package DBIx::Custom::Where;

use Object::Simple -base;

use Carp 'croak';

use DBIx::Custom::Util '_subname';

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

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

# Carp trust relationship

push @DBIx::Custom::CARP_NOT, __PACKAGE__;

has [qw/dbi param/],

    clause => sub { [] };

sub new {

    my $self = shift->SUPER::new(@_);

    # Check attribute names

    my @attrs = keys %$self;

    for my $attr (@attrs) {

        croak qq{"$attr" is invalid attribute name (} . _subname . ")"

          unless $self->can($attr);

    }

    return $self;

}

sub to_string {

    my $self = shift;

    # Clause

    my $clause = $self->clause;

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

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

    # Parse

    my $where = [];

    my $count = {};

    $self->{_query_builder} = $self->dbi->query_builder;

    $self->{_safety_character} = $self->dbi->safety_character;

    $self->{_quote} = $self->dbi->_quote;

    $self->{_tag_parse} = exists $ENV{DBIX_CUSTOM_TAG_PARSE}

      ? $ENV{DBIX_CUSTOM_TAG_PARSE} : $self->dbi->{tag_parse};

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

    # Stringify

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

    return join(' ', @$where);

}

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

sub _parse {

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

    # Array

    if (ref $clause eq 'ARRAY') {

        # Start

        push @$where, '(';

        # Operation

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

        croak qq{First argument must be "and" or "or" in where clause } .

              qq{"$op" is passed} . _subname . ")"

          unless $VALID_OPERATIONS{$op};

        my $pushed_array;

        # Parse internal clause

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

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

            push @$where, $op if $pushed;

            $pushed_array = 1 if $pushed;

        }

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

        # Undo

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

            pop @$where;

            pop @$where if ($where->[-1] || '') eq $op;

        }

        # End

        else { push @$where, ')' }

        return $pushed_array;

    }

    # String

    else {

        # Pushed

        my $pushed;

        # Column

        my $c = $self->{_safety_character};

        my $column;

        if ($self->{_tag_parse} && ($clause =~ /\s\{/ || $clause =~ /^\{/)) {

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

            $column = $columns->[0];

        }

        else {

            my $sql = " " . $clause || '';

            $sql =~ s/([0-9]):/$1\\:/g;

            ($column) = $sql =~ /[^\\]:([$c\.]+)/s

        }

        unless (defined $column) {

            push @$where, $clause;

            $pushed = 1;

            return $pushed;

        }

        # Column count up

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

        # Push

        my $param = $self->{param};

        if (ref $param eq 'HASH') {

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

                my $if = $self->{_if};

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

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

                      && ref $param->{$column}->[$count - 1] ne 'DBIx::Custom::NotExists'

                }

                elsif ($count == 1) { $pushed = 1 }

            }

            push @$where, $clause if $pushed;

        }

        elsif (!defined $param) {

            push @$where, $clause;

            $pushed = 1;

        }

        else {

            croak "Parameter must be hash reference or undfined value ("

                . _subname . ")"

        }

        return $pushed;

    }

    return;

}

1;

=head1 NAME

DBIx::Custom::Where - Where clause

=head1 SYNOPSYS

    # Create DBIx::Custom::Where object

    my $where = $dbi->where;

    # Set clause and parameter

    $where->clause(['and', ':title{like}', ':price{=}']);

    # Create where clause by to_string method

    my $where_clause = $where->to_string;

    # Create where clause by stringify

    my $where_clause = "$where";

    # Created where clause in the above way

    where :title{=} and :price{like}

    # Only price condition

    $where->clause(['and', ':title{like}', ':price{=}']);

    $where->param({price => 1900});

    my $where_clause = "$where";

    # Created where clause in the above way

    where :price{=}

    # Only title condition

    $where->clause(['and', ':title{like}', ':price{=}']);

    $where->param({title => 'Perl'});

    my $where_clause = "$where";

    # Created where clause in the above way

    where :title{like}

    # Nothing

    $where->clause(['and', ':title{like}', ':price{=}']);

    $where->param({});

    my $where_clause = "$where";

    # or condition

    $where->clause(['or', ':title{like}', ':price{=}']);

    # More than one parameter

    $where->clause(['and', ':price{>}', ':price{<}']);

    $where->param({price => [1000, 2000]});

    # Only first condition

    $where->clause(['and', ':price{>}', ':price{<}']);

    $where->param({price => [1000, $dbi->not_exists]});

    # Only second condition

    $where->clause(['and', ':price{>}', ':price{<}']);

    $where->param({price => [$dbi->not_exists, 2000]});

    # More complex condition

    $where->clause(

        [

            'and',

            ':price{=}',

            ['or', ':title{=}', ':title{=}', ':title{=}']

        ]

    );

    my $where_clause = "$where";

    # Created where clause in the above way

    where :price{=} and (:title{=} or :title{=} or :title{=})

    # Using Full-qualified column name

    $where->clause(['and', ':book.title{like}', ':book.price{=}']);

=head1 ATTRIBUTES

=head2 C<clause>

    my $clause = $where->clause;

    $where = $where->clause(

        ['and',

            ':title{=}', 

            ['or', ':date{<}', ':date{>}']

        ]

    );

Where clause. Above one is expanded to the following SQL by to_string

If all parameter names is exists.

    where title = :title and ( date < :date or date > :date )

=head2 C<param>

    my $param = $where->param;

    $where = $where->param({

        title => 'Perl',

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

    });

=head2 C<dbi>

    my $dbi = $where->dbi;

    $where = $where->dbi($dbi);

L<DBIx::Custom> object.

=head1 METHODS

L<DBIx::Custom::Where> inherits all methods from L<Object::Simple>

and implements the following new ones.

=head2 C<to_string>

    $where->to_string;

Convert where clause to string.

double quote is override to execute C<to_string> method.

    my $string_where = "$where";

=cut