Blame for tasks/linkedin/solution/site/implementation/clone/lib/stripe.ts

import { createHash, randomUUID } from "node:crypto";
import { eq } from "drizzle-orm";
import Stripe from "stripe";
import { getDb } from "@/db";
import { subscriptions, type User } from "@/db/schema";
import { ApiError } from "./api";
import { appUrl } from "./app-url";
import { localCheckout } from "@/lib/public-local-account";

type SubscriptionShape = {
  id: string;
  customer: string | { id: string };
  status: string;
  cancel_at_period_end?: boolean;
  current_period_start?: number;
  current_period_end?: number;
  items?: { data?: Array<{ price?: { id?: string } }> };
  metadata?: { userId?: string };
};

let stripeClient: Stripe | undefined;

const STRIPE_TEST_AMOUNT_MINOR = 2999;
const STRIPE_TEST_CURRENCY = "USD";
const STRIPE_TEST_PRODUCT_NAME = "LinkedIn Premium Career (Test Mode)";
const STRIPE_TEST_PRICE_ID = "price_linkedin_premium_test_2999";

function providerPriceId() {
  const value = process.env.LINKEDIN_STRIPE_TEST_PRICE_ID ?? "";
  if (!/^price_[A-Za-z0-9_]{8,240}$/u.test(value)) {
    throw new ApiError(503, "Stripe test pricing is not configured.", "stripe_price_not_configured");
  }
  return value;
}

export function publicBillingDisabled() {
  return process.env.PUBLIC_DEPLOYMENT_DISABLE_STRIPE === "true";
}

function localBillingFallbackEnabled() {
  return process.env.PUBLIC_BILLING_ALLOW_LOCAL_FALLBACK === "true";
}

function assertPublicBillingEnabled() {
  if (publicBillingDisabled()) {
    throw new ApiError(
      503,
      "Premium checkout is unavailable in this public review deployment.",
      "billing_not_available",
    );
  }
}

function sha256(value: string) {
  return createHash("sha256").update(value).digest("hex");
}

function stripeTestProxyUrl() {
  const raw = process.env.STRIPE_TEST_PROXY_URL;
  if (!raw) return null;
  const parsed = new URL(raw);
  if (
    parsed.protocol !== "http:" ||
    parsed.hostname !== "stripe.internal" ||
    parsed.port ||
    parsed.username ||
    parsed.password ||
    parsed.pathname !== "/" ||
    parsed.search ||
    parsed.hash
  ) {
    throw new ApiError(503, "Stripe Test Mode proxy is not configured safely.", "stripe_proxy_invalid");
  }
  return parsed.origin;
}

type StripeTestCheckoutSession = {
  id: string;
  url?: string | null;
  mode: "subscription";
  status: "open" | "complete" | "expired";
  payment_status: "paid" | "unpaid" | "no_payment_required";
  amount_total: number;
  currency: string;
  livemode: false;
  customer?: string | null;
  payment_intent?: string | null;
  subscription?: string | null;
  client_reference_id?: string | null;
  metadata: Record<string, string>;
};

function validateStripeTestCheckout(
  payload: StripeTestCheckoutSession | { error?: string } | null,
  userId: string,
  expectedSessionId?: string,
) {
  if (!payload || !("id" in payload)) {
    throw new ApiError(502, "Stripe returned an invalid Checkout Session.", "stripe_test_response_invalid");
  }
  const flowId = payload.metadata?.flow_id ?? "";
  const fingerprint = sha256(`linkedin\n${userId}\n${flowId}\n${STRIPE_TEST_AMOUNT_MINOR}\n${STRIPE_TEST_CURRENCY}`);
  if (
    !/^cs_test_[A-Za-z0-9_]{8,240}$/u.test(payload.id) ||
    (expectedSessionId && payload.id !== expectedSessionId) ||
    payload.mode !== "subscription" ||
    !["open", "complete", "expired"].includes(payload.status) ||
    !["paid", "unpaid", "no_payment_required"].includes(payload.payment_status) ||
    payload.livemode !== false ||
    payload.amount_total !== STRIPE_TEST_AMOUNT_MINOR ||
    payload.currency.toUpperCase() !== STRIPE_TEST_CURRENCY ||
    payload.client_reference_id !== flowId ||
    !/^[0-9a-f]{64}$/u.test(flowId) ||
    payload.metadata?.site_id !== "linkedin" ||
    payload.metadata?.owner !== userId ||
    payload.metadata?.amount_minor !== String(STRIPE_TEST_AMOUNT_MINOR) ||
    payload.metadata?.currency !== STRIPE_TEST_CURRENCY ||
    payload.metadata?.is_simulation !== "true" ||
    payload.metadata?.fingerprint !== fingerprint
  ) {
    throw new ApiError(502, "Stripe returned an invalid Checkout Session.", "stripe_test_response_invalid");
  }
  return payload;
}

async function retrieveStripeTestCheckout(proxyUrl: string, sessionId: string) {
  const response = await fetch(`${proxyUrl}/v1/checkout/sessions/${encodeURIComponent(sessionId)}`, {
    headers: { Accept: "application/json" },
  });
  const payload = await response.json().catch(() => null) as StripeTestCheckoutSession | { error?: string } | null;
  if (!response.ok) {
    throw new ApiError(502, payload && "error" in payload ? payload.error ?? "Unable to verify Stripe Checkout." : "Unable to verify Stripe Checkout.", "stripe_checkout_verification_failed");
  }
  return payload;
}

async function activateStripeTestCheckout(
  existing: typeof subscriptions.$inferSelect,
  session: StripeTestCheckoutSession,
) {
  const now = new Date();
  const ownerHash = sha256(`linkedin-checkout-owner\n${existing.userId}`);
  const customerId = session.customer && /^cus_[A-Za-z0-9_]{8,240}$/u.test(session.customer)
    ? session.customer
    : `cus_checkout_${ownerHash.slice(0, 24)}`;
  const paymentReference = session.subscription && /^sub_[A-Za-z0-9_]{8,240}$/u.test(session.subscription)
    ? session.subscription
    : session.payment_intent && /^pi_[A-Za-z0-9_]{8,240}$/u.test(session.payment_intent)
      ? session.payment_intent
      : `pay_checkout_${sha256(session.id).slice(0, 24)}`;
  const [updated] = await getDb().update(subscriptions).set({
    stripeCustomerId: customerId,
    stripeSubscriptionId: paymentReference,
    stripePriceId: STRIPE_TEST_PRICE_ID,
    status: "active",
    currentPeriodStart: now,
    currentPeriodEnd: new Date(now.getTime() + 30 * 24 * 60 * 60 * 1000),
    cancelAtPeriodEnd: false,
    checkoutSessionId: session.id,
    updatedAt: now,
  }).where(eq(subscriptions.id, existing.id)).returning();
  return updated;
}

async function createStripeTestCheckout(user: Pick<User, "id" | "email" | "name">, proxyUrl: string) {
  const db = getDb();
  const [existing] = await db.select().from(subscriptions).where(eq(subscriptions.userId, user.id)).limit(1);
  if (existing && ["active", "trialing"].includes(existing.status)) {
    return `${appUrl()}/premium`;
  }

  const flowId = sha256(`linkedin-premium-checkout\n${user.id}\n${randomUUID()}`);
  const fingerprint = sha256(`linkedin\n${user.id}\n${flowId}\n${STRIPE_TEST_AMOUNT_MINOR}\n${STRIPE_TEST_CURRENCY}`);
  const expiresAt = Math.floor(Date.now() / 1000) + 30 * 60;
  const fields = new URLSearchParams([
    ["mode", "subscription"],
    ["payment_method_types[0]", "card"],
    ["name_collection[individual][enabled]", "true"],
    ["wallet_options[link][display]", "never"],
    ["customer_email", user.email],
    ["success_url", `${appUrl()}/premium?session_id={CHECKOUT_SESSION_ID}`],
    ["cancel_url", `${appUrl()}/premium?cancelled=1&session_id={CHECKOUT_SESSION_ID}`],
    ["client_reference_id", flowId],
    ["expires_at", String(expiresAt)],
    ["metadata[site_id]", "linkedin"],
    ["metadata[flow_id]", flowId],
    ["metadata[owner]", user.id],
    ["metadata[amount_minor]", String(STRIPE_TEST_AMOUNT_MINOR)],
    ["metadata[currency]", STRIPE_TEST_CURRENCY],
    ["metadata[fingerprint]", fingerprint],
    ["metadata[is_simulation]", "true"],
    ["line_items[0][price_data][currency]", STRIPE_TEST_CURRENCY.toLowerCase()],
    ["line_items[0][price_data][unit_amount]", String(STRIPE_TEST_AMOUNT_MINOR)],
    ["line_items[0][price_data][product_data][name]", STRIPE_TEST_PRODUCT_NAME],
    ["line_items[0][price_data][recurring][interval]", "month"],
    ["line_items[0][quantity]", "1"],
  ]);
  const response = await fetch(`${proxyUrl}/v1/checkout/sessions`, {
    method: "POST",
    headers: {
      "Content-Type": "application/x-www-form-urlencoded",
      "Idempotency-Key": `linkedin-checkout-${flowId.slice(0, 48)}`,
    },
    body: fields.toString(),
  });
  const payload = await response.json().catch(() => null) as StripeTestCheckoutSession | { error?: string } | null;
  if (!response.ok) {
    throw new ApiError(502, payload && "error" in payload ? payload.error ?? "Unable to open Stripe Checkout." : "Unable to open Stripe Checkout.", "stripe_checkout_unavailable");
  }
  const session = validateStripeTestCheckout(payload, user.id);
  if (session.status !== "open" || session.payment_status !== "unpaid" || !session.url) {
    throw new ApiError(502, "Stripe Checkout did not return an unpaid session.", "stripe_checkout_unavailable");
  }
  const checkoutUrl = new URL(session.url);
  if (checkoutUrl.protocol !== "https:" || checkoutUrl.hostname !== "checkout.stripe.com" || checkoutUrl.username || checkoutUrl.password) {
    throw new ApiError(502, "Stripe Checkout returned an invalid hosted URL.", "stripe_checkout_unavailable");
  }
  const values = {
    stripeCustomerId: null,
    stripeSubscriptionId: null,
    stripePriceId: STRIPE_TEST_PRICE_ID,
    status: "incomplete",
    currentPeriodStart: null,
    currentPeriodEnd: null,
    cancelAtPeriodEnd: false,
    checkoutSessionId: session.id,
    updatedAt: new Date(),
  };
  if (existing) await db.update(subscriptions).set(values).where(eq(subscriptions.id, existing.id));
  else await db.insert(subscriptions).values({ userId: user.id, ...values });
  return session.url;
}

async function createDirectStripeTestCheckout(user: Pick<User, "id" | "email" | "name">) {
  const db = getDb();
  const [existing] = await db.select().from(subscriptions).where(eq(subscriptions.userId, user.id)).limit(1);
  if (existing && ["active", "trialing"].includes(existing.status)) {
    return `${appUrl()}/premium`;
  }

  const flowId = sha256(`linkedin-premium-checkout\n${user.id}\n${randomUUID()}`);
  const fingerprint = sha256(`linkedin\n${user.id}\n${flowId}\n${STRIPE_TEST_AMOUNT_MINOR}\n${STRIPE_TEST_CURRENCY}`);
  const sessionResponse = await getStripe().checkout.sessions.create({
    mode: "subscription",
    payment_method_types: ["card"],
    name_collection: { individual: { enabled: true } },
    wallet_options: { link: { display: "never" } },
    customer_email: user.email,
    success_url: `${appUrl()}/premium?session_id={CHECKOUT_SESSION_ID}`,
    cancel_url: `${appUrl()}/premium?cancelled=1&session_id={CHECKOUT_SESSION_ID}`,
    client_reference_id: flowId,
    expires_at: Math.floor(Date.now() / 1000) + 30 * 60,
    metadata: {
      site_id: "linkedin",
      flow_id: flowId,
      owner: user.id,
      amount_minor: String(STRIPE_TEST_AMOUNT_MINOR),
      currency: STRIPE_TEST_CURRENCY,
      fingerprint,
      is_simulation: "true",
    },
    line_items: [{
      price_data: {
        currency: STRIPE_TEST_CURRENCY.toLowerCase(),
        unit_amount: STRIPE_TEST_AMOUNT_MINOR,
        product_data: { name: STRIPE_TEST_PRODUCT_NAME },
        recurring: { interval: "month" },
      },
      quantity: 1,
    }],
  }, { idempotencyKey: `linkedin-checkout-${flowId.slice(0, 48)}` });
  const session = validateStripeTestCheckout(
    sessionResponse as unknown as StripeTestCheckoutSession,
    user.id,
  );
  if (session.status !== "open" || session.payment_status !== "unpaid" || !session.url) {
    throw new ApiError(502, "Stripe Checkout did not return an unpaid session.", "stripe_checkout_unavailable");
  }
  const checkoutUrl = new URL(session.url);
  if (checkoutUrl.protocol !== "https:" || checkoutUrl.hostname !== "checkout.stripe.com" || checkoutUrl.username || checkoutUrl.password) {
    throw new ApiError(502, "Stripe Checkout returned an invalid hosted URL.", "stripe_checkout_unavailable");
  }
  const values = {
    stripeCustomerId: null,
    stripeSubscriptionId: null,
    stripePriceId: STRIPE_TEST_PRICE_ID,
    status: "incomplete",
    currentPeriodStart: null,
    currentPeriodEnd: null,
    cancelAtPeriodEnd: false,
    checkoutSessionId: session.id,
    updatedAt: new Date(),
  };
  if (existing) await db.update(subscriptions).set(values).where(eq(subscriptions.id, existing.id));
  else await db.insert(subscriptions).values({ userId: user.id, ...values });
  return session.url;
}

export async function completeStripeTestCheckout(userId: string, sessionId: string) {
  assertPublicBillingEnabled();
  const proxyUrl = stripeTestProxyUrl();
  if (!/^cs_test_[A-Za-z0-9_]{8,240}$/u.test(sessionId)) {
    throw new ApiError(400, "Invalid Stripe Checkout Session.", "stripe_checkout_invalid");
  }
  const [existing] = await getDb().select().from(subscriptions).where(eq(subscriptions.userId, userId)).limit(1);
  if (!existing || existing.checkoutSessionId !== sessionId) {
    throw new ApiError(404, "Stripe Checkout Session was not found for this account.", "stripe_checkout_missing");
  }
  if (["active", "trialing"].includes(existing.status)) return existing;
  const payload = proxyUrl
    ? await retrieveStripeTestCheckout(proxyUrl, sessionId)
    : await getStripe().checkout.sessions.retrieve(sessionId) as unknown as StripeTestCheckoutSession;
  const session = validateStripeTestCheckout(payload, userId, sessionId);
  if (session.status !== "complete" || session.payment_status !== "paid") {
    throw new ApiError(409, "Complete payment in Stripe before activating Premium.", "stripe_checkout_unpaid");
  }
  return activateStripeTestCheckout(existing, session);
}

type StripeCardSetupIntent = {
  id: string;
  client_secret?: string | null;
  status: string;
  customer?: string | null;
  payment_method?: string | null;
  usage?: string;
  livemode: false;
  metadata: Record<string, string>;
};

type StripeCardSubscription = {
  id: string;
  status: string;
  customer: string;
  default_payment_method?: string | null;
  livemode: false;
  metadata: Record<string, string>;
};

function cardFlowMetadata(userId: string, flowId: string) {
  return {
    site_id: "linkedin",
    owner: userId,
    flow_id: flowId,
    amount_minor: String(STRIPE_TEST_AMOUNT_MINOR),
    currency: STRIPE_TEST_CURRENCY,
    fingerprint: sha256(`linkedin\n${userId}\n${flowId}\n${STRIPE_TEST_AMOUNT_MINOR}\n${STRIPE_TEST_CURRENCY}`),
    is_simulation: "true",
  };
}

function cardMetadataFields(metadata: ReturnType<typeof cardFlowMetadata>) {
  return Object.entries(metadata).map(([key, value]) => [`metadata[${key}]`, value] as [string, string]);
}

function validateCardMetadata(metadata: Record<string, string> | null | undefined, userId: string) {
  const flowId = metadata?.flow_id ?? "";
  const expected = cardFlowMetadata(userId, flowId);
  if (!/^[0-9a-f]{64}$/u.test(flowId) || Object.entries(expected).some(([key, value]) => metadata?.[key] !== value)) {
    throw new ApiError(502, "Stripe returned invalid card setup metadata.", "stripe_card_response_invalid");
  }
  return flowId;
}

async function proxyFormRequest(proxyUrl: string, path: string, fields: URLSearchParams, idempotencyKey: string) {
  const response = await fetch(`${proxyUrl}${path}`, {
    method: "POST",
    headers: { "Content-Type": "application/x-www-form-urlencoded", "Idempotency-Key": idempotencyKey },
    body: fields.toString(),
  });
  const payload = await response.json().catch(() => null) as Record<string, unknown> | null;
  if (!response.ok || !payload) throw new ApiError(502, "Stripe card setup is unavailable.", "stripe_card_unavailable");
  return payload;
}

export async function createStripeCardSetup(user: Pick<User, "id" | "email" | "name">) {
  assertPublicBillingEnabled();
  const db = getDb();
  const [existing] = await db.select().from(subscriptions).where(eq(subscriptions.userId, user.id)).limit(1);
  if (existing && ["active", "trialing"].includes(existing.status)) {
    throw new ApiError(409, "Premium is already active for this account.", "subscription_active");
  }
  const proxyUrl = stripeTestProxyUrl();
  const flowId = sha256(`linkedin-card-setup\n${user.id}\n${randomUUID()}`);
  const metadata = cardFlowMetadata(user.id, flowId);
  let customerId: string | null = null;
  if (proxyUrl) {
    const payload = await proxyFormRequest(proxyUrl, "/v1/customers", new URLSearchParams([
      ["email", user.email], ["name", user.name], ...cardMetadataFields(metadata),
    ]), `linkedin-customer-${flowId.slice(0, 48)}`);
    customerId = typeof payload.id === "string" && /^cus_[A-Za-z0-9_]{8,240}$/u.test(payload.id) ? payload.id : null;
  } else {
    const customer = await getStripe().customers.create({ email: user.email, name: user.name, metadata }, { idempotencyKey: `linkedin-customer-${flowId.slice(0, 48)}` });
    customerId = customer.id;
  }
  if (!customerId) throw new ApiError(502, "Stripe did not create a Customer.", "stripe_customer_invalid");

  let setupIntent: StripeCardSetupIntent;
  if (proxyUrl) {
    setupIntent = await proxyFormRequest(proxyUrl, "/v1/setup_intents", new URLSearchParams([
      ["customer", customerId], ["payment_method", "pm_card_visa"], ["payment_method_types[0]", "card"],
      ["usage", "off_session"], ["confirm", "true"], ...cardMetadataFields(metadata),
    ]), `linkedin-setup-${flowId.slice(0, 48)}`) as unknown as StripeCardSetupIntent;
  } else {
    setupIntent = await getStripe().setupIntents.create({
      customer: customerId,
      payment_method: "pm_card_visa",
      payment_method_types: ["card"],
      usage: "off_session",
      confirm: true,
      metadata,
    }, { idempotencyKey: `linkedin-setup-${flowId.slice(0, 48)}` }) as unknown as StripeCardSetupIntent;
  }
  if (!/^seti_[A-Za-z0-9_]{8,240}$/u.test(setupIntent.id) || setupIntent.status !== "succeeded" ||
      setupIntent.customer !== customerId || !/^pm_[A-Za-z0-9_]{8,240}$/u.test(setupIntent.payment_method ?? "") || setupIntent.livemode !== false) {
    throw new ApiError(502, "Stripe returned an invalid SetupIntent.", "stripe_card_response_invalid");
  }
  validateCardMetadata(setupIntent.metadata, user.id);
  const values = {
    stripeCustomerId: customerId, stripeSubscriptionId: null, stripePriceId: STRIPE_TEST_PRICE_ID,
    status: "incomplete", currentPeriodStart: null, currentPeriodEnd: null, cancelAtPeriodEnd: false,
    checkoutSessionId: setupIntent.id, updatedAt: new Date(),
  };
  if (existing) await db.update(subscriptions).set(values).where(eq(subscriptions.id, existing.id));
  else await db.insert(subscriptions).values({ userId: user.id, ...values });
  return { setupIntentId: setupIntent.id };
}

export async function completeStripeCardSubscription(userId: string, setupIntentId: string) {
  assertPublicBillingEnabled();
  if (!/^seti_[A-Za-z0-9_]{8,240}$/u.test(setupIntentId)) throw new ApiError(400, "Invalid Stripe card setup.", "stripe_card_invalid");
  const db = getDb();
  const [existing] = await db.select().from(subscriptions).where(eq(subscriptions.userId, userId)).limit(1);
  if (!existing || existing.checkoutSessionId !== setupIntentId || !existing.stripeCustomerId) {
    throw new ApiError(404, "Stripe card setup was not found for this account.", "stripe_card_missing");
  }
  if (["active", "trialing"].includes(existing.status)) return existing;
  const proxyUrl = stripeTestProxyUrl();
  let setupIntent: StripeCardSetupIntent;
  if (proxyUrl) {
    const response = await fetch(`${proxyUrl}/v1/setup_intents/${encodeURIComponent(setupIntentId)}`, { headers: { Accept: "application/json" } });
    setupIntent = await response.json().catch(() => null) as StripeCardSetupIntent;
    if (!response.ok || !setupIntent) throw new ApiError(502, "Unable to verify the card with Stripe.", "stripe_card_verification_failed");
  } else {
    setupIntent = await getStripe().setupIntents.retrieve(setupIntentId) as unknown as StripeCardSetupIntent;
  }
  validateCardMetadata(setupIntent.metadata, userId);
  if (setupIntent.status !== "succeeded" || setupIntent.customer !== existing.stripeCustomerId ||
      !setupIntent.payment_method || !/^pm_[A-Za-z0-9_]{8,240}$/u.test(setupIntent.payment_method) || setupIntent.livemode !== false) {
    throw new ApiError(409, "Verify the card with Stripe before subscribing.", "stripe_card_unverified");
  }
  const flowId = setupIntent.metadata.flow_id;
  const metadata = cardFlowMetadata(userId, flowId);
  let subscription: StripeCardSubscription;
  if (proxyUrl) {
    subscription = await proxyFormRequest(proxyUrl, "/v1/subscriptions", new URLSearchParams([
      ["customer", existing.stripeCustomerId], ["default_payment_method", setupIntent.payment_method],
      ["items[0][price]", STRIPE_TEST_PRICE_ID], ["items[0][quantity]", "1"],
      ["payment_behavior", "error_if_incomplete"], ["payment_settings[save_default_payment_method]", "on_subscription"],
      ...cardMetadataFields(metadata),
    ]), `linkedin-subscription-${setupIntentId.slice(0, 48)}`) as unknown as StripeCardSubscription;
  } else {
    subscription = await getStripe().subscriptions.create({
      customer: existing.stripeCustomerId, default_payment_method: setupIntent.payment_method,
      items: [{ price: providerPriceId(), quantity: 1 }], payment_behavior: "error_if_incomplete",
      payment_settings: { save_default_payment_method: "on_subscription" }, metadata,
    }, { idempotencyKey: `linkedin-subscription-${setupIntentId.slice(0, 48)}` }) as unknown as StripeCardSubscription;
  }
  if (!/^sub_[A-Za-z0-9_]{8,240}$/u.test(subscription.id) || !["active", "trialing"].includes(subscription.status) ||
      subscription.customer !== existing.stripeCustomerId || subscription.livemode !== false) {
    throw new ApiError(502, "Stripe did not activate the test subscription.", "stripe_subscription_invalid");
  }
  validateCardMetadata(subscription.metadata, userId);
  const now = new Date();
  const [updated] = await db.update(subscriptions).set({
    stripeSubscriptionId: subscription.id, stripePriceId: STRIPE_TEST_PRICE_ID, status: subscription.status,
    currentPeriodStart: now, currentPeriodEnd: new Date(now.getTime() + 30 * 24 * 60 * 60 * 1000),
    cancelAtPeriodEnd: false, updatedAt: now,
  }).where(eq(subscriptions.id, existing.id)).returning();
  return updated;
}

function stripeSecretKey() {
  const key = process.env.STRIPE_SECRET_KEY;
  if (!key) throw new ApiError(503, "STRIPE_SECRET_KEY is not configured.", "stripe_not_configured");
  if (!key.startsWith("sk_test_")) {
    throw new ApiError(503, "LinkedIn billing is locked to Stripe Test Mode for this environment.", "stripe_live_key_rejected");
  }
  return key;
}
export function premiumPriceId() {
  const priceId = process.env.STRIPE_PREMIUM_PRICE_ID;
  if (!priceId) throw new ApiError(503, "STRIPE_PREMIUM_PRICE_ID is not configured.", "stripe_not_configured");
  return priceId;
}

export function getStripe() {
  if (!stripeClient) stripeClient = new Stripe(stripeSecretKey());
  return stripeClient;
}

export function stripeWebhookSecret() {
  const secret = process.env.STRIPE_WEBHOOK_SECRET;
  if (!secret) throw new ApiError(503, "STRIPE_WEBHOOK_SECRET is not configured.", "stripe_not_configured");
  return secret;
}

function dateFromUnix(value?: number) {
  return value ? new Date(value * 1000) : null;
}

function customerIdFrom(value: SubscriptionShape["customer"]) {
  return typeof value === "string" ? value : value.id;
}

export async function ensureStripeCustomer(user: Pick<User, "id" | "email" | "name">) {
  const db = getDb();
  const [existing] = await db.select().from(subscriptions).where(eq(subscriptions.userId, user.id)).limit(1);
  if (existing?.stripeCustomerId) return existing.stripeCustomerId;

  const customer = await getStripe().customers.create({
    email: user.email,
    name: user.name,
    metadata: { userId: user.id },
  });

  if (existing) {
    await db.update(subscriptions).set({
      stripeCustomerId: customer.id,
      stripePriceId: premiumPriceId(),
      updatedAt: new Date(),
    }).where(eq(subscriptions.id, existing.id));
  } else {
    await db.insert(subscriptions).values({
      userId: user.id,
      stripeCustomerId: customer.id,
      stripePriceId: premiumPriceId(),
    });
  }
  return customer.id;
}

export async function createCheckoutUrl(user: Pick<User, "id" | "email" | "name">) {
  assertPublicBillingEnabled();
  const proxyUrl = stripeTestProxyUrl();
  if (proxyUrl) return createStripeTestCheckout(user, proxyUrl);
  if (process.env.STRIPE_SECRET_KEY) return createDirectStripeTestCheckout(user);
  if (localBillingFallbackEnabled() || "passwordHash" in user && user.passwordHash === "local-test") {
    if (process.env.PUBLIC_CLONE_AUTH_MODE === "local-dev" || "passwordHash" in user && user.passwordHash === "local-test") {
      const checkoutSessionId = localCheckout(user.id);
      return `${appUrl()}/premium?checkout=success&session_id=${encodeURIComponent(checkoutSessionId)}`;
    }
    const db = getDb();
    const [existing] = await db.select().from(subscriptions).where(eq(subscriptions.userId, user.id)).limit(1);
    const now = new Date();
    const checkoutSessionId = `cs_test_local_${Date.now().toString(36)}_${Math.random().toString(36).slice(2, 10)}`;
    const values = {
      stripeCustomerId: `cus_local_${user.id}`,
      stripeSubscriptionId: `sub_local_${user.id}`,
      stripePriceId: "price_local_test",
      status: "active",
      currentPeriodStart: now,
      currentPeriodEnd: new Date(now.getTime() + 30 * 24 * 60 * 60 * 1000),
      cancelAtPeriodEnd: false,
      checkoutSessionId,
      updatedAt: now,
    };
    if (existing) {
      await db.update(subscriptions).set(values).where(eq(subscriptions.id, existing.id));
    } else {
      await db.insert(subscriptions).values({ userId: user.id, ...values });
    }
    return `${appUrl()}/premium?checkout=success&session_id=${encodeURIComponent(checkoutSessionId)}`;
  }

  const customerId = await ensureStripeCustomer(user);
  const session = await getStripe().checkout.sessions.create({
    mode: "subscription",
    customer: customerId,
    line_items: [{ price: premiumPriceId(), quantity: 1 }],
    success_url: `${appUrl()}/premium?checkout=success`,
    cancel_url: `${appUrl()}/premium?checkout=cancelled`,
    client_reference_id: user.id,
    metadata: { userId: user.id },
    subscription_data: { metadata: { userId: user.id } },
  });

  await getDb().update(subscriptions).set({
    checkoutSessionId: session.id,
    updatedAt: new Date(),
  }).where(eq(subscriptions.userId, user.id));

  if (!session.url) throw new ApiError(502, "Stripe did not return a checkout URL.", "stripe_checkout_unavailable");
  return session.url;
}

export async function createPortalUrl(userId: string) {
  assertPublicBillingEnabled();
  if (stripeTestProxyUrl()) {
    throw new ApiError(409, "Stripe Test Mode subscriptions do not require a billing portal.", "stripe_test_portal_unavailable");
  }
  const [subscription] = await getDb().select().from(subscriptions).where(eq(subscriptions.userId, userId)).limit(1);
  if (!subscription?.stripeCustomerId) throw new ApiError(404, "No Stripe customer exists for this account.", "stripe_customer_missing");
  const session = await getStripe().billingPortal.sessions.create({
    customer: subscription.stripeCustomerId,
    return_url: `${appUrl()}/premium`,
  });
  return session.url;
}

export async function syncStripeSubscription(subscription: SubscriptionShape) {
  const customerId = customerIdFrom(subscription.customer);
  const priceId = subscription.items?.data?.[0]?.price?.id ?? premiumPriceId();
  const db = getDb();
  const [existing] = await db.select().from(subscriptions).where(eq(subscriptions.stripeCustomerId, customerId)).limit(1);
  const userId = subscription.metadata?.userId ?? existing?.userId;
  if (!userId) return null;

  const values = {
    stripeCustomerId: customerId,
    stripeSubscriptionId: subscription.id,
    stripePriceId: priceId,
    status: subscription.status,
    currentPeriodStart: dateFromUnix(subscription.current_period_start),
    currentPeriodEnd: dateFromUnix(subscription.current_period_end),
    cancelAtPeriodEnd: subscription.cancel_at_period_end ?? false,
    updatedAt: new Date(),
  };

  if (existing) {
    const [updated] = await db.update(subscriptions).set(values).where(eq(subscriptions.id, existing.id)).returning();
    return updated;
  }

  const [created] = await db.insert(subscriptions).values({ userId, ...values }).returning();
  return created;
}