package Vertex;
use strict;

sub new {
    my ($class, %params) = @_;
    bless {
	'_x'        => $params{'x'} || 0,
	'_y'        => $params{'y'} || 0,
	'_label'    => $params{'label'} || '',
	'_edges'    => {}, # Neighbouring verteces connected through an edge.
	'_verteces' => {}, # Neighbouring verteces not connected through an edge.
	'_fx'       => 0,
	'_fy'       => 0,
	'_dx'       => 0,
	'_dy'       => 0,
    }, $class;
} # new

sub print_vertex {
    my ($class, $i) = @_;
    my $is;
    
    if (!defined($i)) {
	$is = '';
    }
    else {
	$is = sprintf('%' . $i . 's', '');
    }
    print $is, 'label=', $_[0]->{'_label'}, "\n";
    print $is, 'x='    , $_[0]->{'_x'},     "\n";
    print $is, 'y='    , $_[0]->{'_y'},     "\n";
    print $is, 'fx='   , $_[0]->{'_fx'},    "\n";
    print $is, 'fy='   , $_[0]->{'_fy'},    "\n";

    my @tmp = keys %{$_[0]->{'_edges'}};
    my $tmp;
    
    if ($#tmp >= 0) {
	print $is, 'Edges: (', 1+$#tmp, ") \n";
	for $tmp ( @tmp ) {
	    print "  ", $tmp->query_label(), "\n"; ### ERROR OCCURS HERE.
	}
    }
    else {
	print $is, "No edges.\n";
    }
    
    @tmp = keys %{$_[0]->{'_verteces'}};
    if ($#tmp >= 0) {
	print $is, 'Verteces:', "\n";
	for ( @tmp ) {
	    print $is, "  ", $_->query_label(), "\n";
	}
    }
    else {
	print $is, "No verteces.\n";
    }
} # print_vertex

# Only neighbours not connected through an edge should be added here.
sub add_neighbour_reference {
    my ($self, @params) = @_;
    my $key;
    for $key ( @params ) {
	$self->{_neighbours}[$key] = 1;
    }
} # add_neighbour

sub add_edge_reference {
    my ($self, @params) = @_;
    my $key;
    for $key ( @params ) {
	$self->{_edges}{$key} = 1;
    }
} # add_edge_references

sub query_x {
    $_[0]->{_x};
} # query_x

sub set_x {
    $_[0]->{_x} = $_[1] if defined($_[1]);
} # set_x

sub query_y {
    $_[0]->{_y};
} # query_y

sub set_y {
    $_[0]->{_y} = $_[1] if defined($_[1]);
} # set_y

sub query_label {
    $_[0]->{_label};
} # query_label

sub set_label {
    $_[0]->{_label} = $_[1] if defined($_[1]);
} # set_label

1;