Files
api/app/billing/stripe_service.py
2026-03-03 12:39:32 +01:00

257 lines
8.7 KiB
Python

"""Stripe service: checkout sessions, webhook handling, subscription management.
Subscription records are persisted in the PostgreSQL ``subscriptions`` table.
All Stripe calls are gracefully stubbed when ``STRIPE_SECRET_KEY`` is not
configured, enabling local development without live credentials.
"""
from __future__ import annotations
from datetime import datetime, timezone
from typing import Any
import stripe as stripe_lib
from fastapi import HTTPException, status
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from app.config.settings import settings
# Stripe price IDs per tier — replace with real IDs in production .env
TIER_PRICE_IDS: dict[str, str] = {
"pro": "price_pro_monthly",
"power": "price_power_monthly",
"team": "price_team_monthly",
}
class StripeService:
"""Wraps all Stripe interactions and owns subscription persistence."""
# ── Internal helpers ────────────────────────────────────────────────
def _configured(self) -> bool:
return bool(settings.STRIPE_SECRET_KEY)
def _client(self) -> Any:
stripe_lib.api_key = settings.STRIPE_SECRET_KEY
return stripe_lib
# ── Public API ──────────────────────────────────────────────────────
def create_checkout_session(
self,
user_id: str,
tier: str,
success_url: str = "https://app.adiuva.app/billing/success?session_id={CHECKOUT_SESSION_ID}",
cancel_url: str = "https://app.adiuva.app/billing/cancel",
) -> str:
"""Create a Stripe checkout session and return the URL.
Returns a stub URL when Stripe is not configured.
Raises ``HTTP 400`` for the free tier or an unknown tier.
"""
if tier == "free":
raise HTTPException(
status_code=status.HTTP_400_BAD_REQUEST,
detail="Cannot create a checkout session for the free tier",
)
price_id = TIER_PRICE_IDS.get(tier)
if not price_id:
raise HTTPException(
status_code=status.HTTP_400_BAD_REQUEST,
detail=f"Unknown tier: {tier}",
)
if not self._configured():
return "https://stripe.com/stub-checkout"
s = self._client()
session = s.checkout.Session.create(
payment_method_types=["card"],
mode="subscription",
line_items=[{"price": price_id, "quantity": 1}],
success_url=success_url,
cancel_url=cancel_url,
metadata={"user_id": user_id, "tier": tier},
)
return session.url
async def handle_webhook(
self,
payload: bytes,
sig_header: str,
db: AsyncSession,
) -> None:
"""Process a Stripe webhook event.
Verifies the signature, then dispatches on event type.
Raises ``HTTP 400`` on signature mismatch.
No-ops when Stripe is not configured.
"""
if not self._configured():
return
try:
s = self._client()
event = s.Webhook.construct_event(
payload, sig_header, settings.STRIPE_WEBHOOK_SECRET
)
except stripe_lib.error.SignatureVerificationError:
raise HTTPException(
status_code=status.HTTP_400_BAD_REQUEST,
detail="Invalid Stripe signature",
)
event_type: str = event["type"]
data: dict[str, Any] = event["data"]["object"]
if event_type == "checkout.session.completed":
user_id = data.get("metadata", {}).get("user_id")
tier = data.get("metadata", {}).get("tier", "free")
sub_id = data.get("subscription")
period_end_ts = data.get("current_period_end")
period_end = (
datetime.fromtimestamp(period_end_ts, tz=timezone.utc)
if period_end_ts
else None
)
if user_id:
await self._upsert_subscription(
db, user_id, sub_id, tier, "active", period_end
)
elif event_type == "customer.subscription.updated":
sub_id = data.get("id")
new_status = data.get("status", "active")
period_end_ts = data.get("current_period_end")
period_end = (
datetime.fromtimestamp(period_end_ts, tz=timezone.utc)
if period_end_ts
else None
)
if sub_id:
await self._update_subscription_by_stripe_id(
db, sub_id, status=new_status, current_period_end=period_end
)
elif event_type == "customer.subscription.deleted":
sub_id = data.get("id")
if sub_id:
await self._update_subscription_by_stripe_id(
db, sub_id, tier="free", status="canceled"
)
elif event_type == "invoice.payment_failed":
sub_id = data.get("subscription")
if sub_id:
await self._update_subscription_by_stripe_id(
db, sub_id, status="past_due"
)
await db.commit()
async def get_subscription(
self, user_id: str, db: AsyncSession
) -> dict[str, Any] | None:
"""Return the subscription record for ``user_id``, or ``None`` if absent."""
from app.models import Subscription # noqa: PLC0415
result = await db.execute(
select(Subscription).where(Subscription.user_id == user_id)
)
sub = result.scalar_one_or_none()
if sub is None:
return None
return {
"tier": sub.tier,
"stripe_subscription_id": sub.stripe_subscription_id,
"status": sub.status,
"current_period_end": (
int(sub.current_period_end.timestamp() * 1000)
if sub.current_period_end
else None
),
}
async def cancel_subscription(self, user_id: str, db: AsyncSession) -> None:
"""Cancel the user's Stripe subscription and downgrade them to free.
Raises ``HTTP 404`` when no active subscription exists.
"""
from app.models import Subscription # noqa: PLC0415
result = await db.execute(
select(Subscription).where(Subscription.user_id == user_id)
)
sub = result.scalar_one_or_none()
if sub is None or not sub.stripe_subscription_id:
raise HTTPException(
status_code=status.HTTP_404_NOT_FOUND,
detail="No active subscription found",
)
if self._configured():
s = self._client()
s.Subscription.cancel(sub.stripe_subscription_id)
sub.tier = "free"
sub.status = "canceled"
await db.commit()
# ── Private DB helpers ───────────────────────────────────────────────
async def _upsert_subscription(
self,
db: AsyncSession,
user_id: str,
stripe_subscription_id: str | None,
tier: str,
sub_status: str,
current_period_end: datetime | None,
) -> None:
from app.models import Subscription # noqa: PLC0415
result = await db.execute(
select(Subscription).where(Subscription.user_id == user_id)
)
sub = result.scalar_one_or_none()
if sub is None:
sub = Subscription(user_id=user_id)
db.add(sub)
sub.stripe_subscription_id = stripe_subscription_id
sub.tier = tier
sub.status = sub_status
sub.current_period_end = current_period_end
async def _update_subscription_by_stripe_id(
self,
db: AsyncSession,
stripe_subscription_id: str,
*,
tier: str | None = None,
status: str | None = None,
current_period_end: datetime | None = None,
) -> None:
from app.models import Subscription # noqa: PLC0415
result = await db.execute(
select(Subscription).where(
Subscription.stripe_subscription_id == stripe_subscription_id
)
)
sub = result.scalar_one_or_none()
if sub is None:
return
if tier is not None:
sub.tier = tier
if status is not None:
sub.status = status
if current_period_end is not None:
sub.current_period_end = current_period_end
# Module-level singleton shared across the app.
stripe_service = StripeService()