#!/usr/bin/perl
use strict;
use LWP::Simple;
use XML::XPath;

my $kml_content = <<"END_OF_FILE";
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.0">
<Folder>
<name>Ocean Observing Map Images</name>
<description><![CDATA[The following is a listing of ocean observing map images shared by SEACOOS ( <a href="http://seacoos.org">http://seacoos.org</a> , <a href="http://nautilus.baruch.sc.edu/twiki_dmcc/bin/view/Main/SEACOOSCookbook2">http://nautilus.baruch.sc.edu/twiki_dmcc/bin/view/Main/SEACOOSCookbook2</a> ) using the WMS(<a href="http://twiki.sura.org/twiki/bin/view/Main/OGC101">Web Mapping Service</a>) web services standard supported by the OGC(OpenGeospatial Consortium <a href="http://www.opengeospatial.org">http://www.opengeospatial.org</a> )]]></description>
END_OF_FILE

my $xp = XML::XPath->new(filename => 'wms.xml');

my ($layer_name, $layer_label, $layer_desc_verbiage, $layer_wms, $bbox, $legend_name, $legend_wms, $legend_ref);

#NOTE: make sure that top nodes are wrapped inside another element tag like <xml> or will get errors
#NOTE: Assigning variables using xpath seems to be having some strange side-effect on the variable operations - having to place variables within quotes to get proper comparisons without generating xpath oriented errors

foreach my $this_layer ($xp->findnodes('//layer')) {

$layer_name = $this_layer->find('name');
print "$layer_name\n";
$layer_label = $this_layer->find('label');
$layer_desc_verbiage = $this_layer->find('desc_verbiage');
$layer_wms = $this_layer->find('wms');
$bbox = $this_layer->find('bbox');

$legend_name = $this_layer->find('legend_name');
$legend_wms = $this_layer->find('legend_wms');
$legend_ref = $this_layer->find('legend_ref');

#$legend_ref = '<td><img src="http://nautilus.baruch.sc.edu/gearth/wave.gif"></td>';

#if we aren't supplying a literal legend reference, then generate the following if legend_name, legend_wms supplied
if ($legend_name && ("$legend_ref" eq '')) {
print "$legend_name\n";
my $image_filename = 'image_'.$legend_name.'.jpg';
$legend_ref = 'http://nautilus.baruch.sc.edu/gearth/'.$image_filename;

my $this_content = getstore("$legend_wms","./$image_filename");
die "Couldn't get $legend_wms" unless defined $this_content;
}

my $legend_html = '';
if ("$legend_ref" ne '') { $legend_html = '<td><img src="'.$legend_ref.'"</td>'; }
my $layer_desc = '<![CDATA[<table><tr valign=top>'.$legend_html.'<td>'.$layer_desc_verbiage.'</td></tr></table>]]>';

my @bbox_coord = split(/,/, $bbox);

$layer_wms =~ s/BBOX/$bbox/g; 

my $image_filename = 'image_'.$layer_name.'.jpg';

my $content = getstore($layer_wms,"./$image_filename");
die "Couldn't get $layer_wms" unless defined $content;

$kml_content .= <<"END_OF_FILE";
<GroundOverlay>
  <name>$layer_label</name>
  <description>$layer_desc</description>
END_OF_FILE

#view just a single layer initially, not all
if ("$layer_label" eq 'OI_SST') { $kml_content .= '<visibility>1</visibility>'; } 
else { $kml_content .= '<visibility>0</visibility>'; } 

$kml_content .= <<"END_OF_FILE";
  <Icon>
    <href><![CDATA[http://nautilus.baruch.sc.edu/gearth/$image_filename]]></href>
  </Icon>
  <color>9bffffff</color>
  <LatLonBox>
    <north>$bbox_coord[3]</north>
    <south>$bbox_coord[1]</south>
    <east>$bbox_coord[2]</east>
    <west>$bbox_coord[0]</west>
  </LatLonBox>
</GroundOverlay>
END_OF_FILE

} #foreach $layer

$kml_content .= <<"END_OF_FILE";
</Folder>
</kml>
END_OF_FILE

open (FILE_KML,">./latest_overlays.kml");
print FILE_KML $kml_content;
close (FILE_KML);

exit 0;