# Copyright (c) 2004, 2005 Denis Petrov
# $Id: magic.pl,v 1.8 2005/02/18 02:22:28 Owner Exp $
# Distributed under the terms of the GNU General Public License
#
# Magic Template Processor
#
# Magic Home: http://www.denispetrov.com/magic/

use strict;
# use Data::Dumper;

package main;

sub Magic
{
  my $label_regexp = "[a-zA-z_][a-zA-z0-9_]*";

  my %labels;

  my @parsed = ('<%_%>' . $_[0] . '<%END%>') =~ /(<%.+?(?=%>)%>)(.*?)(?=<%|$)/gs;

  my $i = 0;
  my $len = scalar(@parsed);
  for ( $i = 0; $i < $len; $i++ ) {
    my $l = $parsed[$i];
    if ( $l =~ /<%($label_regexp)%>/ ) {
      if ( exists($labels{$1}) && $labels{$1} != $i )
      {
        warn("Found duplicate label '$1', it has been ignored");
      }
      else
      {
        $labels{$1} = $i;
      }
    }
    elsif ( $l =~ /<%(.+)%>/s ) {
      my $result = eval($1);
      if ( !defined($result) )
      {
         warn("$@\n TEMPLATE CODE:\n$l\nEND TEMPLATE CODE\n");
      }
      elsif ( $result =~ /$label_regexp/ ) {
        if ( exists $labels{$result} )  {
          $i = $labels{$result};
        }
        else { #trace labels forward
          my $j;
          my $found_label = undef;
          for ( $j = $i+1; $j < $len; $j++ ) {
            if ( $parsed[$j] =~ /<%($label_regexp)%>/ ) {
              $labels{$1} = $j;
              if ( $1 eq $result ) {
                $i = $j;
                $found_label = 1;
                last;
              }
            }
          }
          if ( !$found_label )
          {
            warn("Label '$result' does not exist in the template near" .
              "\nTEMPLATE CODE:\n$l\nEND TEMPLATE CODE\n");
          }
        }
      }
    }
    else {
      $l =~ s/\"/\\\"/g;
      my $result = eval("\"".$l."\"");
      if ( !defined($result) )
      {
         warn("$@\n TEMPLATE TEXT:\n$l\nEND TEMPLATE TEXT\n");
      }
      else
      {
         print( $result );
      }
    }
  }


 # print Dumper(\@parsed);
 # print Dumper(%labels);



}


1;