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;

  my $c = $self->dbi->safety_character;

  $self->{_re} = $c eq 'a-zA-Z0-9_' ?

    qr/[^\\]:([$c\.]+)/so : qr/[^\\]:([$c\.]+)/s;

  $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 $re = $self->{_re};

    my $column;

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

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

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

      $column = $columns->[0];

    }

    else {

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

      ($column) = $sql =~ /$re/;

    }

    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;

  # Clause

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

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

  # Stringify where clause

  my $where_clause = "$where";

  my $where_clause = $where->to_string;

    # -> where title like :title and price = :price

  # Only price condition

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

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

    # -> where price = :price

  # Only title condition

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

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

    # -> where title like :title

  # Nothing

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

  $where->param({});

    # => Nothing

  # or condition

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

    # -> where title = :title or price like :price

  # More than one parameter

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

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

    # -> where price > :price and price < :price

  # Only first condition

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

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

    # -> where price > :price

  # Only second condition

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

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

    # -> where price < :price

  # More complex condition

  $where->clause(

    [

      'and',

      ':price{=}',

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

    ]

  );

    # -> pirce = :price and (title = :title or title = :title or tilte = :title)

  # Using Full-qualified column name

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

    # -> book.title like :book.title and book.price = :book.price

=head1 ATTRIBUTES

=head2 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 param

  my $param = $where->param;

  $where = $where->param({

    title => 'Perl',

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

  });

=head2 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 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