Exclude Pages from Navigation

<?php
/*
Plugin Name: Exclude Pages from Navigation
Plugin URI: http://wordpress.org/extend/plugins/exclude-pages/
Description: Provides a checkbox on the editing page which you can check to exclude pages from the primary navigation. IMPORTANT NOTE: This will remove the pages from any "consumer" side page listings, which may not be limited to your page navigation listings.
Version: XXX
Author: Simon Wheatley
Author URI: http://simonwheatley.co.uk/wordpress/

Copyright 2007 Simon Wheatley

This script is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.

This script is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/

// Full filesystem path to this dir
define('EP_PLUGIN_DIR', dirname(__FILE__));

// Option name for exclusion data
define('EP_OPTION_NAME', 'ep_exclude_pages');
// Separator for the string of IDs stored in the option value
define('EP_OPTION_SEP', ',');
// The textdomain for the WP i18n gear
define( 'EP_TD', 'exclude-pages' );

// Take the pages array, and return the pages array without the excluded pages
// Doesn't do this when in the admin area
function ep_exclude_pages( $pages ) {
    // If the URL includes "wp-admin", just return the unaltered list
    // This constant, WP_ADMIN, only came into WP on 2007-12-19 17:56:16 rev 6412, i.e. not something we can rely upon unfortunately.
    // May as well check it though.
    // Also check the URL... let's hope they haven't got a page called wp-admin (probably not)
    // SWTODO: Actually, you can create a page with an address of wp-admin (which is then inaccessible), I consider this a bug in WordPress (which I may file a report for, and patch, another time).
    $bail_out = ( ( defined( 'WP_ADMIN' ) && WP_ADMIN == true ) || ( strpos( $_SERVER[ 'PHP_SELF' ], 'wp-admin' ) !== false ) );
    $bail_out = apply_filters( 'ep_admin_bail_out', $bail_out );
    if ( $bail_out ) return $pages;
    $excluded_ids = ep_get_excluded_ids();
    $length = count($pages);
    // Ensure we catch all descendant pages, so that if a parent
    // is hidden, it's children are too.
    for ( $i=0; $i<$length; $i++ ) {
        $page = & $pages[$i];
        // If one of the ancestor pages is excluded, add it to our exclude array
        if ( $page !== NULL && ep_ancestor_excluded( $page, $excluded_ids, $pages ) ) {
            // Can't actually delete the pages at the moment,
            // it'll screw with our recursive search.
            // For the moment, just tag the ID onto our excluded IDs
            $excluded_ids[] = $page->ID;
        }
    }

    // Ensure the array only has unique values
    $delete_ids = array_unique( $excluded_ids );

    // Loop though the $pages array and actually unset/delete stuff
    for ( $i=0; $i<$length; $i++ ) {
        $page = & $pages[$i];
        // If one of the ancestor pages is excluded, add it to our exclude array
        if ($page !== NULL && in_array( $page->ID, $delete_ids ) ) {
            // Finally, delete something(s)
            unset( $pages[$i] );
        }
    }

    // Reindex the array, for neatness
    // SWFIXME: Is reindexing the array going to create a memory optimisation problem for large arrays of WP post/page objects?
    if ( ! is_array( $pages ) ) $pages = (array) $pages;
    $pages = array_values( $pages );

    return $pages;
}

/**
 * Recurse down an ancestor chain, checking if one is excluded
 *
 * @param
 * @return boolean|int The ID of the "nearest" excluded ancestor, otherwise false
 * @author Simon Wheatley
 **/
function ep_ancestor_excluded( $page, $excluded_ids, $pages ) {
    if($page === NULL) return false;

    $parent = & ep_get_page( $page->post_parent, $pages );
    // Is there a parent?
    if ( ! $parent )
        return false;
    // Is it excluded?
    if ( in_array( $parent->ID, $excluded_ids ) )
        return (int) $parent->ID;
    // Is it the homepage?
    if ( $parent->ID == 0 )
        return false;
    // Otherwise we have another ancestor to check
    return ep_ancestor_excluded( $parent, $excluded_ids, $pages );
}

/**
 * {no description}
 *
 * @param int $page_id The ID of the WP page to search for
 * @param array $pages An array of WP page objects
 * @return boolean|object the page from the $pages array which corresponds to the $page_id
 * @author Simon Wheatley
 **/
function ep_get_page( $page_id, $pages ) {
    // PHP 5 would be much nicer here, we could use foreach by reference, ah well.
    $length = count($pages);
    for ( $i=0; $i<$length; $i++ ) {
        $page = & $pages[$i];
        if ( $page !== NULL && $page->ID == $page_id ) return $page;
    }
    // Unusual.
    return false;
}

// Is this page we're editing (defined by global $post_ID var)
// currently NOT excluded (i.e. included),
// returns true if NOT excluded (i.e. included)
// returns false is it IS excluded.
// (Tricky this upside down flag business.)
function ep_this_page_included() {
    global $post_ID;
    // New post? Must be included then.
    if ( ! $post_ID ) return true;
    $excluded_ids = ep_get_excluded_ids();
    // If there's no exclusion array, we can return true
    if ( empty($excluded_ids) ) return true;
    // Check if our page is in the exclusion array
    // The bang (!) reverses the polarity [1] of the boolean
    return ! in_array( $post_ID, $excluded_ids );
    // fn1. (of the neutron flow, ahem)
}

// Check the ancestors for the page we're editing (defined by
// global $post_ID var), return the ID if the nearest one which
// is excluded (if any);
function ep_nearest_excluded_ancestor() {
    global $post_ID, $wpdb;
    // New post? No problem.
    if ( ! $post_ID ) return false;
    $excluded_ids = ep_get_excluded_ids();
    // Manually get all the pages, to avoid our own filter.
    $sql = "SELECT ID, post_parent FROM $wpdb->posts WHERE post_type = 'page'";
    $pages = $wpdb->get_results( $sql );
    // Start recursively checking the ancestors
    $parent = ep_get_page( $post_ID, $pages );
    return ep_ancestor_excluded( $parent, $excluded_ids, $pages );
}

function ep_get_excluded_ids() {
    $exclude_ids_str = get_option( EP_OPTION_NAME );
    // No excluded IDs? Return an empty array
    if ( empty($exclude_ids_str) ) return array();
    // Otherwise, explode the separated string into an array, and return that
    return explode( EP_OPTION_SEP, $exclude_ids_str );
}

// This function gets all the exclusions out of the options
// table, updates them, and resaves them in the options table.
// We're avoiding making this a postmeta (custom field) because we
// don't want to have to retrieve meta for every page in order to
// determine if it's to be excluded. Storing all the exclusions in
// one row seems more sensible.
function ep_update_exclusions( $post_ID ) {
    // Bang (!) to reverse the polarity of the boolean, turning include into exclude
    $exclude_this_page = ! (bool) @ $_POST['ep_this_page_included'];
    // SWTODO: Also check for a hidden var, which confirms that this checkbox was present
    // If hidden var not present, then default to including the page in the nav (i.e. bomb out here rather
    // than add the page ID to the list of IDs to exclude)
    $ctrl_present = (bool) @ $_POST['ep_ctrl_present'];
    if ( ! $ctrl_present )
        return;

    $excluded_ids = ep_get_excluded_ids();
    // If we need to EXCLUDE the page from the navigation...
    if ( $exclude_this_page ) {
        // Add the post ID to the array of excluded IDs
        array_push( $excluded_ids, $post_ID );
        // De-dupe the array, in case it was there already
        $excluded_ids = array_unique( $excluded_ids );
    }
    // If we need to INCLUDE the page in the navigation...
    if ( ! $exclude_this_page ) {
        // Find the post ID in the array of excluded IDs
        $index = array_search( $post_ID, $excluded_ids );
        // Delete any index found
        if ( $index !== false ) unset( $excluded_ids[$index] );
    }
    $excluded_ids_str = implode( EP_OPTION_SEP, $excluded_ids );
    ep_set_option( EP_OPTION_NAME, $excluded_ids_str );
}

// Take an option, delete it if it exists, then add it.
function ep_set_option( $name, $value ) {
    // Delete option
    delete_option($name);
    // Insert option
    add_option( $name, $value );
}

/**
 * Callback function for the metabox on the page edit screen.
 *
 * @return void
 * @author Simon Wheatley
 **/
function ep_admin_sidebar_wp25() {
    $nearest_excluded_ancestor = ep_nearest_excluded_ancestor();
    echo '  <div id="excludepagediv" class="new-admin-wp25">';
    echo '      <div class="outer"><div class="inner">';
    echo '      <p><label for="ep_this_page_included" class="selectit">';
    echo '      <input ';
    echo '          type="checkbox" ';
    echo '          name="ep_this_page_included" ';
    echo '          id="ep_this_page_included" ';
    if ( ep_this_page_included() )
        echo 'checked="checked"';
    echo ' />';
    echo '          '.__( 'Include this page in lists of pages', EP_TD ).'</label>';
    echo '      <input type="hidden" name="ep_ctrl_present" value="1" /></p>';
    if ( $nearest_excluded_ancestor !== false ) {
        echo '<p class="ep_exclude_alert"><em>';
        printf( __( 'N.B. An ancestor of this page is excluded, so this page is too (<a href="%1$s" title="%2$s">edit ancestor</a>).', EP_TD), "post.php?action=edit&amp;post=$nearest_excluded_ancestor", __( 'edit the excluded ancestor', EP_TD ) );
        echo '</em></p>';
    }
    // If there are custom menus (WP 3.0+) then we need to clear up some
    // potential confusion here.
    if ( ep_has_menu() ) {
        echo '<p id="ep_custom_menu_alert"><em>';
        if ( current_user_can( 'edit_theme_options' ) )
            printf( __( 'N.B. This page can still appear in explicitly created <a href="%1$s">menus</a> (<a id="ep_toggle_more" href="#ep_explain_more">explain more</a>)', EP_TD),
                "nav-menus.php" );
        else
            _e( 'N.B. This page can still appear in explicitly created menus (<a id="ep_toggle_more" href="#ep_explain_more">explain more</a>)', EP_TD);
        echo '</em></p>';
        echo '<div id="ep_explain_more"><p>';
        if ( current_user_can( 'edit_theme_options' ) )
            printf( __( 'WordPress provides a simple function for you to maintain your site <a href="%1$s">menus</a>. If you create a menu which includes this page, the checkbox above will not have any effect on the visibility of that menu item.', EP_TD),
                "nav-menus.php" );
        else
            _e( 'WordPress provides a simple function for you to maintain the site menus, which your site administrator is using. If a menu includes this page, the checkbox above will not have any effect on the visibility of that menu item.', EP_TD);
        echo '</p><p>';
        echo _e( 'If you think you no longer need the Exclude Pages plugin you should talk to your WordPress administrator about disabling it.', EP_TD );
        echo '</p></div>';
    }
    echo '      </div><!-- .inner --></div><!-- .outer -->';
    echo '  </div><!-- #excludepagediv -->';
}

/**
 * A conditional function to determine whether there are any menus
 * defined in this WordPress installation.
 *
 * @return bool Indicates the presence or absence of menus
 * @author Simon Wheatley
 **/
function ep_has_menu() {
    if ( ! function_exists( 'wp_get_nav_menus' ) )
        return false;
    $menus = wp_get_nav_menus();
    foreach ( $menus as $menu_maybe ) {
        if ( $menu_items = wp_get_nav_menu_items($menu_maybe->term_id) )
            return true;
    }
}

/**
 * Hooks the WordPress admin_head action to inject some CSS.
 *
 * @return void
 * @author Simon Wheatley
 **/
function ep_admin_css() {
    echo <<<END
<style type="text/css" media="screen">
    .ep_exclude_alert { font-size: 11px; }
    .new-admin-wp25 { font-size: 11px; background-color: #fff; }
    .new-admin-wp25 .inner {  padding: 8px 12px; background-color: #EAF3FA; border: 1px solid #EAF3FA; -moz-border-radius: 3px; -khtml-border-bottom-radius: 3px; -webkit-border-bottom-radius: 3px; border-bottom-radius: 3px; }
    #ep_admin_meta_box .inner {  padding: inherit; background-color: transparent; border: none; }
    #ep_admin_meta_box .inner label { background-color: none; }
    .new-admin-wp25 .exclude_alert { padding-top: 5px; }
    .new-admin-wp25 .exclude_alert em { font-style: normal; }
</style>
END;
}

/**
 * Hooks the WordPress admin_head action to inject some JS.
 *
 * @return void
 * @author Simon Wheatley
 **/
function ep_admin_js() {
    echo <<<END
<script type="text/javascript">
//<![CDATA[
    jQuery( '#ep_explain_more' ).hide();
    jQuery( '#ep_toggle_more' ).click( function() {
        jQuery( '#ep_explain_more' ).toggle();
        return false;
    } );
//]]>
</script>
END;
}

// Add our ctrl to the list of controls which AREN'T hidden
function ep_hec_show_dbx( $to_show ) {
    array_push( $to_show, 'excludepagediv' );
    return $to_show;
}

// PAUSE & RESUME FUNCTIONS

function pause_exclude_pages() {
    remove_filter('get_pages','ep_exclude_pages');
}

function resume_exclude_pages() {
    add_filter('get_pages','ep_exclude_pages');
}

// INIT FUNCTIONS

function ep_init() {
    // Call this function on the get_pages filter
    // (get_pages filter appears to only be called on the "consumer" side of WP,
    // the admin side must use another function to get the pages. So we're safe to
    // remove these pages every time.)
    add_filter('get_pages','ep_exclude_pages');
    // Load up the translation gear
    $locale = get_locale();
    $folder = rtrim( basename( dirname( __FILE__ ) ), '/' );
    $mo_file = trailingslashit( WP_PLUGIN_DIR ) . "$folder/locale/" . EP_TD . "-$locale.mo";
    load_textdomain( EP_TD, $mo_file );
}

function ep_admin_init() {
    // Add panels into the editing sidebar(s)
    global $wp_version;
    add_meta_box('ep_admin_meta_box', __( 'Exclude Pages', EP_TD ), 'ep_admin_sidebar_wp25', 'page', 'side', 'low');

    // Set the exclusion when the post is saved
    add_action('save_post', 'ep_update_exclusions');

    // Add the JS & CSS to the admin header
    add_action('admin_head', 'ep_admin_css');
    add_action('admin_footer', 'ep_admin_js');

    // Call this function on our very own hec_show_dbx filter
    // This filter is harmless to add, even if we don't have the
    // Hide Editor Clutter plugin installed as it's using a custom filter
    // which won't be called except by the HEC plugin.
    // Uncomment to show the control by default
    // add_filter('hec_show_dbx','ep_hec_show_dbx');
}

// HOOK IT UP TO WORDPRESS

add_action( 'init', 'ep_init' );
add_action( 'admin_init', 'ep_admin_init' )

?>