<?php
namespace W3TC;

class Util_Admin {
	/**
	 * Redirects when in WP Admin
	 *
	 * @param array   $params
	 * @param bool    $check_referrer
	 * @param string  $page
	 */
	static public function redirect( $params = array(), $check_referrer = false, $page = '' ) {
		$url = Util_Request::get_string( 'redirect' );
		$page_url = Util_Request::get_string( 'page' );
		if ( $url == '' ) {
			if ( $check_referrer && !empty( $_SERVER['HTTP_REFERER'] ) ) {
				$url = $_SERVER['HTTP_REFERER'];
			} else {
				$url = 'admin.php';
				if ( empty( $page ) )
					$page = $page_url;
				$params = array_merge( array(
						'page' => $page
					), $params );
			}
		}

		Util_Environment::redirect( $url, $params );
	}

	/**
	 * Redirect function to current admin page with errors and messages specified
	 *
	 * @param array   $params
	 * @param array   $errors
	 * @param array   $notes
	 * @param bool    $check_referrer
	 * @return void
	 */
	static public function redirect_with_custom_messages( $params, $errors = null,
		$notes = null, $check_referrer = false ) {
		if ( empty( $errors ) && Util_Admin::single_system_item( $notes ) ) {
			Util_Admin::redirect( array_merge( $params, array(
						'w3tc_note' => $notes[0] ) ), $check_referrer );
			return;
		}
		if ( Util_Admin::single_system_item( $errors ) && empty( $notes ) ) {
			Util_Admin::redirect( array_merge( $params, array(
						'w3tc_error' => $errors[0] ) ), $check_referrer );
			return;
		}

		$message_id = uniqid();
		set_transient( 'w3tc_message',
			array(
				$message_id => array( 'errors' => $errors, 'notes' => $notes )
			), 600 );

		Util_Admin::redirect( array_merge( $params, array(
					'w3tc_message' => $message_id ) ), $check_referrer );
	}



	/**
	 * Special redirect with ability to pass custom_message_id based on $data
	 *   query_string
	 *   actions - which actions to call on render
	 *   errors
	 *   notes
	 */
	static public function redirect_with_custom_messages2( $data ) {
		if ( !isset( $data['query_string']['page'] ) ) {
			$data['query_string']['page'] =
				Util_Request::get_string( 'page' );
			if ( $data['query_string']['page'] == 'w3tc_extensions' ) {
				$data['query_string']['extension'] =
					Util_Request::get_string( 'extension' );
				$data['query_string']['action'] =
					Util_Request::get_string( 'action' );
			}
		}

		$message_id = uniqid();
		set_transient( 'w3tc_message', array( $message_id => $data ), 600 );
		$data['query_string']['w3tc_message'] = $message_id;

		Util_Environment::redirect( 'admin.php', $data['query_string'] );
	}



	static public function custom_message_id( $errors = null, $notes = null ) {
		$message_id = uniqid();
		set_transient( 'w3tc_message',
			array(
				$message_id => array( 'errors' => $errors, 'notes' => $notes )
			), 600 );

		return 'w3tc_message=' . $message_id;
	}

	/*
	 * Checks if contains single message item
	 *
	 * @param $a array
	 * @return boolean
	 */
	static public function single_system_item( $a ) {
		if ( !is_array( $a ) || count( $a ) != 1 )
			return false;

		$first_key = array_keys( $a );
		$first_key = $first_key[0];
		$pos = strpos( $a[$first_key], ' ' );
		if ( $pos === false )
			return true;

		return false;
	}

	/**
	 * Save config, can't decline save process. (difference from action_save)
	 *
	 * Do some actions on config keys update
	 * Used in several places such as:
	 *
	 * 1. common config save
	 * 2. import settings
	 *
	 * @param Config  $current_config
	 * @param Config  $new_config
	 * @return bool
	 * @throws Exception
	 */
	static public function config_save( $current_config, $new_config ) {
		$master_config = ( $new_config->is_master() ? $new_config : Dispatcher::config_master() );

		if ( $master_config->get_integer( 'common.instance_id', 0 ) == 0 ) {
			$master_config->set( 'common.instance_id', mt_rand() );
			if ( !$new_config->is_master() )
				$master_config->save();
		}

		$old_config = new Config();
		$browsercache_dependencies = array();

		if ( $new_config->get_boolean( 'browsercache.enabled' ) ) {
			$browsercache_dependencies = array_merge( $browsercache_dependencies, array(
					'browsercache.rewrite',
					'browsercache.cssjs.replace',
					'browsercache.html.replace',
					'browsercache.other.replace'
				) );

			if ( $new_config->get_boolean( 'browsercache.cssjs.replace' ) ) {
				$browsercache_dependencies = array_merge( $browsercache_dependencies, array(
						'browsercache.cssjs.compression',
						'browsercache.cssjs.expires',
						'browsercache.cssjs.lifetime',
						'browsercache.cssjs.cache.control',
						'browsercache.cssjs.cache.policy',
						'browsercache.cssjs.etag',
						'browsercache.cssjs.w3tc'
					) );
			}

			if ( $new_config->get_boolean( 'browsercache.html.replace' ) ) {
				$browsercache_dependencies = array_merge( $browsercache_dependencies, array(
						'browsercache.html.compression',
						'browsercache.html.expires',
						'browsercache.html.lifetime',
						'browsercache.html.cache.control',
						'browsercache.html.cache.policy',
						'browsercache.html.etag',
						'browsercache.html.w3tc'
					) );
			}

			if ( $new_config->get_boolean( 'browsercache.other.replace' ) ) {
				$browsercache_dependencies = array_merge( $browsercache_dependencies, array(
						'browsercache.other.compression',
						'browsercache.other.expires',
						'browsercache.other.lifetime',
						'browsercache.other.cache.control',
						'browsercache.other.cache.policy',
						'browsercache.other.etag',
						'browsercache.other.w3tc'
					) );
			}

			$old_bc_dependencies_values = array();
			$new_bc_dependencies_values = array();

			foreach ( $browsercache_dependencies as $key ) {
				$old_bc_dependencies_values[] = $old_config->get( $key );
				$new_bc_dependencies_values[] = $new_config->get( $key );
			}

			if ( serialize( $old_bc_dependencies_values ) != serialize( $new_bc_dependencies_values ) ) {
				$state_note = Dispatcher::config_state_note();
				$state_note->set( 'common.show_note.flush_statics_needed', true );
			}
		}

		/**
		 * Show need empty page cache notification
		 */
		$cache_flush = Dispatcher::component( 'CacheFlush' );
		if ( $cache_flush->flushable_posts() ) {

			$pgcache_dependencies = array_merge( $browsercache_dependencies, array(
					'pgcache.debug',
					'pgcache.cache.query',
					'pgcache.cache.home',
					'pgcache.cache.feed',
					'pgcache.cache.nginx_handle_xml',
					'pgcache.cache.ssl',
					'pgcache.cache.404',
					'pgcache.cache.headers',
					'pgcache.compatibility',
					'pgcache.remove_charset',
					'pgcache.accept.uri',
					'pgcache.accept.files',
					'pgcache.accept.qs',
					'pgcache.late_init',
					'pgcache.mirrors.enabled',
					'pgcache.reject.front_page',
					'pgcache.reject.logged',
					'pgcache.reject.logged_roles',
					'pgcache.reject.uri',
					'pgcache.reject.ua',
					'pgcache.reject.cookie',
					'pgcache.reject.request_head',
					'dbcache.enabled',
					'objectcache.enabled',
					'minify.enabled',
					'mobile.enabled',
					'referrer.enabled'
				) );
			if ( $new_config->get_boolean( 'pgcache.mirrors.enabled' ) ) {
				$pgcache_dependencies = array_merge( $pgcache_dependencies, array(
						'pgcache.mirrors.home_urls'
					) );
			}
			if ( $new_config->get_boolean( 'dbcache.enabled' ) ) {
				$pgcache_dependencies = array_merge( $pgcache_dependencies, array(
						'dbcache.debug'
					) );
			}

			if ( $new_config->get_boolean( 'objectcache.enabled' ) ) {
				$pgcache_dependencies = array_merge( $pgcache_dependencies, array(
						'objectcache.debug'
					) );
			}

			if ( $new_config->get_boolean( 'minify.enabled' ) ) {
				$pgcache_dependencies = array_merge( $pgcache_dependencies, array(
						'minify.auto',
						'minify.debug',
						'minify.rewrite',
						'minify.html.enable',
						'minify.html.engine',
						'minify.html.inline.css',
						'minify.html.inline.js',
						'minify.html.strip.crlf',
						'minify.html.comments.ignore',
						'minify.css.enable',
						'minify.css.engine',
						'minify.css.groups',
						'minify.js.enable',
						'minify.js.engine',
						'minify.js.groups',
						'minify.htmltidy.options.clean',
						'minify.htmltidy.options.hide-comments',
						'minify.htmltidy.options.wrap',
						'minify.reject.logged',
						'minify.reject.ua',
						'minify.reject.uri'
					) );
			}
			/**
			 *
			 *
			 * @var W3_ModuleStatus $modules
			 */
			$modules = Dispatcher::component( 'ModuleStatus' );
			if ( $modules->is_running( 'cdn' ) ) {
				$pgcache_dependencies = array_merge( $pgcache_dependencies, array(
						'cdn.enabled',
						'cdn.debug',
						'cdn.engine',
						'cdn.uploads.enable',
						'cdn.includes.enable',
						'cdn.includes.files',
						'cdn.theme.enable',
						'cdn.theme.files',
						'cdn.minify.enable',
						'cdn.custom.enable',
						'cdn.custom.files',
						'cdn.ftp.domain',
						'cdn.ftp.ssl',
						'cdn.s3.cname',
						'cdn.s3.ssl',
						'cdn.cf.cname',
						'cdn.cf.ssl',
						'cdn.cf2.cname',
						'cdn.cf2.ssl',
						'cdn.rscf.cname',
						'cdn.rscf.ssl',
						'cdn.azure.cname',
						'cdn.azure.ssl',
						'cdn.mirror.domain',
						'cdn.mirror.ssl',
						'cdn.cotendo.domain',
						'cdn.cotendo.ssl',
						'cdn.edgecast.domain',
						'cdn.edgecast.ssl',
						'cdn.att.domain',
						'cdn.att.ssl',
						'cdn.reject.logged_roles',
						'cdn.reject.roles',
						'cdn.reject.ua',
						'cdn.reject.uri',
						'cdn.reject.files'
					) );
			} elseif ( $old_config->get_boolean( 'cdn.enabled' ) && !$new_config->get_boolean( 'cdn.enabled' ) ) {
				$pgcache_dependencies = array_merge( $pgcache_dependencies, array( 'cdn.enabled' ) );
			}

			if ( $new_config->get_boolean( 'mobile.enabled' ) ) {
				$pgcache_dependencies = array_merge( $pgcache_dependencies, array(
						'mobile.rgroups'
					) );
			}

			if ( $new_config->get_boolean( 'referrer.enabled' ) ) {
				$pgcache_dependencies = array_merge( $pgcache_dependencies, array(
						'referrer.rgroups'
					) );
			}


			if ( $new_config->get_boolean( 'browsercache.enabled' ) &&
				$new_config->get_string( 'pgcache.engine' ) == 'file_generic' ) {
				$pgcache_dependencies = array_merge( $pgcache_dependencies, array(
						'browsercache.html.last_modified',
						'browsercache.other.last_modified'
					) );
			}

			$old_pgcache_dependencies_values = array();
			$new_pgcache_dependencies_values = array();

			foreach ( $pgcache_dependencies as $pgcache_dependency ) {
				$old_pgcache_dependencies_values[] = $old_config->get( $pgcache_dependency );
				$new_pgcache_dependencies_values[] = $new_config->get( $pgcache_dependency );
			}

			if ( serialize( $old_pgcache_dependencies_values ) != serialize( $new_pgcache_dependencies_values ) ) {
				$state_note = Dispatcher::config_state_note();
				$state_note->set( 'common.show_note.flush_posts_needed', true );
			}
		}

		/**
		 * Show need empty minify notification
		 */
		if ( $current_config->get_boolean( 'minify.enabled' ) && $new_config->get_boolean( 'minify.enabled' ) && ( ( $new_config->get_boolean( 'minify.css.enable' ) && ( $new_config->get_boolean( 'minify.auto' ) || count( $new_config->get_array( 'minify.css.groups' ) ) ) ) || ( $new_config->get_boolean( 'minify.js.enable' ) && ( $new_config->get_boolean( 'minify.auto' ) || count( $new_config->get_array( 'minify.js.groups' ) ) ) ) ) ) {
			$minify_dependencies = array_merge( $browsercache_dependencies, array(
					'minify.auto',
					'minify.debug',
					'minify.options',
					'minify.symlinks',
					'minify.css.enable',
					'minify.js.enable'
				) );

			if ( $new_config->get_boolean( 'minify.css.enable' ) && ( $new_config->get_boolean( 'minify.auto' ) || count( $new_config->get_array( 'minify.css.groups' ) ) ) ) {
				$minify_dependencies = array_merge( $minify_dependencies, array(
						'minify.css.engine',
						'minify.css.method',
						'minify.css.strip.comments',
						'minify.css.strip.crlf',
						'minify.css.imports',
						'minify.css.groups',
						'minify.yuicss.path.java',
						'minify.yuicss.path.jar',
						'minify.yuicss.options.line-break',
						'minify.csstidy.options.remove_bslash',
						'minify.csstidy.options.compress_colors',
						'minify.csstidy.options.compress_font-weight',
						'minify.csstidy.options.lowercase_s',
						'minify.csstidy.options.optimise_shorthands',
						'minify.csstidy.options.remove_last_;',
						'minify.csstidy.options.remove_space_before_important',
						'minify.csstidy.options.case_properties',
						'minify.csstidy.options.sort_properties',
						'minify.csstidy.options.sort_selectors',
						'minify.csstidy.options.merge_selectors',
						'minify.csstidy.options.discard_invalid_selectors',
						'minify.csstidy.options.discard_invalid_properties',
						'minify.csstidy.options.css_level',
						'minify.csstidy.options.preserve_css',
						'minify.csstidy.options.timestamp',
						'minify.csstidy.options.template'
					) );
			}

			if ( $new_config->get_boolean( 'minify.js.enable' ) && ( $new_config->get_boolean( 'minify.auto' ) || count( $new_config->get_array( 'minify.js.groups' ) ) ) ) {
				$minify_dependencies = array_merge( $minify_dependencies, array(
						'minify.js.engine',
						'minify.js.method',
						'minify.js.combine.header',
						'minify.js.combine.body',
						'minify.js.combine.footer',
						'minify.js.strip.comments',
						'minify.js.strip.crlf',
						'minify.js.groups',
						'minify.yuijs.path.java',
						'minify.yuijs.path.jar',
						'minify.yuijs.options.line-break',
						'minify.yuijs.options.nomunge',
						'minify.yuijs.options.preserve-semi',
						'minify.yuijs.options.disable-optimizations',
						'minify.ccjs.path.java',
						'minify.ccjs.path.jar',
						'minify.ccjs.options.compilation_level',
						'minify.ccjs.options.formatting'
					) );
			}

			/**
			 *
			 *
			 * @var W3_ModuleStatus $modules
			 */
			$modules = Dispatcher::component( 'ModuleStatus' );
			if ( $modules->is_running( 'cdn' ) ) {
				$minify_dependencies = array_merge( $minify_dependencies, array(
						'cdn.engine', 'cdn.enabled'
					) );
			} elseif ( $old_config->get_boolean( 'cdn.enabled' ) && !$new_config->get_boolean( 'cdn.enabled' ) ) {
				$minify_dependencies = array_merge( $minify_dependencies, array( 'cdn.enabled' ) );
			}

			$old_minify_dependencies_values = array();
			$new_minify_dependencies_values = array();

			foreach ( $minify_dependencies as $minify_dependency ) {
				$old_minify_dependencies_values[] = $old_config->get( $minify_dependency );
				$new_minify_dependencies_values[] = $new_config->get( $minify_dependency );
			}

			if ( serialize( $old_minify_dependencies_values ) != serialize( $new_minify_dependencies_values ) ) {
				$state_note = Dispatcher::config_state_note();
				$state_note->set( 'minify.show_note.need_flush', true );
			}
		}

		if ( $new_config->get_boolean( 'cdn.enabled' ) && !Cdn_Util::is_engine_mirror( $new_config->get_string( 'cdn.engine' ) ) ) {
			/**
			 * Show notification when CDN enabled
			 */
			if ( !$old_config->get_boolean( 'cdn.enabled' ) ) {
				$state = Dispatcher::config_state();
				$state->set( 'cdn.show_note_cdn_upload', true );
				$state->save();
			}

			/**
			 * Show notification when Browser Cache settings changes
			 */
			$cdn_dependencies = array(
				'browsercache.enabled'
			);

			if ( $new_config->get_boolean( 'cdn.enabled' ) ) {
				$cdn_dependencies = array(
					'browsercache.cssjs.compression',
					'browsercache.cssjs.expires',
					'browsercache.cssjs.lifetime',
					'browsercache.cssjs.cache.control',
					'browsercache.cssjs.cache.policy',
					'browsercache.cssjs.etag',
					'browsercache.cssjs.w3tc',
					'browsercache.html.compression',
					'browsercache.html.expires',
					'browsercache.html.lifetime',
					'browsercache.html.cache.control',
					'browsercache.html.cache.policy',
					'browsercache.html.etag',
					'browsercache.html.w3tc',
					'browsercache.other.compression',
					'browsercache.other.expires',
					'browsercache.other.lifetime',
					'browsercache.other.cache.control',
					'browsercache.other.cache.policy',
					'browsercache.other.etag',
					'browsercache.other.w3tc'
				);
			}

			$old_cdn_dependencies_values = array();
			$new_cdn_dependencies_values = array();

			foreach ( $cdn_dependencies as $cdn_dependency ) {
				$old_cdn_dependencies_values[] = $old_config->get( $cdn_dependency );
				$new_cdn_dependencies_values[] = $new_config->get( $cdn_dependency );
			}

			if ( serialize( $old_cdn_dependencies_values ) != serialize( $new_cdn_dependencies_values ) ) {
				$state = Dispatcher::config_state();
				$state->set( 'cdn.show_note_cdn_reupload', true );
				$state->save();
			}
		}

		/**
		 * Show need empty object cache notification
		 */
		if ( $current_config->get_boolean( 'objectcache.enabled' ) ) {
			$objectcache_dependencies = array(
				'objectcache.groups.global',
				'objectcache.groups.nonpersistent'
			);

			$old_objectcache_dependencies_values = array();
			$new_objectcache_dependencies_values = array();

			foreach ( $objectcache_dependencies as $objectcache_dependency ) {
				$old_objectcache_dependencies_values[] = $old_config->get( $objectcache_dependency );
				$new_objectcache_dependencies_values[] = $new_config->get( $objectcache_dependency );
			}

			if ( serialize( $old_objectcache_dependencies_values ) != serialize( $new_objectcache_dependencies_values ) ) {
				$state_note = Dispatcher::config_state_note();
				$state_note->set( 'objectcache.show_note.flush_needed', true );
			}
		}

		do_action( 'w3tc_saved_options', $new_config );

		/**
		 * Save config
		 */
		try {
			$new_config->save();
		} catch ( \Exception $ex ) {
			// try to fix environment, it potentially can be fixed silently
			// dont show error here, it will be called again later
			// in admin_notices
			try {
				$environment = Dispatcher::component( 'Root_Environment' );
				$environment->fix_in_wpadmin( $new_config );
			} catch ( \Exception $ex ) {
			}

			// retry save process and complain now on failure
			try {
				$new_config->save();
			} catch ( \Exception $ex ) {
				throw new \Exception(
					'<strong>Can\'t change configuration</strong>: ' .
					$ex->getMessage() );
			}
		}

		$w3_plugin_cdn = Dispatcher::component( 'Cdn_Core_Admin' );

		/**
		 * Empty caches on engine change or cache enable/disable
		 */
		if ( $old_config->get_string( 'pgcache.engine' ) !=
			$new_config->get_string( 'pgcache.engine' ) ||
			$old_config->get_string( 'pgcache.enabled' ) !=
			$new_config->get_string( 'pgcache.enabled' ) ) {
			$pgcacheflush = Dispatcher::component( 'PgCache_Flush' );
			$v = $pgcacheflush->flush();
		}

		if ( $old_config->get_string( 'dbcache.engine' ) != $new_config->get_string( 'dbcache.engine' ) || $old_config->get_string( 'dbcache.enabled' ) != $new_config->get_string( 'dbcache.enabled' ) ) {
			w3tc_dbcache_flush();
		}

		if ( $old_config->get_string( 'objectcache.engine' ) != $new_config->get_string( 'objectcache.engine' ) || $old_config->get_string( 'objectcache.enabled' ) != $new_config->get_string( 'objectcache.enabled' ) ) {
			w3tc_objectcache_flush();
		}

		if ( $old_config->get_string( 'minify.engine' ) != $new_config->get_string( 'minify.engine' ) || $old_config->get_string( 'minify.enabled' ) != $new_config->get_string( 'minify.enabled' ) ) {
			w3tc_minify_flush();
		}

		/**
		 * Update CloudFront CNAMEs
		 */
		if ( $new_config->get_boolean( 'cdn.enabled' ) && in_array( $new_config->get_string( 'cdn.engine' ), array( 'cf', 'cf2' ) ) ) {
			if ( $new_config->get_string( 'cdn.engine' ) == 'cf' ) {
				$old_cnames = $old_config->get_array( 'cdn.cf.cname' );
				$new_cnames = $new_config->get_array( 'cdn.cf.cname' );
			} else {
				$old_cnames = $old_config->get_array( 'cdn.cf2.cname' );
				$new_cnames = $new_config->get_array( 'cdn.cf2.cname' );
			}
		}

		/**
		 * Refresh config
		 */
		$current_config->load();

		/**
		 * React to config changes
		 */
		$environment = Dispatcher::component( 'Root_Environment' );
		$environment->fix_on_event( $new_config, 'config_change', $old_config );

		/**
		 * Auto upload browsercache files to CDN
		 */
		if ( $new_config->get_boolean( 'cdn.enabled' ) && $new_config->get_string( 'cdn.engine' ) == 'ftp' ) {
			Util_Admin::cdn_delete_browsercache( $current_config );
			Util_Admin::cdn_upload_browsercache( $current_config );
		}

		return true;
	}



	/**
	 * Uploads minify files to CDN
	 *
	 * @return void
	 */
	static public function cdn_upload_minify() {
		$w3_plugin_cdn = Dispatcher::component( 'Cdn_Plugin' );
		$common = Dispatcher::component( 'Cdn_Core' );

		$files = $w3_plugin_cdn->get_files_minify();

		$upload = array();
		$results = array();

		foreach ( $files as $file ) {
			$upload[] = $common->build_file_descriptor( $common->docroot_filename_to_absolute_path( $file ),
				$common->uri_to_cdn_uri( $common->docroot_filename_to_uri( $file ) ) );
		}

		$common->upload( $upload, true, $results );
	}

	/**
	 * Uploads Browser Cache .htaccess to FTP
	 *
	 * @var Config $config
	 * @return void
	 */
	static public function cdn_upload_browsercache( $config ) {
		$common = Dispatcher::component( 'Cdn_Core' );
		$Cdn_Core_Admin = Dispatcher::component( 'Cdn_Core_Admin' );

		$ce = Dispatcher::component( 'Cdn_Environment' );
		$rules = $ce->rules_generate_for_ftp( $config );

		if ( $config->get_boolean( 'browsercache.enabled' ) ) {
			$be = Dispatcher::component( 'BrowserCache_Environment' );
			$rules .= $be->rules_cache_generate_for_ftp( $config );
		}

		$cdn_path = Util_Rule::get_cdn_rules_path();
		$tmp_path = W3TC_CACHE_TMP_DIR . '/' . $cdn_path;

		if ( @file_put_contents( $tmp_path, $rules ) ) {
			$results = array();
			$upload = array( $common->build_file_descriptor( $tmp_path, $cdn_path ) );

			$common->upload( $upload, true, $results );
		}
	}

	/**
	 * Deletes Browser Cache .htaccess from FTP
	 *
	 * @return void
	 */
	static public function cdn_delete_browsercache() {
		$common = Dispatcher::component( 'Cdn_Core' );

		$cdn_path = Util_Rule::get_cdn_rules_path();
		$tmp_path = W3TC_CACHE_TMP_DIR . '/' . $cdn_path;

		$results = array();
		$delete = array(
			$common->build_file_descriptor( $tmp_path, $cdn_path )
		);

		$common->delete( $delete, false, $results );
	}


	/**
	 * Returns cookie domain
	 *
	 * @return string
	 */
	static public function get_cookie_domain() {
		$site_url = get_option( 'siteurl' );
		$parse_url = @parse_url( $site_url );

		if ( $parse_url && !empty( $parse_url['host'] ) ) {
			return $parse_url['host'];
		}

		return $_SERVER['HTTP_HOST'];
	}

	/*
	 * Returns current w3tc admin page
	 */
	static public function get_current_page() {
		$page = Util_Request::get_string( 'page' );

		if ( substr( $page, 0, 5 ) == 'w3tc_' )
			return $page;

		return 'w3tc_dashboard';
	}

	/**
	 * Check if current page is a W3TC admin page
	 *
	 * @return bool
	 */
	static public function is_w3tc_admin_page() {
		if ( isset( $_GET['page'] ) && substr( $_GET['page'], 0, 5 ) == 'w3tc_' )
			return true;
		if ( isset( $_REQUEST['action'] ) && substr( $_REQUEST['action'], 0, 5 ) == 'w3tc_' )
			return true;

		return false;
	}


	/**
	 * Returns current WordPress page
	 *
	 * @return string
	 */
	static public function get_current_wp_page() {
		return Util_Request::get_string( 'page' );
	}
}
