package Tie::Scalar::StorageKeyList;

use strict;
use warnings;
use Carp;
use File::Spec;
use Storable;
use base 'Tie::Scalar';

my %objects;

########################################################################

sub TIESCALAR
{
  my $class=shift;
  pop(@_) if(@_%2);
  my %conf=@_;

  my $file =$conf{file}  // croak qq(No file, use "file" in options!);
  my $key  =$conf{key}   // croak qq(No key, use "key" in options!);
  my $value=$conf{value};
  my $pos=defined($conf{position})?int(abs($conf{position})):undef;

  $file=File::Spec->rel2abs($file);
  $objects{$file}{keys}=__load($file) unless(exists($objects{$file}));
  $objects{$file}{counter}++;

  if(defined($pos))
  {
    if($pos >= $objects{$file}{keycount}{$key})
    { $objects{$file}{keycount}{$key}=$pos+1; }
  }
  else
  {
    $objects{$file}{keycount}{$key}++;
    $pos=$objects{$file}{keycount}{$key}-1;
  }

  my $ref=\$objects{$file}{keys}{$key}[$pos];
  $$ref=$value unless(defined($$ref));

  my $self={file=>$file, key=>$key, val=>$ref };
  return bless($self,$class);
}

sub FETCH
{
  my $self=shift;
  return ${$self->{val}};
}

sub STORE
{
  my $self=shift;
  my $val=shift;
  ${$self->{val}}=$val;
}

sub DESTROY
{
  my $self=shift;
  my $file=$self->{file};

  $objects{$file}{counter}--;

  __save($file,$objects{$file}{keys}) if($objects{$file}{counter}==0);
}

sub delete
{
  my $self=shift;


  my $p;
  my $arr=$objects{$self->{file}}{keys}{$self->{key}};
  for(0..$#$arr)
  {
    my $ref=\$arr->[$_];
    if($ref eq $self->{var})
    {
      $p=$_;
      last;
    }
  }

  if(defined($p))
  {
    $objects{$self->{file}}{keycount}{$self->{key}}--;
    return splice(@$arr,$p,1);
  }

  return undef;
}

########################################################################
########################################################################
sub __load
{
  my $file=shift;
  return retrieve($file) if(-f $file);
  return {};
}

sub __save
{
  my $file=shift;
  my $data=shift;
  return 0 unless $data;
  store($data, $file);
}

1;