import datetime
import json
import base64

from contextlib import contextmanager
from data import model

from flask import g
from flask_principal import Identity

CSRF_TOKEN_KEY = '_csrf_token'
CSRF_TOKEN = '123csrfforme'

@contextmanager
def client_with_identity(auth_username, client):
  with client.session_transaction() as sess:
    if auth_username and auth_username is not None:
      loaded = model.user.get_user(auth_username)
      sess['user_id'] = loaded.uuid
      sess['login_time'] = datetime.datetime.now()
      sess[CSRF_TOKEN_KEY] = CSRF_TOKEN
    else:
      sess['user_id'] = 'anonymous'

  yield client

  with client.session_transaction() as sess:
    sess['user_id'] = None
    sess['login_time'] = None
    sess[CSRF_TOKEN_KEY] = None


@contextmanager
def toggle_feature(name, enabled):
  """ Context manager which temporarily toggles a feature. """
  import features
  previous_value = getattr(features, name)
  setattr(features, name, enabled)
  yield
  setattr(features, name, previous_value)


def add_csrf_param(params):
  """ Returns a params dict with the CSRF parameter added. """
  params = params or {}

  if not CSRF_TOKEN_KEY in params:
    params[CSRF_TOKEN_KEY] = CSRF_TOKEN

  return params


def gen_basic_auth(username, password):
  """ Generates a basic auth header. """
  return 'Basic ' + base64.b64encode("%s:%s" % (username, password))


def conduct_call(client, resource, url_for, method, params, body=None, expected_code=200,
                 headers=None, raw_body=None):
  """ Conducts a call to a Flask endpoint. """
  params = add_csrf_param(params)

  final_url = url_for(resource, **params)

  headers = headers or {}
  headers.update({"Content-Type": "application/json"})

  if body is not None:
    body = json.dumps(body)

  if raw_body is not None:
    body = raw_body

  # Required for anonymous calls to not exception.
  g.identity = Identity(None, 'none')

  rv = client.open(final_url, method=method, data=body, headers=headers)
  msg = '%s %s: got %s expected: %s | %s' % (method, final_url, rv.status_code, expected_code,
                                             rv.data)
  assert rv.status_code == expected_code, msg
  return rv