import logging
import uuid

from flask import request, redirect, url_for, Blueprint
from peewee import IntegrityError

import features

from app import app, analytics, get_app_url, oauth_login
from auth.auth_context import get_authenticated_user
from auth.process import require_session_login
from data import model
from endpoints.common import common_login
from endpoints.web import index
from endpoints.csrf import csrf_protect, OAUTH_CSRF_TOKEN_NAME
from oauth.login import OAuthLoginException
from util.validation import generate_valid_usernames

logger = logging.getLogger(__name__)
client = app.config['HTTPCLIENT']
oauthlogin = Blueprint('oauthlogin', __name__)

oauthlogin_csrf_protect = csrf_protect(OAUTH_CSRF_TOKEN_NAME, 'state', all_methods=True)

def _render_ologin_error(service_name, error_message=None, register_redirect=False):
  """ Returns a Flask response indicating an OAuth error. """

  user_creation = bool(features.USER_CREATION and features.DIRECT_LOGIN)
  error_info = {
    'reason': 'ologinerror',
    'service_name': service_name,
    'error_message': error_message or 'Could not load user data. The token may have expired',
    'service_url': get_app_url(),
    'user_creation': user_creation,
    'register_redirect': register_redirect,
  }

  resp = index('', error_info=error_info)
  resp.status_code = 400
  return resp

def _conduct_oauth_login(service_id, service_name, user_id, username, email, metadata=None):
  """ Conducts login from the result of an OAuth service's login flow. """

  to_login = model.user.verify_federated_login(service_id, user_id)
  if not to_login:
    # See if we can create a new user.
    if not features.USER_CREATION:
      error_message = 'User creation is disabled. Please contact your administrator'
      return _render_ologin_error(service_name, error_message)

    # Try to create the user
    try:
      # Generate a valid username.
      new_username = None
      for valid in generate_valid_usernames(username):
        if model.user.get_user_or_org(valid):
          continue

        new_username = valid
        break

      # Generate a valid email. If the email is None and the MAILING feature is turned
      # off, simply place in a fake email address.
      if email is None and not features.MAILING:
        email = '%s@fake.example.com' % (str(uuid.uuid4()))

      prompts = model.user.get_default_user_prompts(features)
      to_login = model.user.create_federated_user(new_username, email, service_id,
                                                  user_id, set_password_notification=True,
                                                  metadata=metadata or {},
                                                  prompts=prompts)

      # Success, tell analytics
      analytics.track(to_login.username, 'register', {'service': service_name.lower()})

    except model.InvalidEmailAddressException:
      message = "The e-mail address %s is already associated " % (email, )
      message = message + "with an existing %s account." % (app.config['REGISTRY_TITLE_SHORT'], )
      message = message + "\nPlease log in with your username and password and "
      message = message + "associate your %s account to use it in the future." % (service_name, )

      return _render_ologin_error(service_name, message, register_redirect=True)

    except model.DataModelException as ex:
      return _render_ologin_error(service_name, ex.message)

  if common_login(to_login):
    if model.user.has_user_prompts(to_login):
      return redirect(url_for('web.updateuser'))
    else:
      return redirect(url_for('web.index'))

  return _render_ologin_error(service_name)


def _register_service(login_service):
  """ Registers the given login service, adding its callback and attach routes to the blueprint. """

  @oauthlogin_csrf_protect
  def callback_func():
    # Check for a callback error.
    error = request.args.get('error', None)
    if error:
      return _render_ologin_error(login_service.service_name(), error)

    # Exchange the OAuth code for login information.
    code = request.args.get('code')
    try:
      lid, lusername, lemail = login_service.exchange_code_for_login(app.config, client, code, '')
    except OAuthLoginException as ole:
      logger.exception('Got login exception')
      return _render_ologin_error(login_service.service_name(), ole.message)

    # Conduct login.
    metadata = {
      'service_username': lusername
    }

    return _conduct_oauth_login(login_service.service_id(), login_service.service_name(), lid,
                                lusername, lemail, metadata=metadata)


  @require_session_login
  @oauthlogin_csrf_protect
  def attach_func():
    # Check for a callback error.
    error = request.args.get('error', None)
    if error:
      return _render_ologin_error(login_service.service_name(), error)

    # Exchange the OAuth code for login information.
    code = request.args.get('code')
    try:
      lid, lusername, _ = login_service.exchange_code_for_login(app.config, client, code, '/attach')
    except OAuthLoginException as ole:
      return _render_ologin_error(login_service.service_name(), ole.message)

    # Conduct attach.
    metadata = {
      'service_username': lusername
    }

    user_obj = get_authenticated_user()

    try:
      model.user.attach_federated_login(user_obj, login_service.service_id(), lid,
                                        metadata=metadata)
    except IntegrityError:
      err = '%s account %s is already attached to a %s account' % (
        login_service.service_name(), lusername, app.config['REGISTRY_TITLE_SHORT'])
      return _render_ologin_error(login_service.service_name(), err)

    return redirect(url_for('web.user_view', path=user_obj.username, tab='external'))


  oauthlogin.add_url_rule('/%s/callback' % login_service.service_id(),
                          '%s_oauth_callback' % login_service.service_id(),
                          callback_func,
                          methods=['GET'])

  oauthlogin.add_url_rule('/%s/callback/attach' % login_service.service_id(),
                          '%s_oauth_attach' % login_service.service_id(),
                          attach_func,
                          methods=['GET'])

# Register the routes for each of the login services.
for current_service in oauth_login.services:
  _register_service(current_service)