package AssocDB;

use Data::Dumper;
use Storable qw{freeze thaw store retrieve};

# Constructor
sub new
{
    my $self = {};
    $self->{'entityhash'} = {};
    $self->{'entityarray'} = ();
    $self->{'relationshiphash'} = {};
    $self->{'predicatearray'} = ();
    $self->{'entitypool'} = ();
    bless($self, 'AssocDB');
}

# Function to insert an entity into the database.
# {{{
sub insertEntity
{
    my $this = shift;
    my $entity = shift;
    if (@{$this->{'entitypool'}})
    {
        my $newIndex = pop(@{$this->{'entitypool'}});
        @{$this->{'entityarray'}}[$newIndex] = $entity;
        if (!exists($this->{'entityhash'}->{$entity}))
        {
            $this->{'entityhash'}->{$entity} = ();
        }
        push(@{$this->{'entityhash'}->{$entity}}, $newIndex + 1);
    }
    else
    {
        push(@{$this->{'entityarray'}}, $entity);
        my $length = @{$this->{'entityarray'}};
        if (!exists($this->{'entityhash'}->{$entity}))
        {
            $this->{'entityhash'}->{$entity} = ();
        }
        push(@{$this->{'entityhash'}->{$entity}}, $length);
    }
}
# }}}

# Function to insert a predicate into the database.
# {{{
sub insertPredicate
{
    my $this = shift;
    my $entity = shift;
    if (@{$this->{'entitypool'}})
    {
        my $newIndex = pop(@{$this->{'entitypool'}});
        @{$this->{'entityarray'}}[$newIndex] = $entity;
        if (!exists($this->{'entityhash'}->{$entity}))
        {
            $this->{'entityhash'}->{$entity} = ();
        }
        push(@{$this->{'entityhash'}->{$entity}}, $newIndex + 1);
        push(@{$this->{'predicatearray'}}, $newIndex + 1);
    }
    else
    {
        push(@{$this->{'entityarray'}}, $entity);
        my $length = @{$this->{'entityarray'}};
        if (!exists($this->{'entityhash'}->{$entity}))
        {
            $this->{'entityhash'}->{$entity} = ();
        }
        push(@{$this->{'entityhash'}->{$entity}}, $length);
        push(@{$this->{'predicatearray'}}, $length);
    }
}
# }}}

# Function to insert a relationship into the database.
# {{{
sub insertRelationship
{
    my $this = shift;
    my $subject = shift;
    my $predicate = shift;
    my $object = shift;
    my $key = qq{$subject:$predicate:$object};

    $this->{'relationshiphash'}->{$key} = 1;
}
# }}}

# Function to delete an entity from the database.
# {{{
sub deleteEntityById
{
    my $this = shift;
    my $entityId = shift;
    my @resultArray = grep { m{\d+:\d+:$entityId}xms }
                      keys %{$this->{'relationshiphash'}};
    return 0 if @resultArray;
    @resultArray = grep { m{$entityId}xms } @{$this->{'predicatearray'}};
    return 0 if @resultArray;
    my $entity = $this->{'entityarray'}->[$entityId - 1];
    $this->{'entityarray'}->[$entityId - 1] = '';
    push(@{$this->{'entitypool'}}, $entityId - 1);
    my @tempArray = @{$this->{'entityhash'}->{$entity}};
    for (my $index; $index < @tempArray; $index++)
    {
        if ($tempArray[$index] == $entityId)
        {
            splice(@{$this->{'entityhash'}->{$entity}}, $index, 1);
        }
    }
    foreach my $index (keys %{$this->{'relationshiphash'}})
    {
        delete($this->{'relationshiphash'}->{$index})
            if $index =~ m{$entityId:\d+:\d+}xms;
    }
    delete($this->{'entityhash'}->{$entity})
        if scalar @{$this->{'entityhash'}->{$entity}} == 0;
    return 1;
}
# }}}

# Function to delete an predicate from the database.
# {{{
sub deletePredicateById
{
    my $this = shift;
    my $entityId = shift;
    my @resultArray = grep { m{\d+:$entityId:\d+}xms }
                      keys %{$this->{'relationshiphash'}};
    return 0 if @resultArray;
    my $entity = $this->{'entityarray'}->[$entityId - 1];
    $this->{'entityarray'}->[$entityId - 1] = '';
    push(@{$this->{'entitypool'}}, $entityId - 1);
    my @tempArray = @{$this->{'entityhash'}->{$entity}};
    for (my $index; $index < @tempArray; $index++)
    {
        if ($tempArray[$index] == $entityId)
        {
            splice(@{$this->{'entityhash'}->{$entity}}, $index, 1);
        }
    }
    @tempArray = @{$this->{'predicatearray'}};
    for (my $index; $index < @tempArray; $index++)
    {
        if ($tempArray[$index] == $entityId)
        {
            splice(@{$this->{'predicatearray'}}, $index, 1);
        }
    }
    delete($this->{'entityhash'}->{$entity})
        if scalar @{$this->{'entityhash'}->{$entity}} == 0;
    return 1;
}
# }}}

# Function to delete an relationship from the database.
# {{{
sub deleteRelationship
{
    my $this = shift;
    my $subject = shift;
    my $predicate = shift;
    my $object = shift;
    my $key = qq{$subject:$predicate:$object};

    delete($this->{'relationshiphash'}->{$key});
}
# }}}

# Function to get an entity from the database using the name.
# {{{
sub getEntityByName
{
    my $this = shift;
    my $entity = shift;

    return @{$this->{'entityhash'}->{$entity}};
}
# }}}

# Function to get an entity from the database using the ID.
# {{{
sub getEntityById
{
    my $this = shift;
    my $entity = shift;

    return $this->{'entityarray'}->[$entity];
}
# }}}

# Function to get the predicates from the database.
# {{{
sub getPredicates
{
    my $this = shift;
    my @tempArray = @{$this->{'predicatearray'}};
    my @resultArray = map { $_ . ':' . $this->{'entityarray'}->[$_ - 1] }
                      @tempArray;
    return @resultArray;
}
# }}}

# Function to get all relationships an entity is the Subject of.
# {{{
sub getSubjectRel
{
    my $this = shift;
    my $entityId = shift;
    my @resultArray = grep { m{$entityId:\d+:\d+}xms }
                      keys %{$this->{'relationshiphash'}};
    return @resultArray;
}
# }}}

# Function to get all relationships an entity is the Object of.
# {{{
sub getObjectRel
{
    my $this = shift;
    my $entityId = shift;
    my @resultArray = grep { m{\d+:\d+:$entityId}xms }
                      keys %{$this->{'relationshiphash'}};
    return @resultArray;
}
# }}}

# Function to write the data to disk using Storable.
# {{{
sub storeData
{
    my $this = shift;
    my $filename = shift;;
    my %dataHash;
    $dataHash{'entityhash'} =
        freeze($this->{'entityhash'});
    $dataHash{'entityarray'} =
        freeze($this->{'entityarray'});
    $dataHash{'relationshiphash'} =
        freeze($this->{'relationshiphash'});
    $dataHash{'predicatearray'} =
        freeze($this->{'predicatearray'});
    $dataHash{'entitypool'} =
        freeze($this->{'entitypool'});
    store($this, $filename);
}
# }}}

# Function to load the data from a file.
# {{{
sub loadData
{
    my $this = shift;
    my $filename = shift;;
    my $temp = retrieve($filename);
    $this->{'entityhash'} = $temp->{'entityhash'};
    $this->{'relationshiphash'} =
        $temp->{'relationshiphash'};
    $this->{'entityarray'} = $temp->{'entityarray'};
    $this->{'predicatearray'} =
        $temp->{'predicatearray'};
    $this->{'entitypool'} = $temp->{'entitypool'};
}
# }}}

1;