import fs from 'fs';
import path from 'path';
import { fileURLToPath } from 'url';
import Fastify from 'fastify';
import fastifyCors from '@fastify/cors';
import fastifyStatic from '@fastify/static';
import config from './config/index.js';
import dbPlugin from './plugins/db.js';
import trackerPlugin from './plugins/tracker.js';
import routes from './routes/index.js';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

export async function buildApp(opts = {}) {
  const fastify = Fastify({
    logger: {
      level: opts.logLevel || 'info',
    },
    ...opts,
  });

  // config 데코레이터 등록
  fastify.decorate('config', config);

  // CORS
  await fastify.register(fastifyCors, {
    origin: true,
  });

  // 플러그인
  await fastify.register(dbPlugin);
  await fastify.register(trackerPlugin);

  // 라우트
  await fastify.register(routes, { prefix: '/api' });

  // 헬스 체크
  fastify.get('/api/health', async () => {
    return { status: 'ok', timestamp: new Date().toISOString() };
  });

  // 정적 파일 서빙 (프론트엔드 빌드 결과물)
  const distPath = path.join(__dirname, '../dist');
  if (fs.existsSync(distPath)) {
    await fastify.register(fastifyStatic, {
      root: distPath,
      prefix: '/',
    });

    // SPA fallback
    fastify.setNotFoundHandler((request, reply) => {
      if (request.url.startsWith('/api/')) {
        return reply.code(404).send({ error: 'Not found' });
      }
      return reply.sendFile('index.html');
    });
  }

  return fastify;
}