#!/usr/bin/env python

import urllib
import sys
from lxml import etree
from optparse import OptionParser, OptionGroup

AVAILABLE_CITIES = [
'California',
'Colorado',
'Florida',
'Massachusetts',
'Minnesota',
'New York',
'Ohio',
'Texas',
'Washington',
'Boston',
'Chicago',
'Cleveland',
'Denver',
'Houston',
'Los Angeles',
'Miami',
'New York City',
'San Francisco',
'Seattle',
]

class NagiosReturn(Exception):
    
    def __init__(self, message, code):
        self.message = message
        self.code = code

def parse_args():
    
    global AVAILABLE_CITIES
    
    city_string = '\n'.join(AVAILABLE_CITIES)
    
    usage = "usage: %prog -L location -w warning -c critical\n\nPossible locations:\n" + city_string
    parser = OptionParser(usage=usage)
    
    required = OptionGroup(parser, "Required Options")
    required.add_option('-L' , '--location', help='Specify the location', default=None)
    parser.add_option_group(required)
    
    nagios = OptionGroup(parser, "Nagios Plugin Information")
    nagios.add_option('-w', '--warning', help='Specify warning range.', default=None)
    nagios.add_option('-c', '--critical', help='Specify critical range.', default=None)
    parser.add_option_group(nagios)
    
    options, _ = parser.parse_args()
    
    if not options.location:
        parser.error('Location is a required option.')
    if not options.location in AVAILABLE_CITIES:
        parser.error('Location not in available location. Suitable locations are:')
        for x in AVAILABLE_CITIES:
            print x
    
    return options
    
def is_within_range(nagstring, value):
    if not nagstring:
        return False
    import re
    import operator
    first_float = r'(?P<first>(-?[0-9]+(\.[0-9]+)?))'
    second_float= r'(?P<second>(-?[0-9]+(\.[0-9]+)?))'
    actions = [ (r'^%s$' % first_float,lambda y: (value > float(y.group('first'))) or (value < 0)),
                (r'^%s:$' % first_float,lambda y: value < float(y.group('first'))),
                (r'^~:%s$' % first_float,lambda y: value > float(y.group('first'))),
                (r'^%s:%s$' % (first_float,second_float), lambda y: (value < float(y.group('first'))) or (value > float(y.group('second')))),
                (r'^@%s:%s$' % (first_float,second_float), lambda y: not((value < float(y.group('first'))) or (value > float(y.group('second')))))]
    for regstr,func in actions:
        res = re.match(regstr,nagstring)
        if res: 
            return func(res)
    raise Exception('Improper warning/critical format.')

def main():
    
    options = parse_args()
    
    filename, fobject = urllib.urlretrieve("http://www.eia.gov/dnav/pet/pet_pri_gnd_a_epm0_pte_dpgal_w.htm")
    f = open(filename, 'r')
    fstr = ''.join(f.readlines())
    html = etree.HTML(fstr)
    
    gas_list = html.xpath("//text()")
    
    index = gas_list.index(options.location)
    price = float(gas_list[index:index+14][-1])
    
    returnval = NagiosReturn('', 2)
    
    if is_within_range(options.critical, price):
        returnval.message = 'CRITICAL: Gas price is at $%.2f | price=%.2f' % (price, price)
        returnval.code = 2
    elif is_within_range(options.warning, price):
        returnval.message = 'WARNING: Gas price is at $%.2f | price=%.2f' % (price, price)
        returnval.code = 1
    else:
        returnval.message = 'OK: Gas price is at $%.2f | price=%.2f' % (price, price)
        returnval.code = 0
    raise returnval



if __name__ == '__main__':
    try:
        main()
    except IOError, e:
        print e
        sys.exit(3)
    except NagiosReturn, e:
        print e.message
        sys.exit(e.code)