/*

  * Copyright 2007-2008 The Kuali Foundation

  *

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  *

  * 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 org.kuali.rice.core.config;

 import org.apache.commons.lang.StringUtils;

 import org.apache.commons.lang.text.StrLookup;

 import org.apache.commons.lang.text.StrSubstitutor;

 import org.apache.log4j.Logger;

 import org.kuali.rice.core.util.RiceUtilities;

 import org.kuali.rice.core.util.XmlJotter;

 import org.w3c.dom.Document;

 import org.w3c.dom.Element;

 import org.w3c.dom.Node;

 import org.w3c.dom.NodeList;

 import org.xml.sax.SAXException;

 import javax.xml.parsers.DocumentBuilderFactory;

 import javax.xml.parsers.ParserConfigurationException;

 import javax.xml.transform.TransformerException;

 import java.io.IOException;

 import java.io.InputStream;

 import java.util.LinkedHashMap;

 import java.util.Map;

 import java.util.Random;

 /**

  * ConfigParser implementation that supports a hierarchy of configs, in which 

  * configs can include other configs.  Variable tokens are resolved at parse time,

  * in the order in which they are encountered.  This class relies on Spring for resource

  * loading and Apache Commons Lang for variable replacement.

  *

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class ConfigParserImpl implements ConfigParser {

     // keep the same random

     private static final Random RANDOM = new Random();

     private static final Logger LOG = Logger.getLogger(ConfigParserImpl.class);

     private static final String IMPORT_NAME = "config.location";

     private static final String PARAM_NAME= "param";

     private static final String NAME_ATTR = "name";

     private static final String OVERRIDE_ATTR = "override";

     private static final String RANDOM_ATTR = "random";

     private static final String INDENT = "  ";

     public static final String ALTERNATE_BUILD_LOCATION_KEY = "alt.build.location";

     /**

      * A StrLookup implementation that delegates to System properties if the key is not

      * found in the supplied map.

      * @author Kuali Rice Team (rice.collab@kuali.org)

      */

     private static class SystemPropertiesDelegatingStrLookup extends StrLookup {

         private final Map map;

         private SystemPropertiesDelegatingStrLookup(Map map) {

             this.map = map;

         }

         @Override

         public String lookup(String key) {

             Object o = map.get(key);

             if (o != null) {

                 return String.valueOf(o);

             } else {

                 String s = System.getProperty(key);

                 if (s != null) {

                     return s;

                 } else {

                     // implement behavior for missing property here...e.g. return ""

                     // returning null will result in the substitutor not substituting

                     return "";

                 }

             }

         }

     }

     /**

      * @see org.kuali.rice.core.config.ConfigParser#parse(java.lang.String[])

      */

     public void parse(Map props, String[] locations) throws IOException {

         LinkedHashMap params = new LinkedHashMap();

         params.putAll(props);

         parse(params, locations);

         props.putAll(params);

     }

     /**

      * Parses a list of locations

      * @param params the current parameter map

      * @param locations a list of locations to parse

      * @throws IOException

      */

     protected void parse(LinkedHashMap<String, Object> params, String[] locations) throws IOException {

         StrSubstitutor subs = new StrSubstitutor(new SystemPropertiesDelegatingStrLookup(params));

         for (String location: locations) {

             parse(params, location, subs, 0);

         }

     }

     /**

      * Parses a single config location

      * @param params the current parameter map

      * @param location the location to parse

      * @param subs a StrSubstitutor used to substitute variable tokens

      * @throws IOException

      */

     protected void parse(LinkedHashMap<String, Object> params, String location, StrSubstitutor subs, int depth) throws IOException {

         InputStream configStream = RiceUtilities.getResourceAsStream(location);

         if (configStream == null) {

             LOG.warn("###############################");

             LOG.warn("#");

             LOG.warn("# Configuration file '" + location + "' not found!");

             LOG.warn("#");

             LOG.warn("###############################");

             return;

         }

         final String prefix = StringUtils.repeat(INDENT, depth); 

         LOG.info(prefix + "+ Parsing config: " + location);

         Document doc;

         try {

             doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(configStream);

             if (LOG.isDebugEnabled()) {

                 LOG.debug("Contents of config " + location + ": \n" + XmlJotter.jotNode(doc, true));

             }

         } catch (SAXException se) {

             IOException ioe = new IOException("Error parsing config resource: " + location);

             ioe.initCause(se);

             throw ioe;

         } catch (ParserConfigurationException pce) {

             IOException ioe = new IOException("Unable to obtain document builder");

             ioe.initCause(pce);

             throw ioe;

         } finally {

             configStream.close();

         }

         Element root = doc.getDocumentElement();

         // ignore the actual type of the document element for now

         // so that plugin descriptors can be parsed

         NodeList list = root.getChildNodes();

         StringBuilder content = new StringBuilder();

         for (int i = 0; i < list.getLength(); i++) {

             Node node = list.item(i);

             if (node.getNodeType() != Node.ELEMENT_NODE)

                 continue;

             if (!PARAM_NAME.equals(node.getNodeName())) {

                 LOG.warn("Encountered non-param config node: " + node.getNodeName());

                 continue;

             }

             Element param = (Element) node;

             String name = param.getAttribute(NAME_ATTR);

             if (name == null) {

                 LOG.error("Unnamed parameter in config resource '" + location + "': " + XmlJotter.jotNode(param));

                 continue;

             }

             Boolean override = Boolean.TRUE;

             String overrideVal = param.getAttribute(OVERRIDE_ATTR);

             if (!StringUtils.isEmpty(overrideVal)) {

                 override = Boolean.valueOf(overrideVal);

             }

             content.setLength(0);

             // accumulate all content (preserving any XML content)

             getNodeValue(name, location, param, content);

             String value = subs.replace(content);

             if (LOG.isDebugEnabled()) {

                 LOG.debug(prefix + INDENT + "* " + name + "=[" + ConfigLogger.getDisplaySafeValue(name, value) + "]");

             }

             if (IMPORT_NAME.equals(name)) {

                 // what is this...we don't follow a string with this substring in it? i.e. if the value does not

                 // resolve then don't try to follow it (it won't find it anyway; this is the case for any path

                 // with unresolved params...)?

                 if (!value.contains(ALTERNATE_BUILD_LOCATION_KEY)) {

                     parse(params, value, subs, depth + 1);

                 }

             } else {

                 if (Boolean.valueOf(param.getAttribute(RANDOM_ATTR))) {

                     // this is a special type of property whose value is a randomly generated number in the range specified

                     value = String.valueOf(generateRandomInteger(value));   

                 }

                 setParam(params, override, name, value, prefix + INDENT);

             }

         }

         LOG.info(prefix + "- Parsed config: " + location);

     }

     /**

      * Generates a random integer in the range specified by the specifier, in the format: min-max

      * @param rangeSpec a range specification, 'min-max'

      * @return a random integer in the range specified by the specifier, in the format: min-max

      */

     protected int generateRandomInteger(String rangeSpec) {

         String[] range = rangeSpec.split("-");

         if (range.length != 2) {

             throw new RuntimeException("Invalid range specifier: " + rangeSpec);

         }

         int from = Integer.parseInt(range[0].trim());

         int to = Integer.parseInt(range[1].trim());

         if (from > to) {

             int tmp = from;

             from = to;

             to = tmp;

         }

         int num;

         // not very random huh...

         if (from == to) {

             num = from;

         } else {

             num = from + RANDOM.nextInt((to - from) + 1);

         }

         return num;

     }

     /**

      * @param name name of the node

      * @param location config file location

      * @param n the node

      * @param sb a StringBuilder into which to set contents of the node, preserving any XML content

      * @throws IOException

      */

     protected void getNodeValue(String name, String location, Node n, StringBuilder sb) throws IOException {

         NodeList children = n.getChildNodes();

         // accumulate all content (preserving any XML content)

         try {

             sb.setLength(0);

             for (int j = 0; j < children.getLength(); j++) {

                 sb.append(XmlJotter.writeNode(children.item(j), true));

             }

         } catch (TransformerException te) {

             IOException ioe = new IOException("Error obtaining parameter '" + name + "' from config resource: " + location);

             ioe.initCause(te);

             throw ioe;

         }

     }

     /**

      * Sets a parameter in the parameter map, based on the override setting and whether a parameter of the same

      * name is already present 

      * @param params the current parameter map

      * @param override whether to override a previous parameter definition

      * @param name the parameter name

      * @param value the parameter value

      */

     private void setParam(Map params, Boolean override, String name, String value, String indent) {

         if (value == null || "null".equals(value)) {

             LOG.warn("Not adding property [" + name + "] because it is null - most likely no token could be found for substituion.");

             return;

         }

         if (override) {

             final String message;

             Object existingValue = params.get(name);

             if (existingValue != null) {

                 //if (!existingValue.equals(value)) {

                     message = indent + "Overriding property " + name + "=[" + existingValue + "] with " + name + "=[" + value + "]"; 

                 //}

                 params.remove(name);

             } else {

                 message = indent + "Defining property " + name + "=[" + value + "]";

             }

             LOG.debug(message);

             params.put(name, value);

         } else if (!params.containsKey(name)) {

             LOG.debug(indent + "Defining property " + name + "=[" + value + "]");

             params.put(name, value);

         } else {

             LOG.debug(indent + "Not overriding existing parameter: " + name + " '" + params.get(name) + "'");

         }

     }

 }