package org.codehaus.plexus.component.configurator.converters.basic;
   
   /*
    * The MIT License
    *
    * Copyright (c) 2004, The Codehaus
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of
    * this software and associated documentation files (the "Software"), to deal in
   * the Software without restriction, including without limitation the rights to
   * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
   * of the Software, and to permit persons to whom the Software is furnished to do
   * so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in all
   * copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   */
  
  import org.codehaus.plexus.component.configurator.ComponentConfigurationException;
  import org.codehaus.plexus.component.configurator.ConfigurationListener;
  import org.codehaus.plexus.component.configurator.converters.AbstractConfigurationConverter;
  import org.codehaus.plexus.component.configurator.converters.lookup.ConverterLookup;
  import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluationException;
  import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluator;
  import org.codehaus.plexus.component.configurator.expression.TypeAwareExpressionEvaluator;
  import org.codehaus.plexus.configuration.PlexusConfiguration;
  
  /**
   */
  public abstract class AbstractBasicConverter extends AbstractConfigurationConverter {
      protected abstract Object fromString(String str) throws ComponentConfigurationException;
  
      protected Object fromExpression(
              PlexusConfiguration configuration, ExpressionEvaluator expressionEvaluator, Class type)
              throws ComponentConfigurationException {
          Object v = null;
  
          String value = configuration.getValue(null);
  
          if (value != null && value.length() > 0) {
              // Object is provided by an expression
              // This seems a bit ugly... canConvert really should return false in this instance, but it doesn't have the
              //   configuration to know better
              try {
                  if (expressionEvaluator instanceof TypeAwareExpressionEvaluator) {
                      v = ((TypeAwareExpressionEvaluator) expressionEvaluator).evaluate(value, type);
                  } else {
                      v = expressionEvaluator.evaluate(value);
                  }
              } catch (ExpressionEvaluationException e) {
                  String msg = "Error evaluating the expression '" + value + "' for configuration value '"
                          + configuration.getName() + "'";
                  throw new ComponentConfigurationException(configuration, msg, e);
              }
          }
  
          if (v == null) {
              value = configuration.getAttribute("default-value", null);
  
              if (value != null && value.length() > 0) {
                  try {
                      if (expressionEvaluator instanceof TypeAwareExpressionEvaluator) {
                          v = ((TypeAwareExpressionEvaluator) expressionEvaluator).evaluate(value, type);
                      } else {
                          v = expressionEvaluator.evaluate(value);
                      }
                  } catch (ExpressionEvaluationException e) {
                      String msg = "Error evaluating the expression '" + value + "' for configuration value '"
                              + configuration.getName() + "'";
                      throw new ComponentConfigurationException(configuration, msg, e);
                  }
              }
          }
  
          /*
           * NOTE: We don't check the type here which would be ugly to do correctly (e.g. value=Short -> type=int), the
           * reflective setter/field injection will fail by itself when the type didn't match.
           */
  
          return v;
      }
  
      public Object fromConfiguration(
              ConverterLookup converterLookup,
              PlexusConfiguration configuration,
              Class type,
              Class baseType,
              ClassLoader classLoader,
              ExpressionEvaluator expressionEvaluator,
              ConfigurationListener listener)
              throws ComponentConfigurationException {
         if (configuration.getChildCount() > 0) {
             throw new ComponentConfigurationException("When configuring a basic element the configuration cannot "
                     + "contain any child elements. " + "Configuration element '" + configuration.getName() + "'.");
         }
 
         Object retValue = fromExpression(configuration, expressionEvaluator, type);
 
         if (retValue instanceof String) {
             try {
                 retValue = fromString((String) retValue);
             } catch (ComponentConfigurationException e) {
                 if (e.getFailedConfiguration() == null) {
                     e.setFailedConfiguration(configuration);
                 }
 
                 throw e;
             }
         }
 
         return retValue;
     }
 }