import type { FastifyInstance } from 'fastify';
import { z } from 'zod';
import { eq } from 'drizzle-orm';
import { getDb, firms } from '@lawdesk/db';
import { env } from '../env';
import { getStripe, getPlanConfig, stripeIsConfigured } from '../lib/stripe';

export async function billingRoutes(app: FastifyInstance) {
  app.addHook('preHandler', app.requireFirm);

  // Reading plan state is fine for anyone in the firm; spending money or opening the Stripe
  // portal (which exposes payment methods and invoice history) is the owner's call alone.
  const ownerOnly = { preHandler: app.requireRole('owner') };

  // Status — what does the UI need to show? Configured at all? Current plan? Has subscription?
  app.get('/api/billing/status', async (req) => {
    const firmId = req.user!.firmId!;
    const [firm] = await getDb().select().from(firms).where(eq(firms.id, firmId)).limit(1);
    return {
      configured: stripeIsConfigured(),
      plan: firm?.plan ?? 'starter',
      hasSubscription: !!firm?.stripeSubscriptionId,
      hasCustomer: !!firm?.stripeCustomerId,
    };
  });

  // Create a Checkout Session — returns the URL to redirect the user to.
  app.post('/api/billing/checkout', ownerOnly, async (req, reply) => {
    const parsed = z
      .object({ plan: z.enum(['pro', 'lifetime']) })
      .safeParse(req.body);
    if (!parsed.success) return reply.code(400).send({ error: 'invalid_plan' });

    if (!stripeIsConfigured()) return reply.code(503).send({ error: 'stripe_not_configured' });

    const firmId = req.user!.firmId!;
    const userEmail = req.user!.email;
    const planCfg = getPlanConfig(parsed.data.plan);
    if (!planCfg) return reply.code(503).send({ error: 'plan_not_configured' });

    const db = getDb();
    const [firm] = await db.select().from(firms).where(eq(firms.id, firmId)).limit(1);
    if (!firm) return reply.code(404).send({ error: 'firm_not_found' });

    // Guard against double-billing: a firm already on a paid plan (or with a live subscription)
    // must not be able to open a second Checkout session. Send them to the portal instead.
    if (firm.plan !== 'starter' || firm.stripeSubscriptionId) {
      return reply.code(409).send({
        error: 'already_on_paid_plan',
        hint: 'Manage or change your current plan from the billing portal.',
      });
    }

    const stripe = getStripe();

    // Reuse the customer if we've made one before; otherwise let Checkout create one and we'll
    // capture it on the webhook.
    const session = await stripe.checkout.sessions.create({
      mode: planCfg.mode,
      line_items: [{ price: planCfg.priceId, quantity: 1 }],
      customer: firm.stripeCustomerId ?? undefined,
      customer_email: firm.stripeCustomerId ? undefined : userEmail,
      client_reference_id: firmId,
      metadata: { firmId, plan: planCfg.planName },
      subscription_data:
        planCfg.mode === 'subscription' ? { metadata: { firmId, plan: planCfg.planName } } : undefined,
      success_url: `${env.PUBLIC_URL}/billing/success?session_id={CHECKOUT_SESSION_ID}`,
      cancel_url: `${env.PUBLIC_URL}/billing/cancel`,
      allow_promotion_codes: true,
    });

    return { url: session.url };
  });

  // Customer Portal — for managing the subscription, updating payment method, viewing invoices.
  app.post('/api/billing/portal', ownerOnly, async (req, reply) => {
    if (!stripeIsConfigured()) return reply.code(503).send({ error: 'stripe_not_configured' });

    const firmId = req.user!.firmId!;
    const [firm] = await getDb().select().from(firms).where(eq(firms.id, firmId)).limit(1);
    if (!firm?.stripeCustomerId) return reply.code(404).send({ error: 'no_customer' });

    const stripe = getStripe();
    const session = await stripe.billingPortal.sessions.create({
      customer: firm.stripeCustomerId,
      return_url: `${env.PUBLIC_URL}/app/settings`,
    });
    return { url: session.url };
  });
}