const async = require('async');
const disk = require('diskusage');
const os = require('os');

const cdm = {};

const getCPU = (fn) => {
  return fn(null, {
    user: os.cpus().reduce((sum, cpu) => sum + cpu.times.user, 0),
    sys: os.cpus().reduce((sum, cpu) => sum + cpu.times.sys, 0)
  });
};

const getMem = (fn) => {
  const free = os.freemem();
  const total = os.totalmem();
  const using = total - free;
  const perc = (using / total) * 100;

  return fn(null, {
    used: perc
  });
};

const getDisk = (fn) => {
  disk.check('/', fn);
};

const getStats = (fn) => {
  async.parallel({
    cpu: getCPU,
    mem: getMem,
    disk: getDisk
  }, fn);
};

module.exports = (server) => ({
  on: (id) => {
    console.log('on', cdm[id]);
    if (cdm[id] && (cdm[id].sockets > 0)) {
      cdm[id].sockets +=1;
      return;
    }

    let messageId = 0;
    const interval = setInterval(() => {
      console.log(`publishing /stats/${id}`);

      getStats((err, stats) => {
        server.publish(`/stats/${id}`, {
          when: new Date().getTime(),
          stats
        });
      });
    }, 1000);

    cdm[id] = {
      interval,
      sockets: 1
    };
  },
  off: (id) => {
    if (!(cdm[id].sockets -= 1)) {
      clearInterval(cdm[id].interval);
    }
  }
});