import { NextRequest } from "next/server";
import { DEFAULT_PAYMENT_API_URL } from "@/config/domain.config";
import { getPaymentConfig } from "@/config/services.config";

function isPrivateHost(hostname: string): boolean {
  if (!hostname) return false;
  if (hostname === "localhost" || hostname === "127.0.0.1" || hostname === "::1") {
    return true;
  }
  if (/^10\./.test(hostname) || /^192\.168\./.test(hostname)) {
    return true;
  }
  const match = hostname.match(/^172\.(\d{1,2})\./);
  if (!match) return false;
  const secondOctet = Number(match[1]);
  return secondOctet >= 16 && secondOctet <= 31;
}

function normalizeBaseUrl(url: string | undefined): string {
  return String(url || "").trim().replace(/\/$/, "");
}

function getRequestHostname(request: NextRequest): string {
  const forwardedHost = request.headers.get("x-forwarded-host");
  const host = forwardedHost || request.headers.get("host") || "";
  return host.split(",")[0].trim().replace(/:\d+$/, "");
}

function getMeetupApiCandidates(request: NextRequest): string[] {
  const configuredApiUrl = normalizeBaseUrl(getPaymentConfig().apiUrl);
  const localApiUrl = normalizeBaseUrl(DEFAULT_PAYMENT_API_URL);
  const hostname = getRequestHostname(request);
  const shouldPreferLocal =
    process.env.NODE_ENV === "development" || isPrivateHost(hostname);

  const urls = shouldPreferLocal
    ? [localApiUrl, configuredApiUrl]
    : [configuredApiUrl, localApiUrl];

  return urls.filter((url, index) => url && urls.indexOf(url) === index);
}

/** 上游 API 请求超时时间（毫秒），避免 serverless 超时导致 502 */
const MEETUP_API_TIMEOUT_MS = 20000;

export async function postMeetupApi(
  request: NextRequest,
  path: string,
  body: unknown
): Promise<{ status: number; data: unknown }> {
  const apiCandidates = getMeetupApiCandidates(request);
  if (apiCandidates.length === 0) {
    throw new Error("PAYMENT_API_URL is not configured");
  }

  let lastResponse: { status: number; data: unknown } | null = null;
  let lastError: unknown = null;

  for (const apiUrl of apiCandidates) {
    const url = `${apiUrl}${path}`;
    const controller = new AbortController();
    const timeoutId = setTimeout(() => controller.abort(), MEETUP_API_TIMEOUT_MS);

    try {
      const res = await fetch(url, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify(body),
        cache: "no-store",
        signal: controller.signal,
      });
      clearTimeout(timeoutId);
      const data = await res.json().catch(() => ({}));

      if (res.ok || (res.status !== 404 && res.status < 500)) {
        return { status: res.status, data };
      }

      lastResponse = { status: res.status, data };
      if (res.status >= 500) {
        console.error(`[meetup-api] ${path} ${apiUrl} returned ${res.status}`, data);
      }
    } catch (error) {
      clearTimeout(timeoutId);
      const errMsg = error instanceof Error ? error.message : String(error);
      const errName = error instanceof Error && "name" in error ? (error as { name?: string }).name : "";
      const isTimeout = errName === "AbortError" || errMsg.toLowerCase().includes("abort") || errMsg.toLowerCase().includes("timeout");
      console.error(`[meetup-api] ${path} ${apiUrl} failed:`, isTimeout ? "timeout" : errMsg);
      lastError = error;
    }
  }

  if (lastResponse) {
    return lastResponse;
  }

  throw lastError instanceof Error ? lastError : new Error("Meetup API request failed");
}