<?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;
use yii\helpers\VarDumper;
use yii\web\Request;

/**
 * Target is the base class for all log target classes.
 *
 * A log target object will filter the messages logged by [[Logger]] according
 * to its [[levels]] and [[categories]] properties. It may also export the filtered
 * messages to specific destination defined by the target, such as emails, files.
 *
 * Level filter and category filter are combinatorial, i.e., only messages
 * satisfying both filter conditions will be handled. Additionally, you
 * may specify [[except]] to exclude messages of certain categories.
 *
 * @property integer $levels The message levels that this target is interested in. This is a bitmap of level
 * values. Defaults to 0, meaning  all available levels. Note that the type of this property differs in getter
 * and setter. See [[getLevels()]] and [[setLevels()]] for details.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
abstract class Target extends Component
{
    /**
     * @var boolean whether to enable this log target. Defaults to true.
     */
    public $enabled = true;
    /**
     * @var array list of message categories that this target is interested in. Defaults to empty, meaning all categories.
     * You can use an asterisk at the end of a category so that the category may be used to
     * match those categories sharing the same common prefix. For example, 'yii\db\*' will match
     * categories starting with 'yii\db\', such as 'yii\db\Connection'.
     */
    public $categories = [];
    /**
     * @var array list of message categories that this target is NOT interested in. Defaults to empty, meaning no uninteresting messages.
     * If this property is not empty, then any category listed here will be excluded from [[categories]].
     * You can use an asterisk at the end of a category so that the category can be used to
     * match those categories sharing the same common prefix. For example, 'yii\db\*' will match
     * categories starting with 'yii\db\', such as 'yii\db\Connection'.
     * @see categories
     */
    public $except = [];
    /**
     * @var array list of the PHP predefined variables that should be logged in a message.
     * Note that a variable must be accessible via `$GLOBALS`. Otherwise it won't be logged.
     * Defaults to `['_GET', '_POST', '_FILES', '_COOKIE', '_SESSION', '_SERVER']`.
     */
    public $logVars = ['_GET', '_POST', '_FILES', '_COOKIE', '_SESSION', '_SERVER'];
    /**
     * @var callable a PHP callable that returns a string to be prefix to every exported message.
     * If not set, [[getMessagePrefix()]] will be used, which prefixes user IP, user ID and session ID
     * to every message. The signature of the callable should be `function ($message)`.
     */
    public $prefix;
    /**
     * @var integer how many messages should be accumulated before they are exported.
     * Defaults to 1000. Note that messages will always be exported when the application terminates.
     * Set this property to be 0 if you don't want to export messages until the application terminates.
     */
    public $exportInterval = 1000;
    /**
     * @var array the messages that are retrieved from the logger so far by this log target.
     * Please refer to [[Logger::messages]] for the details about the message structure.
     */
    public $messages = [];

    private $_levels = 0;

    /**
     * Exports log [[messages]] to a specific destination.
     * Child classes must implement this method.
     */
    abstract public function export();

    /**
     * Processes the given log messages.
     * This method will filter the given messages with [[levels]] and [[categories]].
     * And if requested, it will also export the filtering result to specific medium (e.g. email).
     * @param array $messages log messages to be processed. See [[Logger::messages]] for the structure
     * of each message.
     * @param boolean $final whether this method is called at the end of the current application
     */
    public function collect($messages, $final)
    {
        $this->messages = array_merge($this->messages, $this->filterMessages($messages, $this->getLevels(), $this->categories, $this->except));
        $count = count($this->messages);
        if ($count > 0 && ($final || $this->exportInterval > 0 && $count >= $this->exportInterval)) {
            if (($context = $this->getContextMessage()) !== '') {
                $this->messages[] = [$context, Logger::LEVEL_INFO, 'application', YII_BEGIN_TIME];
            }
            $this->export();
            $this->messages = [];
        }
    }

    /**
     * Generates the context information to be logged.
     * The default implementation will dump user information, system variables, etc.
     * @return string the context information. If an empty string, it means no context information.
     */
    protected function getContextMessage()
    {
        $context = [];
        foreach ($this->logVars as $name) {
            if (!empty($GLOBALS[$name])) {
                $context[] = "\${$name} = " . VarDumper::dumpAsString($GLOBALS[$name]);
            }
        }

        return implode("\n\n", $context);
    }

    /**
     * @return integer the message levels that this target is interested in. This is a bitmap of
     * level values. Defaults to 0, meaning  all available levels.
     */
    public function getLevels()
    {
        return $this->_levels;
    }

    /**
     * Sets the message levels that this target is interested in.
     *
     * The parameter can be either an array of interested level names or an integer representing
     * the bitmap of the interested level values. Valid level names include: 'error',
     * 'warning', 'info', 'trace' and 'profile'; valid level values include:
     * [[Logger::LEVEL_ERROR]], [[Logger::LEVEL_WARNING]], [[Logger::LEVEL_INFO]],
     * [[Logger::LEVEL_TRACE]] and [[Logger::LEVEL_PROFILE]].
     *
     * For example,
     *
     * ~~~
     * ['error', 'warning']
     * // which is equivalent to:
     * Logger::LEVEL_ERROR | Logger::LEVEL_WARNING
     * ~~~
     *
     * @param array|integer $levels message levels that this target is interested in.
     * @throws InvalidConfigException if an unknown level name is given
     */
    public function setLevels($levels)
    {
        static $levelMap = [
            'error' => Logger::LEVEL_ERROR,
            'warning' => Logger::LEVEL_WARNING,
            'info' => Logger::LEVEL_INFO,
            'trace' => Logger::LEVEL_TRACE,
            'profile' => Logger::LEVEL_PROFILE,
        ];
        if (is_array($levels)) {
            $this->_levels = 0;
            foreach ($levels as $level) {
                if (isset($levelMap[$level])) {
                    $this->_levels |= $levelMap[$level];
                } else {
                    throw new InvalidConfigException("Unrecognized level: $level");
                }
            }
        } else {
            $this->_levels = $levels;
        }
    }

    /**
     * Filters the given messages according to their categories and levels.
     * @param array $messages messages to be filtered
     * @param integer $levels the message levels to filter by. This is a bitmap of
     * level values. Value 0 means allowing all levels.
     * @param array $categories the message categories to filter by. If empty, it means all categories are allowed.
     * @param array $except the message categories to exclude. If empty, it means all categories are allowed.
     * @return array the filtered messages.
     */
    public static function filterMessages($messages, $levels = 0, $categories = [], $except = [])
    {
        foreach ($messages as $i => $message) {
            if ($levels && !($levels & $message[1])) {
                unset($messages[$i]);
                continue;
            }

            $matched = empty($categories);
            foreach ($categories as $category) {
                if ($message[2] === $category || substr($category, -1) === '*' && strpos($message[2], rtrim($category, '*')) === 0) {
                    $matched = true;
                    break;
                }
            }

            if ($matched) {
                foreach ($except as $category) {
                    $prefix = rtrim($category, '*');
                    if (strpos($message[2], $prefix) === 0 && ($message[2] === $category || $prefix !== $category)) {
                        $matched = false;
                        break;
                    }
                }
            }

            if (!$matched) {
                unset($messages[$i]);
            }
        }

        return $messages;
    }

    /**
     * Formats a log message.
     * The message structure follows that in [[Logger::messages]].
     * @param array $message the log message to be formatted.
     * @return string the formatted message
     */
    public function formatMessage($message)
    {
        list($text, $level, $category, $timestamp) = $message;
        $level = Logger::getLevelName($level);
        if (!is_string($text)) {
            $text = var_export($text, true);
        }

        $prefix = $this->prefix ? call_user_func($this->prefix, $message) : $this->getMessagePrefix($message);

        return date('Y-m-d H:i:s', $timestamp) . " {$prefix}[$level][$category] $text";
    }

    /**
     * Returns a string to be prefixed to the given message.
     * The default implementation will return user IP, user ID and session ID as a prefix.
     * @param array $message the message being exported
     * @return string the prefix string
     */
    public function getMessagePrefix($message)
    {
        $request = Yii::$app->getRequest();
        $ip = $request instanceof Request ? $request->getUserIP() : '-';
        /** @var \yii\web\User $user */
        $user = Yii::$app->has('user', true) ? Yii::$app->get('user') : null;
        $userID = $user ? $user->getId(false) : '-';
        /** @var \yii\web\Session $session */
        $session = Yii::$app->has('session', true) ? Yii::$app->get('session') : null;
        $sessionID = $session && $session->getIsActive() ? $session->getId() : '-';
        return "[$ip][$userID][$sessionID]";
    }
}
