user
from auth.decorators import process_basic_auth
from auth.permissions import (ModifyRepositoryPermission, ReadRepositoryPermission,
                              CreateRepositoryPermission, AdministerRepositoryPermission)
from endpoints.decorators import anon_protect
from endpoints.v2 import v2_bp
from endpoints.v2.errors import InvalidLogin, NameInvalid, InvalidRequest, Unsupported, Unauthorized
from endpoints.v2.models_pre_oci import data_model as model
from util.cache import no_cache
from util.names import parse_namespace_repository, REPOSITORY_NAME_REGEX
from util.security.registry_jwt import (generate_bearer_token, build_context_and_subject,
                                        QUAY_TUF_ROOT, SIGNER_TUF_ROOT, DISABLED_TUF_ROOT)

logger = logging.getLogger(__name__)

TOKEN_VALIDITY_LIFETIME_S = 60 * 60  # 1 hour
SCOPE_REGEX_TEMPLATE = r'^repository:((?:{}\/)?((?:[\.a-zA-Z0-9_\-]+\/)*[\.a-zA-Z0-9_\-]+)):((?:push|pull|\*)(?:,(?:push|pull|\*))*)$'

scopeResult = namedtuple('scopeResult', ['actions', 'namespace', 'repository', 'registry_and_repo',
                                         'tuf_root'])

@v2_bp.route('/auth')
@process_basic_auth
@no_cache
@anon_protect
def generate_registry_jwt(auth_result):
  """
  This endpoint will generate a JWT conforming to the Docker Registry v2 Auth Spec:
  https://docs.docker.com/registry/spec/auth/token/
  """
  audience_param = request.args.get('service')
  logger.debug('Request audience: %s', audience_param)

  scope_params = request.args.getlist('scope') or []
  logger.debug('Scope request: %s', scope_params)

  auth_header = request.headers.get('authorization', '')
  auth_credentials_sent = bool(auth_header)

  # Load the auth context and verify thatg we've directly received credentials.
  has_valid_auth_context = False
  if get_authenticated_context():
    has_valid_auth_context = not get_authenticated_context().is_anonymous

  if auth_credentials_sent and not has_valid_auth_context:
    # The auth credentials sent for the user are invalid.
    raise InvalidLogin(auth_result.error_message)

  if not has_valid_auth_context and len(scope_params) == 0:
    # In this case, we are doing an auth flow, and it's not an anonymous pull.
    logger.debug('No user and no token sent for empty scope list')
    raise Unauthorized()

  # Build the access list for the authenticated context.
  access = []
  scope_results = []
  for scope_param in scope_params:
    scope_result = _authorize_or_downscope_request(scope_param, has_valid_auth_context)
    if scope_result is None:
      continue

    scope_results.append(scope_result)
    access.append({
      'type': 'repository',
      'name': scope_result.registry_and_repo,
      'actions': scope_result.actions,
    })

  # Issue user events.
  user_event_data = {
    'action': 'login',
  }

  # Set the user event data for when authed.
  if len(scope_results) > 0:
    if 'push' in scope_results[0].actions:
      user_action = 'push_start'
    elif 'pull' in scope_results[0].actions:
      user_action = 'pull_start'
    else:
      user_action = 'login'

    user_event_data = {
      'action': user_action,
      'namespace': scope_results[0].namespace,
      'repository': scope_results[0].repository,
    }

  # Send the user event.
  if get_authenticated_user() is not None:
    event = userevents.get_event(get_authenticated_user().username)
    event.publish_event_data('docker-cli', user_event_data)

  # Build the signed JWT.
  tuf_roots = {'%s/%s' % (scope_result.namespace, scope_result.repository): scope_result.tuf_root
               for scope_result in scope_results}
  context, subject = build_context_and_subject(get_authenticated_context(), tuf_roots=tuf_roots)
  token = generate_bearer_token(audience_param, subject, context, access,
                                TOKEN_VALIDITY_LIFETIME_S, instance_keys)
  return jsonify({'token': token})


@lru_cache(maxsize=1)
def _get_scope_regex():
  hostname = re.escape(app.config['SERVER_HOSTNAME'])
  scope_regex_string = SCOPE_REGEX_TEMPLATE.format(hostname)
  return re.compile(scope_regex_string)


def _get_tuf_root(repo, namespace, reponame):
  if not features.SIGNING or repo is None or not repo.trust_enabled:
    return DISABLED_TUF_ROOT

  # Users with write access to a repo will see signer-rooted TUF metadata
  if ModifyRepositoryPermission(namespace, reponame).can():
    return SIGNER_TUF_ROOT
  return QUAY_TUF_ROOT


def _authorize_or_downscope_request(scope_param, has_valid_auth_context):
  if len(scope_param) == 0:
    if not has_valid_auth_context:
      # In this case, we are doing an auth flow, and it's not an anonymous pull.
      logger.debug('No user and no token sent for empty scope list')
      raise Unauthorized()

    return None

  match = _get_scope_regex().match(scope_param)
  if match is None:
    logger.debug('Match: %s', match)
    logger.debug('len: %s', len(scope_param))
    logger.warning('Unable to decode repository and actions: %s', scope_param)
    raise InvalidRequest('Unable to decode repository and actions: %s' % scope_param)

  logger.debug('Match: %s', match.groups())

  registry_and_repo = match.group(1)
  namespace_and_repo = match.group(2)
  actions = match.group(3).split(',')

  lib_namespace = app.config['LIBRARY_NAMESPACE']
  namespace, reponame = parse_namespace_repository(namespace_and_repo, lib_namespace)

  # Ensure that we are never creating an invalid repository.
  if not REPOSITORY_NAME_REGEX.match(reponame):
    logger.debug('Found invalid repository name in auth flow: %s', reponame)
    if len(namespace_and_repo.split('/')) > 1:
      msg = 'Nested repositories are not supported. Found: %s' % namespace_and_repo
      raise NameInvalid(message=msg)

    raise NameInvalid(message='Invalid repository name: %s' % namespace_and_repo)

  final_actions = []

  repo = model.get_repository(namespace, reponame)
  repo_is_public = repo is not None and repo.is_public
  invalid_repo_message = ''
  if repo is not None and repo.kind != 'image':
    invalid_repo_message = ((
      'This repository is for managing %s resources ' + 'and not container images.') % repo.kind)

  if 'push' in actions:
    # Check if there is a valid user or token, as otherwise the repository cannot be
    # accessed.
    if has_valid_auth_context:
      # Lookup the repository. If it exists, make sure the entity has modify
      # permission. Otherwise, make sure the entity has create permission.
      if repo:
        if ModifyRepositoryPermission(namespace, reponame).can():
          if repo.kind != 'image':
            raise Unsupported(message=invalid_repo_message)

          final_actions.append('push')
        else:
          logger.debug('No permission to modify repository %s/%s', namespace, reponame)
      else:
        user = get_authenticated_user()
        if CreateRepositoryPermission(namespace).can() and user is not None:
          logger.debug('Creating repository: %s/%s', namespace, reponame)
          model.create_repository(namespace, reponame, user)
          final_actions.append('push')
        else:
          logger.debug('No permission to create repository %s/%s', namespace, reponame)

  if 'pull' in actions:
    # Grant pull if the user can read the repo or it is public.
    if ReadRepositoryPermission(namespace, reponame).can() or repo_is_public:
      if repo is not None and repo.kind != 'image':
        raise Unsupported(message=invalid_repo_message)

      final_actions.append('pull')
    else:
      logger.debug('No permission to pull repository %s/%s', namespace, reponame)

  if '*' in actions:
    # Grant * user is admin
    if AdministerRepositoryPermission(namespace, reponame).can():
      if repo is not None and repo.kind != 'image':
        raise Unsupported(message=invalid_repo_message)

      final_actions.append('*')
    else:
      logger.debug("No permission to administer repository %s/%s", namespace, reponame)

  return scopeResult(actions=final_actions, namespace=namespace, repository=reponame,
                     registry_and_repo=registry_and_repo,
                     tuf_root=_get_tuf_root(repo, namespace, reponame))