<?php
/**
 * Akeeba Engine
 * The modular PHP5 site backup engine
 * @copyright Copyright (c)2006-2017 Nicholas K. Dionysopoulos / Akeeba Ltd
 * @license   GNU GPL version 3 or, at your option, any later version
 * @package   akeebaengine
 *
 */

namespace Akeeba\Engine\Util\Log;

// Protection against direct access
defined('AKEEBAENGINE') or die();

/**
 * The interface for Akeeba Engine logger objects
 */
interface LogInterface
{
	/**
	 * Open a new log instance with the specified tag. If another log is already open it is closed before switching to
	 * the new log tag. If the tag is null use the default log defined in the logging system.
	 *
	 * @param  string|null  $tag  The log to open
	 *
	 * @return void
	 */
	public function open($tag = null);

	/**
	 * Close the currently active log and set the current tag to null.
	 *
	 * @return  void
	 */
	public function close();

	/**
	 * Reset (remove entries) of the log with the specified tag.
	 *
	 * @param   string|null  $tag  The log to reset
	 *
	 * @return  void
	 */
	public function reset($tag = null);

	/**
	 * Add a message to the log
	 *
	 * @param   string  $level    One of the Psr\Log\LogLevel constants
	 * @param   string  $message  The message to log
	 * @param   array   $context  Currently not used. Left here for PSR-3 compatibility.
	 *
	 * @return  void
	 */
	public function log($level, $message, array $context = array());

	/**
	 * Temporarily pause log output. The log() method MUST respect this.
	 *
	 * @return  void
	 */
	public function pause();

	/**
	 * Resume the previously paused log output. The log() method MUST respect this.
	 *
	 * @return  void
	 */
	public function unpause();

	/**
	 * Returns the timestamp (in UNIX time long integer format) of the last log message written to the log with the
	 * specific tag. The timestamp MUST be read from the log itself, not from the logger object. It is used by the
	 * engine to find out the age of stalled backups which may have crashed.
	 *
	 * @param   string|null  $tag  The log tag for which the last timestamp is returned
	 *
	 * @return  int|null  The timestamp of the last log message, in UNIX time. NULL if we can't get the timestamp.
	 */
	public function getLastTimestamp($tag = null);
}