import { NextResponse } from 'next/server';
import Stripe from 'stripe';

const stripeSecretKey = process.env.STRIPE_SECRET_KEY;

const stripe = stripeSecretKey
  ? new Stripe(stripeSecretKey, { apiVersion: '2024-06-20' })
  : null;

export async function POST(request: Request) {
  try {
    if (!stripe) {
      return NextResponse.json({ error: 'Stripe is not configured.' }, { status: 500 });
    }

    const body = await request.json();
    const credits = Number(body?.credits);
    const amount = Number(body?.amount);
    const userId = body?.userId as string | undefined;

    // TODO: Get userId from auth token
    const resolvedUserId = userId ?? 'test-user-id';

    if (!resolvedUserId || !Number.isFinite(credits) || credits <= 0) {
      return NextResponse.json({ error: 'Invalid checkout payload.' }, { status: 400 });
    }

    if (!Number.isFinite(amount) || amount <= 0) {
      return NextResponse.json({ error: 'Invalid amount.' }, { status: 400 });
    }

    const origin = request.headers.get('origin') ?? 'http://localhost:3000';

    const session = await stripe.checkout.sessions.create({
      mode: 'payment',
      payment_method_types: ['card'],
      line_items: [
        {
          quantity: 1,
          price_data: {
            currency: 'eur',
            unit_amount: amount * 100,
            product_data: {
              name: `${credits} HolaCompi Credits`,
              description: 'Pay-as-you-go voice call credits',
            },
          },
        },
      ],
      success_url: `${origin}/dashboard/credits?success=true`,
      cancel_url: `${origin}/dashboard/credits?canceled=true`,
      metadata: {
        userId: resolvedUserId,
        credits: credits.toString(),
        amount: amount.toString(),
      },
    });

    return NextResponse.json({ sessionId: session.id, url: session.url });
  } catch (error) {
    console.error('Stripe checkout error:', error);
    return NextResponse.json({ error: 'Failed to create checkout session.' }, { status: 500 });
  }
}