<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\log;

use Yii;
use yii\base\Component;
use yii\base\InvalidConfigException;

/**
 * Logger records logged messages in memory and sends them to different targets as needed.
 *
 * Logger is registered as a core application component and can be accessed using `Yii::$app->log`.
 * You can call the method [[log()]] to record a single log message. For convenience, a set of shortcut
 * methods are provided for logging messages of various severity levels via the [[Yii]] class:
 *
 * - [[Yii::trace()]]
 * - [[Yii::error()]]
 * - [[Yii::warning()]]
 * - [[Yii::info()]]
 * - [[Yii::beginProfile()]]
 * - [[Yii::endProfile()]]
 *
 * When enough messages are accumulated in the logger, or when the current request finishes,
 * the logged messages will be sent to different [[targets]], such as log files, emails.
 *
 * You may configure the targets in application configuration, like the following:
 *
 * ~~~
 * array(
 *     'components' => array(
 *         'log' => array(
 *             'targets' => array(
 *                 'file' => array(
 *                     'class' => 'yii\log\FileTarget',
 *                     'levels' => array('trace', 'info'),
 *                     'categories' => array('yii\*'),
 *                 ),
 *                 'email' => array(
 *                     'class' => 'yii\log\EmailTarget',
 *                     'levels' => array('error', 'warning'),
 *                     'emails' => array('admin@example.com'),
 *                 ),
 *             ),
 *         ),
 *     ),
 * )
 * ~~~
 *
 * Each log target can have a name and can be referenced via the [[targets]] property
 * as follows:
 *
 * ~~~
 * Yii::$app->log->targets['file']->enabled = false;
 * ~~~
 *
 * When the application ends or [[flushInterval]] is reached, Logger will call [[flush()]]
 * to send logged messages to different log targets, such as file, email, Web.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class Logger extends Component
{
	/**
	 * Error message level. An error message is one that indicates the abnormal termination of the
	 * application and may require developer's handling.
	 */
	const LEVEL_ERROR = 0x01;
	/**
	 * Warning message level. A warning message is one that indicates some abnormal happens but
	 * the application is able to continue to run. Developers should pay attention to this message.
	 */
	const LEVEL_WARNING = 0x02;
	/**
	 * Informational message level. An informational message is one that includes certain information
	 * for developers to review.
	 */
	const LEVEL_INFO = 0x04;
	/**
	 * Tracing message level. An tracing message is one that reveals the code execution flow.
	 */
	const LEVEL_TRACE = 0x08;
	/**
	 * Profiling message level. This indicates the message is for profiling purpose.
	 */
	const LEVEL_PROFILE = 0x40;
	/**
	 * Profiling message level. This indicates the message is for profiling purpose. It marks the
	 * beginning of a profiling block.
	 */
	const LEVEL_PROFILE_BEGIN = 0x50;
	/**
	 * Profiling message level. This indicates the message is for profiling purpose. It marks the
	 * end of a profiling block.
	 */
	const LEVEL_PROFILE_END = 0x60;


	/**
	 * @var integer how many messages should be logged before they are flushed from memory and sent to targets.
	 * Defaults to 1000, meaning the [[flush]] method will be invoked once every 1000 messages logged.
	 * Set this property to be 0 if you don't want to flush messages until the application terminates.
	 * This property mainly affects how much memory will be taken by the logged messages.
	 * A smaller value means less memory, but will increase the execution time due to the overhead of [[flush()]].
	 */
	public $flushInterval = 1000;
	/**
	 * @var array logged messages. This property is managed by [[log()]] and [[flush()]].
	 * Each log message is of the following structure:
	 *
	 * ~~~
	 * array(
	 *   [0] => message (mixed, can be a string or some complex data, such as an exception object)
	 *   [1] => level (integer)
	 *   [2] => category (string)
	 *   [3] => timestamp (float, obtained by microtime(true))
	 * )
	 * ~~~
	 */
	public $messages = array();
	/**
	 * @var array the log targets. Each array element represents a single [[Target|log target]] instance
	 * or the configuration for creating the log target instance.
	 */
	public $targets = array();


	/**
	 * @var string
	 */
	private $_tag;


	/**
	 * Initializes the logger by registering [[flush()]] as a shutdown function.
	 */
	public function init()
	{
		parent::init();
		foreach ($this->targets as $name => $target) {
			if (!$target instanceof Target) {
				$this->targets[$name] = Yii::createObject($target);
			}
		}
		register_shutdown_function(array($this, 'flush'), true);
	}

	/**
	 * Logs a message with the given type and category.
	 * If `YII_DEBUG` is true and `YII_TRACE_LEVEL` is greater than 0, then additional
	 * call stack information about application code will be appended to the message.
	 * @param string $message the message to be logged.
	 * @param integer $level the level of the message. This must be one of the following:
	 * `Logger::LEVEL_ERROR`, `Logger::LEVEL_WARNING`, `Logger::LEVEL_INFO`, `Logger::LEVEL_TRACE`,
	 * `Logger::LEVEL_PROFILE_BEGIN`, `Logger::LEVEL_PROFILE_END`.
	 * @param string $category the category of the message.
	 */
	public function log($message, $level, $category = 'application')
	{
		$time = microtime(true);
		if (YII_DEBUG && YII_TRACE_LEVEL > 0) {
			$traces = debug_backtrace();
			$count = 0;
			foreach ($traces as $trace) {
				if (isset($trace['file'], $trace['line']) && strpos($trace['file'], YII_PATH) !== 0) {
					$message .= "\nin {$trace['file']} ({$trace['line']})";
					if (++$count >= YII_TRACE_LEVEL) {
						break;
					}
				}
			}
		}
		$this->messages[] = array($message, $level, $category, $time);
		if ($this->flushInterval > 0 && count($this->messages) >= $this->flushInterval) {
			$this->flush();
		}
	}

	/**
	 * Flushes log messages from memory to targets.
	 * @param boolean $final whether this is a final call during a request.
	 */
	public function flush($final = false)
	{
		/** @var Target $target */
		foreach ($this->targets as $target) {
			if ($target->enabled) {
				$target->collect($this->messages, $final);
			}
		}
		$this->messages = array();
	}

	/**
	 * @return string a tag that uniquely identifies the current request.
	 */
	public function getTag()
	{
		if ($this->_tag === null) {
			$this->_tag = date('Ymd-His', microtime(true));
		}
		return $this->_tag;
	}

	/**
	 * @param string $tag a tag that uniquely identifies the current request.
	 */
	public function setTag($tag)
	{
		$this->_tag = $tag;
	}

	/**
	 * Returns the total elapsed time since the start of the current request.
	 * This method calculates the difference between now and the timestamp
	 * defined by constant `YII_BEGIN_TIME` which is evaluated at the beginning
	 * of [[YiiBase]] class file.
	 * @return float the total elapsed time in seconds for current request.
	 */
	public function getElapsedTime()
	{
		return microtime(true) - YII_BEGIN_TIME;
	}

	/**
	 * Returns the profiling results.
	 *
	 * By default, all profiling results will be returned. You may provide
	 * `$categories` and `$excludeCategories` as parameters to retrieve the
	 * results that you are interested in.
	 *
	 * @param array $categories list of categories that you are interested in.
	 * You can use an asterisk at the end of a category to do a prefix match.
	 * For example, 'yii\db\*' will match categories starting with 'yii\db\',
	 * such as 'yii\db\Connection'.
	 * @param array $excludeCategories list of categories that you want to exclude
	 * @return array the profiling results. Each array element has the following structure:
	 *  `array($token, $category, $time)`.
	 */
	public function getProfiling($categories = array(), $excludeCategories = array())
	{
		$timings = $this->calculateTimings();
		if (empty($categories) && empty($excludeCategories)) {
			return $timings;
		}

		foreach ($timings as $i => $timing) {
			$matched = empty($categories);
			foreach ($categories as $category) {
				$prefix = rtrim($category, '*');
				if (strpos($timing[1], $prefix) === 0 && ($timing[1] === $category || $prefix !== $category)) {
					$matched = true;
					break;
				}
			}

			if ($matched) {
				foreach ($excludeCategories as $category) {
					$prefix = rtrim($category, '*');
					foreach ($timings as $i => $timing) {
						if (strpos($timing[1], $prefix) === 0 && ($timing[1] === $category || $prefix !== $category)) {
							$matched = false;
							break;
						}
					}
				}
			}

			if (!$matched) {
				unset($timings[$i]);
			}
		}
		return array_values($timings);
	}

	/**
	 * Returns the statistical results of DB queries.
	 * The results returned include the number of SQL statements executed and
	 * the total time spent.
	 * @return array the first element indicates the number of SQL statements executed,
	 * and the second element the total time spent in SQL execution.
	 */
	public function getDbProfiling()
	{
		$timings = $this->getProfiling(array('yii\db\Command::query', 'yii\db\Command::execute'));
		$count = count($timings);
		$time = 0;
		foreach ($timings as $timing) {
			$time += $timing[1];
		}
		return array($count, $time);
	}

	private function calculateTimings()
	{
		$timings = array();

		$stack = array();
		foreach ($this->messages as $log) {
			list($token, $level, $category, $timestamp) = $log;
			if ($level == self::LEVEL_PROFILE_BEGIN) {
				$stack[] = $log;
			} elseif ($level == self::LEVEL_PROFILE_END) {
				if (($last = array_pop($stack)) !== null && $last[0] === $token) {
					$timings[] = array($token, $category, $timestamp - $last[3]);
				} else {
					throw new InvalidConfigException("Unmatched profiling block: $token");
				}
			}
		}

		$now = microtime(true);
		while (($last = array_pop($stack)) !== null) {
			$delta = $now - $last[3];
			$timings[] = array($last[0], $last[2], $delta);
		}

		return $timings;
	}
}