#!/usr/bin/perl -w
use strict;

# {{{ 0. Basic modules and declarations.

use Carp;
use Data::Dumper;
use POE;
use POE::Wheel::ReadLine;
use vars qw($parser $player @objects @libmsgs $input);

use constant false => 0;
use constant true => 1;

open LOG, ">log";
sub w { print LOG (@_, "\n") }
# }}}

# {{{ 2. Library messages.
    
use constant UNK_VERB => 0;
use constant UNK_WORD => 1;
use constant NO_FORM  => 2;
sub libmsg { return meval($libmsgs[$_[0]], @_[1..$#_]) }

@libmsgs[UNK_VERB, NO_FORM] = 
    ("I don't know how to do that.\n",
     "Those words don't fit together; I can't understand you.\n");
{ local $" = '';
  $libmsgs[UNK_WORD] = sub { "I only understood you as wanting to @_" };
}


# {{{ 1. The parser.

use constant PARSE_ERR => -1;
use constant PARSE_OK => 0;

# {{{ 1.1. init_parser

sub init_parser
{
    $parser && return 1;
    my $p =
	POE::Session->create
	    (
	     # {{{ 1.1.1. Actual parsing routines.
	     inline_states =>
	     {
	      # {{{ 1.1.1.1. _start
	      _start => sub {
		  w("Parser starting");
		  $parser = $_[SESSION];
	      },
	      # }}}
	      # {{{ 1.1.1.2. parse_line
	      parse_line => sub {
		  my ($heap, $text) = @_[HEAP, ARG0];
		  my (@text, $verb, $counter);
		  w("Parsing line: $text");
		  # {{{ 1.1.1.2.1. Splitting the line into pieces
		  for ($text) {
		      pos = 0;
		      while (
			     /(?:
			       (?<=[a-zA-Z0-9_$%\#\-])
			       ([,!&().\/:; \t]+)
			       (?=[a-zA-Z0-9_$%\#\-]))|
			     (?:
			      (?<=[,!&().\/:; \t]+)
			      ([a-zA-Z0-9_$%\#\-]+)
			      (?=[,!&9).\/:; \t])/gx) {
			  w("Parsed piece: $+");
			  push @text, $+;
		      }
		  }
		  # }}}
		  # {{{ 1.1.1.2.2. Finding the verb
		  ($verb = $heap->{verbs}->{$text[0]}) or
		      (print libmsg(UNK_VERB),
		       return PARSE_ERR);
		  # }}}
		  # {{{ 1.1.1.2.3. Parsing the verb
		  $counter = 0;
		  w("Got verb: \n",Dumper $verb);
	      FORM: foreach (@$verb) {
		      my @usedobjs;
		  TOKEN: foreach (@$verb[0..($#$verb-1)]) {
			  w("Token: $_");
			  next TOKEN unless $_;
			  if (!ref) {
			      if (/[a-zA-Z0-9_$%\#-]/) {
				  ($text[$counter] =~ /^\s*$/) and
				      $counter++;
				  ($_ eq $text[$counter]) or next FORM;
			      } else {
				  my $x = $_;
				  $x =~ tr/ \t//d;
				  ($text[$counter] eq $x) or next FORM;
			      }
			  } elsif (ref eq 'CODE') {
			      my $flag = false;
			  OBJ: foreach my $obj (@objects) {
				  if ($_->($obj)) {
				      push @usedobjs, $obj;
				      $flag = true;
				      last OBJ;
				  }
			      }
			      (!$flag) && next FORM;
			  }
		      }
		      $verb->[$#$verb-1]->(@usedobjs);
		      return PARSE_OK;
		  }
		  # }}}
		  print libmsg(NO_FORM);
		  return PARSE_ERR;
	      },
	      # }}}
	      # {{{ 1.1.1.3. mod_verb
	      mod_verb => sub {
		  my ($heap, $verb, $grammar) = @_[HEAP, ARG0, ARG1];
		  w("Modifying verb $verb to: ",Dumper $grammar);
		  $heap->{verbs}->{$verb} = [ @$grammar ];
	      },
	     }

		# }}}
	   );
}
# }}}
    
# }}}
# }}}
# }}}
# {{{ 3. iscode, meval.

sub iscode { return (ref shift eq 'CODE') }
sub meval { return $_[0]->(@_[1..$#_]) if &iscode; return $_[0] }
# }}}
# {{{ 4. Input.

# {{{ 4.1. init_input
sub init_input
{
    $input && return 1;
    my $i;
    $i = POE::Session->create
	(
	 # {{{ 4.1.1. Actual input subroutines.
	 inline_states => {
			   # {{{ 4.1.1.1. _start
			   _start => sub {
			       w("Input handler starting");
			       my $heap = $_[HEAP];
			       $input = $_[SESSION];
			       $heap->{wheel} = POE::Wheel::ReadLine->new
				   ( InputEvent => 'got_line' );
			       w("Wheel created: ",$heap->{wheel});
			       $heap->{wheel}->get('> ');
			   },
			   # }}}
			   # {{{ 4.1.1.2. got_line
			   got_line => sub {
			       my ($heap, $line) = @_[HEAP, ARG0];
			       if (defined $line) {
				   w("Line input: $line");
				   $heap->{wheel}->addhistory($line);
				   $_[KERNEL]->call($parser, 'parse_line', $line);
				   w("Event posted");
				   $heap->{wheel}->get('> ');
			       } elsif ($_[ARG1] eq 'interrupt') {
				   exit 0;
			       }
			   },
			   # }}}
			  }
	 # }}}
	);
}
# }}}

# }}}
# {{{ 5. Tester.
w("Calling init_input");
init_input();
w("Calling init_parser");
init_parser();
w("Posting mod_verb");
$poe_kernel->post($parser, 'mod_verb', "quit", [ '', sub { print "\n"; exit 0 } ]);
w("Running kernel");
$poe_kernel->run;