import { NextRequest, NextResponse } from 'next/server';
import { authenticatedFetch } from '@/lib/api/authenticated-fetch';

/**
 * 🔵 Catch-All API Proxy (HttpOnly Cookie Pattern)
 *
 * ⚡ 설계 목적:
 * - HttpOnly 쿠키 보안 유지: JavaScript 접근 차단
 * - 모든 백엔드 API를 단일 프록시로 처리
 * - 서버에서 쿠키 읽어 Authorization 헤더 자동 추가
 *
 * 🔄 동작 흐름:
 * 1. 클라이언트 → Next.js /api/proxy/* (토큰 없이)
 * 2. Next.js: HttpOnly 쿠키에서 access_token 읽기 (서버에서만 가능)
 * 3. Next.js → PHP Backend /api/v1/* (Authorization 헤더 포함)
 * 4. PHP Backend → Next.js (응답)
 * 5. Next.js → 클라이언트 (응답 전달)
 *
 * 🔐 보안 특징:
 * - HttpOnly 쿠키: JavaScript 접근 불가 (XSS 방지)
 * - 서버 사이드 토큰 처리: 브라우저에 토큰 노출 안됨
 * - 자동 인증 헤더 추가: 클라이언트는 신경 쓸 필요 없음
 *
 * 📍 사용 예시:
 * - Frontend: fetch('/api/proxy/item-master/init')
 * - Backend: GET https://api.codebridge-x.com/api/v1/item-master/init
 *
 * 🔄 인증 처리:
 * - 401 감지 → refresh → retry 는 authenticatedFetch 게이트웨이에 위임
 * - PROXY는 쿠키 읽기/설정/삭제만 담당
 */

/**
 * 쿠키 생성 헬퍼 함수
 */
function createTokenCookies(tokens: { accessToken?: string; refreshToken?: string; expiresIn?: number }) {
  const cookies: string[] = [];
  const isProduction = process.env.NODE_ENV === 'production';

  if (tokens.accessToken) {
    cookies.push([
      `access_token=${tokens.accessToken}`,
      'HttpOnly',
      ...(isProduction ? ['Secure'] : []),
      'SameSite=Lax',
      'Path=/',
      `Max-Age=${tokens.expiresIn || 7200}`,
    ].join('; '));

    // FCM 등에서 인증 상태 확인용 (non-HttpOnly)
    cookies.push([
      'is_authenticated=true',
      ...(isProduction ? ['Secure'] : []),
      'SameSite=Lax',
      'Path=/',
      `Max-Age=${tokens.expiresIn || 7200}`,
    ].join('; '));
  }

  if (tokens.refreshToken) {
    cookies.push([
      `refresh_token=${tokens.refreshToken}`,
      'HttpOnly',
      ...(isProduction ? ['Secure'] : []),
      'SameSite=Lax',
      'Path=/',
      'Max-Age=604800', // 7 days
    ].join('; '));
  }

  return cookies;
}

/**
 * 쿠키 삭제 헬퍼 함수 (토큰 만료 시)
 */
function createClearTokenCookies(): string[] {
  const isProduction = process.env.NODE_ENV === 'production';
  const secureFlag = isProduction ? '; Secure' : '';
  return [
    `access_token=; HttpOnly${secureFlag}; SameSite=Lax; Path=/; Max-Age=0`,
    `refresh_token=; HttpOnly${secureFlag}; SameSite=Lax; Path=/; Max-Age=0`,
    `is_authenticated=${secureFlag}; SameSite=Lax; Path=/; Max-Age=0`,
  ];
}

/**
 * Catch-all proxy handler for all HTTP methods
 */
async function proxyRequest(
  request: NextRequest,
  params: { path: string[] },
  method: string
) {
  try {
    // 1. HttpOnly 쿠키에서 토큰 읽기
    const token = request.cookies.get('access_token')?.value;
    const refreshToken = request.cookies.get('refresh_token')?.value;

    // 2. 백엔드 URL 구성
    const backendUrl = `${process.env.NEXT_PUBLIC_API_URL}/api/v1/${params.path.join('/')}`;
    const url = new URL(backendUrl);
    request.nextUrl.searchParams.forEach((value, key) => {
      url.searchParams.append(key, value);
    });

    // 3. 요청 바디 읽기 (POST, PUT, DELETE, PATCH)
    let body: string | FormData | undefined;
    const contentType = request.headers.get('content-type') || 'application/json';
    let isFormData = false;

    if (['POST', 'PUT', 'DELETE', 'PATCH'].includes(method)) {
      if (contentType.includes('application/json')) {
        body = await request.text();
      } else if (contentType.includes('multipart/form-data')) {
        isFormData = true;

        const originalFormData = await request.formData();
        const newFormData = new FormData();

        for (const [key, value] of originalFormData.entries()) {
          if (value instanceof File) {
            newFormData.append(key, value, value.name);
          } else {
            newFormData.append(key, value);
          }
        }

        body = newFormData;
      }
    }

    // 4. 헤더 구성
    const headers: Record<string, string> = {
      'Accept': 'application/json',
      'X-API-KEY': process.env.API_KEY || '',
      'Authorization': token ? `Bearer ${token}` : '',
    };
    if (!isFormData) {
      headers['Content-Type'] = contentType;
    }

    // 5. authenticatedFetch 게이트웨이로 요청 실행
    //    401 감지 → refresh → retry 모두 게이트웨이가 처리
    const { response: backendResponse, newTokens, authFailed } = await authenticatedFetch(
      url.toString(),
      { method, headers, body },
      refreshToken,
      'PROXY'
    );

    // 6. 인증 실패 → 쿠키 삭제 + 401 반환
    if (authFailed) {
      if (process.env.NODE_ENV === 'development') {
        console.warn('🔴 [PROXY] Auth failed, clearing cookies...');
      }
      const clearResponse = NextResponse.json(
        { error: 'Authentication failed', needsReauth: true },
        { status: 401 }
      );
      createClearTokenCookies().forEach(cookie => {
        clearResponse.headers.append('Set-Cookie', cookie);
      });
      return clearResponse;
    }

    // 7. 응답 처리 (바이너리 vs 텍스트/JSON)
    const responseContentType = backendResponse.headers.get('content-type') || 'application/json';

    const isBinaryResponse =
      responseContentType.includes('application/pdf') ||
      responseContentType.includes('application/octet-stream') ||
      responseContentType.includes('image/') ||
      responseContentType.includes('application/zip') ||
      responseContentType.includes('application/vnd') ||
      responseContentType.includes('application/msword') ||
      responseContentType.includes('application/x-');

    let clientResponse: NextResponse;

    if (isBinaryResponse) {
      const binaryData = await backendResponse.arrayBuffer();

      clientResponse = new NextResponse(binaryData, {
        status: backendResponse.status,
        headers: {
          'Content-Type': responseContentType,
          'Content-Disposition': backendResponse.headers.get('content-disposition') || '',
          'Content-Length': backendResponse.headers.get('content-length') || '',
        },
      });
    } else {
      const responseData = await backendResponse.text();

      clientResponse = new NextResponse(responseData, {
        status: backendResponse.status,
        headers: {
          'Content-Type': responseContentType,
        },
      });
    }

    // 8. 토큰이 갱신되었으면 새 쿠키 설정
    if (newTokens?.accessToken) {
      createTokenCookies(newTokens).forEach(cookie => {
        clientResponse.headers.append('Set-Cookie', cookie);
      });
    }

    return clientResponse;

  } catch (error) {
    console.error('Proxy request error:', error);
    return NextResponse.json(
      { error: 'Proxy server error' },
      { status: 500 }
    );
  }
}

/**
 * GET 요청 프록시
 * Next.js 15: params는 Promise이므로 await 필요
 */
export async function GET(
  request: NextRequest,
  { params }: { params: Promise<{ path: string[] }> }
) {
  const resolvedParams = await params;
  return proxyRequest(request, resolvedParams, 'GET');
}

/**
 * POST 요청 프록시
 * Next.js 15: params는 Promise이므로 await 필요
 */
export async function POST(
  request: NextRequest,
  { params }: { params: Promise<{ path: string[] }> }
) {
  const resolvedParams = await params;
  return proxyRequest(request, resolvedParams, 'POST');
}

/**
 * PUT 요청 프록시
 * Next.js 15: params는 Promise이므로 await 필요
 */
export async function PUT(
  request: NextRequest,
  { params }: { params: Promise<{ path: string[] }> }
) {
  const resolvedParams = await params;
  return proxyRequest(request, resolvedParams, 'PUT');
}

/**
 * DELETE 요청 프록시
 * Next.js 15: params는 Promise이므로 await 필요
 */
export async function DELETE(
  request: NextRequest,
  { params }: { params: Promise<{ path: string[] }> }
) {
  const resolvedParams = await params;
  return proxyRequest(request, resolvedParams, 'DELETE');
}

/**
 * PATCH 요청 프록시
 * Next.js 15: params는 Promise이므로 await 필요
 * 용도: toggle 엔드포인트 (/clients/{id}/toggle, /client-groups/{id}/toggle)
 */
export async function PATCH(
  request: NextRequest,
  { params }: { params: Promise<{ path: string[] }> }
) {
  const resolvedParams = await params;
  return proxyRequest(request, resolvedParams, 'PATCH');
}