const URL = require('url');
const http = require('http');
const https = require('https');
const qs = require('querystring');
let trends = exports;
trends.getInstance = function () {
  return new Trends;
}
function Trends() {
  this.expireTime = 1800;
  this.accessKey = 'xxxxxxxx';
  this.secretKey = 'xxxxxxxx';
  this.userKey = 'xxxxxxxx';
  this.userSecret = 'xxxxxxxx';
  this.host = 'trends.baidubce.com';
  this.timestamp = _.time();
  this.utcTimestamp = _.utcTime();
}
Trends.prototype.request = async function (method, uri, params) {
  method = method.toUpperCase();
  let token = this.getToken();
  let headers = this.getHeaders(method, uri);
  params = Object.assign({}, params || {}, {
    'user_key': this.userKey,
    'token': token,
    'timestamp': this.timestamp
  });
  let url = `http://${this.host}${uri}`;
  return await this.httpRequest(method, url, params, headers);
}
Trends.prototype.getHeaders = function (method, uri) {
  let authorization = this.getAuthorization(method, uri);
  return {
    'Content-Type': 'application/x-www-form-urlencoded',
    'Host': this.host,
    'x-bce-date': this.utcTimestamp,
    'Authorization': authorization,
  };
}
Trends.prototype.getAuthorization = function (method, uri) {
  let authString = `bce-auth-v1/${this.accessKey}/${this.utcTimestamp}/${this.expireTime}`;
  let signinKey = _.hmac(authString, this.secretKey, 'sha256');
  let header = {
    'host': this.host,
    'x-bce-date': _.urlencode(this.utcTimestamp)
  };
  let headerArr = [];
  for (let name in header) {
    let val = header[name];
    headerArr.push(`${name}:${val}`);
  }
  let headerKeyStr = Object.keys(header).sort().join(';');
  let requestStr = `${method}\n${uri}\n\n${headerArr.join('\n')}`;
  let signautre = _.hmac(requestStr, signinKey, 'sha256');
  return `${authString}/${headerKeyStr}/${signautre}`;
}
Trends.prototype.getToken = function () {
  return _.hmac(this.userKey + this.timestamp, this.userSecret);
}
Trends.prototype.httpRequest = async function (method, url, params, headers) {
  let urlObj = URL.parse(url);
  let protocol = urlObj.protocol;
  let options = {
    hostname: urlObj.hostname,
    port: urlObj.port,
    path: urlObj.path,
    method: method,
    headers: headers,
    timeout: 10000,
  };
  let postData = qs.stringify(params || {});
  return new Promise((resolve, reject) => {
    let req = (protocol == 'http:' ? http : https).request(options, (res) => {
      let chunks = [];
      res.on('data', (data) => {
        chunks.push(data);
      });
      res.on('end', () => {
        let buffer = Buffer.concat(chunks);
        let encoding = res.headers['content-encoding'];
        if (encoding == 'gzip') {
          zlib.unzip(buffer, function (err, decoded) {
            resolve(decoded.toString());
          });
        } else if (encoding == 'deflate') {
          zlib.inflate(buffer, function (err, decoded) {
            resolve(decoded.toString());
          });
        } else {
          resolve(buffer.toString());
        }
      });
    });
    req.on('error', (e) => {
      _.error('request error', method, url, params, e);
      resolve('');
    });
    req.on("timeout", (e) => {
      _.error('request timeout', method, url, params, e);
      resolve('');
    })
    if (method.toUpperCase() == 'POST') {
      req.write(postData);
    }
    req.end();
  });
}

module.exports = function () {
  return new Script;
}
function Script() {}
Script.prototype.run = async function () {
  let rst = this.getTaskList();
  console.log(rst);
}
Script.prototype.getTaskList = async function () {
  let params = {};
  let method = 'post';
  let uri = '/openapi/getTasklist';
  let rst = await _.trends.getInstance().request(method, uri, params);
  return rst;
}