#gives all descendents for a tree, given a root node

use strict;
use warnings;

my ($curr_string, $in, $select, %immed_child, %all_descends);

process_input();
load_hashes();
#make_display_string("$in");
#print "\n$curr_string\n";

load_hashes();
show_results();

sub process_input{
	while(1){
		print qq(enter concept name or "Q" to quit\n);
		chomp($in = <>);
		exit() if $in =~ /^\s*q\s*$/i;
		$in =~s/^\s*(\w+)\s*$/$1/;
		# still need to check if a valid concept
		print qq(enter:\n"A" for all descendents,\n"I" for immediate children\n"P" for parents\n);
		chomp($select = <>);
		$select =~ s/^\s*([aip])\s*$/$1/i;
		last;
	}
}

# key: parent 
# val: list of immediate children
sub load_hashes{
	my ($child, $par);
	while(<DATA>){
		chomp;
		($child, $par) = split/\t/;
		push @{$immed_child{$par}}, $child;
	}
}

#global hash needed to exchange vals w other subs
sub get_descends{
	my $root = shift;
	$all_descends{$root}++ if $root;
	while(1){
	 	last unless my $immed = pop @{$immed_child{$root}};
		get_descends($immed);
		$all_descends{$immed}++;
	}
	return keys %all_descends;
}

sub make_display_string{
	my $root = shift;
	my $level = shift ;
	$curr_string = shift || $root;
	#	$curr_string = "\n". $curr_string;
	$level++;
	while (1){
		last unless my $immed = pop @{$immed_child{$root}};
		$curr_string .="\n".  "\t" x $level .  $immed;
		make_display_string($immed, $level, $curr_string);
	}
	#$curr_string = "\n" . $curr_string;
}
		
sub show_results{
	$" = "\n\t"; 
	if ($select =~ m/a/i){
		print qq(\ndescendents of \n"$in":\n);
		my @descends = get_descends($in);
		print "\t@descends\n";
	} 
	elsif ($select =~m/i/i){
		if (@{$immed_child{$in}}){
			print qq(\nimmediate children of \n"$in":\n);
			print "\t@{$immed_child{$in}}\n";
		}
		else{
			print "no immediate children of $in";
		}
	}
	elsif ($select =~ m/p/i){
		print "working on this\n";
	}
}
		
		
			
__DATA__
vehicle	taxonomy
exercise device	taxonomy
computer topic	taxonomy
automobile	vehicle
ford	automobile
chevy	automobile
bike	vehicles
bike	exercise device
jumprope	exercise device
treadmill	exercise device
perl	computer topic
database	computer topic