#!/usr/bin/env python
#
# Authors:
# rafael@postgresql.org.es / http://www.postgresql.org.es/
#
# Copyright (c) 2014 USIT-University of Oslo

import sys
import os
import time
import json
import urllib2
import xml.etree.ElementTree as ET

# ############################################
# Method: generate_json_output
#
# Parameters: Text = temperature box hostname
# Returns: JSON data
# ############################################

def generate_json_output(temperature_box):

    '''
    Generate the json output needed by Zabbix to define a "low level
    discovery rule".

    We use the macro {#DEVICEID} in the output to identify a
    temperature device. This macro is the one to use when defining a
    "low level discovery rule" that discovery temperature devices in a
    temperature box.

    More information:
    https://www.zabbix.com/documentation/2.2/manual/discovery/low_level_discovery

    '''

    try:
        minutes_since_last_update = 0
        temp_file = '/tmp/' + temperature_box + '_temperature_data.xml'
        
        if os.path.exists(temp_file) == True:
            minutes_since_last_update = (time.time() - os.path.getmtime(temp_file)) / 60
        
        #
        # Get the XML data from
        # http://<temperature_box_hostname>/data.xml only if the local
        # temp file with the XML code does not exist or if the file is
        # older that 5 minutes.
        # 

        if os.path.exists(temp_file) == False or minutes_since_last_update > 5:
            
            req = urllib2.Request('http://' + temperature_box + '/data.xml')
            response = urllib2.urlopen(req,timeout=5)
            the_page = response.read()

            with open (temp_file,'w') as xmlfile:
                xmlfile.write(the_page)

        tree = ET.parse(temp_file)
        root = tree.getroot()

    except Exception as e:
        print e
        sys.exit(1)

    try:

        #
        # Get the list with all devices in this temperature box and
        # return the JSON data needed by Zabbix low-level
        # autodiscovery
        #

        device_list = []

        for child in root.findall("./devices/device"):

            device = {}
            device = {"{#DEVICEID}": child.attrib['id'],"{#DEVICENAME}": child.attrib['name']}
            
            device_list.append(device)

        result = {"data":device_list}
        print json.dumps(result,sort_keys=True,indent=2)

    except Exception as e:
        print e
        sys.exit(1)


# ############################################
# MAIN
# ############################################

if __name__ == '__main__':

    try:
        if len(sys.argv) == 2:
            temperature_box = sys.argv[1].lower()
            generate_json_output(temperature_box)
            
        else:
            print "Error: Wrong number of parameters"
            print 'Format: ' + sys.argv[0] + ' <temperature box hostname>'        
            sys.exit(1)

    except Exception as e:
        print e
        sys.exit(1)