text: 'use strict'
  
  var os = require('os')
  var bin = require('./bin')
  var history = require('./history')
  
  var PLATFORM = os.platform()
  
  function parseTime (timestr, centisec) {
    var time = 0
    var tpart = timestr.split(/-|:|\./)
    var i = tpart.length - 1
    if (i >= 0 && centisec && PLATFORM === 'darwin') {
      time += parseInt(tpart[i--], 10) * 10
    }
    if (i >= 0) { // Seconds
      time += parseInt(tpart[i--], 10) * 1000
    }
    if (i >= 0) { // Minutes
      time += parseInt(tpart[i--], 10) * 60000
    }
    if (i >= 0) { // Hours
      time += parseInt(tpart[i--], 10) * 3600000
    }
    if (i >= 0) { // Days
      time += parseInt(tpart[i--], 10) * 86400000
    }
    return time
  }
  
  /**
    * Get pid informations through ps command.
    * @param  {Number[]} pids
    * @param  {Object} options
    * @param  {Function} done(err, stat)
    */
  function ps (pids, options, done) {
    var pArg = pids.join(',')
    var args = ['-o', 'etime,pid,ppid,pcpu,rss,time', '-p', pArg]
  
    if (PLATFORM === 'aix') {
      args = ['-o', 'etime,pid,ppid,pcpu,rssize,time', '-p', pArg]
    }
  
    bin('ps', args, function (err, stdout, code) {
      if (err) return done(err)
      if (code === 1) {
        return done(new Error('No maching pid found'))
      }
      if (code !== 0) {
        return done(new Error('pidusage ps command exited with code ' + code))
      }
      var date = Date.now()
  
      // Example of stdout on *nix.
      // ELAPSED: format is [[dd-]hh:]mm:ss
      // RSS: is counted as blocks of 1024 bytes
      // TIME: format is [[dd-]hh:]mm:ss
      // %CPU: goes from 0 to vcore * 100
      //
      // Refs: http://www.manpages.info/linux/ps.1.html
      // NB: The columns are returned in the order given inside the -o option
      //
      //    ELAPSED   PID  PPID  %CPU     RSS        TIME
      // 2-40:50:53   430     1   3.0    5145  1-02:03:04
      //   40:50:53   432   430   0.0    2364  1-01:02:03
      //   01:50:50   727     1  10.0  348932       14:27
      //      00:20  7166     1   0.1    3756        0:00
  
      // Example of stdout on Darwin
      // ELAPSED: format is [[dd-]hh:]mm:ss
      // RSS: is counted as blocks of 1024 bytes
      // TIME: format is [[dd-]hh:]mm:ss.cc (cc are centiseconds)
      // %CPU: goes from 0 to vcore * 100
      //
      // Refs: https://ss64.com/osx/ps.html
      // NB: The columns are returned in the order given inside the -o option
      //
      //    ELAPSED   PID  PPID  %CPU     RSS           TIME
      // 2-40:50:53   430     1   3.0    5145  1-02:03:04.07
      //   40:50:53   432   430   0.0    2364  1-01:02:03.10
      //   01:50:50   727     1  10.0  348932       14:27.26
      //      00:20  7166     1   0.1    3756        0:00.02
  
      stdout = stdout.split(os.EOL)
  
      var statistics = {}
      for (var i = 1; i < stdout.length; i++) {
        var line = stdout[i].trim().split(/\s+/)
  
        if (!line || line.length !== 6) {
          continue
        }
  
        var pid = parseInt(line[1], 10)
        var hst = history.get(pid, options.maxage)
        if (hst === undefined) hst = {}
  
        var ppid = parseInt(line[2], 10)
        var memory = parseInt(line[4], 10) * 1024
        var etime = parseTime(line[0])
        var ctime = parseTime(line[5], true)
  
        var total = (ctime - (hst.ctime || 0))
        // time elapsed between calls in seconds
        var seconds = Math.abs(hst.elapsed !== undefined ? etime - hst.elapsed : etime)
        var cpu = seconds > 0 ? (total / seconds) * 100 : 0
  
        statistics[pid] = {
          cpu: cpu,
          memory: memory,
          ppid: ppid,
          pid: pid,
          ctime: ctime,
          elapsed: etime,
          timestamp: date
        }
  
        history.set(pid, statistics[pid], options.maxage)
      }
  
      done(null, statistics)
    })
  }
  
  module.exports = ps
  