import { NextResponse } from 'next/server';

const ANALYTICS_BACKEND = process.env.ANALYTICS_BACKEND_URL || 'http://127.0.0.1:8000';

export const dynamic = 'force-dynamic';

type RouteContext = {
  params: Promise<{ path: string[] }>;
};

function buildBackendUrl(request: Request, path: string[]): string | null {
  if (!path.length || path.some((segment) => !segment || segment.includes('..'))) {
    return null;
  }
  const source = new URL(request.url);
  const target = new URL(`/analytics/${path.map(encodeURIComponent).join('/')}`, ANALYTICS_BACKEND);
  target.search = source.search;
  return target.toString();
}

async function proxyAnalytics(request: Request, context: RouteContext, method: 'GET' | 'POST') {
  const { path } = await context.params;
  const backendUrl = buildBackendUrl(request, path);
  if (!backendUrl) {
    return NextResponse.json({ message: '分析 API 路徑不合法' }, { status: 400 });
  }

  try {
    const response = await fetch(backendUrl, {
      method,
      cache: 'no-store',
      headers: {
        'Content-Type': 'application/json',
      },
      body: method === 'POST' ? await request.text() : undefined,
    });

    const contentType = response.headers.get('content-type') || '';
    if (contentType.includes('application/json')) {
      const data = await response.json();
      return NextResponse.json(data, { status: response.status });
    }

    const text = await response.text();
    return NextResponse.json({ message: text || '分析服務暫時無法回應' }, { status: response.status });
  } catch (error) {
    const message = error instanceof Error ? error.message : '分析服務暫時無法連線';
    return NextResponse.json({ message }, { status: 502 });
  }
}

export async function GET(request: Request, context: RouteContext) {
  return proxyAnalytics(request, context, 'GET');
}

export async function POST(request: Request, context: RouteContext) {
  return proxyAnalytics(request, context, 'POST');
}