package DBIx::Custom::Where;

use strict;

use warnings;

use base 'Object::Simple';

use overload 'bool' => sub {1}, fallback => 1;

use overload '""' => sub { shift->to_string }, fallback => 1;

use Carp 'croak';

__PACKAGE__->attr(

  'query_builder',

  clause => sub { [] },

  param => sub { {} }

);

sub to_string {

    my $self = shift;

    my $clause = $self->clause;

    $clause = ['and', $clause] unless ref $clause eq 'ARRAY';

    $clause->[0] = 'and' unless @$clause;

    my $where = [];

    my $count = {};

    $self->_forward($clause, $where, $count, 'and');

    unshift @$where, 'where' if @$where;

    return join(' ', @$where);

}

our %VALID_OPERATIONS = map { $_ => 1 } qw/and or/;

sub _forward {

    my ($self, $clause, $where, $count, $op) = @_;

    if (ref $clause eq 'ARRAY') {

        push @$where, '(';

        my $op = $clause->[0] || '';

        croak qq{"$op" is invalid operation}

          unless $VALID_OPERATIONS{$op};

        for (my $i = 1; $i < @$clause; $i++) {

            my $pushed = $self->_forward($clause->[$i], $where, $count, $op);

            push @$where, $op if $pushed;

        }

        pop @$where if $where->[-1] eq $op;

        if ($where->[-1] eq '(') {

            pop @$where;

            pop @$where;

        }

        else {

            push @$where, ')';

        }

    }

    else {

        # Column

        my $columns = $self->query_builder->build_query($clause)->columns;

        croak qq{each tag contains one column name: tag "$clause"}

          unless @$columns == 1;

        my $column = $columns->[0];

        # Count up

        my $count = ++$count->{$column};

        # Push element

        my $param    = $self->param;

        my $pushed;

        if (exists $param->{$column}) {

            if (ref $param->{$column} eq 'ARRAY') {

                $pushed = 1 if exists $param->{$column}->[$count - 1];

            }

            elsif ($count == 1) {

                $pushed = 1;

            }

        }

        push @$where, $clause if $pushed;

        return $pushed;

    }

}

1;

=head1 NAME

DBIx::Custom::Where - Where clause

=head1 SYNOPSYS

    $where = DBIx::Custom::Where->new;

    my $sql = "select * from book $where";

=head1 ATTRIBUTES

=head2 C<param>

    my $param = $where->param;

    $where    = $where->param({title => 'Perl',

                               date => ['2010-11-11', '2011-03-05']},

                               name => ['Ken', 'Taro']);

=head1 METHODS

=head2 C<clause>

    $where->clause(title => '{= title}', date => ['{< date}', '{> date}']);

Where clause. These clauses is joined by ' and ' at C<to_string()>

if corresponding parameter name is exists in C<param>.

=head2 C<to_string>

    $where->to_string;