import { NextRequest, NextResponse } from "next/server";
import { prisma } from "@/lib/prisma";
import { requireAuth } from "@/lib/auth";

const TOP_UP_AMOUNTS = {
  500: { usd: 0.99, bonus: 0, priceEnv: "POLAR_FLH_500" },
  1000: { usd: 0.99, bonus: 0, priceEnv: "POLAR_FLH_1000" },
  5000: { usd: 4.99, bonus: 500, priceEnv: "POLAR_FLH_5000" },
  10000: { usd: 9.99, bonus: 2000, priceEnv: "POLAR_FLH_10000" },
  50000: { usd: 49.99, bonus: 15000, priceEnv: "POLAR_FLH_50000" },
} as const;

export async function POST(req: NextRequest) {
  const jwtPayload = await requireAuth(req);
  if (!jwtPayload) {
    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
  }

  try {
    const body = await req.json();
    const { amount } = body;

    if (!amount || !(amount in TOP_UP_AMOUNTS)) {
      return NextResponse.json(
        { error: "Invalid amount. Choose 500, 1000, 5000, 10000, or 50000 FLH." },
        { status: 400 }
      );
    }

    const pricing = TOP_UP_AMOUNTS[amount as keyof typeof TOP_UP_AMOUNTS];
    const totalFlh = amount + (pricing.bonus || 0);

    // Mock mode: use when POLAR_ACCESS_TOKEN is not configured (dev only)
    if (!process.env.POLAR_ACCESS_TOKEN) {
      // Production guard: never allow mock top-ups in production
      if (process.env.NODE_ENV === "production") {
        return NextResponse.json(
          { error: "Payment service not configured" },
          { status: 500 }
        );
      }
      await prisma.user.update({
        where: { id: jwtPayload.userId },
        data: { flhBalance: { increment: totalFlh } },
      });

      return NextResponse.json({
        success: true,
        url: "/wallet?topup=success",
        mock: true,
        amount,
        bonus: pricing.bonus || 0,
        amountUsd: pricing.usd,
      });
    }

    // Production — Polar.sh checkout session
    const productPriceId = process.env[pricing.priceEnv];
    if (!productPriceId) {
      return NextResponse.json(
        { error: `Polar price not configured for ${amount} FLH. Set ${pricing.priceEnv} env var.` },
        { status: 500 }
      );
    }

    const origin = req.headers.get("origin") || req.headers.get("host") || "";
    const baseUrl = origin.startsWith("http") ? origin : `https://${origin}`;

    const polarResponse = await fetch("https://api.polar.sh/v1/checkouts/", {
      method: "POST",
      headers: {
        Authorization: `Bearer ${process.env.POLAR_ACCESS_TOKEN}`,
        "Content-Type": "application/json",
      },
      body: JSON.stringify({
        product_price_id: productPriceId,
        success_url: `${baseUrl}/wallet?topup=success&amount=${amount}`,
        customer_email: jwtPayload.email,
        return_url: `${baseUrl}/wallet`,
        metadata: {
          type: "flh_purchase",
          flh_amount: totalFlh,
          user_id: jwtPayload.userId,
          user_email: jwtPayload.email,
        },
        allow_trial: false,
      }),
    });

    if (!polarResponse.ok) {
      const errorBody = await polarResponse.text();
      console.error("Polar API error:", polarResponse.status, errorBody);
      return NextResponse.json(
        { error: `Checkout creation failed (HTTP ${polarResponse.status})` },
        { status: 502 }
      );
    }

    const polarData = await polarResponse.json();

    return NextResponse.json({
      success: true,
      url: polarData.url,
      checkout_id: polarData.id,
      amount,
      amountUsd: pricing.usd,
      bonus: pricing.bonus || 0,
    });
  } catch (error) {
    console.error("Top-up checkout error:", error);
    return NextResponse.json(
      { error: error instanceof Error ? error.message : "Failed to create checkout" },
      { status: 500 }
    );
  }
}