import re

from django.contrib.auth import logout
from django.db import transaction
from django.db.models import F
from django.shortcuts import redirect, render
from django.utils import timezone
from django.views.decorators.cache import never_cache
from django.views.decorators.http import require_http_methods

from . import access, services
from .models import PaymentAccessLink


@never_cache
@require_http_methods(['GET', 'POST'])
def open_link(request, token):
    # Keep previously issued long links valid until their original expiry/revocation.
    link = access.active_links().filter(token_hash=access.token_digest(token)).first() if re.fullmatch(r'(?:[a-z0-9]{10}|[A-Za-z0-9_-]{43})', token) else None
    if link is None:
        return access.unavailable_link(request)
    if request.user.is_authenticated and request.user.pk != link.customer_id:
        confirmed = request.method == 'POST' and request.POST.get('action') == 'logout_and_open' and request.POST.get('account_id') == str(request.user.pk)
        if not confirmed:
            response = render(request, 'payments/link_confirmation.html')
            response['Referrer-Policy'] = 'same-origin'
            response['X-Robots-Tag'] = 'noindex, nofollow'
            return response
        logout(request)
    if not request.user.is_authenticated:
        access.grant_payment_access(request, link)
    with transaction.atomic():
        PaymentAccessLink.objects.filter(pk=link.pk).update(view_count=F('view_count') + 1, last_used_at=timezone.now())
        services.audit(None, 'PAYMENT_LINK_OPENED', link, {
            'ip_address': request.META.get('REMOTE_ADDR', ''),
            'user_agent': request.META.get('HTTP_USER_AGENT', '')[:500]})
    target = link.receipt or link.notice
    response = redirect('payments:receipt_detail' if link.receipt_id else 'payments:notice_detail', public_id=target.public_id)
    response['Referrer-Policy'] = 'no-referrer'
    response['X-Robots-Tag'] = 'noindex, nofollow'
    return response