import { NextRequest, NextResponse } from "next/server";
import { getApiUrlFromRequest, getPaymentConfig } from "@/config/services.config";
import {
  findAnonymousUserIdForUser,
  findLinkedMemberFromOrder,
  findVipEmailLinkByAnonymousUserId,
  findVipEmailLinkByUserId,
  getAdminToken,
  isAnonymousUserId,
  upsertVipEmailLink,
} from "@/app/api/vip/_helpers";

function resolvePayApiUrl(request: NextRequest): string {
  const payConfig = getPaymentConfig();
  const hostHeader = request.headers.get("host") || request.headers.get("x-forwarded-host");
  return (
    (hostHeader ? getApiUrlFromRequest(hostHeader) : null) ||
    payConfig.apiUrl
  ).replace(/\/$/, "");
}

async function getLinkedEmailFromPayjsapi(
  request: NextRequest,
  userId: string
): Promise<string | null> {
  try {
    const apiUrl = resolvePayApiUrl(request);
    const res = await fetch(
      `${apiUrl}/nomadvip/check_vip?user_id=${encodeURIComponent(userId)}`,
      { cache: "no-store", signal: AbortSignal.timeout(5000) }
    );
    if (!res.ok) {
      return null;
    }

    const data = await res.json().catch(() => ({}));
    const email =
      typeof data?.email === "string" ? data.email.trim().toLowerCase() : "";
    return data?.vip && email ? email : null;
  } catch {
    return null;
  }
}

export async function GET(request: NextRequest) {
  const userId = request.nextUrl.searchParams.get("user_id")?.trim() || "";
  if (!userId) {
    return NextResponse.json(
      { email: null, error: "缺少 user_id" },
      { status: 400 }
    );
  }

  try {
    const adminToken = await getAdminToken();
    if (!adminToken) {
      return NextResponse.json({ email: null }, { status: 500 });
    }

    const linkRecord = isAnonymousUserId(userId)
      ? await findVipEmailLinkByAnonymousUserId(adminToken, userId)
      : await findVipEmailLinkByUserId(adminToken, userId);
    const linkedEmail =
      typeof linkRecord?.email === "string"
        ? linkRecord.email.trim().toLowerCase()
        : "";
    const anonymousUserId =
      typeof linkRecord?.anonymous_user_id === "string" &&
      isAnonymousUserId(linkRecord.anonymous_user_id.trim())
        ? linkRecord.anonymous_user_id.trim()
        : !isAnonymousUserId(userId)
          ? await findAnonymousUserIdForUser(adminToken, userId)
          : isAnonymousUserId(userId)
          ? userId
          : null;
    if (linkedEmail) {
      return NextResponse.json({
        email: linkedEmail,
        anonymousUserId,
      });
    }

    if (isAnonymousUserId(userId)) {
      const linkedMember = await findLinkedMemberFromOrder(adminToken, userId);
      if (linkedMember) {
        await upsertVipEmailLink(
          adminToken,
          linkedMember.email,
          linkedMember.userId,
          userId
        );
        return NextResponse.json({
          email: linkedMember.email,
          anonymousUserId: userId,
        });
      }
    }

    const payjsEmail = await getLinkedEmailFromPayjsapi(request, userId);
    if (payjsEmail) {
      if (anonymousUserId && !isAnonymousUserId(userId)) {
        await upsertVipEmailLink(adminToken, payjsEmail, userId, anonymousUserId);
      }
      return NextResponse.json({
        email: payjsEmail,
        anonymousUserId: anonymousUserId ?? (isAnonymousUserId(userId) ? userId : null),
      });
    }

    return NextResponse.json({ email: null, anonymousUserId: anonymousUserId ?? null });
  } catch (error) {
    console.error("[linked-email] failed:", error);
    return NextResponse.json({ email: null, anonymousUserId: null }, { status: 500 });
  }
}