import re

from django.core.exceptions import ValidationError

from pingcap_sso.validators.username import validate_username
from pingcap_sso.models import User
from pingcap_sso.github.exceptions import AuthUserUnregisteredError


def check_if_user_exists(strategy, details, backend, user=None, *args, **kwargs):
    if user:
        return {'is_new': False}
    raise AuthUserUnregisteredError(backend)

USER_FIELDS = ['username', 'email']
USERNAME_SLUGIFY_PATTERN = re.compile(r'[a-zA-Z\d\u4e00-\u9fa5]+')


def get_username(strategy, details, backend, user=None, *args, **kwargs):
    if 'username' not in backend.setting('USER_FIELDS', USER_FIELDS):
        return

    storage = strategy.storage

    if not user:
        final_username = details.get('username', User.generate_random_username())
        
        try:
            validate_username(final_username)
        except ValidationError:
            final_username = '_'.join(USERNAME_SLUGIFY_PATTERN.findall(final_username))
            try:
                validate_username(final_username)
            except ValidationError:
                final_username = User.generate_random_username()

        if storage.user.user_exists(username=final_username):
            final_username = User.generate_random_username()
    else:
        final_username = storage.user.get_username(user)
    return {'username': final_username}


def track_signup_channel(strategy, details, backend, user=None, is_new=False, *args, **kwargs):
    """新用户记录注册来源"""
    if not user or not is_new:
        return

    from django.urls import reverse
    from pingcap_sso.lib.sso import parse_signup_channel_from_url

    original_redirect = strategy.session_get('next', '') or reverse('index')
    user.signup_source_url = original_redirect[:500]
    user.signup_channel = parse_signup_channel_from_url(original_redirect)
    user.save(update_fields=['signup_channel', 'signup_source_url'])