nei/lib/server/middleware/injector.js

builder for nei platform

'use strict';
let proxy = require("../proxy");

module.exports = function injectify(options) {
  let excludes = options.excludes || [];
  let resource = options.resource;

  return function (req, res, next) {
    if (typeof options.before === 'function') options.before(req, res);

    let oWriteHead = res.writeHead;
    let oWrite = res.write;
    let oEnd = res.end;

    res.injector = Array.isArray(res.injector) ? res.injector : [];
    res.__data = new Buffer('', 'utf8');

    res.proxy = function (options) {
      req.url = "";
      return proxy(req, res, options)
    }
    res.push = function (chunk) {
      if (!chunk) return;
      if (!Buffer.isBuffer(chunk)) chunk = new Buffer(chunk, 'utf8');
      res.__data = Buffer.concat([res.__data, chunk]);
      // res.__data = res.__data || '';
      // res.__data +=  chunk||"";
    }

    res.write = function (chunk, encoding) {
      // if(!isHtml(res) ) return oWrite.apply( res, arguments );
      if (!chunk) return;
      // console.log(chunk.toString('utf8'), res.getHeader('content-type'));
      return res.push(Buffer.isBuffer(chunk) ? chunk : new Buffer(chunk, encoding || 'utf8'))
      // return res.push( Buffer.isBuffer( chunk )? chunk.toString('utf8'): chunk );
    }


    res.writeHead = function () {

      if (res.noinject) return oWriteHead.apply(res, arguments);
      if (res.getHeader('content-length')) res.removeHeader('content-length');
      return oWriteHead.apply(res, arguments);
    }

    res.end = function (chunk, encoding, twice) {

      if (options.delay && !twice) {
        return setTimeout(function () {
          res.send(chunk, encoding, true)
        }, options.delay)
      }
      if (res.noinject) {
        return oEnd.apply(res, arguments);
      }

      res.noinject = true;
      res.push(chunk);
      res.write = oWrite;
      let allChunk = res.__data
      if (typeof res.nei_transform === 'function' && allChunk) {
        allChunk = res.nei_transform(allChunk);
      }
      if (isHtml(res)) {
        allChunk = wrap(allChunk, res.injector);
        if (res._header) {
          res.addTrailers({'content-length': Buffer.byteLength(allChunk, encoding)});
        } else {
          res.setHeader('content-length', Buffer.byteLength(allChunk, encoding));
        }
      }
      oEnd.call(res, allChunk, encoding);
    }

    if (options.after) options.after(req, res);
    next();
  }

}

/**
 * wrap
 * @param  {[type]} trunk [description]
 * @return {[type]}       [description]
 */
function wrap(trunk, injector) {

  let res = trunk.toString('utf8').replace(/\<body[\s\S]*?\>/, function (all) {
    return all + (Array.isArray(injector) ? injector.join("") : injector || '');
  })
  return res;
}

function concat(buffers, length) {
  let buffer = null;
  switch (buffers.length) {
    case 0:
      buffer = new Buffer(0);
      break;
    case 1:
      buffer = buffers[0];
      break;
    default:
      buffer = new Buffer(nread);
      for (let i = 0, pos = 0, l = buffers.length; i < l; i++) {
        let chunk = buffers[i];
        chunk.copy(buffer, pos);
        pos += chunk.length;
      }
      break;
  }
  return buffer;
}

/**
 * accept MineTypesform injector
 * @type {RegExp}
 */
let acceptMineTypes = /\b(xhtml|html|htm|xml)\b/

function isHtml(res) {
  return acceptMineTypes.test(res.getHeader("content-type"))
}