import { NextResponse } from "next/server";

import { assertAgencyAdmin, getRouteAgencyContextOrThrow } from "@/lib/agency";
import { env } from "@/lib/env";
import { getStripeClient } from "@/lib/stripe";
import { createSupabaseRouteClient } from "@/lib/supabase/route";

export async function POST() {
  try {
    const context = await getRouteAgencyContextOrThrow();
    assertAgencyAdmin(context);

    if (!env.stripePriceId) {
      throw new Error("STRIPE_PRICE_ID is not configured");
    }

    const stripe = getStripeClient();
    const supabase = createSupabaseRouteClient();

    const { data: billing, error: billingError } = await supabase
      .from("billing_accounts")
      .select("id, stripe_customer_id")
      .eq("agency_id", context.agencyId)
      .maybeSingle();

    if (billingError) throw billingError;

    let customerId = billing?.stripe_customer_id ?? null;

    if (!customerId) {
      const customer = await stripe.customers.create({
        metadata: {
          agency_id: context.agencyId,
        },
      });

      customerId = customer.id;

      const upsertPayload = {
        agency_id: context.agencyId,
        stripe_customer_id: customerId,
      };

      if (billing?.id) {
        await supabase.from("billing_accounts").update(upsertPayload).eq("id", billing.id);
      } else {
        await supabase.from("billing_accounts").insert(upsertPayload);
      }
    }

    const session = await stripe.checkout.sessions.create({
      mode: "subscription",
      customer: customerId,
      line_items: [{ price: env.stripePriceId, quantity: 1 }],
      success_url: `${env.appUrl}/dashboard?checkout=success`,
      cancel_url: `${env.appUrl}/dashboard?checkout=cancelled`,
      metadata: {
        agency_id: context.agencyId,
      },
    });

    return NextResponse.json({ url: session.url });
  } catch (error) {
    return NextResponse.json(
      { error: error instanceof Error ? error.message : "Failed to create checkout session" },
      { status: 400 },
    );
  }
}