gistfile1.php

<?php

/**
* Better Limit Submissions Per Time Period by User or IP
* http://gravitywiz.com/2012/05/12/limit-ip-to-one-submission-per-time-period
*/

class GWSubmissionLimit {
    
    private $_args;
    
    function __construct($args) {
        
        $this->_args = wp_parse_args($args, array(
            'form_id' => false,
            'limit' => 1,
            'time_period' => 60 * 60 * 24, // must be provided in seconds: 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day
            'limit_message' => __('Sorry, you have reached the submission limit for this form.'),
            'limit_by' => 'ip' // also accepts "user_id"
            ));
        
        $form_filter = $this->_args['form_id'] ? "_{$this->_args['form_id']}" : '';
        
        add_filter("gform_pre_render{$form_filter}", array($this, 'pre_render'));
        add_filter("gform_validation{$form_filter}", array($this, 'validate'));
        
    }
    
    function pre_render($form) {
        
        if( !$this->is_limit_reached($form['id']) )
            return $form;
    
        $submission_info = rgar(GFFormDisplay::$submission, $form['id']);
    
        // if no submission, hide form
        // if submission and not valid, hide form
        if(!$submission_info || !rgar($submission_info, 'is_valid')) {
            add_filter('gform_get_form_filter', create_function('', "return '<div class=\"limit-message\">{$this->_args['limit_message']}</div>';") );
            //add_filter('gform_get_form_filter', create_function('$form_string, $form', 'return $form["id"] == ' . $form['id'] . ' ? \'<div class=\"limit-message\">' . $this->_args['limit_message'] . '</div>\' : $form_string;'), 10, 2 );
        }
         
        return $form;
        
    }
    
    function validate($validation_result) {
    
        if($this->is_limit_reached($validation_result['form']['id']))
            $validation_result['is_valid'] = false;
        
        return $validation_result;
    }
    
    public function is_limit_reached($form_id) {
        global $wpdb;
        
        $limit_by = is_array($this->_args['limit_by']) ? $this->_args['limit_by'] : array($this->_args['limit_by']);
        $where = array();
        
        foreach($limit_by as $limiter) {
            switch($limiter) {
            case 'user_id':
                $where[] = $wpdb->prepare('created_by = %s', get_current_user_id());
                break;
            case 'embed_url':
                $where[] = $wpdb->prepare('source_url = %s', RGFormsModel::get_current_page_url());
                break;
            default:
                $where[] = $wpdb->prepare('ip = %s', RGFormsModel::get_ip());
            }
        }
        
        $where[] = $wpdb->prepare('form_id = %d', $form_id);
        $where[] = $wpdb->prepare('date_created BETWEEN DATE_SUB(utc_timestamp(), INTERVAL %d SECOND) AND utc_timestamp()', $this->_args['time_period']);
        $where = implode(' AND ', $where);
        
        $sql = "SELECT count(id)
                FROM {$wpdb->prefix}rg_lead
                WHERE $where";
        
        $entry_count = $wpdb->get_var($sql);
        
        return $entry_count >= $this->_args['limit'];
    }
    
}

// standard usage
new GWSubmissionLimit(array(
    'form_id' => 86,
    'limit' => 2,
    'limit_message' => 'Aha! You have been limited.'
    ));