kml.pl: don't add duplicate places

kml.pl

@@ -17,6 +17,7 @@ unless(defined($mode))
 {
     USAGE();
 }
+
 if ($mode eq 'add')
 {
     my ($name, $coordinates) = @ARGV;
@@ -25,12 +26,19 @@ if ($mode eq 'add')
         say "Not enough args for add operation";
         USAGE(1);
     }
+    my $name_id = to_id($name);
+    my ($placemark) = $xpc->findnodes("//k:Placemark[\@id=\"$name_id\"]");
+    if(defined($placemark))
+    {
+        say "$name already exists in $filename";
+        exit(1);
+    }
     append_placemark($name, $coordinates, uri_escape($name));
     print $dom->toString(1);
 }
+
 elsif ($mode eq 'remove')
 {
-    # say "Remove mode";
     my ($name) = @ARGV;
     unless (defined($name))
     {
@@ -49,12 +57,13 @@ elsif ($mode eq 'remove')
         say "$name was not found in $filename";
         exit(1);
     }
-    # say $placemark->toString(1);
 }
+
 elsif ($mode eq 'set')
 {
     say "Set mode";
 }
+
 else
 {
     say "Invalid operation";