/*
    * 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.configuration2;
  
  import java.io.IOException;
  import java.io.Reader;
  import java.io.Writer;
  import java.math.BigDecimal;
  import java.math.BigInteger;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Objects;
  import java.util.Properties;
  
  import org.apache.commons.configuration2.event.Event;
  import org.apache.commons.configuration2.event.EventListener;
  import org.apache.commons.configuration2.event.EventType;
  import org.apache.commons.configuration2.ex.ConfigurationException;
  import org.apache.commons.configuration2.io.FileBased;
  import org.apache.commons.configuration2.tree.ExpressionEngine;
  import org.apache.commons.configuration2.tree.ImmutableNode;
  
  /**
   * Wraps a BaseHierarchicalConfiguration and allows subtrees to be accessed via a configured path with replaceable
   * tokens derived from the ConfigurationInterpolator. When used with injection frameworks such as Spring it allows
   * components to be injected with subtrees of the configuration.
   *
   * @since 1.6
   */
  public class PatternSubtreeConfigurationWrapper extends BaseHierarchicalConfiguration implements FileBasedConfiguration {
      /** The wrapped configuration */
      private final HierarchicalConfiguration<ImmutableNode> config;
  
      /** The path to the subtree */
      private final String path;
  
      /** True if the path ends with '/', false otherwise */
      private final boolean trailing;
  
      /** True if the constructor has finished */
      private final boolean init;
  
      /**
       * Constructor
       *
       * @param config The Configuration to be wrapped.
       * @param path The base path pattern.
       */
      public PatternSubtreeConfigurationWrapper(final HierarchicalConfiguration<ImmutableNode> config, final String path) {
          this.config = Objects.requireNonNull(config, "config");
          this.path = path;
          this.trailing = path.endsWith("/");
          this.init = true;
      }
  
      @Override
      protected void addPropertyInternal(final String key, final Object value) {
          config.addProperty(makePath(key), value);
      }
  
      @Override
      protected void clearInternal() {
          getConfig().clear();
      }
  
      @Override
      protected void clearPropertyDirect(final String key) {
          config.clearProperty(makePath(key));
      }
  
      @Override
      protected boolean containsKeyInternal(final String key) {
          return config.containsKey(makePath(key));
      }
  
      @Override
      public BigDecimal getBigDecimal(final String key, final BigDecimal defaultValue) {
          return config.getBigDecimal(makePath(key), defaultValue);
      }
  
      @Override
      public BigDecimal getBigDecimal(final String key) {
          return config.getBigDecimal(makePath(key));
     }
 
     @Override
     public BigInteger getBigInteger(final String key, final BigInteger defaultValue) {
         return config.getBigInteger(makePath(key), defaultValue);
     }
 
     @Override
     public BigInteger getBigInteger(final String key) {
         return config.getBigInteger(makePath(key));
     }
 
     @Override
     public boolean getBoolean(final String key, final boolean defaultValue) {
         return config.getBoolean(makePath(key), defaultValue);
     }
 
     @Override
     public Boolean getBoolean(final String key, final Boolean defaultValue) {
         return config.getBoolean(makePath(key), defaultValue);
     }
 
     @Override
     public boolean getBoolean(final String key) {
         return config.getBoolean(makePath(key));
     }
 
     @Override
     public byte getByte(final String key, final byte defaultValue) {
         return config.getByte(makePath(key), defaultValue);
     }
 
     @Override
     public Byte getByte(final String key, final Byte defaultValue) {
         return config.getByte(makePath(key), defaultValue);
     }
 
     @Override
     public byte getByte(final String key) {
         return config.getByte(makePath(key));
     }
 
     @Override
     public double getDouble(final String key, final double defaultValue) {
         return config.getDouble(makePath(key), defaultValue);
     }
 
     @Override
     public Double getDouble(final String key, final Double defaultValue) {
         return config.getDouble(makePath(key), defaultValue);
     }
 
     @Override
     public double getDouble(final String key) {
         return config.getDouble(makePath(key));
     }
 
     @Override
     public float getFloat(final String key, final float defaultValue) {
         return config.getFloat(makePath(key), defaultValue);
     }
 
     @Override
     public Float getFloat(final String key, final Float defaultValue) {
         return config.getFloat(makePath(key), defaultValue);
     }
 
     @Override
     public float getFloat(final String key) {
         return config.getFloat(makePath(key));
     }
 
     @Override
     public int getInt(final String key, final int defaultValue) {
         return config.getInt(makePath(key), defaultValue);
     }
 
     @Override
     public int getInt(final String key) {
         return config.getInt(makePath(key));
     }
 
     @Override
     public Integer getInteger(final String key, final Integer defaultValue) {
         return config.getInteger(makePath(key), defaultValue);
     }
 
     @Override
     protected Iterator<String> getKeysInternal() {
         return config.getKeys(makePath());
     }
 
     @Override
     protected Iterator<String> getKeysInternal(final String prefix) {
         return config.getKeys(makePath(prefix));
     }
 
     @Override
     public List<Object> getList(final String key, final List<?> defaultValue) {
         return config.getList(makePath(key), defaultValue);
     }
 
     @Override
     public List<Object> getList(final String key) {
         return config.getList(makePath(key));
     }
 
     @Override
     public long getLong(final String key, final long defaultValue) {
         return config.getLong(makePath(key), defaultValue);
     }
 
     @Override
     public Long getLong(final String key, final Long defaultValue) {
         return config.getLong(makePath(key), defaultValue);
     }
 
     @Override
     public long getLong(final String key) {
         return config.getLong(makePath(key));
     }
 
     @Override
     public Properties getProperties(final String key) {
         return config.getProperties(makePath(key));
     }
 
     @Override
     protected Object getPropertyInternal(final String key) {
         return config.getProperty(makePath(key));
     }
 
     @Override
     public short getShort(final String key, final short defaultValue) {
         return config.getShort(makePath(key), defaultValue);
     }
 
     @Override
     public Short getShort(final String key, final Short defaultValue) {
         return config.getShort(makePath(key), defaultValue);
     }
 
     @Override
     public short getShort(final String key) {
         return config.getShort(makePath(key));
     }
 
     @Override
     public String getString(final String key, final String defaultValue) {
         return config.getString(makePath(key), defaultValue);
     }
 
     @Override
     public String getString(final String key) {
         return config.getString(makePath(key));
     }
 
     @Override
     public String[] getStringArray(final String key) {
         return config.getStringArray(makePath(key));
     }
 
     @Override
     protected boolean isEmptyInternal() {
         return getConfig().isEmpty();
     }
 
     @Override
     protected void setPropertyInternal(final String key, final Object value) {
         getConfig().setProperty(key, value);
     }
 
     @Override
     public Configuration subset(final String prefix) {
         return getConfig().subset(prefix);
     }
 
     @Override
     public ExpressionEngine getExpressionEngine() {
         return config.getExpressionEngine();
     }
 
     @Override
     public void setExpressionEngine(final ExpressionEngine expressionEngine) {
         if (init) {
             config.setExpressionEngine(expressionEngine);
         } else {
             super.setExpressionEngine(expressionEngine);
         }
     }
 
     @Override
     protected void addNodesInternal(final String key, final Collection<? extends ImmutableNode> nodes) {
         getConfig().addNodes(key, nodes);
     }
 
     @Override
     public HierarchicalConfiguration<ImmutableNode> configurationAt(final String key, final boolean supportUpdates) {
         return config.configurationAt(makePath(key), supportUpdates);
     }
 
     @Override
     public HierarchicalConfiguration<ImmutableNode> configurationAt(final String key) {
         return config.configurationAt(makePath(key));
     }
 
     @Override
     public List<HierarchicalConfiguration<ImmutableNode>> configurationsAt(final String key) {
         return config.configurationsAt(makePath(key));
     }
 
     @Override
     protected Object clearTreeInternal(final String key) {
         config.clearTree(makePath(key));
         return Collections.emptyList();
     }
 
     @Override
     protected int getMaxIndexInternal(final String key) {
         return config.getMaxIndex(makePath(key));
     }
 
     @Override
     public Configuration interpolatedConfiguration() {
         return getConfig().interpolatedConfiguration();
     }
 
     @Override
     public <T extends Event> void addEventListener(final EventType<T> eventType, final EventListener<? super T> listener) {
         getConfig().addEventListener(eventType, listener);
     }
 
     @Override
     public <T extends Event> boolean removeEventListener(final EventType<T> eventType, final EventListener<? super T> listener) {
         return getConfig().removeEventListener(eventType, listener);
     }
 
     @Override
     public <T extends Event> Collection<EventListener<? super T>> getEventListeners(final EventType<T> eventType) {
         return getConfig().getEventListeners(eventType);
     }
 
     @Override
     public void clearEventListeners() {
         getConfig().clearEventListeners();
     }
 
     @Override
     public void clearErrorListeners() {
         getConfig().clearErrorListeners();
     }
 
     @Override
     public void write(final Writer writer) throws ConfigurationException, IOException {
         fetchFileBased().write(writer);
     }
 
     @Override
     public void read(final Reader reader) throws ConfigurationException, IOException {
         fetchFileBased().read(reader);
     }
 
     private BaseHierarchicalConfiguration getConfig() {
         return (BaseHierarchicalConfiguration) config.configurationAt(makePath());
     }
 
     private String makePath() {
         final String pathPattern = trailing ? path.substring(0, path.length() - 1) : path;
         return substitute(pathPattern);
     }
 
     /*
      * Resolve the root expression and then add the item being retrieved. Insert a separator character as required.
      */
     private String makePath(final String item) {
         final String pathPattern;
         if ((item.isEmpty() || item.startsWith("/")) && trailing) {
             pathPattern = path.substring(0, path.length() - 1);
         } else if (!item.startsWith("/") || !trailing) {
             pathPattern = path + "/";
         } else {
             pathPattern = path;
         }
         return substitute(pathPattern) + item;
     }
 
     /**
      * Uses this configuration's {@code ConfigurationInterpolator} to perform variable substitution on the given pattern
      * string.
      *
      * @param pattern the pattern string
      * @return the string with variables replaced
      */
     private String substitute(final String pattern) {
         return Objects.toString(getInterpolator().interpolate(pattern), null);
     }
 
     /**
      * Returns the wrapped configuration as a {@code FileBased} object. If this cast is not possible, an exception is
      * thrown.
      *
      * @return the wrapped configuration as {@code FileBased}
      * @throws ConfigurationException if the wrapped configuration does not implement {@code FileBased}
      */
     private FileBased fetchFileBased() throws ConfigurationException {
         if (!(config instanceof FileBased)) {
             throw new ConfigurationException("Wrapped configuration does not implement FileBased!" + " No I/O operations are supported.");
         }
         return (FileBased) config;
     }
 }