#!/usr/local/bin/perl -w

require 5.005;

my $VERSION = "1.0";

use strict;
use XML::XPath;
use CGI qw(header param);

print header(-type=>'text/html');

my $template = "iching.template";

if (open TEMPLATE, $template) {
  while ( <TEMPLATE> ) {
    print;
    last if /<!-- ICHING -->/; 
  }
}

if (my $question = param('askme')) {
  print "<p>You asked the oracle: &quot;$question&quot;</p>"; 
}

my ($main_hex,$changed_hex,$moving_lines);

# Toss three coins six times to get the lines of the 
# main hexagram and the changed hexagram.

for (my $i=0; $i<6; $i++) {
  my $line = cast();
  $main_hex .= $line; 
}

sub cast {

  # Casts three coins. Heads worth three, tails worth two.
  # Returns between 6 and 9 representing one line of the
  # hexagram:
  #   6  - x -  moving Yin
  #   7  -----  Yang
  #   8  -- --  Yin
  #   9  --o--  moving Yang

  my $line = 0;
  for (my $x=0; $x<3; $x++) {
    $line += int (rand(2)) + 2;
  }
  return $line;
}


# In the changed hexagram, moving Yin becomes Yang
# and moving Yang becomes Yin.

$changed_hex = ($moving_lines = $main_hex);
$changed_hex =~ tr/6789/9966/;
$moving_lines =~ tr/6789/1001/;
$main_hex =~ tr/6789/6969/;

# reverse moving_lines so we can use chop later
$moving_lines = reverse $moving_lines;

# Now we have the hexagrams, we need to consult the book.

my $xml_data;
while (<DATA>) { $xml_data .= $_ }
my $parser = XML::XPath->new( xml=>$xml_data );

foreach my $pattern ($main_hex, $changed_hex) {

  my $nodeset = $parser->find( "/hexagrams/hexagram/pattern" ); 

  foreach my $node ($nodeset->get_nodelist()) {

    if ( $parser->getNodeText($node) eq $pattern ) {

      my $hexagram = $node->getParentNode();

      my %entry;
      foreach ('title','hexnum','above','below','judgement',
               'image','extra') {
        $entry{$_} = $parser->getNodeText(
          $parser->find("./$_",$hexagram));
      } 

      print "<h2>$entry{hexnum} - $entry{title}</h2>";
      print "<p>$entry{above} is above.<br />$entry{below} is below.</p>";
      print "<p><em>Judgment:</em> $entry{judgement}</p>"; 
      print "<p><em>Image:</em> $entry{image}</p>"; 

      if (length($moving_lines) > 0) {
        my $c = 0;
        my @headings = ('', 'First', 'Second', 'Third',
                        'Fourth', 'Fifth', 'Top');
        foreach my $l ($parser->find('./lines/line', $hexagram)->get_nodelist) {
          $c++;
          if (chop $moving_lines) {
            print "<p><em>$headings[$c]:</em> ", 
                  $parser->getNodeText($l), 
                  '</p>';
          }
        }
      }

      print "<p>$entry{extra}</p>" if $entry{extra}; 

      last;
    }
  }
}

print while (<TEMPLATE>);

exit;