package Tangram::Schema;

use Tangram::Schema::ClassHash;
use Tangram::Schema::Class;

use strict;
#our @ISA = qw( SelfLoader );
use Carp;

use vars qw( %TYPES );

%TYPES = 
(
   %TYPES,
#   ref      => new Tangram::Type::Ref::FromMany,
);

use Scalar::Util qw(reftype weaken);

sub new
{
    my $pkg = shift;

    my $self = ref $_[0] ? shift() : { @_ };

    bless $self, $pkg;

    $self->{make_object} ||= sub { shift()->new() };

    $self->{normalize} ||= sub
	{ my $class = shift;
	  $class =~ s{::}{_}g;
	  $class;
      };
    $self->{class_table} ||= 'OpalClass';

    $self->{control} ||= 'Tangram';

    $self->{sql}{default_null} = 'NULL' unless exists $self->{sql}{default_null};
    $self->{sql}{id_col} ||= 'id';
    $self->{sql}{id} ||= 'INTEGER';
    # commented out because of layout1 compatibility $self->{sql}{class_col} ||= 'type';
    $self->{sql}{cid} ||= 'INTEGER';
    $self->{sql}{oid} ||= 'INTEGER';
    $self->{sql}{cid_size} ||= 4;

    $self->{sql}{dumper} ||= "Storable";
    $self->{sql}{dumper_type} ||= "BLOB";

    my $types = $self->{types} ||= {};

    %$types = ( %TYPES, %$types );

    my @class_list = reftype($self->{'classes'}) eq 'HASH' ? %{ $self->{'classes'} } : @{ $self->{'classes'} };
    my $class_hash = $self->{'classes'} = {};

    bless $class_hash, 'Tangram::Schema::ClassHash';

    my $autoid = 0;

    while (my ($class, $def) = splice @class_list, 0, 2)
    {
		my $classdef = $class_hash->{$class} ||= {};
		%$classdef = (%$def, %$classdef);

		if (exists $classdef->{id}) {
		  $autoid = $classdef->{id};
		} else {
		  $classdef->{id} = ++$autoid;
		}

		bless $classdef, 'Tangram::Schema::Class';

		$classdef->{name} = $class;
		$classdef->{table} ||= $self->{normalize}->($class, 'tablename');

		$classdef->{fields} ||= $classdef->{members};

		if ( $classdef->{members} and
		     $classdef->{fields} != $classdef->{members} ) {
		    # some other class' definition put something
		    # in our "members" hash.
		    while (
			   my ($type, $fields)
			   = each %{$classdef->{members}}
			  )
		    {
			# so, we have to merge them.  we could use
			#  %{ $classdef->{fields} } =
			#    (%{$classdef->{fields}},
			#     %{$classdef->{members}});
			# but I'm not 100% sure that we will never
			# have common types in the "fields" and
			# "members" hash.
			($classdef->{fields}{$type}{$_}
			 = delete $fields->{$_})
			    foreach (keys %$fields);
		    }
		}
		$classdef->{members} = $classdef->{fields};

		my $cols = 0;

		foreach my $typetag (keys %{$classdef->{members}})
		{
			my $memdefs = $classdef->{members}{$typetag};

			# Aha, so *here* is where the array is reschema'd.
			$memdefs = $classdef->{members}{$typetag}
			    = { map { $_, $_ } @$memdefs }
				if (ref $memdefs eq 'ARRAY');

			my $type = $self->{types}{$typetag};

			croak("Unknown field type '$typetag', ",
			      "did you forget some 'use Tangram::SomeType' ",
			      "in your program?\n")
			    unless defined $types->{$typetag};

			my @members = $types->{$typetag}->reschema
			    ($memdefs, $class, $self)
				if $memdefs;

			for my $field (keys %$memdefs) {
			    $memdefs->{$field}{name} = $field;
			    my $fielddef = bless $memdefs->{$field}, ref $type;
			    my @cols = $fielddef->get_export_cols( {} );
			    $cols += @cols;
			}

			@{$classdef->{member_type}}{@members}
			    = ($type) x @members;
			@{$classdef->{MEMDEFS}}{keys %$memdefs}
			    = values %$memdefs;
		}

		$classdef->{stateless} = !$cols
			&& (!exists $classdef->{stateless} || $classdef->{stateless});

		foreach my $base (@{$classdef->{bases}})
		{
			push @{$class_hash->{$base}{specs}}, $class;
		}
    }

    while (my ($class, $classdef) = each %$class_hash)
    {
		my $root = $class;

		confess "no bases for $root" unless ref $class_hash->{$root}{bases} eq "ARRAY";
		while (@{$class_hash->{$root}{bases}})
		{
			$root = @{$class_hash->{$root}{bases}}[0];
		}

		$classdef->{root} = $class_hash->{$root};
		delete $classdef->{stateless} if $root eq $class;

		$classdef->{BASES} = [ map { $class_hash->{$_} } @{ $classdef->{bases} } ];
		$classdef->{SPECS} = [ map { $class_hash->{$_} } @{ $classdef->{specs} } ];
		
		if (0) { # currently causes 'panic: magic_killbackrefs, <CONFIG> line 1 during global destruction.'
		  for my $ref (@{ $classdef->{SPECS} }) {
			weaken($ref);
		  }
		}
    }

    return $self;
}

sub all_classes
  {
	return values %{ shift->{classes} };
  }

sub check_class
{
   my ($self, $class) = @_;
   confess "unknown class '$class'" unless exists $self->{classes}{$class};
}

sub classdef
{
   my ($self, $class) = @_;
   return $self->{classes}{$class} or confess "unknown class '$class'";
}

*get_class_by_name = \&classdef;

sub classes
{
   my ($self) = @_;
   return keys %{$self->{'classes'}};
}

sub direct_members
{
   my ($self, $class) = @_;
   return $self->{'classes'}{$class}{member_type};
}

sub all_members
{
   my ($self, $class) = @_;
   my $classes = $self->{'classes'};
	my $members = {};
   
	$self->visit_up($class, sub
	{
		my $direct_members = $classes->{shift()}{member_type};
		@$members{keys %$direct_members} = values %$direct_members;
	} );

	$members;
}

sub all_bases
{
   my ($self, $class) = @_;
   my $classes = $self->{'classes'};
	$self->visit_down($class, sub { @{ $classes->{shift()}{bases} } } );
}

sub find_member
{
   my ($self, $class, $member) = @_;
   my $classes = $self->{'classes'};
   my $result;
   local $@;

   eval
   {
      $self->visit_down($class, sub {
         die if $result = $classes->{shift()}{member_type}{$member}
         })
   };

   $result;
}

sub find_member_class
{
   my ($self, $class, $member) = @_;
   my $classes = $self->{'classes'};
   my $result;
   local $@;

   eval
   {
      $self->visit_down($class,
         sub
         {
            my $class = shift;

            if (exists $classes->{$class}{member_type}{$member})
            {
               $result = $class;
               die;
            }
         })
   };

   $result;
}

sub visit_up
{
   my ($self, $class, $fun) = @_;
   _visit_up($self, $class, $fun, { });
}

sub _visit_up
{
   my ($self, $class, $fun, $done) = @_;
   
   return if $done->{$class};

   my @results = ();

   foreach my $base (@{$self->{'classes'}{$class}{bases}})
   {
      push @results, _visit_up($self, $base, $fun, $done);
   }

   $done->{$class} = 1;

   return @results, &$fun($class);
}

sub visit_down
{
   my ($self, $class, $fun) = @_;
   _visit_down($self, $class, $fun, { });
}

sub _visit_down
{
   my ($self, $class, $fun, $done) = @_;
   
   return if $done->{$class};

   my @results = &$fun($class);

   foreach my $base (@{$self->{'classes'}{$class}{bases}})
   {
      push @results, _visit_down($self, $base, $fun, $done);
   }

   $done->{$class} = 1;

   @results
}

sub for_bases
{
   my ($self, $class, $fun) = @_;
   my %done;
   my $classes = $self->{classes};

   my $traverse;

   $traverse = sub {
	 my $class = shift;
	 return if $done{$class}++;
	 my $def = $classes->{$class};

	 foreach my $base (@{ $def->{bases} }) {
	   $traverse->($base);
	 }

	 $fun->($def);
   };

   foreach my $base (@{ $classes->{$class}{bases} }) {
	 $traverse->($base);
   }
 }

sub for_each_spec
{
   my ($self, $class, $fun) = @_;
   my $done = {};

   foreach my $spec (@{$self->{'classes'}{$class}{specs}})
   {
      _for_each_spec($self, $spec, $fun, $done);
   }
}

sub _for_each_spec
{
   my ($self, $class, $fun, $done) = @_;
   
   return if $done->{$class};

   &$fun($class);
   $done->{$class} = 1;

   foreach my $spec (@{$self->{'classes'}{$class}{specs}})
   {
      _for_each_spec($self, $spec, $fun, $done);
   }

}

sub declare_classes
{
   my ($self, $root) = @_;
   
   foreach my $class ($self->classes)
   {
		my $decl = "package $class;";

      my $bases = @{$self->{classes}{$class}{bases}}
         ? (join ' ', @{$self->{'classes'}{$class}{bases}})
         : $root;

		$decl .= "\@$class\:\:ISA = qw( $bases );" if $bases;

      eval $decl;
   }
}

sub is_persistent
{
   my ($self, $x) = @_;
   my $class = ref($x) || $x;
   return $self->{classes}{$class} && $self->{classes}{$class};
}

#use SelfLoader;
#sub DESTROY { }

1;