<?php
/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 * @package log4php
 */

/**
 * Converts XML configuration files to a PHP array.
 * 
 * @package log4php
 * @subpackage configurators
 * @license http://www.apache.org/licenses/LICENSE-2.0 Apache License, Version 2.0
 * @version $Revision$
 * @since 2.2
 */
class LoggerConfigurationAdapterXML implements LoggerConfigurationAdapter
{
	/** Path to the XML schema used for validation. */
	const SCHEMA_PATH = '/../xml/log4php.xsd';
	
	private $config = array(
		'appenders' => array(),
		'loggers' => array(),
		'renderers' => array(),
	);
	
	public function convert($url) {
		$xml = $this->loadXML($url);
		
		$this->parseConfiguration($xml);

		// Parse the <root> node
		if (isset($xml->root)) {		
			$this->parseRootLogger($xml->root);
		}
		
		// Process <logger> nodes
		foreach($xml->logger as $logger) {
			$this->parseLogger($logger);
		} 
		
		// Process <appender> nodes
		foreach($xml->appender as $appender) {
			$this->parseAppender($appender);
		}
		
		// Process <renderer> nodes
		foreach($xml->renderer as $rendererNode) {
			$this->parseRenderer($rendererNode);
		}
		return $this->config;
	}
	
	/**
	 * Loads and validates the XML.
	 * @param string $url Input XML.
	 */
	private function loadXML($url) {
		if (!file_exists($url)) {
			throw new LoggerException("File [$url] does not exist.");
		}

		libxml_clear_errors();
		$oldValue = libxml_use_internal_errors(true);
		
		// Load XML
		$xml = @simplexml_load_file($url);
		if ($xml === false) {
			
			$errorStr = "";
			foreach(libxml_get_errors() as $error) {
				$errorStr .= $error->message;
			}
			
			throw new LoggerException("Error loading configuration file: " . trim($errorStr));
		}
		
		libxml_clear_errors();
		libxml_use_internal_errors($oldValue);
		
		return $xml;
	}
	
	/**
	 * Parses the <configuration> node.
	 */
	private function parseConfiguration(SimpleXMLElement $xml) {
		$attributes = $xml->attributes();
		if (isset($attributes['threshold'])) {
			$this->config['threshold'] = (string) $attributes['threshold'];
		}
	}
	
	/** Parses an <appender> node. */
	private function parseAppender(SimpleXMLElement $node) {
		$name = $this->getAttributeValue($node, 'name');
		if (empty($name)) {
			$this->warn("An <appender> node is missing the required 'name' attribute. Skipping appender definition.");
			return;
		}
		
		$appender = array();
		$appender['class'] = $this->getAttributeValue($node, 'class');
		
		if (isset($node['threshold'])) {
			$appender['threshold'] = $this->getAttributeValue($node, 'threshold');
		}
		
		if (isset($node->layout)) {
			$appender['layout']= $this->parseLayout($node->layout, $name);
		}
		
		if (count($node->param) > 0) {
			$appender['params'] = $this->parseParameters($node);
		}
		
		foreach($node->filter as $filterNode) {
			$appender['filters'][] = $this->parseFilter($filterNode);
		}
		
		$this->config['appenders'][$name] = $appender;
	}
	
	/** Parses a <layout> node. */
	private function parseLayout(SimpleXMLElement $node, $appenderName) {
		$layout = array();
		$layout['class'] = $this->getAttributeValue($node, 'class');
		
		if (count($node->param) > 0) {
			$layout['params'] = $this->parseParameters($node);
		}
		
		return $layout;
	}
	/** Parses any <param> child nodes returning them in an array. */
	private function parseParameters($paramsNode) {
		$params = array();

		foreach($paramsNode->param as $paramNode) {
			if (empty($paramNode['name'])) {
				$this->warn("A <param> node is missing the required 'name' attribute. Skipping parameter.");
				continue;
			}
			
			$name = $this->getAttributeValue($paramNode, 'name');
			$value = $this->getAttributeValue($paramNode, 'value');
			
			$params[$name] = $value;
		}

		return $params;
	}
	
	/** Parses a <root> node. */
	private function parseRootLogger(SimpleXMLElement $node) {
		$logger = array();
		
		if (isset($node->level)) {
			$logger['level'] = $this->getAttributeValue($node->level, 'value');
		}
		
		$logger['appenders'] = $this->parseAppenderReferences($node);
		
		$this->config['rootLogger'] = $logger;
	}
	
	/** Parses a <logger> node. */
	private function parseLogger(SimpleXMLElement $node) {
		$logger = array();
		
		$name = $this->getAttributeValue($node, 'name');
		if (empty($name)) {
			$this->warn("A <logger> node is missing the required 'name' attribute. Skipping logger definition.");
			return;
		}
		
		if (isset($node->level)) {
			$logger['level'] = $this->getAttributeValue($node->level, 'value');
		}
		
		if (isset($node['additivity'])) {
			$logger['additivity'] = $this->getAttributeValue($node, 'additivity');
		}
		
		$logger['appenders'] = $this->parseAppenderReferences($node);

		// Check for duplicate loggers
		if (isset($this->config['loggers'][$name])) {
			$this->warn("Duplicate logger definition [$name]. Overwriting.");
		}
		
		$this->config['loggers'][$name] = $logger;
	}
	
	/** 
	 * Parses a <logger> node for appender references and returns them in an array.
	 * 
	 * Previous versions supported appender-ref, as well as appender_ref so both
	 * are parsed for backward compatibility.
	 */
	private function parseAppenderReferences(SimpleXMLElement $node) {
		$refs = array();
		foreach($node->appender_ref as $ref) {
			$refs[] = $this->getAttributeValue($ref, 'ref');
		}
		
		foreach($node->{'appender-ref'} as $ref) {
			$refs[] = $this->getAttributeValue($ref, 'ref');
		}

		return $refs;
	}
	
	/** Parses a <filter> node. */
	private function parseFilter($filterNode) {
		$filter = array();
		$filter['class'] = $this->getAttributeValue($filterNode, 'class');
		
		if (count($filterNode->param) > 0) {
			$filter['params'] = $this->parseParameters($filterNode);
		}
		
		return $filter;
	}
	
	/** Parses a <renderer> node. */
	private function parseRenderer(SimpleXMLElement $node) {
		$renderedClass = $this->getAttributeValue($node, 'renderedClass');
		$renderingClass = $this->getAttributeValue($node, 'renderingClass');
		
		$this->config['renderers'][] = compact('renderedClass', 'renderingClass');
	}
	
	// ******************************************
	// ** Helper methods                       **
	// ******************************************
	
	private function getAttributeValue(SimpleXMLElement $node, $name) {
		return isset($node[$name]) ? (string) $node[$name] : null;
	}
	
	private function warn($message) {
		trigger_error("log4php: " . $message, E_USER_WARNING);
	}
}