/**
    * This file Copyright (c) 2008-2010 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.cms.beans.config;
  
  import info.magnolia.cms.core.Path;
  import info.magnolia.cms.core.SystemProperty;
  import info.magnolia.module.ModuleManagementException;
  import info.magnolia.module.ModuleManager;
  import info.magnolia.module.model.ModuleDefinition;
  import info.magnolia.module.model.PropertyDefinition;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.text.MessageFormat;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Properties;
  import java.util.Set;
  
  import javax.servlet.ServletContext;
  
  import info.magnolia.objectfactory.Components;
  import org.apache.commons.io.IOUtils;
  import org.apache.commons.lang.ArrayUtils;
  import org.apache.commons.lang.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  
  /**
   * This class is responsible for loading the various "magnolia.properties" files, merging them,
   * and substituting variables in their values.
   * @author pbracher
   * @author fgiust
   */
  public class PropertiesInitializer {
      private static final Logger log = LoggerFactory.getLogger(PropertiesInitializer.class);
  
      /**
       * The properties file containing the bean default implementations.
       */
      private static final String MGNL_BEANS_PROPERTIES = "/mgnl-beans.properties";
  
      /**
       * Placeholder prefix: "${"-
       */
      public static final String PLACEHOLDER_PREFIX = "${";
  
      /**
       * Placeholder suffix: "}".
       */
      public static final String PLACEHOLDER_SUFFIX = "}";
  
      /**
       * Context attribute prefix, to obtain a property definition like ${contextAttribute/property}, that can refer to
       * any context attribute.
       */
      public static final String CONTEXT_ATTRIBUTE_PLACEHOLDER_PREFIX = "contextAttribute/"; //$NON-NLS-1$
  
      /**
       * Context parameter prefix, to obtain a property definition like ${contextParam/property}, that can refer to any
       * context parameter.
       */
      public static final String CONTEXT_PARAM_PLACEHOLDER_PREFIX = "contextParam/"; //$NON-NLS-1$
 
     public static PropertiesInitializer getInstance() {
         return Components.getSingleton(PropertiesInitializer.class);
     }
 
     /**
      * Default value for the MAGNOLIA_INITIALIZATION_FILE parameter.
      */
     public static final String DEFAULT_INITIALIZATION_PARAMETER = //
     "WEB-INF/config/${servername}/${webapp}/magnolia.properties," //$NON-NLS-1$
         + "WEB-INF/config/${servername}/magnolia.properties," //$NON-NLS-1$
         + "WEB-INF/config/${webapp}/magnolia.properties," //$NON-NLS-1$
         + "WEB-INF/config/default/magnolia.properties," //$NON-NLS-1$
         + "WEB-INF/config/magnolia.properties"; //$NON-NLS-1$
 
     public void loadAllProperties(String propertiesFilesString, String rootPath) {
         // load mgnl-beans.properties first
         loadBeanProperties();
 
         loadAllModuleProperties();
 
         // complete or override with WEB-INF properties files
         loadPropertiesFiles(propertiesFilesString, rootPath);
 
         // complete or override with JVM system properties
         overloadWithSystemProperties();
 
         // resolve nested properties
         resolveNestedProperties();
     }
 
     private void resolveNestedProperties() {
 
         Properties sysProps = SystemProperty.getProperties();
 
         for (Iterator it = sysProps.keySet().iterator(); it.hasNext();) {
             String key = (String) it.next();
             String oldValue = (String) sysProps.get(key);
             String value = parseStringValue(oldValue, new HashSet<String>());
             SystemProperty.getProperties().put(key, value);
         }
 
     }
 
     public void loadAllModuleProperties() {
         // complete or override with modules' properties
         final ModuleManager moduleManager = ModuleManager.Factory.getInstance();
         try {
             final List<ModuleDefinition> moduleDefinitions = moduleManager.loadDefinitions();
             loadModuleProperties(moduleDefinitions);
         }
         catch (ModuleManagementException e) {
             log.error(e.getMessage());
             throw new RuntimeException(e); // TODO
         }
     }
 
     /**
      * Load the properties defined in the module descriptors. They can get overridden later in the properties files in
      * WEB-INF
      */
     protected void loadModuleProperties(List<ModuleDefinition> moduleDefinitions) {
         for (ModuleDefinition module : moduleDefinitions) {
             for (PropertyDefinition property : module.getProperties()) {
                 SystemProperty.setProperty(property.getName(), property.getValue());
             }
         }
     }
 
     public void loadPropertiesFiles(String propertiesLocationString, String rootPath) {
 
         String[] propertiesLocation = StringUtils.split(propertiesLocationString, ',');
 
         boolean found = false;
         // attempt to load each properties file at the given locations in reverse order: first files in the list
         // override the later ones
         for (int j = propertiesLocation.length - 1; j >= 0; j--) {
             String location = StringUtils.trim(propertiesLocation[j]);
 
             if (loadPropertiesFile(rootPath, location)) {
                 found = true;
             }
         }
 
         if (!found) {
             final String msg = MessageFormat.format("No configuration found using location list {0}. Base path is [{1}]", ArrayUtils.toString(propertiesLocation), rootPath); //$NON-NLS-1$
             log.error(msg);
             throw new ConfigurationException(msg);
         }
     }
 
     public void loadBeanProperties() {
         InputStream mgnlbeansStream = getClass().getResourceAsStream(MGNL_BEANS_PROPERTIES);
 
         if (mgnlbeansStream != null) {
             Properties mgnlbeans = new Properties();
             try {
                 mgnlbeans.load(mgnlbeansStream);
             }
             catch (IOException e) {
                 log.error("Unable to load {} due to an IOException: {}", MGNL_BEANS_PROPERTIES, e.getMessage());
             }
             finally {
                 IOUtils.closeQuietly(mgnlbeansStream);
             }
 
             for (Iterator iter = mgnlbeans.keySet().iterator(); iter.hasNext();) {
                 String key = (String) iter.next();
                 SystemProperty.setProperty(key, mgnlbeans.getProperty(key));
             }
 
         }
         else {
             log.warn("{} not found in the classpath. Check that all the needed implementation classes are defined in your custom magnolia.properties file.", MGNL_BEANS_PROPERTIES);
         }
     }
 
     /**
      * Try to load a magnolia.properties file.
      * @param rootPath
      * @param location
      * @return
      */
     public boolean loadPropertiesFile(String rootPath, String location) {
         final File initFile;
         if (Path.isAbsolute(location)) {
             initFile = new File(location);
         }
         else {
             initFile = new File(rootPath, location);
         }
 
         if (!initFile.exists() || initFile.isDirectory()) {
             log.debug("Configuration file not found with path [{}]", initFile.getAbsolutePath()); //$NON-NLS-1$
             return false;
         }
 
         InputStream fileStream = null;
         try {
             fileStream = new FileInputStream(initFile);
         }
         catch (FileNotFoundException e1) {
             log.debug("Configuration file not found with path [{}]", initFile.getAbsolutePath());
             return false;
         }
 
         try {
             SystemProperty.getProperties().load(fileStream);
             log.info("Loading configuration at {}", initFile.getAbsolutePath());//$NON-NLS-1$
         }
         catch (Exception e) {
             log.error(e.getMessage(), e);
             return false;
         }
         finally {
             IOUtils.closeQuietly(fileStream);
         }
         return true;
     }
 
     /**
      * Overload the properties with set system properties.
      */
     public void overloadWithSystemProperties() {
         Iterator it = SystemProperty.getProperties().keySet().iterator();
         while (it.hasNext()) {
             String key = (String) it.next();
             if (System.getProperties().containsKey(key)) {
                 log.info("system property found: {}", key);
                 String value = System.getProperty(key);
                 SystemProperty.setProperty(key, value);
             }
         }
     }
 
     /**
      * Returns the property files configuration string passed, replacing all the needed values: ${servername} will be
      * reaplced with the name of the server, ${webapp} will be replaced with webapp name, and ${contextAttribute/*} and
      * ${contextParam/*} will be replaced with the corresponding attributes or parameters taken from servlet context.
      * This can be very useful for all those application servers that has multiple instances on the same server, like
      * WebSphere. Typical usage in this case:
      * <code>WEB-INF/config/${servername}/${contextAttribute/com.ibm.websphere.servlet.application.host}/magnolia.properties</code>
      * @param context Servlet context
      * @param servername Server name
      * @param webapp Webapp name
      * @param propertiesFilesString Property file configuration string.
      * @return Property file configuration string with everything replaced.
      */
     public static String processPropertyFilesString(ServletContext context, String servername, String webapp,
         String propertiesFilesString) {
         // Replacing basic properties.
         propertiesFilesString = StringUtils.replace(propertiesFilesString, "${servername}", servername); //$NON-NLS-1$
         propertiesFilesString = StringUtils.replace(propertiesFilesString, "${webapp}", webapp); //$NON-NLS-1$
 
         // Replacing servlet context attributes (${contextAttribute/something})
         String[] contextAttributeNames = getNamesBetweenPlaceholders(propertiesFilesString, CONTEXT_ATTRIBUTE_PLACEHOLDER_PREFIX);
         if (contextAttributeNames != null) {
             for (String ctxAttrName : contextAttributeNames) {
                 if (ctxAttrName != null) {
                     // Some implementation may not accept a null as attribute key, but all should accept an empty
                     // string.
                     final String originalPlaceHolder = PLACEHOLDER_PREFIX + CONTEXT_ATTRIBUTE_PLACEHOLDER_PREFIX + ctxAttrName + PLACEHOLDER_SUFFIX;
                     final Object attrValue = context.getAttribute(ctxAttrName);
                     if (attrValue != null) {
                         propertiesFilesString = propertiesFilesString.replace(originalPlaceHolder, attrValue.toString());
                     }
                 }
             }
         }
 
         // Replacing servlet context parameters (${contextParam/something})
         String[] contextParamNames = getNamesBetweenPlaceholders(propertiesFilesString, CONTEXT_PARAM_PLACEHOLDER_PREFIX);
         if (contextParamNames != null) {
             for (String ctxParamName : contextParamNames) {
                 if (ctxParamName != null) {
                     // Some implementation may not accept a null as param key, but an empty string? TODO Check.
                     final String originalPlaceHolder = PLACEHOLDER_PREFIX + CONTEXT_PARAM_PLACEHOLDER_PREFIX + ctxParamName + PLACEHOLDER_SUFFIX;
                     final String paramValue = context.getInitParameter(ctxParamName);
                     if (paramValue != null) {
                         propertiesFilesString = propertiesFilesString.replace(originalPlaceHolder, paramValue);
                     }
                 }
             }
         }
 
         return propertiesFilesString;
     }
 
     private static String[] getNamesBetweenPlaceholders(String propertiesFilesString, String contextNamePlaceHolder) {
         final String[] names = StringUtils.substringsBetween(
                 propertiesFilesString,
                 PLACEHOLDER_PREFIX + contextNamePlaceHolder,
                 PLACEHOLDER_SUFFIX);
         return StringUtils.stripAll(names);
     }
 
     /**
      * Parse the given String value recursively, to be able to resolve nested placeholders. Partly borrowed from
      * org.springframework.beans.factory.config.PropertyPlaceholderConfigurer (original author: Juergen Hoeller)
      */
     protected String parseStringValue(String strVal, Set<String> visitedPlaceholders) {
 
         StringBuffer buf = new StringBuffer(strVal);
 
         int startIndex = strVal.indexOf(PLACEHOLDER_PREFIX);
         while (startIndex != -1) {
             int endIndex = -1;
 
             int index = startIndex + PLACEHOLDER_PREFIX.length();
             int withinNestedPlaceholder = 0;
             while (index < buf.length()) {
                 if (PLACEHOLDER_SUFFIX.equals(buf.subSequence(index, index + PLACEHOLDER_SUFFIX.length()))) {
                     if (withinNestedPlaceholder > 0) {
                         withinNestedPlaceholder--;
                         index = index + PLACEHOLDER_SUFFIX.length();
                     }
                     else {
                         endIndex = index;
                         break;
                     }
                 }
                 else if (PLACEHOLDER_PREFIX.equals(buf.subSequence(index, index + PLACEHOLDER_PREFIX.length()))) {
                     withinNestedPlaceholder++;
                     index = index + PLACEHOLDER_PREFIX.length();
                 }
                 else {
                     index++;
                 }
             }
 
             if (endIndex != -1) {
                 String placeholder = buf.substring(startIndex + PLACEHOLDER_PREFIX.length(), endIndex);
                 if (!visitedPlaceholders.add(placeholder)) {
 
                     log.warn("Circular reference detected in properties, \"{}\" is not resolvable", strVal);
                     return strVal;
                 }
                 // Recursive invocation, parsing placeholders contained in the placeholder key.
                 placeholder = parseStringValue(placeholder, visitedPlaceholders);
                 // Now obtain the value for the fully resolved key...
                 String propVal = SystemProperty.getProperty(placeholder);
                 if (propVal != null) {
                     // Recursive invocation, parsing placeholders contained in the
                     // previously resolved placeholder value.
                     propVal = parseStringValue(propVal, visitedPlaceholders);
                     buf.replace(startIndex, endIndex + PLACEHOLDER_SUFFIX.length(), propVal);
                     startIndex = buf.indexOf(PLACEHOLDER_PREFIX, startIndex + propVal.length());
                 }
                 else {
                     // Proceed with unprocessed value.
                     startIndex = buf.indexOf(PLACEHOLDER_PREFIX, endIndex + PLACEHOLDER_SUFFIX.length());
                 }
                 visitedPlaceholders.remove(placeholder);
             }
             else {
                 startIndex = -1;
             }
         }
 
         return buf.toString();
     }
 
 }