Glued Posts

<?php

register_activation_hook(__FILE__, 'create_glued_tables');
if (is_admin()) {
    add_action('load-post.php', 'pti_glued_posts');
    add_action('load-post-new.php', 'pti_glued_posts');
}

add_filter('posts_results', 'pti_insert_glued_post');
add_action('pre_get_posts', 'pti_exclude_glued_post');

function pti_exclude_glued_post($query) {
    if (!is_admin() && $query->is_main_query()) {
        global $wpdb;
        $rows = $wpdb->get_results('SELECT `ID` FROM `'.$wpdb->prefix.'postGlued`');
        if (count($rows)) {
            $found_glued = array();
            foreach ($rows as $row) $found_glued[] = $row->ID;
            $query->set('post__not_in', $found_glued);
        }
    }
}

function pti_insert_glued_post($posts) {
    global $wpdb, $wp_query;
//print_r($posts);
    if (!is_admin() && is_main_query() && !is_single() && !defined('_RUN_ONCE')) {
        define('_RUN_ONCE', TRUE);
        $page = (get_query_var('paged')) ? get_query_var('paged') : 1;
        $rows = $wpdb->get_results('SELECT * FROM `'.$wpdb->prefix.'postGlued` WHERE `page` = '.$page);
        $found_glued = array();

        if (count($rows)) {
            foreach ($rows as $row) $found_glued[] = $row->ID;
            $p2insert = new WP_Query(array('post__in' => $found_glued, 'suppress_filters' => true));

            if ($p2insert->have_posts()) {
                while ($p2insert->have_posts()) {
                    $p2insert->next_post();
                    foreach ($rows as $row) {
                        if ($p2insert->post->ID == $row->ID) {
                            array_splice($posts, $row->position - 1, 0, array($p2insert->post));
//print_r($p2insert->post);
                        }
                    }
                }
            }

/*
            $insert_at = 3;
            if (!empty($p2insert->posts)) {
                array_splice($posts,$insert_at,0,$p2insert->posts);
            }
*/
        }
    }
//print_r($posts);
    return $posts;
}

function create_glued_tables() {
    global $wpdb;
    $query = 'CREATE TABLE IF NOT EXISTS `'.$wpdb->prefix.'postGlued` (`ID` BIGINT(20) NOT NULL, `page` INT NOT NULL, `position` INT NOT NULL, primary key(`ID`), key(`page`))';
    require_once(ABSPATH.'wp-admin/includes/upgrade.php');
    dbDelta($query);
}

function get_glued_data($post_id) {
    global $wpdb;
    if ($post = $wpdb->get_row('SELECT * FROM `'.$wpdb->prefix.'postGlued` WHERE `ID` = '.$post_id)) {
        return $post;
    } else {
        return FALSE;
    }
}

function set_glued_data($post_id, $data) {
    global $wpdb;
    if (!$data->page) {
        if ($wpdb->query('DELETE FROM `'.$wpdb->prefix.'postGlued` WHERE `ID` = '.$post_id)) {
            return TRUE;
        } else {
            return FALSE;
        }
    } else {
        if ($wpdb->query('REPLACE INTO `'.$wpdb->prefix.'postGlued` (`ID`, `page`, `position`) VALUES ('.$post_id.', '.$data->page.', '.$data->position.')')) {
            return TRUE;
        } else {
            return FALSE;
        }
    }
}

function pti_glued_posts() {
    new pti_glued_posts();
}
class pti_glued_posts {
    function __construct() {
        add_action('add_meta_boxes', array($this, 'add_meta_box'));
        add_action('save_post', array($this, 'save'));
    }
    function add_meta_box($post_type) {
        $post_types = array('post');     //limit meta box to certain post types
        if (in_array($post_type, $post_types)) {
            add_meta_box(
                'pti_glued_posts'
                ,'Glued Post Options'
                ,array($this, 'render_meta_box_content')
                ,$post_type
                ,'advanced'
                ,'high'
            );
        }
    }
    function render_meta_box_content($post) {
        // Add an nonce field so we can check for it later.
        wp_nonce_field('pti_glued_inner_custom_box', 'pti_glued_inner_custom_box_nonce');

        // Use get_post_meta to retrieve an existing value from the database.
        $post_data = get_glued_data($post->ID);

        // Display the form, using the current value.
?>
    <label for="pti_glued_page_field">Page:</label>
    <select name="pti_glued_page_field" id="pti_glued_page_field">
<?php
    $count_pages = ceil(wp_count_posts()->publish / get_option('posts_per_page'));
    for ($i = 0; $i <= $count_pages; $i++) {
?>
        <option <?php if ($post_data) selected($i, $post_data->page); ?> value="<?=$i?>"><?=$i == 0 ? 'Unset' : ($i == 1 ? 'Homepage' : $i)?></option>
<?php
    }
?>
    </select>
    <label for="pti_glued_position_field">Position:</label>
    <select name="pti_glued_position_field" id="pti_glued_position_field">
<?php
    $count_posts = get_option('posts_per_page');
    for ($i = 1; $i <= $count_posts; $i++) {
?>
        <option <?php if ($post_data) selected($i, $post_data->position); ?> value="<?=$i?>"><?=$i == 1 ? 'First' : ($i == $count_posts ? 'Last' : ($i == round($count_posts / 2) ? 'Middle' : $i))?></option>
<?php
    }
?>
    </select>
<?php
    }
    function save($post_id) {
        // Check if our nonce is set.
        if (!isset($_POST['pti_glued_inner_custom_box_nonce'])) return $post_id;

        $nonce = $_POST['pti_glued_inner_custom_box_nonce'];

        // Verify that the nonce is valid.
        if (!wp_verify_nonce($nonce, 'pti_glued_inner_custom_box')) return $post_id;

        if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) return $post_id;

        // Check the user's permissions.
        if ($_POST['post_type'] == 'post') {
            if (!current_user_can('edit_post', $post_id)) return $post_id;
        }

        /* OK, its safe for us to save the data now. */

        $data = new STDClass();
        $data->page = $_POST['pti_glued_page_field'];
        $data->position = $_POST['pti_glued_position_field'];

        set_glued_data($post_id, $data);
    }
}