import { NextRequest, NextResponse } from "next/server";
import Stripe from "stripe";
import nodemailer from "nodemailer";

const stripe = new Stripe(process.env.STRIPE_SECRET_KEY!);

const mailer = nodemailer.createTransport({
  host: "smtp.gmail.com",
  port: 587,
  secure: false,
  auth: {
    user: process.env.SMTP_USER,   // nolankovacs@verimundsolutions.com Gmail address
    pass: process.env.SMTP_PASS,   // Gmail App Password
  },
});

// Tier → expiry days (null = lifetime)
const TIER_EXPIRY: Record<string, number | null> = {
  Weekly:   7,
  Monthly:  30,
  Annual:   365,
  Lifetime: null,
};

async function generateLicense(tier: string, email: string): Promise<string> {
  const res = await fetch(`${process.env.API_URL}/admin/generate-license`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "X-Admin-Key": process.env.ADMIN_KEY!,
    },
    body: JSON.stringify({
      tier:       tier.toLowerCase(),
      email,
      days_valid: TIER_EXPIRY[tier],
      channel:    "stable",
      source:     "stripe",
    }),
  });

  if (!res.ok) throw new Error(`License generation failed: ${res.status}`);
  const data = await res.json();
  return data.license_key;
}

async function sendLicenseEmail(email: string, tier: string, licenseKey: string) {
  const expiryText = TIER_EXPIRY[tier] === null
    ? "Your license never expires."
    : `Your license is valid for ${TIER_EXPIRY[tier]} days from today.`;

  await mailer.sendMail({
    from: `"Verimund Solutions" <noreply@verimundsolutions.com>`,
    to: email,
    subject: `Your UIT ${tier} License Key`,
    html: `
      <div style="background:#0a0a0a;color:#ffffff;font-family:Arial,sans-serif;padding:40px;max-width:520px;margin:0 auto;">
        <p style="color:#4ade80;font-size:11px;font-weight:600;letter-spacing:0.2em;text-transform:uppercase;margin-bottom:24px;">
          Verimund Solutions
        </p>
        <h1 style="font-size:24px;font-weight:600;margin-bottom:8px;">Your license key is ready.</h1>
        <p style="color:#888888;font-size:14px;margin-bottom:32px;">
          Thank you for purchasing UIT ${tier}. ${expiryText}
        </p>

        <div style="background:#111111;border:1px solid #222222;border-radius:4px;padding:20px;margin-bottom:32px;">
          <p style="color:#888888;font-size:11px;text-transform:uppercase;letter-spacing:0.15em;margin-bottom:8px;">License Key</p>
          <p style="font-family:monospace;font-size:18px;font-weight:600;letter-spacing:0.05em;color:#ffffff;word-break:break-all;">
            ${licenseKey}
          </p>
        </div>

        <p style="color:#888888;font-size:13px;line-height:1.7;margin-bottom:16px;">
          To activate, open UIT and enter this key when prompted. The license will bind to your machine on first use.
        </p>
        <p style="color:#888888;font-size:13px;line-height:1.7;margin-bottom:32px;">
          If you need to transfer your license to a new machine, contact us at
          <a href="mailto:support@verimundsolutions.com" style="color:#ffffff;">support@verimundsolutions.com</a>.
        </p>

        <hr style="border:none;border-top:1px solid #222222;margin-bottom:24px;" />
        <p style="color:#3a3a3a;font-size:11px;">
          © ${new Date().getFullYear()} Verimund Solutions. This email was sent to ${email} because you purchased a UIT license.
        </p>
      </div>
    `,
  });
}

export async function POST(req: NextRequest) {
  const body = await req.text();
  const sig  = req.headers.get("stripe-signature")!;

  let event: Stripe.Event;
  try {
    event = stripe.webhooks.constructEvent(body, sig, process.env.STRIPE_WEBHOOK_SECRET!);
  } catch {
    return NextResponse.json({ error: "Invalid signature" }, { status: 400 });
  }

  if (event.type === "checkout.session.completed") {
    const session = event.data.object as Stripe.Checkout.Session;
    const email   = session.customer_details?.email;
    const tier    = session.metadata?.tier;

    if (!email || !tier) {
      console.error("[WEBHOOK] Missing email or tier", { email, tier });
      return NextResponse.json({ error: "Missing data" }, { status: 400 });
    }

    try {
      const licenseKey = await generateLicense(tier, email);
      await sendLicenseEmail(email, tier, licenseKey);
      console.log(`[WEBHOOK] License issued: ${tier} → ${email}`);
    } catch (err) {
      console.error("[WEBHOOK] Failed to issue license:", err);
      // Return 200 so Stripe doesn't retry — log the failure for manual follow-up
      // TODO: add to a failed_deliveries table for retry
    }
  }

  return NextResponse.json({ received: true });
}