const http = require('http')
const fs = require('fs')
const path = require('path')

const PORT = 3001
const BACKEND = 'http://127.0.0.1:8583'
const STATIC_DIR = path.join(__dirname, 'dist', 'build', 'h5')
const API_PREFIX = '/forge-h5-api'
const APP_BASE = '/forge-h5'

const MIME_TYPES = {
  '.html': 'text/html; charset=utf-8',
  '.js': 'application/javascript; charset=utf-8',
  '.css': 'text/css; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.png': 'image/png',
  '.jpg': 'image/jpeg',
  '.jpeg': 'image/jpeg',
  '.gif': 'image/gif',
  '.svg': 'image/svg+xml',
  '.ico': 'image/x-icon',
  '.woff': 'font/woff',
  '.woff2': 'font/woff2',
  '.ttf': 'font/ttf',
  '.map': 'application/json',
}

function getMimeType(filePath) {
  const ext = path.extname(filePath).toLowerCase()
  return MIME_TYPES[ext] || 'application/octet-stream'
}

function proxyRequest(req, res) {
  const url = req.url.replace(API_PREFIX, '')
  const options = {
    hostname: '127.0.0.1',
    port: 8583,
    path: url,
    method: req.method,
    headers: {
      ...req.headers,
      host: '127.0.0.1:8583',
    },
  }

  const proxyReq = http.request(options, (proxyRes) => {
    // 复制响应头
    const headers = {}
    for (const [key, value] of Object.entries(proxyRes.headers)) {
      if (key !== 'transfer-encoding') {
        headers[key] = value
      }
    }
    res.writeHead(proxyRes.statusCode, headers)
    proxyRes.pipe(res)
  })

  proxyReq.on('error', (err) => {
    console.error(`[API Proxy Error] ${req.method} ${url}:`, err.message)
    res.writeHead(502, { 'Content-Type': 'application/json' })
    res.end(JSON.stringify({ error: 'Backend service unavailable' }))
  })

  req.pipe(proxyReq)
}

function serveStatic(req, res) {
  let urlPath = req.url

  // 去掉 /forge-h5 前缀，映射到静态文件目录
  if (urlPath.startsWith(APP_BASE)) {
    urlPath = urlPath.slice(APP_BASE.length) || '/'
  }

  let filePath = path.join(STATIC_DIR, urlPath === '/' ? '/index.html' : urlPath)

  // 安全检查：防止路径遍历
  if (!filePath.startsWith(STATIC_DIR)) {
    res.writeHead(403)
    res.end('Forbidden')
    return
  }

  fs.readFile(filePath, (err, data) => {
    if (err) {
      // SPA 回退：如果文件不存在，返回 index.html
      fs.readFile(path.join(STATIC_DIR, 'index.html'), (err2, data2) => {
        if (err2) {
          res.writeHead(500)
          res.end('Internal Server Error')
          return
        }
        res.writeHead(200, { 'Content-Type': 'text/html; charset=utf-8' })
        res.end(data2)
      })
      return
    }
    res.writeHead(200, { 'Content-Type': getMimeType(filePath) })
    res.end(data)
  })
}

const server = http.createServer((req, res) => {
  // API 请求代理到后端
  if (req.url.startsWith(API_PREFIX)) {
    console.log(`[API] ${req.method} ${req.url} -> ${BACKEND}${req.url.replace(API_PREFIX, '')}`)
    proxyRequest(req, res)
  } else {
    // 静态文件服务
    console.log(`[Static] ${req.method} ${req.url}`)
    serveStatic(req, res)
  }
})

server.listen(PORT, '0.0.0.0', () => {
  console.log(`Server running at http://0.0.0.0:${PORT}`)
  console.log(`Static files: ${STATIC_DIR}`)
  console.log(`API proxy: ${API_PREFIX} -> ${BACKEND}`)
})