Alzabo::Create::Schema - Schema objects for schema creation

  use Alzabo::Create::Schema;

package Alzabo::Create::Schema;

use strict;
use vars qw($VERSION);

use Alzabo::ChangeTracker;
use Alzabo::Config;
use Alzabo::Create;
use Alzabo::Driver;
use Alzabo::Exceptions
    ( abbr => [ qw( params_exception system_exception ) ] );
use Alzabo::RDBMSRules;
use Alzabo::Runtime;
use Alzabo::SQLMaker;
use Alzabo::Utils;

use File::Spec;

use Params::Validate qw( :all );
Params::Validate::validation_options
    ( on_fail => sub { params_exception join '', @_ } );

use Storable ();
use Tie::IxHash;

use base qw( Alzabo::Schema );

$VERSION = 2.0;

1;

sub new
{
    my $proto = shift;
    my $class = ref $proto || $proto;

    validate( @_, { rdbms    => { type => SCALAR },
                    name     => { type => SCALAR },
                    no_cache => { type => SCALAR, default => 0 },
                  } );
    my %p = @_;

    my $self = bless {}, $class;

    params_exception "Alzabo does not support the '$p{rdbms}' RDBMS"
        unless ( ( grep { $p{rdbms} eq $_ } Alzabo::Driver->available ) &&
                 ( grep { $p{rdbms} eq $_ } Alzabo::RDBMSRules->available ) );

    $self->{driver} = Alzabo::Driver->new( rdbms => $p{rdbms},
                                           schema => $self );
    $self->{rules} = Alzabo::RDBMSRules->new( rdbms => $p{rdbms} );

    $self->{sql} = Alzabo::SQLMaker->load( rdbms => $p{rdbms} );

    params_exception "Alzabo::Create::Schema->new requires a name parameter\n"
        unless exists $p{name};

    $self->set_name($p{name});

    $self->{tables} = Tie::IxHash->new;

    $self->_save_to_cache unless $p{no_cache};

    return $self;
}

sub load_from_file
{
    return shift->_load_from_file(@_);
}

sub reverse_engineer
{
    my $proto = shift;
    my $class = ref $proto || $proto;
    my %p = @_;

    my $self = $class->new( name     => $p{name},
                            rdbms    => $p{rdbms},
                            no_cache => 1,
                          );

    delete $p{rdbms};
    $self->{driver}->connect(%p);

    $self->{rules}->reverse_engineer($self);

    $self->set_instantiated(1);
    my $driver = delete $self->{driver};
    $self->{original} = Storable::dclone($self);
    $self->{driver} = $driver;
    delete $self->{original}{original};
    return $self;
}

sub set_name
{
    my $self = shift;

    validate_pos( @_, { type => SCALAR } );
    my $name = shift;

    return if defined $self->{name} && $name eq $self->{name};

    my $old_name = $self->{name};
    $self->{name} = $name;

    eval { $self->rules->validate_schema_name($self); };
    if ($@)
    {
        $self->{name} = $old_name;

        rethrow_exception($@);
    }

    # Gotta clean up old files or we have a mess!
    $self->delete( name => $old_name ) if $old_name;
    $self->set_instantiated(0);
    undef $self->{original};
}

sub set_instantiated
{
    my $self = shift;

    validate_pos( @_, 1 );
    $self->{instantiated} = shift;
}

sub make_table
{
    my $self = shift;
    my %p = @_;

    my %p2;
    foreach ( qw( before after ) )
    {
        $p2{$_} = delete $p{$_} if exists $p{$_};
    }
    $self->add_table( table => Alzabo::Create::Table->new( schema => $self,
                                                           %p ),
                      %p2 );

    return $self->table( $p{name} );
}

sub add_table
{
    my $self = shift;

    validate( @_, { table  => { isa => 'Alzabo::Create::Table' },
                    before => { optional => 1 },
                    after  => { optional => 1 } } );
    my %p = @_;

    my $table = $p{table};

    params_exception "Table " . $table->name . " already exists in schema"
        if $self->{tables}->EXISTS( $table->name );

    $self->{tables}->STORE( $table->name, $table );

    foreach ( qw( before after ) )
    {
        if ( exists $p{$_} )
        {
            $self->move_table( $_ => $p{$_},
                               table => $table );
            last;
        }
    }
}

sub delete_table
{
    my $self = shift;

    validate_pos( @_, { isa => 'Alzabo::Create::Table' } );
    my $table = shift;

    params_exception "Table " . $table->name ." doesn't exist in schema"
        unless $self->{tables}->EXISTS( $table->name );

    foreach my $fk ($table->all_foreign_keys)
    {
        foreach my $other_fk ( $fk->table_to->foreign_keys_by_table($table) )
        {
            $fk->table_to->delete_foreign_key($other_fk);
        }
    }

    $self->{tables}->DELETE( $table->name );
}

sub move_table
{
    my $self = shift;

    validate( @_, { table  => { isa => 'Alzabo::Create::Table' },
                    before => { isa => 'Alzabo::Create::Table',
                                optional => 1 },
                    after  => { isa => 'Alzabo::Create::Table',
                                optional => 1 } } );
    my %p = @_;

    if ( exists $p{before} && exists $p{after} )
    {
        params_exception
            "move_table method cannot be called with both 'before' and 'after' parameters";
    }

    if ( $p{before} )
    {
        params_exception "Table " . $p{before}->name . " doesn't exist in schema"
            unless $self->{tables}->EXISTS( $p{before}->name );
    }
    else
    {
        params_exception "Table " . $p{after}->name . " doesn't exist in schema"
            unless $self->{tables}->EXISTS( $p{after}->name );
    }

    params_exception "Table " . $p{table}->name . " doesn't exist in schema"
        unless $self->{tables}->EXISTS( $p{table}->name );

    $self->{tables}->DELETE( $p{table}->name );

    my $index;
    if ( $p{before} )
    {
        $index = $self->{tables}->Indices( $p{before}->name );
    }
    else
    {
        $index = $self->{tables}->Indices( $p{after}->name ) + 1;
    }

    $self->{tables}->Splice( $index, 0, $p{table}->name => $p{table} );
}

sub register_table_name_change
{
    my $self = shift;

    validate( @_, { table => { isa => 'Alzabo::Create::Table' },
                    old_name => { type => SCALAR } } );
    my %p = @_;

    params_exception "Table $p{old_name} doesn't exist in schema"
        unless $self->{tables}->EXISTS( $p{old_name} );

    my $index = $self->{tables}->Indices( $p{old_name} );
    $self->{tables}->Replace( $index, $p{table}, $p{table}->name );
}

sub add_relationship
{
    my $self = shift;

    my %p = @_;

    my $tracker = Alzabo::ChangeTracker->new;

    $self->_check_add_relationship_args(%p);

    # This requires an entirely new table.
    unless ( grep { $_ ne 'n' } @{ $p{cardinality} } )
    {
        $self->_create_linking_table(%p);
        return;
    }

    params_exception "Must provide 'table_from' or 'columns_from' parameter"
        unless $p{table_from} || $p{columns_from};

    params_exception "Must provide 'table_to' or 'columns_to' parameter"
        unless $p{table_to} || $p{columns_to};

    $p{columns_from} =
        ( defined $p{columns_from} ?
          ( Alzabo::Utils::is_arrayref( $p{columns_from} ) ?
            $p{columns_from} :
            [ $p{columns_from} ] ) :
          undef );

    $p{columns_to} =
        ( defined $p{columns_to} ?
          ( Alzabo::Utils::is_arrayref( $p{columns_to} ) ?
            $p{columns_to} :
            [ $p{columns_to} ] ) :
          undef );

    my $f_table = $p{table_from} || $p{columns_from}->[0]->table;
    my $t_table = $p{table_to} || $p{columns_to}->[0]->table;

    if ( $p{columns_from} && $p{columns_to} )
    {
        params_exception
            "Cannot create a relationship with differing numbers of columns " .
            "on either side of the relation"
                unless @{ $p{columns_from} } == @{ $p{columns_to} };
    }

    foreach ( [ columns_from => $f_table ], [ columns_to => $t_table ] )
    {
        my ($key, $table) = @$_;
        if ( defined $p{$key} )
        {
            params_exception
                "All the columns in a given side of the relationship ".
                "must be from the same table"
                    if grep { $_->table ne $table } @{ $p{$key} };
        }
    }

    # Determined later.  This is the column that the relationship is
    # to.  As in table A/column B maps _to_ table X/column Y
    my ($col_from, $col_to);

    # cardinality from -> to
    my $cardinality =
        ( $p{cardinality}->[0] eq '1' && $p{cardinality}->[1] eq '1' ?
          '1_to_1' :
          $p{cardinality}->[0] eq '1' && $p{cardinality}->[1] eq 'n' ?
          '1_to_n' :
          'n_to_1'
        );
    my $method = "_create_${cardinality}_relationship";

    ($col_from, $col_to) = $self->$method( %p,
                                           table_from => $f_table,
                                           table_to   => $t_table,
                                         );

    eval
    {
        $f_table->make_foreign_key( columns_from => $col_from,
                                    columns_to   => $col_to,
                                    cardinality  => $p{cardinality},
                                    from_is_dependent => $p{from_is_dependent},
                                    to_is_dependent   => $p{to_is_dependent},
                                    comment => $p{comment},
                                  );
    };
    if ($@)
    {
        $tracker->backout;

        rethrow_exception($@);
    }

    my @fk;
    eval
    {
        foreach my $c ( @$col_from )
        {
            push @fk, $f_table->foreign_keys( table => $t_table,
                                              column => $c );
        }
    };
    if ($@)
    {
        $tracker->backout;

        rethrow_exception($@);
    }

    $tracker->add( sub { $f_table->delete_foreign_key($_) foreach @fk } );

    # cardinality to -> to
    my $inverse_cardinality =
        ( $p{cardinality}->[1] eq '1' && $p{cardinality}->[0] eq '1' ?
          '1_to_1' :
          $p{cardinality}->[1] eq '1' && $p{cardinality}->[0] eq 'n' ?
          '1_to_n' :
          'n_to_1'
        );
    my $inverse_method = "_create_${inverse_cardinality}_relationship";

    ($col_from, $col_to) = $self->$method( table_from => $t_table,
                                           table_to   => $f_table,
                                           columns_from => $col_to,
                                           columns_to   => $col_from,
                                           cardinality  => [ @{ $p{cardinality} }[1,0] ],
                                           from_is_dependent => $p{to_is_dependent},
                                           to_is_dependent   => $p{from_is_dependent},
                                         );

    if ($p{from_is_dependent})
    {
        $_->nullable(0) foreach @{ $p{columns_from} };
    }

    if ($p{to_is_dependent})
    {
        $_->nullable(0) foreach @{ $p{columns_to} };
    }

    eval
    {
        $t_table->make_foreign_key( columns_from => $col_from,
                                    columns_to   => $col_to,
                                    cardinality  => [ @{ $p{cardinality} }[1,0] ],
                                    from_is_dependent => $p{to_is_dependent},
                                    to_is_dependent   => $p{from_is_dependent},
                                    comment => $p{comment},
                                  );
    };
    if ($@)
    {
        $tracker->backout;

        rethrow_exception($@);
    }
}
# old name - deprecated
*add_relation = \&add_relationship;

sub _check_add_relationship_args
{
    my $self = shift;
    my %p = @_;

    foreach my $t ( $p{table_from}, $p{table_to} )
    {
        next unless defined $t;
        params_exception "Table " . $t->name . " doesn't exist in schema"
            unless $self->{tables}->EXISTS( $t->name );
    }

    params_exception "Incorrect number of cardinality elements"
        unless scalar @{ $p{cardinality} } == 2;

    foreach my $c ( @{ $p{cardinality} } )
    {
        params_exception "Invalid cardinality: $c"
            unless $c =~ /^[01n]$/i;
    }

    # No such thing as 1..0 or n..0
    params_exception "Invalid cardinality: $p{cardinality}->[0]..$p{cardinality}->[1]"
        if  $p{cardinality}->[1] eq '0';
}

sub _create_1_to_1_relationship
{
    my $self = shift;
    my %p = @_;

    return @p{ 'columns_from', 'columns_to' }
        if $p{columns_from} && $p{columns_to};

    # Add these columns to the table which _must_ participate in the
    # relationship, if there is one.  This reduces NULL values.
    # Otherwise, just add to the first table specified in the
    # relation.
    my @order;

    # If the from table is dependent or neither one is or both are ...
    if ( $p{from_is_dependent} ||
         $p{from_is_dependent} == $p{to_is_dependent} )
    {
        @order = ( 'from', 'to' );
    }
    # The to table is dependent
    else
    {
        @order = ( 'to', 'from' );
    }

    # Determine which table we are linking from.  This gets a new
    # column or has its column adjusted) ...
    my $f_table = $p{"table_$order[0]"};

    # And which table we are linking to.  We use the primary key from
    # this table if no column has been provided.
    my $t_table = $p{"table_$order[1]"};

    # Determine whether there is a column in 'to' table we can use.
    my $col_to;
    if ( $p{"columns_$order[1]"} )
    {
        $col_to = $p{"columns_$order[1]"};
    }
    else
    {
        my @c = $t_table->primary_key;

        params_exception $t_table->name . " has no primary key."
            unless @c;

        $col_to = \@c;
    }

    my ($col_from);
    if ($p{"columns_$order[0]"})
    {
        $col_from = $p{"columns_$order[0]"};
    }
    else
    {
        my @new_col;
        foreach my $c ( @$col_to )
        {
            push @new_col, $self->_add_foreign_key_column( table  => $f_table,
                                                           column => $c );
        }

        $col_from = \@new_col;
    }

    return ($col_from, $col_to);
}

# This one's simple.  We always add/adjust the column in the table on
# the 'to' side of the relationship.  This table only relates to one
# row in the 'from' table, but a row in the 'from' table can relate to
# 'n' rows in the 'to' table.
sub _create_1_to_n_relationship
{
    my $self = shift;
    my %p = @_;

    my $f_table = $p{table_from};
    my $t_table = $p{table_to};

    my $col_from;
    if ( $p{columns_from} )
    {
        $col_from = $p{columns_from};
    }
    else
    {
        my @c = $f_table->primary_key;

        # Is there a way to handle this properly?
        params_exception $f_table->name . " has no primary key."
            unless @c;

        $col_from = \@c;
    }

    my $col_to;
    if ($p{columns_to})
    {
        $col_to = $p{columns_to};
    }
    else
    {
        # If the columns this links to in the 'to' table ares not specified
        # explicitly we assume that the user wants to have this coumn
        # created/adjusted in the 'to' table.
        my @new_col;
        foreach my $c ( @$col_from )
        {
            push @new_col, $self->_add_foreign_key_column( table  => $t_table,
                                                           column => $c );
        }

        $col_to = \@new_col;
    }

    return ($col_from, $col_to);
}

sub _create_n_to_1_relationship
{
    my $self = shift;
    my %p = @_;

    # reverse everything ...
    ($p{table_from}, $p{table_to}) = ($p{table_to}, $p{table_from});
    ($p{columns_from}, $p{columns_to}) = ($p{columns_to}, $p{columns_from});
    ($p{from_is_dependent}, $p{to_is_dependent}) =
        ($p{to_is_dependent}, $p{from_is_dependent});

    # pass it into the inverse method and then swap the return values.
    # Tada!
    return ( $self->_create_1_to_n_relationship(%p) )[1,0];
}

# Given two tables and a column, it will add the column to the table
# if it doesn't exist.  Otherwise, it adjusts the column in the table
# to match the given column.  In either case, the two columns (the one
# passed to the method and the one altered/created) will share a
# ColumnDefinition object.

# This is called when a relationship is created and the columns aren't
# specified.  This means that changes to the column in one table are
# automatically reflected in the other table, which is generally a
# good thing.
sub _add_foreign_key_column
{
    my $self = shift;

    validate( @_, { table => { isa => 'Alzabo::Create::Table' },
                    column => { isa => 'Alzabo::Create::Column' } } );
    my %p = @_;

    my $tracker = Alzabo::ChangeTracker->new;

    # Note: This code _does_ explicitly want to compare the string
    # representation of the $p{column}->definition reference.
    my $new_col;
    if ( eval { $p{table}->column( $p{column}->name ) } &&
         ( $p{column}->definition ne $p{table}->column( $p{column}->name )->definition ) )
    {
        # This will make the two column share a single definition
        # object.
        my $old_def = $p{table}->column( $p{column}->name )->definition;
        $p{table}->column( $p{column}->name )->set_definition($p{column}->definition);

        $tracker->add
            ( sub { $p{table}->column
                        ( $p{column}->name )->set_definition($old_def) } );
    }
    else
    {
        # Just add the new column, but use the existing definition
        # object.
        $p{table}->make_column( name => $p{column}->name,
                                definition => $p{column}->definition );

        my $del_col = $p{table}->column( $p{column}->name );
        $tracker->add( sub { $p{table}->delete_column($del_col) } );
    }

    # Return the new column we just made.
    return $p{table}->column( $p{column}->name );
}

sub _create_linking_table
{
    my $self = shift;
    my %p = @_;

    my $tracker = Alzabo::ChangeTracker->new;

    my $t1 = $p{table_from} || $p{columns_from}->[0]->table;
    my $t2 = $p{table_to} || $p{columns_to}->[0]->table;

    my $t1_col;
    if ($p{columns_from})
    {
        $t1_col = $p{columns_from};
    }
    else
    {
        my @c = $t1->primary_key;

        params_exception $t1->name . " has no primary key."
            unless @c;

        $t1_col = \@c;
    }

    my $t2_col;
    if ($p{columns_to})
    {
        $t2_col = $p{columns_to};
    }
    else
    {
        my @c = $t2->primary_key;

        params_exception $t2->name . " has no primary key."
            unless @c;

        $t2_col = \@c;
    }

    # First we create the table.
    my $linking;
    my $name;

    if ( exists $p{name} )
    {
        $name = $p{name};
    }
    elsif ( lc $t1->name eq $t1->name )
    {
        $name = join '_', $t1->name, $t2->name;
    }
    else
    {
        $name = join '', $t1->name, $t2->name;
    }

    $linking = $self->make_table( name => $name );
    $tracker->add( sub { $self->delete_table($linking) } );

    eval
    {
        foreach my $c ( @$t1_col, @$t2_col )
        {
            $linking->make_column( name => $c->name,
                                   definition => $c->definition,
                                   primary_key => 1,
                                 );
        }

        $self->add_relationship
            ( table_from => $t1,
              table_to   => $linking,
              columns_from => $t1_col,
              columns_to   => [ $linking->columns( map { $_->name } @$t1_col ) ],
              cardinality  => [ '1', 'n' ],
              from_is_dependent => $p{from_is_dependent},
              to_is_dependent => 1,
              comment => $p{comment},
            );

        $self->add_relationship
            ( table_from => $t2,
              table_to   => $linking,
              columns_from => $t2_col,
              columns_to   => [ $linking->columns( map { $_->name } @$t2_col ) ],
              cardinality  => [ '1', 'n' ],
              from_is_dependent => $p{to_is_dependent},
              to_is_dependent => 1,
              comment => $p{comment},
            );
    };

    if ($@)
    {
        $tracker->backout;

        rethrow_exception($@);
    }
}

sub instantiated
{
    my $self = shift;

    return $self->{instantiated};
}

sub create
{
    my $self = shift;
    my %p = @_;

    my @sql = $self->make_sql;

    local $self->{db_schema_name} = delete $p{schema_name}
        if exists $p{schema_name};

    $self->{driver}->create_database(%p)
        unless $self->_has_been_instantiated(%p);

    $self->{driver}->connect(%p);

    foreach my $statement (@sql)
    {
        $self->{driver}->do( sql => $statement );
    }

    $self->save_current_name;

    $self->set_instantiated(1);
    my $driver = delete $self->{driver};
    $self->{original} = Storable::dclone($self);
    $self->{driver} = $driver;
    delete $self->{original}{original};
}

sub _has_been_instantiated
{
    my $self = shift;

    my $db_schema_name = $self->db_schema_name;

    return 1 if grep { $db_schema_name eq $_ } $self->{driver}->schemas(@_);
}

sub make_sql
{
    my $self = shift;

    if ($self->{instantiated})
    {
        return $self->rules->schema_sql_diff( old => $self->{original},
                                              new => $self );
    }
    else
    {
        return $self->rules->schema_sql($self);
    }
}

sub sync_backend_sql
{
    my $self = shift;
    my %p = @_;

    local $self->{db_schema_name} = delete $p{schema_name}
        if exists $p{schema_name};

    unless ( $self->_has_been_instantiated(%p) )
    {
        return $self->rules->schema_sql($self);
    }

    my $existing = $self->reverse_engineer( %p,
                                            name => $self->db_schema_name,
                                            rdbms => $self->driver->driver_id,
                                          );

    return $self->rules->schema_sql_diff( old => $existing,
                                          new => $self );
}

sub sync_backend
{
    my $self = shift;
    my %p = @_;

    local $self->{db_schema_name} = delete $p{schema_name}
        if exists $p{schema_name};

    unless ( $self->_has_been_instantiated(%p) )
    {
        $self->set_instantiated(0);
        return $self->create(%p);
    }

    $self->{driver}->connect(%p);

    foreach my $statement ( $self->sync_backend_sql(%p) )
    {
        $self->driver->do( sql => $statement );
    }

    $self->save_current_name;

    $self->set_instantiated(1);
    my $driver = delete $self->{driver};
    $self->{original} = Storable::dclone($self);
    $self->{driver} = $driver;
    delete $self->{original}{original};
}

sub drop
{
    my $self = shift;
    my %p = @_;

    local $self->{db_schema_name} = delete $p{schema_name}
        if exists $p{schema_name};

    $self->{driver}->drop_database(%p);
    $self->set_instantiated(0);
}

sub delete
{
    my $self = shift;
    my %p = @_;

    my $name = $p{name} || $self->name;

    my $schema_dir = File::Spec->catdir( Alzabo::Config::schema_dir(), $name );

    my $dh = do { local *DH; };
    opendir $dh, $schema_dir
        or system_exception "Unable to open $schema_dir directory: $!";

    foreach my $f ( grep { /\.alz|\.rdbms|\.version/ } readdir $dh )
    {
        my $file = File::Spec->catfile( $schema_dir, $f );
        next unless -f $file;

        # untaint
        ($file) = $file =~ /^(.+)$/;

        unlink $file
            or system_exception "Unable to delete $file: $!";
    }
    closedir $dh
        or system_exception "Unable to close $schema_dir: $!";

    rmdir $schema_dir
        or system_exception "Unable to delete $schema_dir: $!";
}

sub is_saved
{
    my $self = shift;

    my %p = @_;

    my $name = $p{name} || $self->name;

    my $schema_dir = File::Spec->catdir( Alzabo::Config::schema_dir(), $name );

    return -d $schema_dir;
}

sub save_to_file
{
    my $self = shift;

    my $schema_dir = File::Spec->catdir( Alzabo::Config::schema_dir(), $self->{name} );
    unless (-e $schema_dir)
    {
        mkdir $schema_dir, 0775
            or system_exception "Unable to make directory $schema_dir: $!";
    }

    my $create_save_name = $self->_base_filename( $self->{name} ) . '.create.alz';

    my $fh = do { local *FH; };
    open $fh, ">$create_save_name"
        or system_exception "Unable to write to $create_save_name: $!\n";

    my $driver = delete $self->{driver};
    Storable::nstore_fd( $self, $fh )
        or system_exception "Can't store to filehandle";

    $self->{driver} = $driver;
    close $fh
        or system_exception "Unable to close $create_save_name: $!";

    my $rdbms_save_name = $self->_base_filename( $self->{name} ) . '.rdbms';

    open $fh, ">$rdbms_save_name"
        or system_exception "Unable to write to $rdbms_save_name: $!\n";

    print $fh $self->{driver}->driver_id
        or system_exception "Can't write to $rdbms_save_name: $!";
    close $fh
        or system_exception "Unable to close $rdbms_save_name: $!";

    my $version_save_name = $self->_base_filename( $self->{name} ) . '.version';

    open $fh, ">$version_save_name"
        or system_exception "Unable to write to $version_save_name: $!\n";
    print $fh $Alzabo::VERSION
        or system_exception "Can't write to $version_save_name: $!";
    close $fh
        or system_exception "Unable to close $version_save_name: $!";

    my $rt = $self->runtime_clone;

    my $runtime_save_name = $self->_base_filename( $self->{name} ) . '.runtime.alz';

    open $fh, ">$runtime_save_name"
        or system_exception "Unable to write to $runtime_save_name: $!\n";
    Storable::nstore_fd( $rt, $fh )
        or system_exception "Can't store to filehandle";
    close $fh
        or system_exception "Unable to close $runtime_save_name: $!";

    $self->_save_to_cache;
}

sub clone
{
    my $self = shift;

    validate( @_, { name  => { type => SCALAR } } );
    my %p = @_;

    my $driver = delete $self->{driver};
    my $clone = Storable::dclone($self);
    $self->{driver} = $driver;

    $clone->{name} = $p{name};
    $clone->{driver} = Alzabo::Driver->new( rdbms => $self->{driver}->driver_id,
                                            schema => $clone );

    $clone->rules->validate_schema_name($clone);
    $clone->{original}{name} = $p{name} if $p{name};

    $clone->set_instantiated(0);

    return $clone;
}

sub runtime_clone
{
    my $self = shift;

    my %s;
    my $driver = delete $self->{driver};
    my $clone = Storable::dclone($self);
    $self->{driver} = $driver;

    foreach my $f ( qw( original instantiated rules driver ) )
    {
        delete $clone->{$f};
    }

    foreach my $t ($clone->tables)
    {
        foreach my $c ($t->columns)
        {
            my $def = $c->definition;
            bless $def, 'Alzabo::Runtime::ColumnDefinition';
            bless $c, 'Alzabo::Runtime::Column';

            delete $c->{last_instantiation_name};
        }

        foreach my $fk ($t->all_foreign_keys)
        {
            bless $fk, 'Alzabo::Runtime::ForeignKey';
        }

        foreach my $i ($t->indexes)
        {
            bless $i, 'Alzabo::Runtime::Index';
        }

        delete $t->{last_instantiation_name};

        bless $t, 'Alzabo::Runtime::Table';
    }
    bless $clone, 'Alzabo::Runtime::Schema';

    return $clone;
}

sub save_current_name
{
    my $self = shift;

    $self->{last_instantiated_name} = $self->name;

    foreach my $table ( $self->tables )
    {
        $table->save_current_name;
    }
}

sub former_name { $_[0]->{last_instantiated_name} }

# Overrides method in base to load create schema instead of runtime
# schema
sub _schema_file_type
{
    return 'create';
}

__END__