/**
 * HTTP后端数据发送处理函数
 * 更新: 2016/05/07
 */

'use strict';

const fs = require('fs'),
  iconv = require('iconv-lite'),
  jschardet = require('jschardet'),
  through = require('through'),
  CONF = require('./config'),
  superagent = require('superagent'),
  superagentProxy = require('superagent-proxy');
const { Readable } = require("stream");

let logger;
// 请求UA
const USER_AGENT = 'antSword/v2.0';

// 请求超时
const REQ_TIMEOUT = 10000;

// 代理配置
const APROXY_CONF = {
  mode: 'noproxy',
  uri: ''
}

class Request {

  constructor(electron) {
    logger = new electron.Logger('Request');
    const ipcMain = electron.ipcMain;

    ipcMain.on('aproxy', this.onAproxy.bind(this));
    ipcMain.on('aproxytest', this.onAproxyTest.bind(this));
    ipcMain.on('request', this.onRequest.bind(this));
    ipcMain.on('download', this.onDownlaod.bind(this));
  }


  /**
   * 加载代理配置
   * @param  {Object} event ipcMain事件
   * @param  {Object} opts  代理配置
   * @return {[type]}       [description]
   */
  onAproxy(event, opts) {
    logger.debug(
      'aProxy::Set Proxy Mode -',
      APROXY_CONF['mode'] === 'manualproxy' ? APROXY_CONF['uri'] : 'noproxy'
    );

    APROXY_CONF['mode'] = opts['aproxymode'];
    APROXY_CONF['uri'] = opts['aproxyuri'];

    if (APROXY_CONF['mode'] === 'noproxy') {
      return superagent.Request.prototype.proxy = function() { return this };
    }
    superagentProxy(superagent);
  }

  /**
   * 监听代理连接测试
   * @param  {Object} event ipcMain事件
   * @param  {Object} opts  测试配置
   * @return {[type]}       [description]
   */
  onAproxyTest(event, opts) {
    logger.debug('aProxy::Test Proxy -', opts['aproxyuri'], '- Connect to ', opts['url']);
    if(opts['url'].match(CONF.urlblacklist)) {
      return event.sender.send('request-error-' + opts['hash'], "Blacklist URL");
    }
    superagentProxy(superagent);
    superagent
      .get(opts['url'])
      .set('User-Agent', USER_AGENT)
      .proxy(opts['aproxyuri'])
      .timeout(REQ_TIMEOUT)
      .end((err, ret) => {
        if (err) {
          logger.fatal("aProxy::Test Error", err);
          return event.sender.send('aproxytest-error-' + opts['hash'], err);
        }else{
          logger.info("aProxy::Test Success");
          return event.sender.send('aproxytest-success-' + opts['hash'], ret);
        }
      });
  }


  /**
   * 监听HTTP请求
   * @param  {Object} event ipcMain事件对象
   * @param  {Object} opts  请求配置
   * @return {[type]}       [description]
   */
  onRequest(event, opts) {
    logger.debug('onRequest::opts', opts);
    if(opts['url'].match(CONF.urlblacklist)) {
      return event.sender.send('request-error-' + opts['hash'], "Blacklist URL");
    }
    let _request = superagent.post(opts['url']);
    // 设置headers
    _request.set('User-Agent', USER_AGENT);
    // 自定义headers
    for (let _ in opts.headers) {
      _request.set(_, opts.headers[_]);
    }
    // 自定义body
    const _postData = Object.assign({}, opts.body, opts.data);
    if (opts['useChunk'] == 1){
      logger.debug("request with Chunked");
      let _postarr = [];
      for(var key in _postData){
        if(_postData.hasOwnProperty(key)){
          _postarr.push(`${key}=${encodeURIComponent(_postData[key])}`);
        }
      }
      let antstream = new AntRead(_postarr.join("&"), {'step': parseInt(opts['chunkStepMin']), 'stepmax': parseInt(opts['chunkStepMax'])});
      let _datasuccess = false; // 表示是否是 404 类shell
      _request
        .proxy(APROXY_CONF['uri'])
        .type('form')
        // .set('Content-Type', 'application/x-www-form-urlencoded')
        .timeout(opts.timeout || REQ_TIMEOUT)
        .ignoreHTTPS(opts['ignoreHTTPS'])
        .parse((res, callback) => {
          this.parse(opts['tag_s'], opts['tag_e'], (chunk) => {
            event.sender.send('request-chunk-' + opts['hash'], chunk);
          }, res, (err, ret)=>{
            let buff = ret ? ret : Buffer.from();
            // 自动猜测编码
            let encoding = detectEncoding(buff, {defaultEncoding: "unknown"});
            logger.debug("detect encoding:", encoding);
            encoding = encoding != "unknown" ? encoding : opts['encode'];
            let text = iconv.decode(buff, encoding);
            if (err && text == "") {
              return event.sender.send('request-error-' + opts['hash'], err);
            };
            // 回调数据
            event.sender.send('request-' + opts['hash'], {
              text: text,
              buff: buff,
              encoding: encoding
            });
            _datasuccess = true;
            callback(null, ret);
          });
        }).on('error', (err) => {
          if(_datasuccess == false) {
            return event.sender.send('request-error-' + opts['hash'], err);
          }
        });
        antstream.pipe(_request);
    }else{
      // 通过替换函数方式来实现发包方式切换, 后续可改成别的
      const old_send = _request.send;
      if(opts['useMultipart'] == 1) {
        _request.send = _request.field;
      }else{
        _request.send = old_send;
      }
      _request
        .proxy(APROXY_CONF['uri'])
        .type('form')
        // 超时
        .timeout(opts.timeout || REQ_TIMEOUT)
        // 忽略HTTPS
        .ignoreHTTPS(opts['ignoreHTTPS'])
        .send(_postData)
        .parse((res, callback) => {
          this.parse(opts['tag_s'], opts['tag_e'], (chunk) => {
            event.sender.send('request-chunk-' + opts['hash'], chunk);
          }, res, callback);
        })
        .end((err, ret) => {
          if (!ret) {
            // 请求失败 TIMEOUT
            return event.sender.send('request-error-' + opts['hash'], err);
          }
          let buff = ret.hasOwnProperty('body') ? ret.body : Buffer.from();
          // 解码
          let text = "";
          // 自动猜测编码
          let encoding = detectEncoding(buff, {defaultEncoding:"unknown"});
          logger.debug("detect encoding:", encoding);
          encoding = encoding != "unknown" ? encoding : opts['encode'];
          text = iconv.decode(buff, encoding);
          if (err && text == "") {
            return event.sender.send('request-error-' + opts['hash'], err);
          };
          // 回调数据
          event.sender.send('request-' + opts['hash'], {
            text: text,
            buff: buff,
            encoding: encoding
          });
        });
      }
  }

  /**
   * 监听下载请求
   * @param  {Object} event ipcMain事件对象
   * @param  {Object} opts  下载配置
   * @return {[type]}       [description]
   */
  onDownlaod(event, opts) {
    logger.debug('onDownlaod', opts);
    if(opts['url'].match(CONF.urlblacklist)) {
      return event.sender.send('request-error-' + opts['hash'], "Blacklist URL");
    }
    // 创建文件流
    const rs = fs.createWriteStream(opts['path']);

    let indexStart = -1;
    let indexEnd = -1;
    let tempData = [];

    let _request = superagent.post(opts['url']);
    // 设置headers
    _request.set('User-Agent', USER_AGENT);
    // 自定义headers
    for (let _ in opts.headers) {
      _request.set(_, opts.headers[_]);
    }
    // 自定义body
    const _postData = Object.assign({}, opts.body, opts.data);
    if (opts['useChunk'] == 1){
      logger.debug("request with Chunked");
      let _postarr = [];
      for(var key in _postData){
        if(_postData.hasOwnProperty(key)){
          _postarr.push(`${key}=${_postData[key]}`);
        }
      }
      let antstream = new AntRead(_postarr.join("&"), {'step': parseInt(opts['chunkStepMin']), 'stepmax': parseInt(opts['chunkStepMax'])});
      let _datasuccess = false; // 表示是否是 404 类shell
      _request
        .proxy(APROXY_CONF['uri'])
        .type('form')
        .ignoreHTTPS(opts['ignoreHTTPS'])
        .pipe(through(
          (chunk) => {
            // 判断数据流中是否包含后截断符？长度++
            let temp = chunk.indexOf(opts['tag_e']);
            if (temp !== -1) {
              indexEnd = Buffer.concat(tempData).length + temp;
            };
            tempData.push(chunk);
            event.sender.send('download-progress-' + opts['hash'], chunk.length);
          },
          () => {
            let tempDataBuffer = Buffer.concat(tempData);

            indexStart = tempDataBuffer.indexOf(opts['tag_s']) || 0;
            // 截取最后的数据
            let finalData = Buffer.from(tempDataBuffer.slice(
              indexStart + opts['tag_s'].length,
              indexEnd
            ), 'binary');
            // 写入文件流&&关闭
            rs.write(finalData);
            rs.close();
            event.sender.send('download-' + opts['hash'], finalData.length);
            // 删除内存数据
            finalData = tempDataBuffer = tempData = null;
          }
      ));
      antstream.pipe(_request);
    }else{
      // 通过替换函数方式来实现发包方式切换, 后续可改成别的
      const old_send = _request.send;
      if(opts['useMultipart'] == 1) {
        _request.send = _request.field;
      }else{
        _request.send = old_send;
      }
      _request
        .proxy(APROXY_CONF['uri'])
        .type('form')
        // 设置超时会导致文件过大时写入出错
        // .timeout(timeout)
        // 忽略HTTPS
        .ignoreHTTPS(opts['ignoreHTTPS'])
        .send(_postData)
        .pipe(through(
          (chunk) => {
            // 判断数据流中是否包含后截断符？长度++
            let temp = chunk.indexOf(opts['tag_e']);
            if (temp !== -1) {
              indexEnd = Buffer.concat(tempData).length + temp;
            };
            tempData.push(chunk);
            event.sender.send('download-progress-' + opts['hash'], chunk.length);
          },
          () => {
            let tempDataBuffer = Buffer.concat(tempData);

            indexStart = tempDataBuffer.indexOf(opts['tag_s']) || 0;
            // 截取最后的数据
            let finalData = Buffer.from(tempDataBuffer.slice(
              indexStart + opts['tag_s'].length,
              indexEnd
            ), 'binary');
            // 写入文件流&&关闭
            rs.write(finalData);
            rs.close();
            event.sender.send('download-' + opts['hash'], finalData.length);
            // 删除内存数据
            finalData = tempDataBuffer = tempData = null;
          }
      ));
    }
  }

  /**
   * 二进制数据流解析
   * @param  {String}   tag_s         数据截断符号(前)
   * @param  {String}   tag_e         数据截断符号(后)
   * @param  {Function}   chunkCallBack 数据流回调函数
   * @param  {Object}   res           Superagent::res对象
   * @param  {Function} callback      数据获取完毕回调事件
   * @return {[type]}                 [description]
   */
  parse(tag_s, tag_e, chunkCallBack, res, callback) {
    // 数据转换二进制处理
    res.setEncoding('binary');
    res.data = '';
    // 2. 把分隔符转换为16进制
    const tagHexS = Buffer.from(tag_s).toString('hex');
    const tagHexE = Buffer.from(tag_e).toString('hex');

    let foundTagS = false;
    let foundTagE = false;
    res.on('data', (chunk) => {

      // 这样吧，我们尝试一种新的数据截取算法：
      // 1. 把数据流转换为16进制
      let chunkHex = Buffer.from(chunk).toString('hex');
      // 3. 根据分隔符进行判断截断数据流
      let temp = '';
      // 如果包含前后截断，则截取中间
      if (chunkHex.indexOf(tagHexS) >= 0 && chunkHex.lastIndexOf(tagHexE) >= 0) {
        let index_s = chunkHex.indexOf(tagHexS);
        let index_e = chunkHex.lastIndexOf(tagHexE);
        temp = chunkHex.substr(index_s + tagHexS.length, index_e - index_s - tagHexE.length);
        foundTagS = foundTagE = true;
      }
      // 如果只包含前截断，则截取后边
      else if (chunkHex.indexOf(tagHexS) >= 0 && chunkHex.lastIndexOf(tagHexE) === -1) {
        temp = chunkHex.split(tagHexS)[1];
        foundTagS = true;
      }
      // 如果只包含后截断，则截取前边
      else if (chunkHex.indexOf(tagHexS) === -1 && chunkHex.lastIndexOf(tagHexE) >= 0) {
        temp = chunkHex.split(tagHexE)[0];
        foundTagE = true;
      }
      // 如果有没有，那就是中途迷路的数据啦 ^.^
      else if (foundTagS && !foundTagE) {
        temp = chunkHex;
      }
      // 4. 十六进制还原为二进制
      let finalData = Buffer.from(temp, 'hex');
      // 5. 返回还原好的数据
      chunkCallBack(finalData);

      res.data += finalData;
    });
    res.on('end', () => {
      logger.info(`end.size=${res.data.length}`, res.data);
      callback(null, Buffer.from(res.data, 'binary'));
    });
  }

}

/**
 * 判断指定buffer对象的字符编码
 * ref: https://github.com/LeoYuan/leoyuan.github.io/issues/25
 * @param buffer
 * @param options
 *  - defaultEncoding 指定默认编码集
 *  - minConfidence   指定可接受的最小confidence，如果判断结果小于此值，则用defaultEncoding
 *  - verbose         返回更加详细的字符编码数据
 * @returns {*}
 */
function detectEncoding(buffer, options) {

  options = options || {};
  buffer = buffer || Buffer('');

  var DEFAULT_ENCODING = 'GBK', MIN_CONFIDENCE = 0.96;
  var verbose = options.verbose;
  var defaultEncoding = options.defaultEncoding || DEFAULT_ENCODING;
  var minConfidence = options.minConfidence || MIN_CONFIDENCE;
  var ret = jschardet.detect(buffer), encoding = ret.encoding === 'ascii' ? 'utf-8' : ret.encoding,
      confidence = ret.confidence;
  // var VALID_ENCODINGS = ['gb2312', 'gbk', 'utf-8', 'big5', 'euc-kr','euc-jp'];

  if (encoding === null || !iconv.encodingExists(encoding) || confidence < minConfidence) {
      return verbose ? {
          encoding: defaultEncoding,
          oriEncoding: encoding,
          confidence: confidence
      } : defaultEncoding;
  } else {
      encoding = encoding.toUpperCase();
      return verbose ? {
          encoding: encoding,
          oriEncoding: encoding,
          confidence: confidence
      } : encoding;
  }
};


/**
 * 控步长的可读流
 * @param data  [string|buffer] 输入源
 * @param options {} 配置
 *    step     步长
 *    stepmax  最大步长,默认与步长相等,如果大于步长，则每次读取时后随机返回 [step, stepmax] 长度的数据
 */
class AntRead extends Readable {
  constructor(data, options={}) {
    super();
    this.index = 0;
    let o = {};
    o.step = options.hasOwnProperty('step') ? parseInt(options['step']) : 2;
    o.step = o.step < 1 ? 2 : o.step;
    o.stepmax = options.hasOwnProperty('stepmax') ? options['stepmax'] : o.step ;
    if (o.stepmax < o.step) {
      o.stepmax = o.step;
    }
    let chunk;
    if('string' === typeof data) {
      chunk = data;
    }else if('object' === typeof data && Buffer.isBuffer(data)) { // buffer
      chunk = Buffer.from(data).toString();
    }else{
      throw Error("data must be string, buffer.");
    }
    this.chunk = chunk;
    this.o = o;
  }

  // 重写自定义的可读流的 _read 方法
  _read() {
      let blakwords = /eval|assert|base64_decode|preg_replace|call_user_func|create_function|str_replace|array_map|system|popen|exec|function_exists|passthru|shell_exec|frombase64string|unsafe|response|execute/i;
      let step = this.randomNum(this.o.step, this.o.stepmax);
      if (this.index >= this.chunk.length) {
          this.push(null);
      }else{
          let _subcode = this.chunk.substring(this.index, this.index + step) + "";
          let m = _subcode.match(blakwords);
          if(m) {
            let sub_step = this.randomNum(1, m[0].length - 1);
            _subcode = _subcode.substring(0, m.index + sub_step);
            step = m.index + sub_step;
          }
          this.push(_subcode);
      }
      this.index += step;
  }

  // random [n, m]
  randomNum(minNum, maxNum){ 
    switch(arguments.length){ 
        case 1: 
          return parseInt(Math.random()*minNum+1,10);
        case 2: 
          return parseInt(Math.random()*(maxNum-minNum+1)+minNum,10); 
        default:
          return 0; 
    } 
  }
}

module.exports = Request;
