use strictures 1;
use Data::Query::ExprBuilder::Identifier;
use Data::Query::ExprHelpers;
use Data::Query::Constants;

sub expr (&) {
  _run_expr($_[0])->{expr};
}

sub _run_expr {
  local $_ = Data::Query::ExprBuilder::Identifier->new({
    expr => Identifier(),
  });
  $_[0]->();
}

sub AS {
  my $as = shift;
  (bless(\$as, 'LIES::AS'), @_);
}

sub SELECT (&;@) {
  my @select = map +(
    ref()
      ? $_
      : { expr => perl_scalar_value($_) }
  ), _run_expr(shift);
  my @final;
  while (@select) {
    my $e = shift @select;
    push @final,
      (ref($select[0]) eq 'LIES::AS'
        ? Alias(${shift(@select)}, $e->{expr})
        : $e->{expr}
     );
  }
      
  return +{
    expr => Select(\@final, ($_[0]||{})->{expr})
  };
}

sub BY (&;@) { @_ }

sub FROM (&;@) {
  my @from = _run_expr(shift);
  if (@from == 2 and ref($from[1]) eq 'LIES::AS') {
    return +{
      expr => Alias(${$from[1]}, $from[0])
    };
  } elsif (@from == 1) {
    return { expr => $from[0] };
  }
  die "Huh?"
}

1;