// 1. Create checkout session
stripe.checkout.sessions.create({
customer: "cus_1234567890",
line_items: [{
price: "price_1MotwRLkdIwHu7ixYcPLm5uZ",
quantity: 1,
}],
success_url: "https://useartha.com",
mode: "subscription",
});

// 2. Update subscription (upgrades)
const currentSub = await stripe.subscriptions.retrieve(subscriptionId)

const newSubItems = currentSub.items.map((item) => ({
id: item.id,
deleted: true,
}));

newSubItems.push({
price: "price_1MotwRLkdIwHu7ixYcPLm5uZ", // new price
quantity: 1,
});

await stripe.subscriptions.update(subscriptionId, { 
items: newSubItems,
proration_behavior: "create_prorations",
});

// 3. One time payments / add ons
stripe.invoices.create({
customer: "cus_1234567890",
items: [{
price: "price_1MotwRLkdIwHu7ixYcPLm5uZ",
quantity: 1,
}],
});

// 4. Schedule downgrade
stripe.subscriptionSchedules.create({
customer: "cus_1234567890",
start_date: endOfBillingPeriod,
phases: [{
items: [{
price: "price_1MotwRLkdIwHu7ixYcPLm5uZ",
quantity: 1,
}],
default_payment_method: paymentMethod?.id,
}],
});