#!/usr/bin/env python

import subprocess
import sys

from optparse import OptionParser

class SarMetric:
    def sarfetch(self, cmd, col):
        p = subprocess.Popen(cmd, stdout=subprocess.PIPE, shell=True)
        value = p.communicate()[0]
        return value.split('\n')[3].split()[col]

    def _get_user(self):
        '''
        return %user value
        %user is in the 3rd colum of sar output
        '''
        cmd = 'sar 1'
        col = -6
        return self.sarfetch(cmd, col)

    def _get_nice(self):
        '''
        return %nice value
        %nice is in the 4th colum of sar output
        '''
        cmd = 'sar 1'
        col = -5
        return self.sarfetch(cmd, col)

    def _get_system(self):
        '''
        return %system value
        %system is in the 5th colum of sar output
        '''
        cmd = 'sar 1'
        col = -4
        return self.sarfetch(cmd, col)

    def _get_iowait(self):
        '''
        return iowait value
        iowait value is in 6th column of sar output
        '''
        cmd = 'sar 1'
        col = -3
        return self.sarfetch(cmd, col)

 
    def _get_steal(self):
        '''
        return %steal value
        %steal is in the 7th column of sar output
        '''
        cmd = 'sar 1'
        col = -2
        return self.sarfetch(cmd, col)

    def _get_idle(self):
        '''
        return %idle value
        %idle is in the 8th column of sar output
        '''
        cmd = 'sar 1'
        col = -1
        return self.sarfetch(cmd, col)







def get_options():
    parser = OptionParser()
    # use list comprehension to retrieve list of supported metrics
    # by finding functions of the class with _get_ appended
    supported_metrics = [ i[5:] for i in dir(sar) if i[:5]=="_get_"]

    (options, args) = parser.parse_args()
    metric = args[0]

    if not metric in supported_metrics:
        sys.exit('unsupported metric %s' %metric)

    return metric

if __name__ == '__main__':
    sar = SarMetric()
    
    
    metric = get_options()
    handler_prefix = '_get_'
    handler = handler_prefix + metric

    value = getattr(sar, handler)()
    print value