use diagnostics;
use strict;
use Vertex;
use Edge;

sub make_vertex($);
sub make_edge($$$);
if (1) {}; # Emacs Perl-mode does not like prototypes; indentation destroyed.

my ( @data,  $i, $comment, $nr_edges, $nr_verteces );
my ( $v1, $v2 );
my ( @verteces, %verteces, @edges, %edges );

$comment = '#.*$';
while (<>) {
    my ( $vertex_1, $vertex_2, $edge, $key);

    $i++;
    s/$comment//;
    next if /^\s*$/;
    /^\s*(\S+)\s+(\S+)/;

    if (!$1 || !$2) {
	print STDERR "Non-valid data on line $i.\n";
	next;
    }
    ($v1, $v2) = ($1, $2);
    
    $vertex_1 = $verteces{$v1};
    if (!$vertex_1) {
	$vertex_1 = make_vertex($v1);
	$verteces{$v1} = $vertex_1;
	push @verteces, $vertex_1;
    }
    $vertex_2 = $verteces{$v2};
    if (!$vertex_2) {
	$vertex_2 = make_vertex($v2);
	$verteces{$v2} = $vertex_2;
	push @verteces, $vertex_2;
    }
    $key = $v1 . '_' . $v2;
    $edge = $edges{$key};
    if (!$edge) {
	$edge = make_edge($vertex_1, $vertex_2, $key);
	$edges{$key} = $edge;
	push @edges, $edge;
    }
    $vertex_1 -> add_edge_reference($edge);
    $vertex_2 -> add_edge_reference($edge);
}

$verteces[0] -> print_vertex(2);

#--------------------------------------
# Subroutines and functions.
sub make_vertex ($) {
    my ( $label ) = @_;

    return Vertex->new('x' => int(rand(100)),
		       'y' => int(rand(100)),
		       'label' => $label);
} # make_vertex

sub make_edge ($$$) {
    my ( $vertex_1, $vertex_2, $label ) = @_;

    return Edge->new('vertex_1' => $vertex_1,
		     'vertex_2' => $vertex_2,
		     'label'    => $label
		     );
} # make_vertex