Fey::Role::SQL::HasWhereClause - A role for queries which can include a WHERE clause

  use Moose;

  with 'Fey::Role::SQL::HasWhereClause';

  The Artistic License 2.0 (GPL Compatible)

package Fey::Role::SQL::HasWhereClause;
BEGIN {
  $Fey::Role::SQL::HasWhereClause::VERSION = '0.40';
}

use strict;
use warnings;
use namespace::autoclean;

use Fey::Exceptions qw( param_error );

use Fey::SQL::Fragment::Where::Boolean;
use Fey::SQL::Fragment::Where::Comparison;
use Fey::SQL::Fragment::Where::SubgroupStart;
use Fey::SQL::Fragment::Where::SubgroupEnd;
use Fey::Types qw( ArrayRef );

use Moose::Role;

has '_where' => (
    traits  => ['Array'],
    is      => 'bare',
    isa     => ArrayRef,
    default => sub { [] },
    handles => {
        _add_where_element  => 'push',
        _has_where_elements => 'count',
        _last_where_element => [ 'get', -1 ],
        _where              => 'elements',
    },
    init_arg => undef,
);

sub where {
    my $self = shift;

    $self->_condition( 'where', @_ );

    return $self;
}

# Just some sugar
sub and {
    my $self = shift;

    return $self->where(@_);
}

{
    my %dispatch = (
        'and' => '_and',
        'or'  => '_or',
        '('   => '_subgroup_start',
        ')'   => '_subgroup_end',
    );

    sub _condition {
        my $self = shift;
        my $key  = shift;

        if ( @_ == 1 ) {
            if ( my $meth = $dispatch{ lc $_[0] } ) {
                $self->$meth($key);
                return;
            }
            else {
                param_error
                    qq|Cannot pass one argument to $key() unless it is one of "and", "or", "(", or ")".|;
            }
        }

        $self->_add_and_if_needed($key);

        my $add_method = '_add_' . $key . '_element';
        $self->$add_method(
            Fey::SQL::Fragment::Where::Comparison->new(
                $self->auto_placeholders(), @_
            )
        );
    }
}

sub _add_and_if_needed {
    my $self = shift;
    my $key  = shift;

    my $has_method = '_has_' . $key . '_elements';

    return unless $self->$has_method();

    my $last_method = '_last_' . $key . '_element';
    my $last        = $self->$last_method();

    return if $last->isa('Fey::SQL::Fragment::Where::Boolean');
    return if $last->isa('Fey::SQL::Fragment::Where::SubgroupStart');

    $self->_and($key);
}

sub _and {
    my $self = shift;
    my $key  = shift;

    my $add_method = '_add_' . $key . '_element';
    $self->$add_method(
        Fey::SQL::Fragment::Where::Boolean->new( comparison => 'AND' ) );

    return $self;
}

sub _or {
    my $self = shift;
    my $key  = shift;

    my $add_method = '_add_' . $key . '_element';
    $self->$add_method(
        Fey::SQL::Fragment::Where::Boolean->new( comparison => 'OR' ) );

    return $self;
}

sub _subgroup_start {
    my $self = shift;
    my $key  = shift;

    $self->_add_and_if_needed($key);

    my $add_method = '_add_' . $key . '_element';
    $self->$add_method( Fey::SQL::Fragment::Where::SubgroupStart->new() );

    return $self;
}

sub _subgroup_end {
    my $self = shift;
    my $key  = shift;

    my $add_method = '_add_' . $key . '_element';
    $self->$add_method( Fey::SQL::Fragment::Where::SubgroupEnd->new() );

    return $self;
}

sub where_clause {
    my $self       = shift;
    my $dbh        = shift;
    my $skip_where = shift;

    return unless $self->_has_where_elements();

    my $sql = '';
    $sql = 'WHERE '
        unless $skip_where;

    return (
        $sql
            . (
            join ' ',
            map { $_->sql($dbh) } $self->_where()
            )
    );
}

sub bind_params {
    my $self = shift;

    return (
        map  { $_->bind_params() }
        grep { $_->can('bind_params') } $self->_where()
    );
}

1;

# ABSTRACT: A role for queries which can include a WHERE clause

__END__