const Koa = require('koa');
const path = require('path');
const fs = require('fs');
let mimes = {
  'css': 'text/css',
  'html': 'text/html',
  'jpg': 'image/jpeg',
  'jpeg': 'image/jpeg',
  'json': 'application/json',
  'js': 'text/javascript',
  'xml': 'text/xml',
  'png': 'image/png',
  'pdf': 'application/pdf',
  'less': 'text/css',
  'gif': 'image/gif',
  'txt': 'text/plain',
  'tiff': 'image/tiff',
  'svg': 'image/svg+xml'
};
// Scan dir
function walk(reqPath) {
  let files = fs.readdirSync(reqPath);
  let fileList = [];
  for (let i = 0, len = files.length; i< len; i++) {
    let item = files[i];
    if (item.startsWith('.')) {
      continue;
    }
    let realPath = reqPath + '/' + files[i];
    if (isDir(realPath)) {
      fileList.push(filter(reqPath, files[i]));
    } else {
      fileList.push(files[i]);
    }
  }
  return fileList;
}

function isDir(path){ 
  return fs.existsSync(path) && fs.statSync(path).isDirectory(); 
} 
//
function filter(reqPath, filePath) {
  let files = fs.readdirSync(reqPath + '/' + filePath);
  for (let i = 0; i < files.length; i++) {
    let item = files[i];
    if (item.endsWith('index.html')) {
      return filePath + '/' + 'index.html';
    }
  }
  return filePath;
}

function dir(url, reqPath) {
  let contentList = walk(reqPath);
  let result = '<div align="center" style="font-family:arial;font-size:30px;">Product Document</div><ul>';
  if (url == '/') {
    url = '';
  }
  for (let [index, item] of contentList.entries()) {
    let realHref = url + '/' + item;
    let realItem = item.split('/');
    result += '<li> <a style="font-family:arial;font-size:20px;" href=' + realHref + '>' + realItem[0] + '</a></li>';
  }
  result = result + '</ul>';
  return result;
}

async function file (url, filePath) {
  let resultMime = parseMime(url);
  let content;
  if (resultMime && resultMime.indexOf('image/') >= 0) {
    content = fs.readFileSync(filePath, 'binary');
  } else {
    content = fs.readFileSync(filePath, 'utf8');
  }
  return content;
}

async function content(ctx, fullStaticPath) {
  let url = decodeURI(ctx.url);
  let reqPath = path.join(fullStaticPath, url);
  let exist = fs.existsSync(reqPath);
  let content = '';
  if (!exist) {
    content = 'Local file not exists';
  } else {
    let stat = fs.statSync(reqPath);
    if (stat.isDirectory()) {
      content = dir(ctx.url, reqPath);
    } else {
      content = await file(ctx.url, reqPath);
    }
  }
  return content;
}

function parseMime(url) {
  let extName = path.extname(url);
  extName = extName ? extName.slice(1) : 'unknown';
  return mimes[extName];
}
const app = new Koa();
const staticPath = '../onlinedoc';`请输入代码`
app.use(async(ctx) => {
  let fullStaticPath = path.join(__dirname, staticPath);
  let resultContent = await content(ctx, fullStaticPath);
  let resultMime = parseMime(ctx.url);
  if (resultMime) {
    ctx.type = resultMime;
  } 
  if(resultMime && resultMime.indexOf('image/') >= 0) {
    ctx.res.writeHead(200);
    ctx.res.write(resultContent, 'binary');
    ctx.res.end();
  } else {
    ctx.body = resultContent;
  }
});
app.listen(8080, () => {
  console.log('Running');
});