#!/usr/bin/perl -w
#
# Copyright (C) 2006 Lars Strand
#
# Plugin to fetch temperature from tgftp.nws.noaa.gov
#
# Parameters supported:
#
#       config
#       autoconf
#
# Magic markers:
#%# family=auto
#%# capabilities=autoconf

use strict;

my $usehum = $ENV{humidity} || undef;   # set to "yes" to enable humidity
my $wcode  = $ENV{wcode}    || "ENGM";  # Find areacode here http://tgftp.nws.noaa.gov/
my $unit   = $ENV{unit}     || "C";     # "C" = Celsius, "F" = Fahrenheit
my $proxy  = $ENV{proxy}    || undef;   # Example: "http://proxy.foo.bar:8080/"

my $ret = undef;
if (! eval "require LWP::UserAgent;") {
    $ret = "LWP::UserAgent not found";
}

if (defined $ARGV[0] and $ARGV[0] eq "autoconf") {
    if (defined $ret) {
	print "no ($ret)\n";
    } else {
	print "yes\n";
    }
    exit 0;
}

# Extract weather-code from filename. Example: weather_CODE
if ($0 =~ /^(?:|.*\/)temperature_([^_]+)$/) {
    $wcode  = $1;
}


my $datasource = "http://tgftp.nws.noaa.gov/data/observations/metar/decoded/$wcode.TXT";

my $ua = LWP::UserAgent->new(timeout => 30);
$ua->agent('Munin');

# Use proxy, if defined.
if (defined $proxy) {
    $ua->proxy(['http'], $proxy);
}

my $response = $ua->request(HTTP::Request->new('GET',$datasource));

if (defined $ARGV[0] and $ARGV[0] eq "config") {

    if ($response->content =~ /^((.*?),.*\)).*\n/) {
	print "graph_title Temperature at $2\n";
    } else {
	print "graph_title Temperature at locationcode $wcode\n";
    }

    if ($unit =~ /F/) {
	print "graph_vlabel temp in F\n";
    } else {
	print "graph_vlabel temp in C\n";
    }

    print "graph_args --base 1000 -l 0\n";
    print "graph_category sensors\n";
    print "graph_info Temperatures at $1 (fetched from weather.nooa.gov).\n";
    print "temperature.label temperature\n";
    if (defined $usehum) {
	print "humidity.label humidity\n";
	print "humidity.info Humidity in %.\n";
    }
    exit 0;
}

if ($response->content =~ /Temperature:\s*(.*)\s+F\s*\(\s*(.*)\s+C/) {
    my ($f, $c) = ($1, $2);
    if ($unit =~ /F/) {
	print "temperature.value $f\n";
    } else {
	print "temperature.value $c\n";
    }
} else {
    print "temperature.value U\n";
}

if (defined $usehum) {
    if ($response->content =~ /Relative Humidity:\s*(\d+)\%.*/) {
	print "humidity.value $1\n";
    }
}