import Stripe from "stripe";
import { prisma } from "@/lib/db";
import { stripePriceId, type BillingInterval } from "./catalog";
import type { PlanKey } from "./plans";

let client: Stripe | null = null;

export function stripe(): Stripe {
  if (!client) {
    const key = process.env.STRIPE_SECRET_KEY;
    if (!key) throw new Error("STRIPE_SECRET_KEY is not set");
    client = new Stripe(key);
  }
  return client;
}

export function isStripeConfigured(): boolean {
  return !!process.env.STRIPE_SECRET_KEY;
}

const appUrl = () => process.env.NEXT_PUBLIC_APP_URL ?? "http://localhost:3000";

/** Find-or-create the Stripe customer for a user and persist the id. */
export async function ensureStripeCustomer(user: {
  id: string;
  email: string;
  name: string;
  stripeCustomerId: string | null;
}): Promise<string> {
  if (user.stripeCustomerId) return user.stripeCustomerId;
  const customer = await stripe().customers.create({
    email: user.email,
    name: user.name,
    metadata: { userId: user.id },
  });
  await prisma.user.update({ where: { id: user.id }, data: { stripeCustomerId: customer.id } });
  return customer.id;
}

/** Create a Stripe Checkout Session for a subscription; returns the redirect URL. */
export async function createStripeCheckout(args: {
  user: { id: string; email: string; name: string; stripeCustomerId: string | null };
  plan: PlanKey;
  interval: BillingInterval;
  subjectId: string;
  subjectType: "user" | "organization";
}): Promise<string> {
  const price = stripePriceId(args.plan, args.interval);
  if (!price) throw new Error(`No Stripe price configured for ${args.plan}/${args.interval}`);
  const customer = await ensureStripeCustomer(args.user);

  const session = await stripe().checkout.sessions.create({
    mode: "subscription",
    customer,
    line_items: [{ price, quantity: 1 }],
    client_reference_id: args.subjectId,
    metadata: { plan: args.plan, subjectId: args.subjectId, subjectType: args.subjectType },
    subscription_data: {
      metadata: { plan: args.plan, subjectId: args.subjectId, subjectType: args.subjectType },
    },
    allow_promotion_codes: true,
    success_url: `${appUrl()}/billing?status=success`,
    cancel_url: `${appUrl()}/billing?status=cancel`,
  });
  if (!session.url) throw new Error("Stripe did not return a checkout URL");
  return session.url;
}

/** Create a Stripe Billing Portal session for managing/cancelling a subscription. */
export async function createStripePortal(customerId: string): Promise<string> {
  const session = await stripe().billingPortal.sessions.create({
    customer: customerId,
    return_url: `${appUrl()}/billing`,
  });
  return session.url;
}