"""passbook SAML IDP Views"""
from logging import getLogger

from django.contrib import auth
from django.contrib.auth.decorators import login_required
from django.core.exceptions import ValidationError
from django.core.validators import URLValidator
from django.http import (HttpResponse, HttpResponseBadRequest,
                         HttpResponseRedirect)
from django.shortcuts import redirect, render
from django.urls import reverse
from django.utils.datastructures import MultiValueDictKeyError
# from django.utils.html import escape
# from django.utils.translation import ugettext as _
from django.views.decorators.csrf import csrf_exempt

from passbook.lib.config import CONFIG
# from passbook.core.models import Event, Setting, UserAcquirableRelationship
from passbook.lib.utils.template import render_to_string
# from passbook.core.views.common import ErrorResponseView
# from passbook.core.views.settings import GenericSettingView
from passbook.saml_idp import exceptions, registry, xml_signing

# from OpenSSL.crypto import FILETYPE_PEM
# from OpenSSL.crypto import Error as CryptoError
# from OpenSSL.crypto import load_certificate


LOGGER = getLogger(__name__)
URL_VALIDATOR = URLValidator(schemes=('http', 'https'))


def _generate_response(request, processor, remote):
    """Generate a SAML response using processor and return it in the proper Django
    response."""
    try:
        ctx = processor.generate_response()
        ctx['remote'] = remote
    except exceptions.UserNotAuthorized:
        return render(request, 'saml/idp/invalid_user.html')

    return render(request, 'saml/idp/login.html', ctx)


def render_xml(request, template, ctx):
    """Render template with content_type application/xml"""
    return render(request, template, context=ctx, content_type="application/xml")


@csrf_exempt
def login_begin(request):
    """Receives a SAML 2.0 AuthnRequest from a Service Provider and
    stores it in the session prior to enforcing login."""
    if request.method == 'POST':
        source = request.POST
    else:
        source = request.GET
    # Store these values now, because Django's login cycle won't preserve them.

    try:
        request.session['SAMLRequest'] = source['SAMLRequest']
    except (KeyError, MultiValueDictKeyError):
        return HttpResponseBadRequest('the SAML request payload is missing')

    request.session['RelayState'] = source.get('RelayState', '')
    return redirect(reverse('passbook_saml_idp:saml_login_process'))


def redirect_to_sp(request, acs_url, saml_response, relay_state):
    """Return autosubmit form"""
    return render(request, 'core/autosubmit_form.html', {
        'url': acs_url,
        'attrs': {
            'SAMLResponse': saml_response,
            'RelayState': relay_state
        }
    })


@login_required
def login_process(request):
    """Processor-based login continuation.
    Presents a SAML 2.0 Assertion for POSTing back to the Service Provider."""
    LOGGER.debug("Request: %s", request)
    proc, remote = registry.find_processor(request)
    # Check if user has access
    access = True
    # if remote.productextensionsaml2_set.exists() and \
    #         remote.productextensionsaml2_set.first().product_set.exists():
    #     # Only check if there is a connection from OAuth2 Application to product
    #     product = remote.productextensionsaml2_set.first().product_set.first()
    #     relationship = UserAcquirableRelationship.objects.filter(user=request.user, model=product)
    #     # Product is invite_only = True and no relation with user exists
    #     if product.invite_only and not relationship.exists():
    #         access = False
    # Check if we should just autosubmit
    if remote.skip_authorization and access:
        # full_res = _generate_response(request, proc, remote)
        ctx = proc.generate_response()
        # User accepted request
        # Event.create(
        #     user=request.user,
        #     message=_('You authenticated %s (via SAML) (skipped Authz)' % remote.name),
        #     request=request,
        #     current=False,
        #     hidden=True)
        return redirect_to_sp(
            request=request,
            acs_url=ctx['acs_url'],
            saml_response=ctx['saml_response'],
            relay_state=ctx['relay_state'])
    if request.method == 'POST' and request.POST.get('ACSUrl', None) and access:
        # User accepted request
        # Event.create(
        #     user=request.user,
        #     message=_('You authenticated %s (via SAML)' % remote.name),
        #     request=request,
        #     current=False,
        #     hidden=True)
        return redirect_to_sp(
            request=request,
            acs_url=request.POST.get('ACSUrl'),
            saml_response=request.POST.get('SAMLResponse'),
            relay_state=request.POST.get('RelayState'))
    try:
        full_res = _generate_response(request, proc, remote)
        # if not access:
        #     LOGGER.warning("User '%s' has no invitation to '%s'", request.user, product)
        #     messages.error(request, "You have no access to '%s'" % product.name)
        #     raise Http404
        return full_res
    except exceptions.CannotHandleAssertion as exc:
        LOGGER.debug(exc)
        # return ErrorResponseView.as_view()(request, str(exc))


@csrf_exempt
def logout(request):
    """Allows a non-SAML 2.0 URL to log out the user and
    returns a standard logged-out page. (SalesForce and others use this method,
    though it's technically not SAML 2.0)."""
    auth.logout(request)

    redirect_url = request.GET.get('redirect_to', '')

    try:
        URL_VALIDATOR(redirect_url)
    except ValidationError:
        pass
    else:
        return HttpResponseRedirect(redirect_url)

    return render(request, 'saml/idp/logged_out.html')


@login_required
@csrf_exempt
def slo_logout(request):
    """Receives a SAML 2.0 LogoutRequest from a Service Provider,
    logs out the user and returns a standard logged-out page."""
    request.session['SAMLRequest'] = request.POST['SAMLRequest']
    # TODO: Parse SAML LogoutRequest from POST data, similar to login_process().
    # TODO: Add a URL dispatch for this view.
    # TODO: Modify the base processor to handle logouts?
    # TODO: Combine this with login_process(), since they are so very similar?
    # TODO: Format a LogoutResponse and return it to the browser.
    # XXX: For now, simply log out without validating the request.
    auth.logout(request)
    return render(request, 'saml/idp/logged_out.html')


def descriptor(request):
    """Replies with the XML Metadata IDSSODescriptor."""
    entity_id = CONFIG.y('saml_idp.issuer')
    slo_url = request.build_absolute_uri(reverse('passbook_saml_idp:saml_logout'))
    sso_url = request.build_absolute_uri(reverse('passbook_saml_idp:saml_login_begin'))
    pubkey = xml_signing.load_certificate(strip=True)
    ctx = {
        'entity_id': entity_id,
        'cert_public_key': pubkey,
        'slo_url': slo_url,
        'sso_url': sso_url
    }
    metadata = render_to_string('saml/xml/metadata.xml', ctx)
    response = HttpResponse(metadata, content_type='application/xml')
    response['Content-Disposition'] = 'attachment; filename="passbook_metadata.xml'
    return response


# class IDPSettingsView(GenericSettingView):
#     """IDP Settings"""

#     form = IDPSettingsForm
#     template_name = 'saml/idp/settings.html'

#     def dispatch(self, request, *args, **kwargs):
#         self.extra_data['metadata'] = escape(descriptor(request).content.decode('utf-8'))

#         # Show the certificate fingerprint
#         sha1_fingerprint = _('<failed to parse certificate>')
#         try:
#             cert = load_certificate(FILETYPE_PEM, CONFIG.y('saml_idp.certificate'))
#             sha1_fingerprint = cert.digest("sha1")
#         except CryptoError:
#             pass
#         self.extra_data['fingerprint'] = sha1_fingerprint
#         return super().dispatch(request, *args, **kwargs)