/ajax.php

<?php

/*
 * Enano - an open-source CMS capable of wiki functions, Drupal-like sidebar blocks, and everything in between
 * Copyright (C) 2006-2009 Dan Fuhry
 *
 * This program is Free Software; you can redistribute and/or modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
 *
 * This program 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 details.
 */
 
define('ENANO_INTERFACE_AJAX', '');

require('includes/common.php');

global $db, $session, $paths, $template, $plugins; // Common objects
if(!isset($_GET['_mode'])) die('This script cannot be accessed directly.');

$_ob = '';

switch($_GET['_mode']) {
	case "checkusername":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		echo PageUtils::checkusername($_GET['name']);
		break;
	case "getsource":
		header('Content-type: text/plain');
		$password = ( isset($_GET['pagepass']) ) ? $_GET['pagepass'] : false;
		$revid = ( isset($_GET['revid']) ) ? intval($_GET['revid']) : 0;
		$page = new PageProcessor($paths->page_id, $paths->namespace, $revid);
		$page->password = $password;
		
		$have_draft = false;
		// Kinda hacky fix for issue 7: draft restore not offered for nonexistent pages
		if ( ($src = $page->fetch_source()) || !$page->exists() )
		{
			$allowed = true;
			$q = $db->sql_query('SELECT author, time_id, page_text, edit_summary, page_format FROM ' . table_prefix . 'logs WHERE log_type = \'page\' AND action = \'edit\'
														AND page_id = \'' . $db->escape($paths->page_id) . '\'
														AND namespace = \'' . $db->escape($paths->namespace) . '\'
														AND is_draft = 1;');
			if ( !$q )
				$db->die_json();
			
			if ( $db->numrows() > 0 )
			{
				$have_draft = true;
				$draft_row = $db->fetchrow($q);
			}
		}
		else if ( $src !== false )
		{
			$allowed = true;
			$src = '';
		}
		else
		{
			$allowed = false;
			$src = '';
		}
		
		$auth_edit = ( $session->get_permissions('edit_page') && ( $session->get_permissions('even_when_protected') || !$page->ns->page_protected ) );
		$auth_wysiwyg = ( $session->get_permissions('edit_wysiwyg') );
		
		$return = array(
				'mode' => 'editor',
				'src' => $src,
				'auth_view_source' => $allowed,
				'auth_edit' => $auth_edit,
				'time' => time(),
				'require_captcha' => false,
				'allow_wysiwyg' => $auth_wysiwyg,
				'revid' => $revid,
				'have_draft' => false
			);
		
		$return['page_format'] = $page->ns->cdata['page_format'];
		$code = $plugins->setHook('get_page_source');
		foreach ( $code as $cmd )
		{
			eval($cmd);
		}
		
		if ( $have_draft )
		{
			$row =& $draft_row;
			$return['have_draft'] = true;
			$return['draft_author'] = $row['author'];
			$return['draft_time'] = enano_date(ED_DATE | ED_TIME, intval($row['time_id']));
			if ( isset($_GET['get_draft']) && @$_GET['get_draft'] === '1' )
			{
				$return['src'] = $row['page_text'];
				$return['edit_summary'] = $row['edit_summary'];
				$return['page_format'] = $row['page_format'];
			}
		}
		
		$return['undo_info'] = array();
		
		if ( $revid > 0 )
		{
			// Retrieve information about this revision and the current one
			$q = $db->sql_query('SELECT l1.author AS currentrev_author, l2.author AS oldrev_author FROM ' . table_prefix . 'logs AS l1
LEFT JOIN ' . table_prefix . 'logs AS l2
	ON ( l2.log_id = ' . $revid . '
			AND l2.log_type  = \'page\'
			AND l2.action    = \'edit\'
			AND l2.page_id   = \'' . $db->escape($paths->page_id)   . '\'
			AND l2.namespace = \'' . $db->escape($paths->namespace) . '\'
			AND l2.is_draft != 1
			)
WHERE l1.log_type  = \'page\'
	AND l1.action    = \'edit\'
	AND l1.page_id   = \'' . $db->escape($paths->page_id)   . '\'
	AND l1.namespace = \'' . $db->escape($paths->namespace) . '\'
	AND l1.time_id   > ' . $page->revision_time . '
	AND l1.is_draft != 1
ORDER BY l1.time_id DESC;');
			if ( !$q )
				$db->die_json();
			
			if ( $db->numrows() > 0 )
			{
				$rev_count = $db->numrows() - 1;
				if ( $rev_count == -1 )
				{
					$return = array(
							'mode' => 'error',
							'error' => '[Internal] No rows returned by revision info query. SQL:<pre>' . $db->latest_query . '</pre>'
						);
				}
				else
				{
					$row = $db->fetchrow();
					$return['undo_info'] = array(
						'old_author'     => $row['oldrev_author'],
						'current_author' => $row['currentrev_author'],
						'undo_count'     => $rev_count
					);
				}
			}
			else
			{
				$return['revid'] = $revid = 0;
			}
		}
		
		if ( $auth_edit && !$session->user_logged_in && getConfig('guest_edit_require_captcha') == '1' )
		{
			$return['require_captcha'] = true;
			$return['captcha_id'] = $session->make_captcha();
		}
		
		$template->load_theme();
		$return['toolbar_templates'] = $template->extract_vars('toolbar.tpl');
		$return['edit_notice'] = $template->get_wiki_edit_notice();
		
		$code = $plugins->setHook('ajax_getsource_send_data');
		foreach ( $code as $cmd )
		{
			eval($cmd);
		}
		
		echo enano_json_encode($return);
		break;
	case "getpage":
		// echo PageUtils::getpage($paths->page, false, ( (isset($_GET['oldid'])) ? $_GET['oldid'] : false ));
		$output = new Output_Striptease();
		
		$revision_id = ( (isset($_GET['oldid'])) ? intval($_GET['oldid']) : 0 );
		$page = new PageProcessor( $paths->page_id, $paths->namespace, $revision_id );
		$template->set_page($page);
		
		$pagepass = ( isset($_REQUEST['pagepass']) ) ? $_REQUEST['pagepass'] : '';
		$page->password = $pagepass;
		$page->allow_redir = ( !isset($_GET['redirect']) || (isset($_GET['redirect']) && $_GET['redirect'] !== 'no') );
					
		$page->send();
		break;
	case "savepage":
		/* **** OBSOLETE **** */
		
		break;
	case "savepage_json":
		header('Content-type: application/json');
		if ( !isset($_POST['r']) )
			die('Invalid request');
		
		try
		{
			$request = enano_json_decode($_POST['r']);
			if ( !isset($request['src']) || !isset($request['summary']) || !isset($request['minor_edit']) || !isset($request['time']) || !isset($request['draft']) )
				die('Invalid request');
		}
		catch(Zend_Json_Exception $e)
		{
			die("JSON parsing failed. View as HTML to see full report.\n<br /><br />\n<pre>" . htmlspecialchars(strval($e)) . "</pre><br />Request: <pre>" . htmlspecialchars($_POST['r']) . "</pre>");
		}
		
		$time = intval($request['time']);
		
		if ( $request['draft'] )
		{
			//
			// The user wants to save a draft version of the page.
			//
			
			// Validate permissions
			if ( !$session->get_permissions('edit_page') )
			{
				$return = array(
					'mode' => 'error',
					'error' => 'access_denied'
				);
			}
			else
			{
				// Delete any draft copies if they exist
				$q = $db->sql_query('DELETE FROM ' . table_prefix . 'logs WHERE log_type = \'page\' AND action = \'edit\'
															AND page_id = \'' . $db->escape($paths->page_id) . '\'
															AND namespace = \'' . $db->escape($paths->namespace) . '\'
															AND is_draft = 1;');
				if ( !$q )
					$db->die_json();
				
				// are we just supposed to delete the draft?
				if ( $request['src'] === -1 )
				{
					$return = array(
						'mode' => 'success',
						'is_draft' => 'delete'
					);
				}
				else
				{
					$src = RenderMan::preprocess_text($request['src'], false, false);
					$draft_format = $db->escape($request['format']);
					
					// Save the draft
					if ( !preg_match('/^[a-z0-9_]+$/', $draft_format) )
					{
						$return = array(
								'mode' => 'error',
								'error' => 'Page format must match /^[a-z0-9_]+$/'
							);
					}
					else
					{
						$q = $db->sql_query('INSERT INTO ' . table_prefix . 'logs ( log_type, action, page_id, namespace, author, author_uid, edit_summary, page_text, is_draft, time_id, page_format )
											VALUES (
												\'page\',
												\'edit\',
												\'' . $db->escape($paths->page_id) . '\',
												\'' . $db->escape($paths->namespace) . '\',
												\'' . $db->escape($session->username) . '\',
												' . $session->user_id . ',
												\'' . $db->escape($request['summary']) . '\',
												\'' . $db->escape($src) . '\',
												1,
												' . time() . ',
												\'' . $draft_format . '\'
											);');
						// Done!
						$return = array(
								'mode' => 'success',
								'is_draft' => true
							);
					}
				}
			}
		}
		else
		{
			// Verify that no edits have been made since the editor was requested
			$q = $db->sql_query('SELECT time_id, author FROM ' . table_prefix . "logs WHERE log_type = 'page' AND action = 'edit' AND page_id = '{$paths->page_id}' AND namespace = '{$paths->namespace}' AND is_draft != 1 ORDER BY time_id DESC LIMIT 1;");
			if ( !$q )
				$db->die_json();
			
			$row = $db->fetchrow();
			$db->free_result();
			
			if ( $row['time_id'] > $time )
			{
				$return = array(
					'mode' => 'obsolete',
					'author' => $row['author'],
					'date_string' => enano_date(ED_DATE | ED_TIME, $row['time_id']),
					'time' => $row['time_id'] // time() ???
					);
				echo enano_json_encode($return);
				break;
			}
			
			// Verify captcha, if needed
			if ( !$session->user_logged_in && getConfig('guest_edit_require_captcha') == '1' )
			{
				if ( !isset($request['captcha_id']) || !isset($request['captcha_code']) )
				{
					die('Invalid request, need captcha metadata');
				}
				$code_correct = strtolower($session->get_captcha($request['captcha_id']));
				$code_input = strtolower($request['captcha_code']);
				if ( $code_correct !== $code_input )
				{
					$return = array(
						'mode' => 'errors',
						'errors' => array($lang->get('editor_err_captcha_wrong')),
						'new_captcha' => $session->make_captcha()
					);
					echo enano_json_encode($return);
					break;
				}
			}
			
			// Verification complete. Start the PageProcessor and let it do the dirty work for us.
			$page = new PageProcessor($paths->page_id, $paths->namespace);
			if ( $page->update_page($request['src'], $request['summary'], ( $request['minor_edit'] == 1 ), $request['format'], $request) )
			{
				$return = array(
						'mode' => 'success',
						'is_draft' => false
					);
			}
			else
			{
				$errors = array();
				while ( $err = $page->pop_error() )
				{
					$errors[] = $err;
				}
				$return = array(
					'mode' => 'errors',
					'errors' => array_values($errors)
					);
				if ( !$session->user_logged_in && getConfig('guest_edit_require_captcha') == '1' )
				{
					$return['new_captcha'] = $session->make_captcha();
				}
			}
		}
		
		// If this is based on a draft version, delete the draft - we no longer need it.
		if ( @$request['used_draft'] && !$request['draft'] )
		{
			$q = $db->sql_query('DELETE FROM ' . table_prefix . 'logs WHERE log_type = \'page\' AND action = \'edit\'
														AND page_id = \'' . $db->escape($paths->page_id) . '\'
														AND namespace = \'' . $db->escape($paths->namespace) . '\'
														AND is_draft = 1;');
		}
		
		echo enano_json_encode($return);
		
		break;
	case "diff_cur":
		
		// Lie about our content type to fool ad scripts
		header('Content-type: application/xhtml+xml');
		
		if ( !isset($_POST['text']) )
			die('Invalid request');
		
		$page = new PageProcessor($paths->page_id, $paths->namespace);
		if ( !($src = $page->fetch_source()) )
		{
			die('Access denied');
		}
		
		$diff = RenderMan::diff($src, $_POST['text']);
		if ( $diff == '<table class="diff"></table>' )
		{
			$diff = '<p>' . $lang->get('editor_msg_diff_empty') . '</p>';
		}
		
		echo '<div class="info-box">' . $lang->get('editor_msg_diff') . '</div>';
		echo $diff;
		
		break;
	case "protect":
		// echo PageUtils::protect($paths->page_id, $paths->namespace, (int)$_POST['level'], $_POST['reason']);
		
		if ( @$_POST['reason'] === '__ROLLBACK__' )
		{
			// __ROLLBACK__ is a keyword for log entries.
			die('"__ROLLBACK__" ain\'t gonna do it, buddy. Try to _not_ use reserved keywords next time, ok?');
		}
		
		$page = new PageProcessor($paths->page_id, $paths->namespace);
		header('Content-type: application/json');
		
		$result = $page->protect_page(intval($_POST['level']), $_POST['reason']);
		echo enano_json_encode($result);
		break;
	case "histlist":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		echo PageUtils::histlist($paths->page_id, $paths->namespace);
		break;
	case "rollback":
		$id = intval(@$_GET['id']);
		$page = new PageProcessor($paths->page_id, $paths->namespace);
		header('Content-type: application/json');
		
		$result = $page->rollback_log_entry($id);
		echo enano_json_encode($result);
		break;
	case "comments":
		require_once(ENANO_ROOT.'/includes/comment.php');
		$comments = new Comments($paths->page_id, $paths->namespace);
		if ( isset($_POST['data']) )
		{
			$comments->process_json($_POST['data']);
		}
		else
		{
			die('{ "mode" : "error", "error" : "No input" }');
		}
		break;
	case "rename":
		$page = new PageProcessor($paths->page_id, $paths->namespace);
		header('Content-type: application/json');
		
		$result = $page->rename_page($_POST['newtitle']);
		echo enano_json_encode($result);
		break;
	case "flushlogs":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		echo PageUtils::flushlogs($paths->page_id, $paths->namespace);
		break;
	case "deletepage":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		$reason = ( isset($_POST['reason']) ) ? $_POST['reason'] : false;
		if ( empty($reason) )
			die($lang->get('page_err_need_reason'));
		echo PageUtils::deletepage($paths->page_id, $paths->namespace, $reason);
		break;
	case "delvote":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		echo PageUtils::delvote($paths->page_id, $paths->namespace);
		break;
	case "resetdelvotes":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		echo PageUtils::resetdelvotes($paths->page_id, $paths->namespace);
		break;
	case "getstyles":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		echo PageUtils::getstyles($_GET['id']);
		break;
	case "catedit":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		echo PageUtils::catedit($paths->page_id, $paths->namespace);
		break;
	case "catsave":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		$categories = !empty($_POST['categories']) ? $_POST['categories'] : array();
		echo PageUtils::catsave($paths->page_id, $paths->namespace, $categories);
		break;
	case "setwikimode":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		echo PageUtils::setwikimode($paths->page_id, $paths->namespace, (int)$_GET['mode']);
		break;
	case "setpass":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		echo PageUtils::setpass($paths->page_id, $paths->namespace, $_POST['password']);
		break;
	case "fillusername":
		break;
	case "fillpagename":
		break;
	case "preview":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		$template->init_vars();
		echo PageUtils::genPreview($_POST['text']);
		break;
	case "transform":
		header('Content-type: text/javascript');
		if ( !isset($_GET['to']) )
		{
			echo enano_json_encode(array(
					'mode' => 'error',
					'error' => '"to" not specified'
				));
			break;
		}
		if ( !isset($_POST['text']) )
		{
			echo enano_json_encode(array(
					'mode' => 'error',
					'error' => '"text" not specified (must be on POST)'
				));
			break;
		}
		switch($_GET['to'])
		{
			case 'xhtml':
				$result = RenderMan::render($_POST['text'], RENDER_BLOCK | RENDER_NOSMILIES, false);
				break;
			case 'wikitext':
				$result = RenderMan::reverse_render($_POST['text']);
				break;
			default:
				$text =& $_POST['text'];
				$result = false;
				$code = $plugins->setHook('ajax_transform');
				foreach ( $code as $cmd )
				{
					eval($cmd);
				}
				if ( !$result )
				{
					echo enano_json_encode(array(
							'mode' => 'error',
							'error' => 'Invalid target format'
						));
					break;
				}
				break;
		}
		
		// mostly for debugging, but I suppose this could be useful elsewhere.
		if ( isset($_POST['plaintext']) )
			die($result);
		
		echo enano_json_encode(array(
				'mode' => 'transformed_text',
				'text' => $result
			));
		break;
	case "pagediff":
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		$id1 = ( isset($_GET['diff1']) ) ? (int)$_GET['diff1'] : false;
		$id2 = ( isset($_GET['diff2']) ) ? (int)$_GET['diff2'] : false;
		if(!$id1 || !$id2) { echo '<p>Invalid request.</p>'; $template->footer(); break; }
		if(!preg_match('#^([0-9]+)$#', (string)$_GET['diff1']) ||
			!preg_match('#^([0-9]+)$#', (string)$_GET['diff2']  )) { echo '<p>SQL injection attempt</p>'; $template->footer(); break; }
		echo PageUtils::pagediff($paths->page_id, $paths->namespace, $id1, $id2);
		break;
	case "jsres":
		die('// ERROR: this section is deprecated and has moved to includes/clientside/static/enano-lib-basic.js.');
		break;
	case "rdns":
		if(!$session->get_permissions('mod_misc')) die('Go somewhere else for your reverse DNS info!');
		$ip = $_GET['ip'];
		if ( !is_valid_ip($ip) )
		{
			echo $lang->get('acpsl_err_invalid_ip');
		}
		$rdns = gethostbyaddr($ip);
		if ( $rdns == $ip )
			echo $lang->get('acpsl_err_ptr_no_resolve');
		else echo $rdns;
		break;
	case 'acljson':
		require_once(ENANO_ROOT.'/includes/pageutils.php');
		$parms = ( isset($_POST['acl_params']) ) ? rawurldecode($_POST['acl_params']) : false;
		echo PageUtils::acl_json($parms);
		break;
	case 'theme_list':
		header('Content-type: application/json');
		
		$return = array();
		foreach ( $template->theme_list as $theme )
		{
			if ( $theme['enabled'] != 1 )
				continue;
			
			$return[] = array(
					'theme_name' => $theme['theme_name'],
					'theme_id' => $theme['theme_id'],
					'have_thumb' => file_exists(ENANO_ROOT . "/themes/{$theme['theme_id']}/preview.png")
				);
		}
		
		echo enano_json_encode($return);
		
		break;
	case "get_styles":
		if ( !preg_match('/^[A-z0-9_-]+$/', $_GET['theme_id']) )
			die(enano_json_encode(array()));
		
		$theme_id = $_GET['theme_id'];
		$return = array();
		
		if ( $dr = @opendir(ENANO_ROOT . "/themes/$theme_id/css/") )
		{
			while ( $dh = @readdir($dr) )
			{
				if ( preg_match('/\.css$/', $dh) && $dh != '_printable.css' )
				{
					$return[] = preg_replace('/\.css$/', '', $dh);
				}
			}
		}
		else
		{
			$return = array(
					'mode' => 'error',
					'error' => 'Could not open directory.'
				);
		}
		echo enano_json_encode($return);
		break;
	case "change_theme":
		if ( !isset($_POST['theme_id']) || !isset($_POST['style_id']) )
		{
			die(enano_json_encode(array('mode' => 'error', 'error' => 'Invalid parameter')));
		}
		if ( !preg_match('/^([a-z0-9_-]+)$/i', $_POST['theme_id']) || !preg_match('/^([a-z0-9_-]+)$/i', $_POST['style_id']) )
		{
			die(enano_json_encode(array('mode' => 'error', 'error' => 'Invalid parameter')));
		}
		if ( !file_exists(ENANO_ROOT . '/themes/' . $_POST['theme_id'] . '/css/' . $_POST['style_id'] . '.css') )
		{
			die(enano_json_encode(array('mode' => 'error', 'error' => 'Can\'t find theme file: ' . ENANO_ROOT . '/themes/' . $_POST['theme_id'] . '/css/' . $_POST['style_id'] . '.css')));;
		}
		if ( !$session->user_logged_in )
		{
			die(enano_json_encode(array('mode' => 'error', 'error' => 'You must be logged in to change your theme')));
		}
		// Just in case something slipped through...
		$theme_id = $db->escape($_POST['theme_id']);
		$style_id = $db->escape($_POST['style_id']);
		$e = $db->sql_query('UPDATE ' . table_prefix . "users SET theme = '$theme_id', style = '$style_id' WHERE user_id = $session->user_id;");
		if ( !$e )
			die( $db->get_error() );
		
		echo enano_json_encode(array(
				'success' => true
			));
		break;
	case 'get_tags':
		
		$ret = array('tags' => array(), 'user_level' => $session->user_level, 'can_add' => $session->get_permissions('tag_create'));
		$q = $db->sql_query('SELECT t.tag_id, t.tag_name, pg.pg_target IS NOT NULL AS used_in_acl, t.user_id FROM '.table_prefix.'tags AS t
			LEFT JOIN '.table_prefix.'page_groups AS pg
				ON ( ( pg.pg_type = ' . PAGE_GRP_TAGGED . ' AND pg.pg_target=t.tag_name ) OR ( pg.pg_type IS NULL AND pg.pg_target IS NULL ) )
			WHERE t.page_id=\'' . $db->escape($paths->page_id) . '\' AND t.namespace=\'' . $db->escape($paths->namespace) . '\';');
		if ( !$q )
			$db->_die();
		
		while ( $row = $db->fetchrow() )
		{
			$can_del = true;
			
			$perm = ( $row['user_id'] != $session->user_id ) ?
							'tag_delete_other' :
							'tag_delete_own';
			
			if ( $row['user_id'] == 1 && !$session->user_logged_in )
				// anonymous user trying to delete tag (hardcode blacklisted)
				$can_del = false;
				
			if ( !$session->get_permissions($perm) )
				$can_del = false;
			
			if ( $row['used_in_acl'] == 1 && !$session->get_permissions('edit_acl') && $session->user_level < USER_LEVEL_ADMIN )
				$can_del = false;
			
			$ret['tags'][] = array(
				'id' => $row['tag_id'],
				'name' => $row['tag_name'],
				'can_del' => $can_del,
				'acl' => ( $row['used_in_acl'] == 1 )
			);
		}
		
		echo enano_json_encode($ret);
		
		break;
	case 'addtag':
		$resp = array(
				'success' => false,
				'error' => 'No error',
				'can_del' => ( $session->get_permissions('tag_delete_own') && $session->user_logged_in ),
				'in_acl' => false
			);
		
		// first of course, are we allowed to tag pages?
		if ( !$session->get_permissions('tag_create') )
		{
			$resp['error'] = 'You are not permitted to tag pages.';
			die(enano_json_encode($resp));
		}
		
		// sanitize the tag name
		$tag = sanitize_tag($_POST['tag']);
		$tag = $db->escape($tag);
		
		if ( strlen($tag) < 2 )
		{
			$resp['error'] = 'Tags must consist of at least 2 alphanumeric characters.';
			die(enano_json_encode($resp));
		}
		
		// check if tag is already on page
		$q = $db->sql_query('SELECT 1 FROM '.table_prefix.'tags WHERE page_id=\'' . $db->escape($paths->page_id) . '\' AND namespace=\'' . $db->escape($paths->namespace) . '\' AND tag_name=\'' . $tag . '\';');
		if ( !$q )
			$db->_die();
		if ( $db->numrows() > 0 )
		{
			$resp['error'] = 'This page already has this tag.';
			die(enano_json_encode($resp));
		}
		$db->free_result();
		
		// tricky: make sure this tag isn't being used in some page group, and thus adding it could affect page access
		$can_edit_acl = ( $session->get_permissions('edit_acl') || $session->user_level >= USER_LEVEL_ADMIN );
		$q = $db->sql_query('SELECT 1 FROM '.table_prefix.'page_groups WHERE pg_type=' . PAGE_GRP_TAGGED . ' AND pg_target=\'' . $tag . '\';');
		if ( !$q )
			$db->_die();
		if ( $db->numrows() > 0 && !$can_edit_acl )
		{
			$resp['error'] = 'This tag is used in an ACL page group, and thus can\'t be added to a page by people without administrator privileges.';
			die(enano_json_encode($resp));
		}
		$resp['in_acl'] = ( $db->numrows() > 0 );
		$db->free_result();
		
		// we're good
		$q = $db->sql_query('INSERT INTO '.table_prefix.'tags(tag_name,page_id,namespace,user_id) VALUES(\'' . $tag . '\', \'' . $db->escape($paths->page_id) . '\', \'' . $db->escape($paths->namespace) . '\', ' . $session->user_id . ');');
		if ( !$q )
			$db->_die();
		
		$resp['success'] = true;
		$resp['tag'] = $tag;
		$resp['tag_id'] = $db->insert_id();
		
		echo enano_json_encode($resp);
		break;
	case 'deltag':
		
		$tag_id = intval($_POST['tag_id']);
		if ( empty($tag_id) )
			die('Invalid tag ID');
		
		$q = $db->sql_query('SELECT t.tag_id, t.user_id, t.page_id, t.namespace, pg.pg_target IS NOT NULL AS used_in_acl FROM '.table_prefix.'tags AS t
LEFT JOIN '.table_prefix.'page_groups AS pg
	ON ( pg.pg_id IS NULL OR ( pg.pg_target = t.tag_name AND pg.pg_type = ' . PAGE_GRP_TAGGED . ' ) )
WHERE t.tag_id=' . $tag_id . ';');
		
		if ( !$q )
			$db->_die();
		
		if ( $db->numrows() < 1 )
			die('Could not find a tag with that ID');
		
		$row = $db->fetchrow();
		$db->free_result();
		
		if ( $row['page_id'] == $paths->page_id && $row['namespace'] == $paths->namespace )
			$perms =& $session;
		else
			$perms = $session->fetch_page_acl($row['page_id'], $row['namespace']);
			
		$perm = ( $row['user_id'] != $session->user_id ) ?
							'tag_delete_other' :
							'tag_delete_own';
		
		if ( $row['user_id'] == 1 && !$session->user_logged_in )
			// anonymous user trying to delete tag (hardcode blacklisted)
			die('You are not authorized to delete this tag.');
			
		if ( !$perms->get_permissions($perm) )
			die('You are not authorized to delete this tag.');
		
		if ( $row['used_in_acl'] == 1 && !$perms->get_permissions('edit_acl') && $session->user_level < USER_LEVEL_ADMIN )
			die('You are not authorized to delete this tag.');
		
		// We're good
		$q = $db->sql_query('DELETE FROM '.table_prefix.'tags WHERE tag_id = ' . $tag_id . ';');
		if ( !$q )
			$db->_die();
		
		echo 'success';
		
		break;
	case 'ping':
		echo 'pong';
		break;
	default:
		die('Hacking attempt');
		break;
}

?>