from urllib.parse import quote

from django.conf import settings
from django.contrib.auth import REDIRECT_FIELD_NAME
from django.http.multipartparser import MultiPartParserError
from django.utils.functional import SimpleLazyObject

try:
    from django.utils.functional import empty as _empty

    empty = _empty
except ImportError:  # django < 1.4
    empty = None


from social_core.backends.utils import user_backends_data

from .utils import Storage


class LazyDict(SimpleLazyObject):
    """Lazy dict initialization."""

    def __getitem__(self, name):
        if self._wrapped is empty:
            self._setup()
        return self._wrapped[name]

    def __setitem__(self, name, value):
        if self._wrapped is empty:
            self._setup()
        self._wrapped[name] = value


def backends(request):
    """Load Social Auth current user data to context under the key 'backends'.
    Will return the output of social_core.backends.utils.user_backends_data."""
    return {
        "backends": LazyDict(
            lambda: user_backends_data(
                request.user, settings.AUTHENTICATION_BACKENDS, Storage
            )
        )
    }


def login_redirect(request):
    """Load current redirect to context."""
    try:
        value = (
            request.method == "POST"
            and request.POST.get(REDIRECT_FIELD_NAME)
            or request.GET.get(REDIRECT_FIELD_NAME)
        )
    except MultiPartParserError:
        # request POST may be malformed
        value = None
    if value:
        value = quote(value)
        querystring = REDIRECT_FIELD_NAME + "=" + value
    else:
        querystring = ""

    return {
        "REDIRECT_FIELD_NAME": REDIRECT_FIELD_NAME,
        "REDIRECT_FIELD_VALUE": value,
        "REDIRECT_QUERYSTRING": querystring,
    }