const http = require('http')
const fs = require('fs')
const path = require('path')
const { URL } = require('url')

const projectRoot = __dirname
const defaultWebRoot = path.join(projectRoot, 'unpackage', 'dist', 'build', 'web')
const defaultHost = '127.0.0.1'
const defaultPort = 5500

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

function getOption(name, fallback) {
  const prefix = `${name}=`
  const argument = process.argv.find((item) => item.startsWith(prefix))
  return argument ? argument.slice(prefix.length) : fallback
}

function getPort() {
  const value = getOption('--port', process.env.PORT || String(defaultPort))
  const port = Number(value)

  if (!Number.isInteger(port) || port < 1 || port > 65535) {
    throw new Error(`端口无效：${value}`)
  }

  return port
}

function getWebRoot() {
  const configuredRoot = getOption('--dir', defaultWebRoot)
  return path.resolve(projectRoot, configuredRoot)
}

function isInsideRoot(root, target) {
  const relativePath = path.relative(root, target)
  return relativePath === '' || (!relativePath.startsWith('..') && !path.isAbsolute(relativePath))
}

function sendText(response, statusCode, message) {
  response.writeHead(statusCode, {
    'Content-Type': 'text/plain; charset=utf-8',
    'Cache-Control': 'no-store'
  })
  response.end(message)
}

function sendFile(response, filePath) {
  const extension = path.extname(filePath).toLowerCase()
  const contentType = mimeTypes[extension] || 'application/octet-stream'

  response.writeHead(200, {
    'Content-Type': contentType,
    'Cache-Control': extension === '.html' ? 'no-cache' : 'public, max-age=3600'
  })
  fs.createReadStream(filePath).pipe(response)
}

function tryServeFile(response, webRoot, pathname) {
  const decodedPath = decodeURIComponent(pathname)
  const relativePath = decodedPath === '/' ? 'index.html' : decodedPath.slice(1)
  const filePath = path.resolve(webRoot, relativePath)

  if (!isInsideRoot(webRoot, filePath)) {
    sendText(response, 403, 'Forbidden')
    return true
  }

  if (!fs.existsSync(filePath) || !fs.statSync(filePath).isFile()) {
    return false
  }

  sendFile(response, filePath)
  return true
}

function createServer(webRoot) {
  return http.createServer((request, response) => {
    if (request.method !== 'GET' && request.method !== 'HEAD') {
      sendText(response, 405, 'Method Not Allowed')
      return
    }

    let requestUrl
    try {
      requestUrl = new URL(request.url, 'http://localhost')
    } catch {
      sendText(response, 400, 'Bad Request')
      return
    }

    try {
      if (tryServeFile(response, webRoot, requestUrl.pathname)) {
        return
      }

      // Web 发行项目使用前端路由时，未知路径回退到入口页面。
      if (!path.extname(requestUrl.pathname) && tryServeFile(response, webRoot, '/index.html')) {
        return
      }

      sendText(response, 404, 'Not Found')
    } catch (error) {
      console.error(`[serve-web] ${error.message}`)
      sendText(response, 500, 'Internal Server Error')
    }
  })
}

function printUsage() {
  console.log('用法：node serve-web.js [--port=5500] [--host=127.0.0.1] [--dir=unpackage/dist/build/web]')
}

function start() {
  if (process.argv.includes('--help') || process.argv.includes('-h')) {
    printUsage()
    return
  }

  const webRoot = getWebRoot()
  const host = getOption('--host', process.env.HOST || defaultHost)
  const port = getPort()

  if (!fs.existsSync(webRoot)) {
    console.error(`未找到 Web 文件目录：${webRoot}`)
    console.error('请先在 HBuilderX 中发行 Web，或使用 --dir 指定已打包的目录。')
    process.exitCode = 1
    return
  }

  const server = createServer(webRoot)
  server.listen(port, host, () => {
    console.log(`Web 文件目录：${webRoot}`)
    console.log(`本机访问：http://localhost:${port}`)
    console.log(`局域网访问：http://<本机IP>:${port}`)
    console.log('按 Ctrl+C 停止服务器')
  })
}

start()