// 最先加载 server/.env（dotenv），确保 DATA_DIR / PORT / AI_* 在模块读取前就位
import './env.js'

import { pathToFileURL } from 'node:url'
import Fastify from 'fastify'
import cors from '@fastify/cors'
import swagger from '@fastify/swagger'
import swaggerUi from '@fastify/swagger-ui'
import { initializeData } from './data/seed.js'
import { registerRoutes, routeCount } from './routes.js'
import { errorHandler, notFoundHandler } from './errors.js'

/** 构建 Fastify 实例（不监听端口，供运行与 OpenAPI 导出共用） */
export async function buildServer() {
  const app = Fastify({ logger: true, exposeHeadRoutes: false })

  // 允许「Content-Type: application/json 但无 body」的请求（如 DELETE 常带该头但无体）。
  // 默认 JSON 解析器遇到空 body 会抛 400「请求参数不合法」；这里把空 body 视为 undefined，避免误伤。
  app.addContentTypeParser('application/json', { parseAs: 'string' }, (_req, body, done) => {
    if (body === undefined || body === null || body === '') return done(null, undefined)
    try {
      done(null, JSON.parse(body as string))
    } catch (err) {
      done(err as Error, undefined)
    }
  })

  // 允许浏览器跨域调用本地后端（GET/POST/PATCH/DELETE 均为现有接口用到的语义化方法）
  await app.register(cors, {
    origin: true,
    methods: ['GET', 'HEAD', 'POST', 'PATCH', 'DELETE']
  })

  await app.register(swagger, {
    openapi: {
      info: {
        title: '备考通 API',
        description: '个人本地部署的公务员考试备考工具接口（语义化路径，统一错误格式）',
        version: '1.0.0'
      },
      servers: [{ url: `http://localhost:${process.env.PORT ?? 3000}`, description: '本地服务' }],
      tags: [
        { name: '数据中枢', description: '备考数据概览与学习趋势' },
        { name: '刷题', description: '模块组卷、作答与结果' },
        { name: '错题复习', description: '错题沉淀与间隔复习' },
        { name: '备考计划', description: '今日与本周任务' },
        { name: '模考分析', description: '行测模考成绩与分析' },
        { name: '要闻', description: '时政要闻列表与导入' },
        { name: '题库管理', description: '题目导入导出与删除' },
        { name: 'AI 讲解', description: 'AI 题目讲解（Token 仅在后端配置）' },
        { name: '个人档案', description: '学习档案' },
        { name: '设置', description: '偏好设置' }
      ]
    }
  })
  await app.register(swaggerUi, { routePrefix: '/api/docs' })

  app.setErrorHandler(errorHandler)
  app.setNotFoundHandler(notFoundHandler)

  // OpenAPI 文档端点（需求文档 2.2 约定的访问地址）
  app.get('/api/openapi.json', async () => app.swagger())

  app.get('/health', async () => ({ status: 'ok', service: 'gwy-server', routes: routeCount }))

  await app.register(registerRoutes)
  return app
}

const invokedDirectly =
  process.argv[1] !== undefined && import.meta.url === pathToFileURL(process.argv[1]).href

if (invokedDirectly) {
  const app = await buildServer()
  await initializeData()
  await app.listen({ port: Number(process.env.PORT ?? 3000), host: process.env.HOST ?? '0.0.0.0' })
}