/*

  * 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 org.apache.any23.configuration;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 import java.io.IOException;

 import java.util.Properties;

 /**

  * Default implementation of {@link Configuration}.

  * The default property values are read from the

  * <i>/default-configuration.properties</i> properties file

  * in classpath.

  *

  * @author Michele Mostarda (michele.mostarda@gmail.com)

  */

 public class DefaultConfiguration implements Configuration {

     /**

      * Default configuration file.

      */

     public static final String DEFAULT_CONFIG_FILE = "/default-configuration.properties";

     public static final String FLAG_PROPERTY_ON  = "on";

     public static final String FLAG_PROPERTY_OFF = "off";

     protected static final Logger logger = LoggerFactory.getLogger(DefaultConfiguration.class);

     protected static final DefaultConfiguration singleton = new DefaultConfiguration();

     protected final Properties properties;

     /**

      * @return the singleton configuration instance.

      *         Such instance is unmodifiable.

      */

     public static synchronized DefaultConfiguration singleton() {

         return singleton;

     }

     /**

      * @return a copy of the singleton instance. such instance is modifiable.

      */

     public static synchronized ModifiableConfiguration copy() {

         final Properties propertiesCopy = (Properties) singleton.properties.clone();

         return new DefaultModifiableConfiguration(propertiesCopy);

     }

     private static Properties loadDefaultProperties() {

         final Properties properties = new Properties();

         try {

             properties.load( DefaultConfiguration.class.getResourceAsStream(DEFAULT_CONFIG_FILE) );

         } catch (IOException ioe) {

             throw new IllegalStateException("Error while loading default configuration.", ioe);

         }

         return properties;

     }

     protected DefaultConfiguration(Properties properties) {

         this.properties = properties;

     }

     private DefaultConfiguration() {

         this( loadDefaultProperties() );

     }

     public synchronized String[] getProperties() {

         return properties.keySet().toArray( new String[properties.size()] );

     }

     public synchronized boolean defineProperty(String propertyName) {

         return properties.containsKey(propertyName);

     }

     public synchronized String getProperty(String propertyName, String defaultValue) {

         final String value = getPropertyValue(propertyName);

         if(value == null) {

             return defaultValue;

         }

         return value;

     }

     public synchronized String getPropertyOrFail(String propertyName) {

         final String propertyValue = getPropertyValue(propertyName);

         if(propertyValue == null) {

             throw new IllegalArgumentException("The property '" + propertyName + "' is expected to be declared.");

         }

         if(  propertyValue.trim().length() == 0) {

             throw new IllegalArgumentException(

                     "Invalid value '" + propertyValue + "' for property '" + propertyName + "'"

             );

         }

         return propertyValue;

     }

     public synchronized int getPropertyIntOrFail(String propertyName) {

         final String value = getPropertyOrFail(propertyName);

         final String trimValue = value.trim();

         try {

             return Integer.parseInt(trimValue);

         } catch (NumberFormatException nfe) {

             throw new NumberFormatException("The retrieved property is not a valid Integer: '" + trimValue + "'");

         }

     }

     public synchronized boolean getFlagProperty(final String propertyName) {

         final String value = getPropertyOrFail(propertyName);

         if(value == null) {

             return false;

         }

         if(FLAG_PROPERTY_ON.equals(value)) {

             return true;

         }

         if(FLAG_PROPERTY_OFF.equals(value)) {

             return false;

         }

         throw new IllegalArgumentException(

                 String.format(

                     "Invalid value [%s] for flag property [%s]. Supported values are %s|%s",

                     value, propertyName, FLAG_PROPERTY_ON, FLAG_PROPERTY_OFF

                 )

         );

     }

     public synchronized String getConfigurationDump() {

         final String[] defaultProperties = getProperties();

         final StringBuilder sb = new StringBuilder();

         sb.append("\n======================= Configuration Properties =======================\n");

         for (String defaultProperty : defaultProperties) {

             sb.append(defaultProperty).append('=').append(getPropertyValue(defaultProperty)).append('\n');

         }

         sb.append("========================================================================\n");

         return sb.toString();

     }

     private String getPropertyValue(String propertyName) {

         if( ! defineProperty(propertyName) ) {

             if(logger.isDebugEnabled()) {

                 logger.debug(

                         String.format(

                                 "Property '%s' is not declared in default configuration file [%s]",

                                 propertyName,

                                 DEFAULT_CONFIG_FILE

                         )

                 );

             }

             return null;

         }

         final String systemValue = System.getProperties().getProperty(propertyName);

         if(systemValue == null) {

             return properties.getProperty(propertyName);

         }

         return systemValue;

     }

 }