www/membership/members/views.py

import hashlib
import logging
import re
import secrets
import uuid
from datetime import timedelta
from functools import wraps
from urllib.parse import urlsplit

import stripe
from authlib.integrations.django_client import OAuth
from django.conf import settings
from django.core.validators import validate_email
from django.core.mail import send_mail
from django.db import ProgrammingError, transaction
from django.http import HttpResponse
from django.shortcuts import get_object_or_404, redirect, render
from django.db.models import Q
from django.urls import reverse
from django.utils import timezone
from django.utils.crypto import salted_hmac
from django.views.decorators.csrf import csrf_exempt
from django.views.decorators.debug import sensitive_post_parameters
from django.views.decorators.http import require_GET, require_POST, require_http_methods

from . import billing, directory, newsletter, profiles, shkeeper
from .forms import PasswordForm, RegistrationForm
from .service_groups import configured_groups, service_access_catalog
from .profile_forms import CurrentPasswordForm, ProfileEmailForm, ProfileForm, ProfilePasswordForm
from .models import Account, CryptoInvoice, ManagedGroup, ProfileEmailChange, RateWindow, Registration, Subscription, WebhookEvent

logger = logging.getLogger(__name__)


def page(request, **context):
    return render(request, "members.html", context)


def limited(scope, value, limit, seconds=3600):
    now = timezone.now()
    window = int(now.timestamp()) // seconds
    key = salted_hmac("membership-rate", f"{scope}:{value}:{window}").hexdigest()
    with transaction.atomic():
        entry, _ = RateWindow.objects.get_or_create(key=key, defaults={"expires_at": now + timedelta(seconds=seconds)})
        entry = RateWindow.objects.select_for_update().get(pk=entry.pk)
        entry.count += 1
        entry.save(update_fields=["count"])
        return entry.count > limit


def client_ip(request):
    if getattr(settings, "SECURE_PROXY_SSL_HEADER", None):
        return request.META.get("HTTP_X_MEMBERSHIP_CLIENT_IP", request.META.get("REMOTE_ADDR", ""))
    return request.META.get("REMOTE_ADDR", "")


def account_required(view):
    @wraps(view)
    def wrapped(request, *args, **kwargs):
        try:
            request.member = Account.objects.get(pk=request.session.get("account_id"))
        except (Account.DoesNotExist, ValueError, TypeError):
            return redirect("members:home")
        return view(request, *args, **kwargs)
    return wrapped


def remember_groups(account):
    for dn in configured_groups(settings.MEMBERSHIP_TIERS, settings.MEMBERSHIP_SERVICE_GROUPS):
        ManagedGroup.objects.get_or_create(account=account, dn=dn)


@require_GET
def home(request):
    account = Account.objects.filter(pk=request.session.get("account_id")).first() if request.session.get("account_id") else None
    subscriptions = Subscription.objects.filter(account=account) if account else []
    invoices = CryptoInvoice.objects.filter(account=account).order_by("-created_at")[:20] if account else []
    # Presentation copies only: never mutate authorization/payment settings.
    tiers = settings.MEMBERSHIP_TIERS
    services = service_access_catalog(tiers, settings.MEMBERSHIP_SERVICE_GROUPS)
    # Public total across every level (free and paid); never a per-tier breakdown.
    member_count = Account.objects.count()
    return page(request, account=account, tiers=tiers, services=services, subscriptions=subscriptions, crypto_invoices=invoices, shkeeper_enabled=settings.SHKEEPER_ENABLED, now=timezone.now(), member_count=member_count)


@require_http_methods(["GET", "POST"])
def register(request):
    form = RegistrationForm(request.POST or None)
    if request.method == "POST" and form.is_valid():
        email = form.cleaned_data["email"]
        if limited("signup-ip", client_ip(request), 20) or limited("signup-email", email, 3):
            return HttpResponse("Please try again later.", status=429)
        token = secrets.token_urlsafe(32)
        digest = hashlib.sha256(token.encode()).hexdigest()
        Registration.objects.create(token_hash=digest, uid=form.cleaned_data["uid"], email=email, newsletter=form.cleaned_data.get("newsletter", False), expires_at=timezone.now() + timedelta(hours=1))
        url = settings.PUBLIC_URL + reverse("members:verify", args=[token])
        try:
            send_mail("Verify your eom.dev account", f"Finish creating your account (expires in one hour):\n\n{url}\n\nIf you did not request this, ignore this message. Existing accounts are never changed by this link.", settings.DEFAULT_FROM_EMAIL, [email])
        except Exception as exc:
            Registration.objects.filter(pk=digest).delete()
            logger.error("Registration email failed kind=%s", type(exc).__name__)
            return page(request, title="Email unavailable", message="Account email could not be sent. Please try again later.")
        return page(request, title="Check your inbox", message="Follow the confirmation link in your email to choose a password and finish creating your free eom.dev account. If you already have an account, sign in instead.")
    return page(request, title="Create your free account", form=form, submit="Send verification email", registration=True)


@sensitive_post_parameters("password", "confirm_password")
@require_http_methods(["GET", "POST"])
def verify(request, token):
    if limited("verify-ip", client_ip(request), 60):
        return HttpResponse("Please try again later.", status=429)
    digest = hashlib.sha256(token.encode()).hexdigest()
    # Exchange the emailed bearer token for server-side session state, then
    # redirect so passwords are never posted to a URL containing that token.
    if request.method == "GET":
        if not Registration.objects.filter(pk=digest, expires_at__gt=timezone.now()).exists():
            return page(request, title="Link expired", message="Request a new verification email.")
        request.session["registration_hash"] = digest
        return redirect("members:finish_registration")
    return HttpResponse(status=405)


@sensitive_post_parameters("password", "confirm_password")
@require_http_methods(["GET", "POST"])
def finish_registration(request):
    digest = request.session.get("registration_hash")
    if not digest or not Registration.objects.filter(pk=digest, expires_at__gt=timezone.now()).exists():
        return page(request, title="Link expired", message="Request a new verification email.")
    form = PasswordForm(request.POST or None)
    if request.method == "POST" and form.is_valid():
        if limited("provision-ip", client_ip(request), 10):
            return HttpResponse("Please try again later.", status=429)
        try:
            with transaction.atomic():
                registration = Registration.objects.select_for_update().get(pk=digest, expires_at__gt=timezone.now())
                identity = directory.create_account(registration.uid, registration.email, form.cleaned_data["password"])
                account = Account.objects.create(**identity)
                remember_groups(account)
                Registration.objects.filter(uid=registration.uid).delete()
            request.session.pop("registration_hash", None)
            subscribed = registration.newsletter and _subscribe_newsletter(account)
            # Server-side, short-lived proof permits first binding of ONLY the
            # account just provisioned in this browser, never an email match.
            request.session["registration_identity"] = {"account_id": str(account.pk), "expires_at": (timezone.now() + timedelta(hours=1)).timestamp()}
            message = "Your free eom.dev account is ready. Sign in to explore the community and its services, or choose an optional paid membership for additional benefits."
            if subscribed:
                message += " You're subscribed to premiere emails; you can change that from your profile."
            elif registration.newsletter:
                message += " We couldn't sign you up for premiere emails just now; you can try again from your profile."
            return page(request, title="Account created", message=message)
        except ValueError:
            form.add_error(None, "An account with those details may already exist. Try signing in or contact us for help.")
        except Exception as exc:
            logger.error("Account provisioning failed kind=%s", type(exc).__name__)
            form.add_error(None, "Account creation could not finish. Try signing in first, or contact us for help before retrying.")
    return page(request, title="Choose your password", form=form, submit="Create free account")


def _subscribe_newsletter(account):
    # The address was verified by the registration link, so it is preconfirmed.
    # Best effort: the account already exists whatever happens here.
    try:
        return newsletter.subscribe(account.email, uid=account.uid) == newsletter.SUBSCRIBED
    except Exception as exc:
        logger.error("Newsletter subscribe failed account=%s kind=%s", account.pk, type(exc).__name__)
        return False


def _newsletter_status(account):
    if not newsletter.enabled():
        return None
    try:
        return newsletter.status(account.email)
    except Exception as exc:
        logger.error("Newsletter status failed account=%s kind=%s", account.pk, type(exc).__name__)
        return "unavailable"


def dex():
    oauth = OAuth()
    remote = oauth.register("dex", client_id=settings.DEX_CLIENT_ID, client_secret=settings.DEX_CLIENT_SECRET, server_metadata_url=settings.DEX_ISSUER.rstrip("/") + "/.well-known/openid-configuration", client_kwargs={"scope": "openid email profile groups federated:id", "code_challenge_method": "S256", "timeout": 10})
    metadata = remote.load_server_metadata()
    if metadata.get("issuer") != settings.DEX_ISSUER:
        raise ValueError("Dex discovery issuer mismatch.")
    metadata["id_token_signing_alg_values_supported"] = ["RS256"]
    for endpoint in ("authorization_endpoint", "token_endpoint", "jwks_uri"):
        url = urlsplit(metadata.get(endpoint, ""))
        if url.scheme != "https" or url.netloc != urlsplit(settings.DEX_ISSUER).netloc or url.username:
            raise ValueError("Dex endpoints must be HTTPS URLs on the configured issuer origin.")
    return remote


@require_POST
def login(request):
    if limited("login-ip", client_ip(request), 60):
        return HttpResponse(status=429)
    try:
        return dex().authorize_redirect(request, settings.PUBLIC_URL + reverse("members:callback"), nonce=secrets.token_urlsafe(32), connector_id=settings.DEX_CONNECTOR_ID)
    except Exception as exc:
        logger.error("Dex login unavailable kind=%s", type(exc).__name__)
        return page(request, title="Sign-in unavailable", message="Please try again later.")


def link_identity(claims, *, registration_account_id=None):
    if claims.get("iss") != settings.DEX_ISSUER or claims.get("email_verified") is not True or not isinstance(claims.get("sub"), str) or not claims["sub"] or len(claims["sub"]) > 512:
        raise ValueError("A verified Dex identity is required.")
    uid, email = claims.get("preferred_username"), claims.get("email")
    if not isinstance(uid, str) or not re.fullmatch(r"[a-z][a-z0-9._-]{2,47}", uid):
        raise ValueError("Dex must return a valid uid as preferred_username.")
    if not isinstance(email, str) or len(email) > 254:
        raise ValueError("A verified Dex email is required.")
    validate_email(email)
    federated = claims.get("federated_claims") or {}
    if not isinstance(federated, dict) or federated.get("connector_id") != settings.DEX_CONNECTOR_ID or federated.get("user_id") != uid:
        raise ValueError("Dex must authenticate the configured LDAP connector with uid as idAttr.")
    # Authentication is entirely OIDC. Never contact LDAP or silently rebind an
    # existing account to a different subject based on username/email matches.
    with transaction.atomic():
        account = Account.objects.select_for_update().filter(oidc_issuer=claims["iss"], oidc_sub=claims["sub"]).first()
        if account:
            if account.uid != uid:
                raise ValueError("Dex identity username changed; an explicit migration is required.")
        else:
            account, created = Account.objects.select_for_update().get_or_create(uid=uid, defaults={"email": email, "oidc_issuer": claims["iss"], "oidc_sub": claims["sub"]})
            if not created:
                if account.oidc_sub:
                    if account.oidc_issuer != claims["iss"] or account.oidc_sub != claims["sub"]:
                        raise ValueError("Existing account requires an explicit Dex identity mapping.")
                elif str(account.pk) != registration_account_id:
                    raise ValueError("Existing account requires an explicit Dex identity mapping.")
        account.oidc_issuer = claims["iss"]
        account.oidc_sub = claims["sub"]
        account.email = email
        account.save(update_fields=["oidc_issuer", "oidc_sub", "email"])
        remember_groups(account)
        return account


@require_GET
def callback(request):
    try:
        token = dex().authorize_access_token(request, claims_options={"iss": {"essential": True, "value": settings.DEX_ISSUER}}, leeway=30)
        if not token.get("id_token"):
            raise ValueError("ID token is required.")
        proof = request.session.get("registration_identity") or {}
        expires_at = proof.get("expires_at") if isinstance(proof, dict) else None
        registration_account_id = proof.get("account_id") if isinstance(expires_at, (int, float)) and expires_at > timezone.now().timestamp() else None
        account = link_identity(token.get("userinfo") or {}, registration_account_id=registration_account_id)
    except ProgrammingError as exc:
        # PostgreSQL diagnostics and SQL text can contain identity data. Log
        # only a validated SQLSTATE, never the exception message or traceback.
        sqlstate = getattr(exc.__cause__, "sqlstate", None)
        sqlstate = sqlstate if isinstance(sqlstate, str) and re.fullmatch(r"[0-9A-Z]{5}", sqlstate) else "unknown"
        hint = {
            "42703": "undefined_column: check pending migrations, especially members.0004_dex_login_identity, against the web database",
            "42P01": "undefined_table: check migrations and the configured database/schema",
            "42501": "insufficient_privilege: check database role permissions",
        }.get(sqlstate, "check database schema, permissions and matching application/migration images")
        logger.error("Membership database failure during Dex callback kind=ProgrammingError sqlstate=%s; %s", sqlstate, hint)
        return page(request, title="Sign-in could not be verified", message="Try signing in again, or contact the administrator.")
    except Exception as exc:
        logger.error("Dex callback rejected kind=%s", type(exc).__name__)
        return page(request, title="Sign-in could not be verified", message="Try signing in again, or contact the administrator.")
    # Do not persist access/refresh/ID tokens or stale group claims in sessions.
    request.session.flush()
    request.session["account_id"] = str(account.pk)
    return redirect("members:home")


@require_POST
def logout(request):
    request.session.flush()
    return redirect("members:home")


def _profile_context(account, values):
    return {"account": account, "profile_loaded": True, "form": ProfileForm(initial=profiles.initial(values)), "email_form": ProfileEmailForm(), "password_form": ProfilePasswordForm(), "email_values": values["mail"], "revision": profiles.revision(account, values)}


@sensitive_post_parameters()
@require_http_methods(["GET", "POST"])
@account_required
def profile(request):
    member = request.member
    # Bound before any password verification; never log posted values or LDAP
    # diagnostic messages. Account and IP limits protect directory binds.
    if limited("profile-read", str(member.pk), 120):
        return HttpResponse("Please try again later.", status=429)
    try:
        values = profiles.read_profile(member)
    except Exception as exc:
        logger.error("Profile read failed account=%s kind=%s", member.pk, type(exc).__name__)
        return render(request, "profile.html", {"account": member, "profile_loaded": False}, status=503)
    context = _profile_context(member, values)
    context.update(saved=request.GET.get("saved") == "1", email_sent=request.GET.get("email_sent") == "1", newsletter_status=_newsletter_status(member))
    if request.method == "POST":
        if limited("profile-write", str(member.pk), 20) or limited("profile-write-ip", client_ip(request), 40):
            return HttpResponse("Please try again later.", status=429)
        action = request.POST.get("action")
        forms = {"profile": ("form", ProfileForm), "email": ("email_form", ProfileEmailForm), "password": ("password_form", ProfilePasswordForm)}
        if action not in forms:
            return HttpResponse(status=400)
        form_key, form_class = forms[action]
        form = form_class(request.POST)
        context[form_key] = form
        if form.is_valid():
            try:
                # Serialize directory pinning and edits against the worker.
                with transaction.atomic():
                    member = Account.objects.select_for_update().get(pk=member.pk)
                    if action == "profile":
                        profiles.update_profile(member, form.cleaned_data, request.POST.get("revision", ""))
                    elif action == "password":
                        profiles.change_password(member, form.cleaned_data["current_password"], form.cleaned_data["password"])
                    else:
                        profiles.verify_password(member, form.cleaned_data["current_password"])
                        token = secrets.token_urlsafe(32)
                        digest = hashlib.sha256(token.encode()).hexdigest()
                        ProfileEmailChange.objects.filter(account=member).delete()
                        ProfileEmailChange.objects.create(token_hash=digest, account=member, email=form.cleaned_data["email"], ldap_uuid=member.ldap_uuid, expires_at=timezone.now() + timedelta(hours=1))
                        url = settings.PUBLIC_URL + reverse("members:verify_profile_email", args=[token])
                        send_mail("Verify your new eom.dev email", f"Confirm this email address for your account (expires in one hour):\n\n{url}\n\nYou must sign in to the same account and enter your current password to confirm. If you did not request this, ignore this message.", settings.DEFAULT_FROM_EMAIL, [form.cleaned_data["email"]])
                logger.info("Profile change completed account=%s action=%s", member.pk, action)
                if action == "password":
                    request.session.flush()
                    return page(request, title="Password changed", message="Your password was changed. Sign in again. Existing Dex and other service sessions are not automatically signed out.")
                return redirect(reverse("members:profile") + ("?email_sent=1" if action == "email" else "?saved=1"))
            except Exception as exc:
                logger.error("Profile change failed account=%s kind=%s", member.pk, type(exc).__name__)
                form.add_error(None, "Changes could not be completed. Check your current password and reload your profile before retrying. Contact the administrator if this continues.")
        # Keep the original revision on validation errors, never silently allow
        # a stale bound form to overwrite concurrently updated directory data.
        if action == "profile":
            context["revision"] = request.POST.get("revision", "")
    return render(request, "profile.html", context)


@require_GET
@account_required
def verify_profile_email(request, token):
    if limited("profile-email-verify", client_ip(request), 60):
        return HttpResponse(status=429)
    digest = hashlib.sha256(token.encode()).hexdigest()
    if not ProfileEmailChange.objects.filter(pk=digest, account=request.member, expires_at__gt=timezone.now()).exists():
        return page(request, title="Link unavailable", message="Request a new email change from your profile.")
    request.session["profile_email_hash"] = digest
    return redirect("members:confirm_profile_email")


@sensitive_post_parameters("current_password")
@require_http_methods(["GET", "POST"])
@account_required
def confirm_profile_email(request):
    digest = request.session.get("profile_email_hash")
    pending = ProfileEmailChange.objects.filter(pk=digest, account=request.member, expires_at__gt=timezone.now()).first()
    if not pending:
        return page(request, title="Link unavailable", message="Request a new email change from your profile.")
    form = CurrentPasswordForm(request.POST if request.method == "POST" else None)
    if request.method == "POST":
        if limited("profile-write", str(request.member.pk), 20) or limited("profile-write-ip", client_ip(request), 40):
            return HttpResponse("Please try again later.", status=429)
        if form.is_valid():
            try:
                with transaction.atomic():
                    member = Account.objects.select_for_update().get(pk=request.member.pk)
                    pending = ProfileEmailChange.objects.select_for_update().get(pk=digest, account=member, expires_at__gt=timezone.now())
                    profiles.read_profile(member)
                    if member.ldap_uuid != pending.ldap_uuid:
                        raise ValueError("Directory identity changed.")
                    profiles.change_email(member, form.cleaned_data["current_password"], pending.email)
                    old_email = member.email
                    member.email = pending.email
                    member.save(update_fields=["email"])
                    ProfileEmailChange.objects.filter(account=member).delete()
                request.session.pop("profile_email_hash", None)
                if newsletter.enabled():
                    try:
                        newsletter.change_email(old_email, member.email)
                    except Exception as exc:
                        logger.error("Newsletter email change failed account=%s kind=%s", member.pk, type(exc).__name__)
                request.session.cycle_key()
                return redirect(reverse("members:profile") + "?saved=1")
            except Exception as exc:
                logger.error("Profile email confirmation failed account=%s kind=%s", request.member.pk, type(exc).__name__)
                form.add_error(None, "Email change could not be completed. Check your current password or request a new verification link.")
    return render(request, "profile.html", {"account": request.member, "confirm_email": True, "confirmation_email": pending.email, "confirmation_form": form})


@require_POST
@account_required
def newsletter_preference(request):
    member = request.member
    action = request.POST.get("action")
    if not newsletter.enabled() or action not in ("subscribe", "unsubscribe"):
        return HttpResponse(status=400)
    if limited("newsletter", str(member.pk), 20) or limited("newsletter-ip", client_ip(request), 40):
        return HttpResponse("Please try again later.", status=429)
    try:
        if action == "subscribe":
            result = newsletter.subscribe(member.email, uid=member.uid)
        else:
            result = newsletter.unsubscribe(member.email)
        logger.info("Newsletter preference changed account=%s action=%s result=%s", member.pk, action, result)
    except Exception as exc:
        logger.error("Newsletter preference failed account=%s kind=%s", member.pk, type(exc).__name__)
        return redirect(reverse("members:profile") + "?newsletter=error#newsletter")
    return redirect(reverse("members:profile") + "?newsletter=saved#newsletter")


def stripe_redirect(url, host):
    parsed = urlsplit(url or "")
    if parsed.scheme != "https" or parsed.hostname != host or parsed.username:
        raise ValueError("Unexpected Stripe redirect host.")
    return redirect(url)


@require_POST
@account_required
def checkout(request, tier):
    config = settings.MEMBERSHIP_TIERS.get(tier)
    if not config:
        return HttpResponse(status=404)
    if limited("checkout", str(request.member.pk), 20):
        return HttpResponse(status=429)
    try:
        with transaction.atomic():
            account = Account.objects.select_for_update().get(pk=request.member.pk)
            if CryptoInvoice.objects.filter(account=account).filter(Q(credited_at__isnull=True) | Q(access_end__gt=timezone.now())).exists():
                return page(request, title="Prepaid membership already exists", message="Finish your SHKeeper invoice or wait for prepaid membership to expire before starting a recurring Stripe subscription.")
            api = billing.client()
            if not account.stripe_customer:
                customer = api.customers.create({"email": account.email, "metadata": {"membership_account": str(account.pk)}}, options={"idempotency_key": f"member-customer-{account.pk}"})
                account.stripe_customer = customer["id"]
                account.save(update_fields=["stripe_customer"])
            # Canonical check prevents duplicate subscriptions even before sync.
            existing = api.subscriptions.list({"customer": account.stripe_customer, "status": "all", "limit": 100})
            if any(sub.get("status") not in {"canceled", "incomplete_expired"} for sub in existing.auto_paging_iter()):
                return page(request, title="You already have a subscription", message="Use Manage billing to change your plan or payment details.")
            if account.checkout_id:
                session = api.checkout.sessions.retrieve(account.checkout_id)
                if session.get("status") == "open":
                    return stripe_redirect(session["url"], "checkout.stripe.com")
                account.checkout_key = uuid.uuid4()
            session = api.checkout.sessions.create({
                "mode": "subscription", "customer": account.stripe_customer,
                "line_items": [{"price": config["price_id"], "quantity": 1}],
                "client_reference_id": str(account.pk),
                "subscription_data": {"metadata": {"membership_account": str(account.pk)}},
                "success_url": settings.PUBLIC_URL + reverse("members:home") + "?checkout=complete",
                "cancel_url": settings.PUBLIC_URL + reverse("members:home"),
            }, options={"idempotency_key": f"member-checkout-{account.pk}-{account.checkout_key}"})
            account.checkout_id = session["id"]
            account.save(update_fields=["checkout_id", "checkout_key"])
        return stripe_redirect(session["url"], "checkout.stripe.com")
    except Exception as exc:
        logger.error("Checkout failed account=%s kind=%s", request.member.pk, type(exc).__name__)
        return page(request, title="Checkout unavailable", message="Please try again later. Membership is only granted after Stripe confirms payment.")


@require_POST
@account_required
def portal(request):
    if not request.member.stripe_customer or not settings.STRIPE_PORTAL_CONFIGURATION:
        return page(request, title="Billing unavailable", message="No billing account or billing portal configuration is available.")
    if limited("portal", str(request.member.pk), 30):
        return HttpResponse(status=429)
    try:
        session = billing.client().billing_portal.sessions.create({"customer": request.member.stripe_customer, "configuration": settings.STRIPE_PORTAL_CONFIGURATION, "return_url": settings.PUBLIC_URL + reverse("members:home")})
        return stripe_redirect(session["url"], "billing.stripe.com")
    except Exception as exc:
        logger.error("Billing portal failed kind=%s", type(exc).__name__)
        return page(request, title="Billing unavailable", message="Please try again later.")


@csrf_exempt
@require_POST
def webhook(request):
    if not settings.STRIPE_WEBHOOK_SECRET:
        return HttpResponse(status=503)
    try:
        event = stripe.Webhook.construct_event(request.body, request.headers.get("Stripe-Signature", ""), settings.STRIPE_WEBHOOK_SECRET, tolerance=300)
        if event.get("livemode") != settings.STRIPE_LIVE_MODE or event.get("account"):
            return HttpResponse(status=400)
        obj = event["data"]["object"]
        customer = billing._id(obj.get("customer"))
        account = Account.objects.filter(stripe_customer=customer).first() if customer else None
        # Store no raw payload/PII. The worker rereads canonical Stripe state;
        # duplicate, delayed and reordered events can never restore expired time.
        WebhookEvent.objects.get_or_create(stripe_id=event["id"], defaults={"account": account, "processed_at": None if account else timezone.now()})
    except (ValueError, KeyError, TypeError, stripe.SignatureVerificationError):
        return HttpResponse(status=400)
    return HttpResponse(status=200)


@require_http_methods(["GET", "POST"])
@account_required
def crypto_checkout(request, tier):
    config = settings.MEMBERSHIP_TIERS.get(tier)
    if not settings.SHKEEPER_ENABLED or not config or not config.get("usd_amount"):
        return HttpResponse(status=404)
    if request.method == "GET":
        return render(request, "crypto_checkout.html", {"tier": config, "tier_key": tier, "currencies": settings.SHKEEPER_CURRENCIES})
    crypto = request.POST.get("crypto", "")
    if crypto not in settings.SHKEEPER_CURRENCIES:
        return HttpResponse("Choose an available cryptocurrency.", status=400)
    if limited("crypto-checkout", str(request.member.pk), 20):
        return HttpResponse(status=429)
    try:
        with transaction.atomic():
            account = Account.objects.select_for_update().get(pk=request.member.pk)
            invoice = CryptoInvoice.objects.filter(account=account, credited_at__isnull=True).first()
            if invoice:
                # Reuse the existing asset/tier even if a stale tab asks for a
                # different one. Never orphan an address a user may have paid.
                return redirect("members:crypto_invoice", invoice_id=invoice.pk)
            if account.stripe_customer:
                api = billing.client()
                subs = api.subscriptions.list({"customer": account.stripe_customer, "status": "all", "limit": 100})
                if any(sub.get("status") not in {"canceled", "incomplete_expired"} for sub in subs.auto_paging_iter()):
                    return page(request, title="Recurring membership already exists", message="Use Stripe billing to cancel renewal and wait until that subscription ends before paying through SHKeeper. This avoids double payments.")
                if account.checkout_id:
                    checkout_session = api.checkout.sessions.retrieve(account.checkout_id)
                    if checkout_session.get("status") == "open":
                        return page(request, title="Stripe checkout is still open", message="Finish or let the existing Stripe Checkout expire before changing payment providers.")
            if CryptoInvoice.objects.filter(account=account, access_end__gt=timezone.now()).exclude(tier=tier).exists():
                return page(request, title="Another prepaid tier is active", message="Renew the same tier, or wait for the current prepaid membership to expire before changing tiers.")
            invoice = CryptoInvoice.objects.create(account=account, tier=tier, crypto=crypto, usd_amount=config["usd_amount"])
            remember_groups(account)
        # Reserve/commit UUID BEFORE API call, so retries and worker recovery
        # use the same external ID if the process dies after invoice creation.
        shkeeper.prepare_invoice(account.pk, invoice.pk)
        return redirect("members:crypto_invoice", invoice_id=invoice.pk)
    except Exception as exc:
        logger.error("SHKeeper checkout failed account=%s kind=%s", request.member.pk, type(exc).__name__)
        return page(request, title="Crypto checkout unavailable", message="Please try again later. If an invoice was reserved, it remains on your membership page and will be retried automatically. Do not send funds until payment details appear.")


@require_GET
@account_required
def crypto_invoice(request, invoice_id):
    invoice = get_object_or_404(CryptoInvoice, pk=invoice_id, account=request.member)
    return render(request, "crypto_invoice.html", {"invoice": invoice, "tiers": settings.MEMBERSHIP_TIERS, "now": timezone.now()})


@csrf_exempt
@require_POST
def shkeeper_callback(request):
    # SHKeeper documents no callback signature. Treat ALL incoming payloads as
    # untrusted hints: do not parse them, write billing data, trigger network
    # requests or grant access. The durable worker polls known invoice UUIDs.
    return HttpResponse(status=200 if settings.SHKEEPER_ENABLED else 503)