package SQL::Statement::Util;

use strict;
use warnings;

use vars qw($VERSION);
$VERSION = '1.33';

sub type
{
    my ($self) = @_;
    return 'function' if $self->isa('SQL::Statement::Util::Function');
    return 'column'   if $self->isa('SQL::Statement::Util::Column');
}

package SQL::Statement::Util::Column;

use vars qw(@ISA);
@ISA = qw(SQL::Statement::Util);

use Params::Util qw(_ARRAY _HASH0 _STRING);

sub new
{
    my ( $class, $col_name, $table_name, $term, $display_name, $full_orig_name, $coldef ) = @_;
    $display_name ||= $col_name;

    if ( $col_name && ( $col_name =~ m/^((?:"[^"]+")|(?:[^.]*))\.(.*)$/ ) )
    {
        $table_name = $1;
        $col_name   = $2;
    }
    elsif ( defined( _ARRAY($table_name) ) && ( scalar( @{$table_name} ) == 1 ) )
    {
        $table_name = $table_name->[0];
    }

    my %instance = (
                     name           => $col_name,
                     table          => $table_name,
                     display_name   => $display_name,
                     term           => $term,
                     full_orig_name => $full_orig_name,
                     coldef         => $coldef,
                   );

    my $self = bless( \%instance, $class );

    return $self;
}

sub value($)         { $_[0]->{term}->value( $_[1] ); }
sub term()           { $_[0]->{term} }
sub display_name()   { $_[0]->{display_name} }
sub full_orig_name() { $_[0]->{full_orig_name} }
sub name()           { $_[0]->{name} }
sub table()          { $_[0]->{table} }
sub coldef()         { $_[0]->{coldef} }

package SQL::Statement::Util::Function;

use vars qw(@ISA);
@ISA = qw(SQL::Statement::Util);

sub new
{
    my ( $class, $name, $sub_name, $args ) = @_;
    my ( $pkg, $sub ) = $sub_name =~ /^(.*::)([^:]+$)/;
    if ( !$sub )
    {
        $pkg = 'main';
        $sub = $sub_name;
    }
    $pkg = 'main' if $pkg eq '::';
    $pkg =~ s/::$//;
    my %newfunc = (
                    name     => $name,
                    sub_name => $sub,
                    pkg_name => $pkg,
                    args     => $args,
                    type     => 'function',
                  );
    return bless \%newfunc, $class;
}
sub name     { shift->{name} }
sub pkg_name { shift->{pkg_name} }
sub sub_name { shift->{sub_name} }
sub args     { shift->{args} }

sub validate
{
    my ($self) = @_;
    my $pkg    = $self->pkg_name;
    my $sub    = $self->sub_name;
    $pkg =~ s,::,/,g;
    eval { require "$pkg.pm" }
      unless $pkg eq 'SQL/Statement/Functions'
          or $pkg eq 'main';
    die $@ if $@;
    $pkg =~ s,/,::,g;
    die "Can't find subroutine $pkg" . "::$sub\n" unless $pkg->can($sub);
    return 1;
}

sub run
{
    use SQL::Statement::Functions;

    my ($self) = shift;
    my $sub    = $self->sub_name;
    my $pkg    = $self->pkg_name;
    return $pkg->$sub(@_);
}

1;

=pod

=head1 NAME

SQL::Statement::Util

=head1 SYNOPSIS

  SQL::Statement::Util::Column->new($col_name, $table_name, $term, $display_name)
  SQL::Statement::Util::AggregatedColumns($col_name, $table_name, $term, $display_name)
  SQL::Statement::Util::Function($name, $sub_name, $args)

=head1 DESCRIPTION

This package contains three utility classes to handle deliverable columns.

=head1 INHERITANCE

  SQL::Statement::Util::Column
  ISA SQL::Statement::Util

  SQL::Statement::Util::AggregatedColumns
  ISA SQL::Statement::Util::Column
    ISA SQL::Statement::Util

  SQL::Statement::Util::Function
  ISA SQL::Statement::Util

=begin undocumented

=head1 METHODS

=head2 type

Returns the type of the SQL::Statement::Util instance.

=end undocumented

=cut
