package Rose::DB::Object::Metadata::ColumnList;
use strict;
use Rose::DB::Object::Metadata::Object;
our @ISA = qw(Rose::DB::Object::Metadata::Object);
our $VERSION = '0.02';
use overload
(
  '""' => sub 
  {
    my($self) = shift; 
    return join($", map { "$_" } @{$self->{'columns'} ||= $self->auto_init_columns});
  },
  fallback => 1,
);
sub columns
{
  my($self) = shift;
  my $meta = $self->parent;
  if(@_)
  {
    # Force stringification in case they're column objects
    # instead of just column names.
    if(@_ == 1 && ref $_[0] eq 'ARRAY')
    {
      $self->{'columns'} = [ map { "$_" } @{$_[0]} ];
    }
    else
    {
      $self->{'columns'} = [ map { "$_" } @_ ];
    }
  }
  return  unless(defined wantarray);
  unless($meta)
  {
    return wantarray ? @{$self->{'columns'} ||= []} :  ($self->{'columns'} ||= []);
  }
  unless(@{$self->{'columns'} ||= []})
  {
    $self->{'columns'} = $self->auto_init_columns;
  }
  # Expand into columns on return
  return wantarray ?  map { $meta->column($_) || $_ } @{$self->{'columns'} ||= []} : 
                    [ map { $meta->column($_) || $_ } @{$self->{'columns'} ||= []} ];
}
sub auto_init_columns { [] }
sub column_names
{
  my($self) = shift;
  if(@{$self->{'columns'} ||= []})
  {
    return wantarray ? @{$self->{'columns'}} : $self->{'columns'};
  }
  # This call with auto-init the columns if necessary
  my $columns = $self->columns; 
  return wantarray ? @$columns : $columns;
}
sub add_columns
{
  my($self) = shift;
  if(@_ == 1 && ref $_[0] eq 'ARRAY')
  {
    push @{$self->{'columns'}}, map { "$_" } @{$_[0]};
  }
  else
  {
    push @{$self->{'columns'}}, map { "$_" } @_;
  }
  return;
}
*add_column = \&add_columns;
sub delete_columns
{
  shift->{'columns'} = [];
  return;
}
1;