import { defineConfig, loadEnv } from 'vite'
import react from '@vitejs/plugin-react'

// 单一配置文件 + 多环境 .env：
// - .env.development / .env.production / .env.staging 中配置变量
// - 通过 loadEnv 读取并应用到开发服务器与代理
export default defineConfig(({ mode }) => {
  const env = loadEnv(mode, '.', '')
  const port = Number(env.VITE_PORT || 5173)
  const open = String(env.VITE_OPEN ?? 'true').toLowerCase() === 'true' || env.VITE_OPEN === '1'
  const proxyTarget = env.VITE_ADMIN_PROXY_PATH || 'http://127.0.0.1:9898'

  return {
    plugins: [
      react({
        babel: {
          plugins: [
            ['@babel/plugin-proposal-decorators', { legacy: true }],
            ['babel-plugin-transform-typescript-metadata'],
            ['@babel/plugin-proposal-class-properties', { loose: true }],
            ['@babel/plugin-proposal-private-methods', { loose: true }],
            ['@babel/plugin-proposal-private-property-in-object', { loose: true }]
          ]
        }
      })
    ],
    server: {
      port,
      open,
      proxy: {
        '/api': {
          target: proxyTarget,
          changeOrigin: true,
          ws: true,
          // 为 SSE 透传加固：禁用超时并保持连接
          proxyTimeout: 0,
          timeout: 0,
          headers: { 'Connection': 'keep-alive' },
          // 关键：在 dev 代理层面禁止缓冲/缓存，强制以 chunk 方式向浏览器侧回传，避免一次性聚合
          configure: (proxy: any) => {
            // 移除 Accept-Encoding，避免后端压缩导致中间件缓冲
            proxy.on('proxyReq', (proxyReq: any, req: any) => {
              const url: string = req?.url || ''
              if (url.includes('/run/stream')) {
                try {
                  if (typeof proxyReq.removeHeader === 'function') proxyReq.removeHeader('accept-encoding')
                  proxyReq.setHeader('accept', 'text/event-stream')
                  proxyReq.setHeader('connection', 'keep-alive')
                } catch {}
              }
            })

            proxy.on('proxyRes', (proxyRes: any, req: any, res: any) => {
              const url: string = req?.url || ''
              const ct: string = String(proxyRes.headers?.['content-type'] || '')
              const isSse = url.includes('/run/stream') || ct.includes('text/event-stream')
              if (!isSse) return
              try {
                // 直接改写后端返回头，确保为 SSE 且无长度/压缩
                proxyRes.headers['content-type'] = 'text/event-stream; charset=utf-8'
                proxyRes.headers['cache-control'] = 'no-cache'
                proxyRes.headers['pragma'] = 'no-cache'
                proxyRes.headers['x-accel-buffering'] = 'no'
                delete proxyRes.headers['content-length']
                delete proxyRes.headers['content-encoding']

                // 同步确保 devServer 给浏览器的头一致，并尽早发送
                res.setHeader('Content-Type', 'text/event-stream; charset=utf-8')
                res.setHeader('Cache-Control', 'no-cache')
                res.setHeader('Pragma', 'no-cache')
                res.setHeader('X-Accel-Buffering', 'no')
                if (typeof res.removeHeader === 'function') res.removeHeader('Content-Length')
                if (typeof res.removeHeader === 'function') res.removeHeader('Content-Encoding')
                if (typeof res.flushHeaders === 'function') res.flushHeaders()
              } catch {}
            })
          }
        }
      }
    }
  }
})