/*
    * 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.commons.lang3.exception;
  
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Set;
  
  import org.apache.commons.lang3.StringUtils;
  import org.apache.commons.lang3.tuple.ImmutablePair;
  import org.apache.commons.lang3.tuple.Pair;
  
  /**
   * Default implementation of the context storing the label-value pairs for contexted exceptions.
   * <p>
   * This implementation is serializable, however this is dependent on the values that
   * are added also being serializable.
   * </p>
   * 
   * @see ContextedException
   * @see ContextedRuntimeException
   * @since 3.0
   */
  public class DefaultExceptionContext implements ExceptionContext, Serializable {
  
      /** The serialization version. */
      private static final long serialVersionUID = 20110706L;
  
      /** The list storing the label-data pairs. */
      private final List<Pair<String, Object>> contextValues = new ArrayList<Pair<String,Object>>();
  
      /**
       * {@inheritDoc}
       */
      @Override
      public DefaultExceptionContext addContextValue(final String label, final Object value) {
          contextValues.add(new ImmutablePair<String, Object>(label, value));
          return this;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public DefaultExceptionContext setContextValue(final String label, final Object value) {
          for (final Iterator<Pair<String, Object>> iter = contextValues.iterator(); iter.hasNext();) {
              final Pair<String, Object> p = iter.next();
              if (StringUtils.equals(label, p.getKey())) {
                  iter.remove();
              }
          }
          addContextValue(label, value);
          return this;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public List<Object> getContextValues(final String label) {
          final List<Object> values = new ArrayList<Object>();
          for (final Pair<String, Object> pair : contextValues) {
              if (StringUtils.equals(label, pair.getKey())) {
                  values.add(pair.getValue());
              }
          }
          return values;
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public Object getFirstContextValue(final String label) {
          for (final Pair<String, Object> pair : contextValues) {
              if (StringUtils.equals(label, pair.getKey())) {
                  return pair.getValue();
              }
          }
          return null;
      }
  
     /**
      * {@inheritDoc}
      */
     @Override
     public Set<String> getContextLabels() {
         final Set<String> labels = new HashSet<String>();
         for (final Pair<String, Object> pair : contextValues) {
             labels.add(pair.getKey());
         }
         return labels;
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public List<Pair<String, Object>> getContextEntries() {
         return contextValues;
     }
 
     /**
      * Builds the message containing the contextual information.
      * 
      * @param baseMessage  the base exception message <b>without</b> context information appended
      * @return the exception message <b>with</b> context information appended, never null
      */
     @Override
     public String getFormattedExceptionMessage(final String baseMessage){
         final StringBuilder buffer = new StringBuilder(256);
         if (baseMessage != null) {
             buffer.append(baseMessage);
         }
         
         if (contextValues.size() > 0) {
             if (buffer.length() > 0) {
                 buffer.append('\n');
             }
             buffer.append("Exception Context:\n");
             
             int i = 0;
             for (final Pair<String, Object> pair : contextValues) {
                 buffer.append("\t[");
                 buffer.append(++i);
                 buffer.append(':');
                 buffer.append(pair.getKey());
                 buffer.append("=");
                 final Object value = pair.getValue();
                 if (value == null) {
                     buffer.append("null");
                 } else {
                     String valueStr;
                     try {
                         valueStr = value.toString();
                     } catch (final Exception e) {
                         valueStr = "Exception thrown on toString(): " + ExceptionUtils.getStackTrace(e);
                     }
                     buffer.append(valueStr);
                 }
                 buffer.append("]\n");
             }
             buffer.append("---------------------------------");
         }
         return buffer.toString();
     }
 
 }