import { NextResponse } from "next/server";
import { getPayload } from "payload";
import config from "@payload-config";
import { checkRateLimit, getClientIp } from "@/lib/auth/rateLimit";
import { EMAIL_VERIFICATION_TTL_MS, generateVerificationToken, hashVerificationToken, verificationExpiryISO } from "@/lib/auth/verification";
import { verificationEmail } from "@/lib/email/authTemplates";
import { sendEmail } from "@/lib/email/sendBookingEmails";
import type { Customer } from "@/payload-types";

export const dynamic = "force-dynamic";

// Deliberately identical whether or not an account exists / is already
// verified — this endpoint must never let a caller find out either of
// those things about an email address that isn't their own session.
const GENERIC_RESPONSE = {
  ok: true,
  message: "Falls ein Konto mit dieser E-Mail-Adresse existiert und noch nicht bestätigt ist, wurde eine neue Bestätigungs-E-Mail gesendet.",
};

async function issueAndSend(payload: Awaited<ReturnType<typeof getPayload>>, customer: Customer) {
  const token = generateVerificationToken();
  await payload.update({
    collection: "customers",
    id: customer.id,
    data: {
      emailVerificationTokenHash: hashVerificationToken(token),
      emailVerificationExpires: verificationExpiryISO(),
    },
  });

  const serverUrl = process.env.NEXT_PUBLIC_SERVER_URL || "http://localhost:3000";
  await sendEmail(
    customer.email,
    verificationEmail({
      name: customer.name,
      verifyUrl: `${serverUrl}/auth/verify-email/${token}`,
      expiresHours: Math.round(EMAIL_VERIFICATION_TTL_MS / (60 * 60 * 1000)),
    }),
  );
}

export async function POST(request: Request) {
  const ip = getClientIp(request);
  if (!checkRateLimit(`resend-verification:ip:${ip}`, { max: 10, windowMs: 60 * 60 * 1000 })) {
    return NextResponse.json({ error: "Zu viele Anfragen. Bitte versuche es später erneut." }, { status: 429 });
  }

  try {
    const payload = await getPayload({ config });
    const { user } = await payload.auth({ headers: request.headers });

    let customer: Customer | null = null;

    if (user && user.collection === "customers") {
      customer = user as Customer;
    } else {
      let body: { email?: unknown } = {};
      try {
        body = await request.json();
      } catch {
        // no body — handled below as a missing email
      }
      const email = typeof body.email === "string" ? body.email.trim().toLowerCase() : "";
      if (!email) {
        return NextResponse.json({ error: "E-Mail-Adresse erforderlich." }, { status: 400 });
      }
      if (!checkRateLimit(`resend-verification:email:${email}`, { max: 3, windowMs: 60 * 60 * 1000 })) {
        return NextResponse.json({ error: "Zu viele Anfragen. Bitte versuche es später erneut." }, { status: 429 });
      }

      const { docs } = await payload.find({
        collection: "customers",
        where: { email: { equals: email } },
        limit: 1,
      });
      customer = (docs[0] as Customer) ?? null;
    }

    if (customer && !customer.emailVerified) {
      if (!checkRateLimit(`resend-verification:customer:${customer.id}`, { max: 3, windowMs: 60 * 60 * 1000 })) {
        return NextResponse.json({ error: "Zu viele Anfragen. Bitte versuche es später erneut." }, { status: 429 });
      }
      await issueAndSend(payload, customer);
    }

    return NextResponse.json(GENERIC_RESPONSE);
  } catch (error) {
    console.error("resend verification failed", error);
    return NextResponse.json({ error: "Die Bestätigungs-E-Mail konnte nicht gesendet werden." }, { status: 500 });
  }
}