Global Payment Integration: Wir unterstützen 135 Währungen mit 1% Ausfallrate

// server/billing/stripe.ts
import Stripe from "stripe"

const stripe = new Stripe(env.STRIPE_SECRET_KEY, {
  apiVersion: "2025-02-24.acacia",
})

export const createCheckoutSession = createServerFn({ method: "POST" }).handler(
  async ({ data, context }: {
    data: { priceId: string; locale: string }
  }) => {
    // Zahlungsmethoden basierend auf dem Locale bestimmen
    const paymentMethods = getPaymentMethodsForLocale(data.locale)

    const session = await stripe.checkout.sessions.create({
      line_items: [{ price: data.priceId, quantity: 1 }],
      mode: "subscription",
      success_url: `https://tanstackship.com/${data.locale}/billing/success`,
      cancel_url: `https://tanstackship.com/${data.locale}/billing/cancel`,
      payment_method_types: paymentMethods,
      customer_creation: "always",
      locale: mapStripeLocale(data.locale),
      metadata: {
        locale: data.locale,
        userId: context.user.id,
      },
      ...(paymentMethods.includes("sepa_debit") && {
        payment_intent_data: {
          // SEPA erfordert die Anzeige des Mandats
          mandate_data: {
            type: "online",
          },
        },
      }),
    })

    return { sessionId: session.id, url: session.url }
  }
)

function getPaymentMethodsForLocale(locale: string): string[] {
  const methods: Record<string, string[]> = {
    en: ["card", "paypal"],
    de: ["card", "paypal", "sepa_debit"],
    zh: ["card", "alipay", "wechat_pay"],
  }
  return methods[locale] ?? ["card"]
}

function mapStripeLocale(locale: string): Stripe.Checkout.SessionCreateParams.Locale {
  const locales: Record<string, Stripe.Checkout.SessionCreateParams.Locale> = {
    en: "auto",
    de: "de",
    zh: "zh",
  }
  return locales[locale] ?? "auto"
}

// Preise pro Markt mit entsprechender Währung definieren
export const prices = {
  starter: {
    en: { price: 2900, currency: "usd" },                          // $29
    de: { price: 2900, currency: "eur" },                          // €29
    zh: { price: 12900, currency: "cny" },                         // ¥129
  },
  pro: {
    en: { price: 7900, currency: "usd" },                          // $79
    de: { price: 7900, currency: "eur" },                          // €79
    zh: { price: 34900, currency: "cny" },                         // ¥349
  },
}

// Stripe-Preise pro Währung erstellen
async function createPricesForLocale(locale: string) {
  const stripePrices = []

  for (const [plan, currencies] of Object.entries(prices)) {
    const { price, currency } = currencies[locale as keyof typeof currencies]

    const stripePrice = await stripe.prices.create({
      unit_amount: price,
      currency,
      recurring: { interval: "month" },
      product_data: {
        name: plan.charAt(0).toUpperCase() + plan.slice(1),
        metadata: { locale },
      },
    })

    stripePrices.push({ plan, stripePriceId: stripePrice.id })
  }

  return stripePrices
}

export const createSepaSubscription = createServerFn({ method: "POST" }).handler(
  async ({ data, context }: { data: { priceId: string; iban: string } }) => {
    // 1. Stripe-Kunden erstellen
    const customer = await stripe.customers.create({
      email: context.user.email,
      metadata: { userId: context.user.id },
    })

    // 2. SEPA-Zahlungsmethode erstellen
    const paymentMethod = await stripe.paymentMethods.create({
      type: "sepa_debit",
      sepa_debit: { iban: data.iban },
      billing_details: { email: context.user.email },
    })

    // 3. Zahlungsmethode anfügen
    await stripe.paymentMethods.attach(paymentMethod.id, { customer: customer.id })

    // 4. Als Standard festlegen
    await stripe.customers.update(customer.id, {
      invoice_settings: { default_payment_method: paymentMethod.id },
    })

    // 5. Abonnement erstellen
    const subscription = await stripe.subscriptions.create({
      customer: customer.id,
      items: [{ price: data.priceId }],
      default_payment_method: paymentMethod.id,
      payment_settings: {
        payment_method_types: ["sepa_debit"],
      },
    })

    return { subscriptionId: subscription.id }
  }
)

export const createAlipaySession = createServerFn({ method: "POST" }).handler(
  async ({ data, context }: { data: { priceId: string } }) => {
    // Stripe Checkout verarbeitet die Generierung von QR-Codes für Alipay/WeChat Pay
    const session = await stripe.checkout.sessions.create({
      line_items: [{ price: data.priceId, quantity: 1 }],
      mode: "payment",
      payment_method_types: ["alipay", "wechat_pay"],
      success_url: `https://tanstackship.com/zh/billing/success`,
      cancel_url: `https://tanstackship.com/zh/billing/cancel`,
    })

    return {
      url: session.url,
      // Stripe Checkout zeigt den QR-Code auf mobilen Geräten automatisch an
    }
  }
)

export const createTaxAwareSession = createServerFn({ method: "POST" }).handler(
  async ({ data, context }: { data: { priceId: string; locale: string } }) => {
    // Stripe Tax berechnet automatisch MwSt., GST, Sales Tax
    const session = await stripe.checkout.sessions.create({
      line_items: [{ price: data.priceId, quantity: 1 }],
      mode: "subscription",
      automatic_tax: { enabled: true },
      customer_update: { address: "auto" },
      // Rechnungsadresse für die Steuerberechnung erfasst
      billing_address_collection: "required",
    })

    return { url: session.url }
  }
)

// Abonnementänderungen über Märkte hinweg handhaben
export const updateSubscriptionLocale = createServerFn({ method: "POST" }).handler(
  async ({ data, context }: {
    data: { subscriptionId: string; newLocale: string }
  }) => {
    const subscription = await stripe.subscriptions.retrieve(data.subscriptionId)

    // Locale-Metadaten aktualisieren
    await stripe.subscriptions.update(data.subscriptionId, {
      metadata: { locale: data.newLocale },
    })

    // Wenn sich das Locale der Rechnung geändert hat, Standardzahlungsmethode aktualisieren
    if (data.newLocale === "de") {
      // Sicherstellen, dass das SEPA-Mandat aktiv ist
    } else if (data.newLocale === "zh") {
      // Sicherstellen, dass Alipay/WeChat verfügbar ist
    }

    return { updated: true }
  }
)

// Lokalisierte Mahnungs-E-Mails basierend auf dem Nutzer-Locale
async function handleFailedPayment(invoice: Stripe.Invoice) {
  const subscription = await stripe.subscriptions.retrieve(
    invoice.subscription as string
  )
  const locale = subscription.metadata.locale ?? "en"

  // Intelligenter Neuversuch basierend auf der Zahlungsmethode
  if (subscription.metadata.payment_method === "sepa_debit") {
    // SEPA-Neuversuche werden von Stripe abgewickelt – 3-5 Tage warten
    await scheduleEmail(invoice.customer, "sepa_pending", locale)
  } else {
    // Kreditkarte: Sofortiger Neuversuch mit intelligentem Timing
    await stripe.invoices.pay(invoice.id, {
      payment_method: invoice.payment_method as string,
    })
  }

  // E-Mail-Vorlage lokalisieren
  const emailTemplates = {
    en: "Your payment failed. Update your billing info here: {link}",
    de: "Ihre Zahlung ist fehlgeschlagen. Aktualisieren Sie hier: {link}",
    zh: "支付失败。点击此处更新账单信息：{link}",
  }

  await sendEmail({
    to: invoice.customer_email,
    subject: subjectTranslations[locale],
    body: emailTemplates[locale as keyof typeof emailTemplates].replace(
      "{link}",
      `https://tanstackship.com/${locale}/billing`
    ),
  })
}

function PriceDisplay({
  amount,
  locale,
  currency,
}: {
  amount: number
  locale: string
  currency: string
}) {
  return new Intl.NumberFormat(locale, {
    style: "currency",
    currency,
  }).format(amount)
  // Beispielergebnisse:
  // en, USD → "$29.99"
  // de, EUR → "29,99 €"
  // zh, CNY → "¥129.99"
}