import { type NextRequest, NextResponse } from "next/server";
import { getToken } from "next-auth/jwt";
import { isBlockedIP, getClientIP } from "@/lib/security/ip-blocklist";
import {
  checkRateLimit,
  checkRateLimitByIdentifier,
  rateLimiters,
} from "@/lib/security/rate-limiter";
import { isSuspiciousRequest, logSuspiciousRequest } from "@/lib/security/request-monitor";

function isHighFrequencyReadApi(pathname: string, method: string) {
  if (method !== "GET") return false;
  if (/^\/api\/canvas\/[^/]+\/detail-archives$/.test(pathname)) return true;

  return [
    "/api/models",
    "/api/canvas",
    "/api/nav-links",
    "/api/site-settings",
    "/api/messages",
    "/api/history",
    "/api/video-tasks",
    "/api/tutorial-videos",
    "/api/user/membership-summary",
    "/api/user/account-center",
  ].includes(pathname);
}

export async function proxy(request: NextRequest) {
  const { pathname } = request.nextUrl;
  const isSecure =
    process.env.AUTH_URL?.startsWith("https://") ||
    request.nextUrl.protocol === "https:";
  let cachedToken: Awaited<ReturnType<typeof getToken>> | null | undefined;
  const resolveToken = async () => {
    if (cachedToken !== undefined) {
      return cachedToken;
    }
    cachedToken = await getToken({
      req: request,
      secret: process.env.AUTH_SECRET,
      secureCookie: isSecure,
    });
    return cachedToken;
  };

  // 🛡️ 安全检查1：阻止黑名单IP
  const clientIP = getClientIP(request);
  if (isBlockedIP(clientIP)) {
    console.warn(`[Security] Blocked request from blacklisted IP: ${clientIP}`, {
      pathname,
      method: request.method,
      userAgent: request.headers.get("user-agent"),
    });
    return new NextResponse("Forbidden", { status: 403 });
  }

  // 🛡️ 安全检查2：检测可疑请求模式
  const suspiciousCheck = isSuspiciousRequest(request);
  if (suspiciousCheck.suspicious) {
    logSuspiciousRequest(request, suspiciousCheck.reason || "Unknown suspicious pattern");
    // 对于可疑请求，记录但不立即阻止（避免误报）
    // 可以在这里添加更严格的检查
  }

  // 🛡️ 安全检查3：速率限制
  // 对API路径应用速率限制
  if (pathname === "/api/chat") {
    const chatRateLimit = checkRateLimit(request, rateLimiters.chat);
    if (!chatRateLimit.allowed) {
      console.warn(`[Security] Chat rate limit exceeded for IP: ${clientIP}`, {
        pathname,
        resetTime: new Date(chatRateLimit.resetTime).toISOString(),
      });
      return NextResponse.json(
        { error: "Too many chat requests", retryAfter: Math.ceil((chatRateLimit.resetTime - Date.now()) / 1000) },
        { status: 429 }
      );
    }
  } else if (pathname === "/api/files/upload" && request.method === "POST") {
    const token = await resolveToken();
    const userId =
      typeof token?.sub === "string" && token.sub.length > 0
        ? token.sub
        : "anonymous";
    const uploadRateLimit = checkRateLimitByIdentifier(
      `${userId}:${request.method}:${pathname}`,
      rateLimiters.upload
    );
    if (!uploadRateLimit.allowed) {
      const retryAfter = Math.max(1, Math.ceil((uploadRateLimit.resetTime - Date.now()) / 1000));
      console.warn(`[Security] Upload rate limit exceeded for IP: ${clientIP}`, {
        pathname,
        method: request.method,
        userId,
        resetTime: new Date(uploadRateLimit.resetTime).toISOString(),
      });
      return NextResponse.json(
        { error: "Too many upload requests", retryAfter },
        { status: 429, headers: { "Retry-After": String(retryAfter) } }
      );
    }
  } else if (pathname.startsWith("/api/canvas/") && request.method === "PUT") {
    const canvasRateLimit = checkRateLimit(request, rateLimiters.canvas);
    if (!canvasRateLimit.allowed) {
      console.warn(`[Security] Canvas rate limit exceeded for IP: ${clientIP}`, {
        pathname,
        resetTime: new Date(canvasRateLimit.resetTime).toISOString(),
      });
      return NextResponse.json(
        { error: "Too many canvas requests", retryAfter: Math.ceil((canvasRateLimit.resetTime - Date.now()) / 1000) },
        { status: 429 }
      );
    }
  } else if (
    pathname.startsWith("/api/realtime/") ||
    pathname.startsWith("/api/fal/proxy")
  ) {
    const realtimeRateLimit = checkRateLimit(request, rateLimiters.realtime);
    if (!realtimeRateLimit.allowed) {
      console.warn(`[Security] Realtime rate limit exceeded for IP: ${clientIP}`, {
        pathname,
        resetTime: new Date(realtimeRateLimit.resetTime).toISOString(),
      });
      return NextResponse.json(
        { error: "Too many realtime requests", retryAfter: Math.ceil((realtimeRateLimit.resetTime - Date.now()) / 1000) },
        { status: 429 }
      );
    }
  } else if (isHighFrequencyReadApi(pathname, request.method)) {
    const pollingRateLimit = checkRateLimit(request, rateLimiters.uiPolling);
    if (!pollingRateLimit.allowed) {
      console.warn(`[Security] UI polling rate limit exceeded for IP: ${clientIP}`, {
        pathname,
        resetTime: new Date(pollingRateLimit.resetTime).toISOString(),
      });
      return NextResponse.json(
        {
          error: "Too many polling requests",
          retryAfter: Math.ceil((pollingRateLimit.resetTime - Date.now()) / 1000),
        },
        { status: 429 }
      );
    }
  } else if (pathname.startsWith("/api/")) {
    const rateLimit = checkRateLimit(request, rateLimiters.api);
    if (!rateLimit.allowed) {
      console.warn(`[Security] Rate limit exceeded for IP: ${clientIP}`, {
        pathname,
        resetTime: new Date(rateLimit.resetTime).toISOString(),
      });
      return NextResponse.json(
        { error: "Too many requests", retryAfter: Math.ceil((rateLimit.resetTime - Date.now()) / 1000) },
        { status: 429 }
      );
    }
  }

  // 🛡️ 安全检查4：认证相关API的严格速率限制
  if (pathname.startsWith("/api/auth/")) {
    const rateLimit = checkRateLimit(request, rateLimiters.auth);
    if (!rateLimit.allowed) {
      console.warn(`[Security] Auth rate limit exceeded for IP: ${clientIP}`);
      return NextResponse.json(
        { error: "Too many authentication attempts", retryAfter: Math.ceil((rateLimit.resetTime - Date.now()) / 1000) },
        { status: 429 }
      );
    }
  }

  // 允许访问 ping 端点
  if (pathname.startsWith("/ping")) {
    return NextResponse.next();
  }

  // 允许访问认证相关 API
  if (pathname.startsWith("/api/auth")) {
    return NextResponse.next();
  }

  // 允许访问公开的网站设置 API（登录页面需要）
  if (pathname === "/api/site-settings") {
    return NextResponse.next();
  }

  // 允许定时任务接口由服务端调用（具体鉴权由接口内部 CRON_SECRET 负责）
  if (pathname.startsWith("/api/jobs/")) {
    return NextResponse.next();
  }

  // 允许公开访问动态 favicon（浏览器标签图标）
  if (pathname === "/api/favicon") {
    return NextResponse.next();
  }

  // 允许访问公开的认证配置（登录弹窗需要）
  if (pathname === "/api/auth-settings") {
    return NextResponse.next();
  }

  // 允许匿名访问新版首页灵感数据
  if (pathname === "/api/featured" || pathname.startsWith("/api/featured/")) {
    return NextResponse.next();
  }

  // 允许访问钉钉回调页面（public 文件夹中的文件）
  if (pathname === "/dingtalk-callback.html") {
    return NextResponse.next();
  }

  // 允许 DuluPay 支付回调（服务端回调无 session cookie）
  if (pathname.startsWith("/api/payment/")) {
    return NextResponse.next();
  }

  const token = await resolveToken();

  const externalBase =
    process.env.AUTH_URL ??
    `${request.nextUrl.protocol}//${request.headers.get("host") ?? request.nextUrl.host}`;

  // 未登录用户允许访问 /（新版首页）、/login、/register，其余需要登录
  if (!token && !["/", "/login", "/register"].includes(pathname)) {
    // 对于 API 路由的非 GET 请求，直接返回 401 JSON 响应（不重定向）
    if (pathname.startsWith("/api/") && request.method !== "GET") {
      return NextResponse.json(
        { error: "未授权，请先登录" },
        { status: 401 }
      );
    }
    
    // 对于页面路由（GET 请求），重定向到登录页面
    const loginUrl = new URL("/login", externalBase);
    // 保存当前路径作为回调 URL
    loginUrl.searchParams.set("callbackUrl", pathname);
    return NextResponse.redirect(loginUrl);
  }

  // 已登录用户访问 /login 或 /register 时重定向到首页
  if (token && ["/login", "/register"].includes(pathname)) {
    return NextResponse.redirect(new URL("/", externalBase));
  }

  return NextResponse.next();
}

export const config = {
  matcher: [
    /*
     * 匹配所有请求路径，除了：
     * - api/auth (NextAuth.js)
     * - _next/static (静态文件)
     * - _next/image (图片优化文件)
     * - favicon.ico (favicon文件)
     * - public 文件夹中的文件
     */
    "/((?!api/auth|_next/static|_next/image|favicon.ico|.*\\.(?:svg|png|jpg|jpeg|gif|webp)$).*)",
  ],
};