Yahoo Weather

#!/usr/bin/perl

#################################################################
# Yahoo Weather Rss Information Atomizer
# Version 0.7.7
# Loud-Soft.com
# danl@loud-soft.com
# Provided As Is
#################################################################

use strict;
use XML::XPath;
use LWP::Simple;
use XML::XPath::XMLParser;
use Getopt::Long;
use File::Copy;

#################################################################
# Variables
#################################################################
# Constants (Change these to localize)
my $zipcode = "CAXX0504";
my $unit = "c";
my $scripthome = "/Users/haroon/Documents/yweather-dir/";
my $icondir = $scripthome."images/";
my $datadir = $scripthome."data/";
my $datafile = $datadir."weather.xml";
my $imagefile = $icondir."weather.png";

# Constants (Do not change these)
my $pre="yweather";
my $uri="http://xml.weather.yahoo.com/ns/rss/1.0";
my $url="http://xml.weather.yahoo.com/forecastrss?p=$zipcode&u=$unit";
my %data;
my $xp;

#################################################################
# Subroutines
#################################################################
# Print usage
sub usage {
    print "Yahoo Weather Information\n\n";
    print "Usage:\n";
    print " ./yweather.pl -ct   Displays current temperature\n\n";
    print "Arguments: \n";
    print " -lc             City    \n";
    print " -lr         Region\n";
    print " -lt         Country\n";
    print " -cc         Weather Code (used for images)\n";
    print " -ct         Current Temperature\n";
    print " -cfl        Current Feels Like\n";
    print " -cw         Current Weather Description\n";
    print " -cd         Current Date\n";
    print " -ah         Current Humidity\n";
    print " -av         Current Visibilty\n";
    print " -ap         Current Barometric Pressure\n";
    print " -ar         Change in Barometric Pressure\n";
    print " -sr         Time of Sunrise\n";
    print " -ss         Time of Sunset\n";
    print " -wc         Current Wind Chill\n";
    print " -wd         Current Wind Direction\n";
    print " -ws         Current Wind Speed\n";
    print " -ut         Temperature Unit\n";
    print " -ud         Distance Unit\n";
    print " -up         Pressure Unit \n";
    print " -us         Speed Unit\n";
    print " -fd1            Today's Day\n";
    print " -fg1            Today's Date\n";
    print " -fl1            Today's Low Temp\n";
    print " -fh1            Today's High Temp\n";
    print " -ft1            Today's Description\n";
    print " -fc1            Today's Weather Code\n";
    print " -fd2            Tomorrow's Day\n";
    print " -fg2            Tomorrow's Date\n";
    print " -fl2            Tomorrow's Low Temp\n";
    print " -fh2            Tomorrow's High Temp\n";
    print " -ft2            Tomorrow's Description\n";
    print " -fc2            Tomorrow's Weather Code\n";
    print " --copyimage     Copy Appropriate Image to Current Image (deprecated)\n";
    print " --update        Update xml source file\n"   ;
    print " \n";
    print "All data is returned without units. To get data with units,\n";
    print "use a combination of commands.\n\n";
    print "Example: (Displays Current temperature with unit)\n";
    print " ./yweather.pl -ct && ./yweather.pl -ut\n";
}

# Print data
sub args{
    my ($arg) = @_;
    print $data{$arg} . "\n";
}

# Subroutine to update xml data from yahoo
sub update_weather {
    LWP::Simple::getstore($url,$datafile);
}

# Subroutine to download images from yahoo
sub get_images {
    my $imgurl = "http://l.yimg.com/a/i/us/nws/weather/gr/";
    for (0..47) {
        LWP::Simple::getstore($imgurl.$_."d.png",$icondir.$_."d.png");
        LWP::Simple::getstore($imgurl.$_."n.png",$icondir.$_."n.png");
    }
}

# Parse XML
sub get_data {
    my $ret;
    my($element, $attribute, $index) = @_;
    if ($index){$index=1;}

    my $nodeset = $xp->find("//yweather:$element");
    my $node = $nodeset->get_node($index);
    $ret = $node->getAttribute($attribute);
    return $ret;
}

# Calculate Feels Like (given temperature in fahrenheit and humidity)
# source http://en.wikipedia.org/wiki/Heat_index#Formula
sub calculate_feels_like {
    my $unit = $data{'ut'};

    # convert temperature to Fahrenheit
    my $tempf = $unit eq 'C' ? $data{'ct'} * 9/5 + 32 : $data{'ct'};
    my $humid = $data{'ah'};

    my $feels;

    # heat index calculation is only useful when temperature > 80F and humidity > 40%
    if ($humid > 40 && $tempf > 80) {
        $feels = -42.379 + 2.04901523 * $tempf + 10.14333127 * $humid
            - 0.22475541 * $tempf * $humid - 6.83783 * 10**(-3)*($tempf**(2))
            - 5.481717 * 10**(-2)*($humid**(2))
            + 1.22874 * 10**(-3)*($tempf**(2))*($humid)
            + 8.5282 * 10**(-4)*($tempf)*($humid**(2))
            - 1.99 * 10**(-6)*($tempf**(2))*($humid**(2));

        # convert back to original unit if necessary
        if ($unit eq 'C') {
            $feels = ($feels - 32) * 5/9;
        }
    } else {
        # simply return wind chill
        $feels = $data{'wc'};
    }
    return ($feels == int($feels)) ? int($feels) : int($feels + 1);
}

# Copy correct image to the image define in $imagefile
sub copy_image {
    my ($second, $minute, $hour, $dayOfMonth, $month,
        $yearOffset, $dayOfWeek, $dayOfYear, $daylightSavings) = localtime();
    my $night = $data{'ss'};
    my $morning = $data{'sr'};
    my $imagesub;
   if ($hour > 11){
        if(($hour-12) < int(substr($night,0,1))){
            $imagesub = "d";
        }elsif(($minute) < int(substr($night,2,3))){
            $imagesub = "d";
        }else{
            $imagesub = "n";
        }
    } else {
        if(($hour) < int(substr($morning,0,1))){
            $imagesub = "n";
        }elsif(($minute) < int(substr($morning,2,3))){
            $imagesub = "n";
        }else{
            $imagesub = "d";
        }
    }
    File::Copy::copy($icondir.$data{'cc'}.$imagesub.".png", $imagefile)
        or die $icondir . $data{'cc'}.$imagesub.".png" . " could not be copied to " .
        $imagefile;
}

#################################################################
# Check that files exist
#################################################################
#ensure directories exist
unless(-d $datadir){
    mkdir $datadir or die;
}
unless(-d $icondir){
    mkdir $icondir or die;
}

# Check if images exist
if (!(-e $icondir."0d.png")){get_images()}

# Check if weather.xml exists
if (!(-e $datafile)){update_weather()}
$xp = XML::XPath->new(filename => $datafile);
$xp->set_namespace($pre, $uri);


#################################################################
# Data Setup
#################################################################
# Location Information
$data{'lc'} = get_data("location","city");
$data{'lr'} = get_data("location","region");
$data{'lt'} = get_data("location","country");

# Current Weather Information
$data{'cc'} = get_data("condition","code");
$data{'ct'} = get_data("condition","temp");
$data{'cw'} = get_data("condition","text");
$data{'cd'} = get_data("condition","date");

# Current Atmosphere Information
$data{'ah'} = get_data("atmosphere","humidity");
$data{'av'} = get_data("atmosphere","visibility");
$data{'ap'} = get_data("atmosphere","pressure");
$data{'ar'} = get_data("atmosphere","rising");

# Todays Sunrise and sunset
$data{'sr'} = get_data("astronomy","sunrise");
$data{'ss'} = get_data("astronomy","sunset");

# Current wind information
$data{'wc'} = get_data("wind","chill");
$data{'wd'} = get_data("wind","direction");
$data{'ws'} = get_data("wind","speed");

# Unit information
$data{'ut'} =get_data("units","temperature");
$data{'ud'} =get_data("units","distance");
$data{'up'} =get_data("units","pressure");
$data{'us'} =get_data("units","speed");

# Forecast (Today)
$data{'fd1'} =get_data("forecast[1]","day");
$data{'fg1'} =get_data("forecast[1]","date");
$data{'fl1'} =get_data("forecast[1]","low");
$data{'fh1'} =get_data("forecast[1]","high");
$data{'ft1'} =get_data("forecast[1]","text");
$data{'fc1'} =get_data("forecast[1]","code");

# Forecast (Tomorrow)
$data{'fd2'} =get_data("forecast[2]","day");
$data{'fg2'} =get_data("forecast[2]","date");
$data{'fl2'} =get_data("forecast[2]","low");
$data{'fh2'} =get_data("forecast[2]","high");
$data{'ft2'} =get_data("forecast[2]","text");
$data{'fc2'} =get_data("forecast[2]","code");

# Current feels like
$data{'cfl'} = calculate_feels_like();

# Check if image exist
if (!(-e $imagefile)){copy_image()}

#################################################################
# Parse arguments
#################################################################
if(($#ARGV + 1) == 1){
    my $arg = substr($ARGV[0],1);
    if (defined($data{$arg})){
        args($arg);
    } elsif($arg eq "-update"){
        update_weather();
    } elsif($arg eq "-copyimage"){
        copy_image();
    } else {
        usage();
    }
} else {
    usage();
}