/* ***************************************************************************
    * Copyright (c) 2008 Brabenetz Harald, Austria.
    *
    * Licensed 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.settings4j.contentresolver;
  
  import java.io.File;
  import java.io.IOException;
  
  import org.apache.commons.io.FileUtils;
  import org.settings4j.ContentResolver;
  
  /**
   * {@link ContentResolver} implementation to read content from the File System.
   * <p>
   * The optional Path Prefix is "file:".
   * <p>
   * Absolute Windows paths contains a <b>":"</b>.<br/>
   * Absolute Unix paths starts with <b>"/"</b>.<br/>
   * Other Paths are relative and uses the {@link #getRootFolder()} as root.
   * Which is per default <code>new File(".")</code>.<br/>
   * 
   * @author Harald.Brabenetz
   */
  public class FSContentResolver implements ContentResolver {
  
      /** General Logger for this Class. */
      private static final org.slf4j.Logger LOG = org.slf4j.LoggerFactory.getLogger(FSContentResolver.class);
  
      /** Pseudo URL prefix for loading from the class path: "classpath:". */
      public static final String FILE_URL_PREFIX = "file:";
  
      private File rootFolder;
  
      /** {@inheritDoc} */
      public void addContentResolver(final ContentResolver contentResolver) {
          throw new UnsupportedOperationException("FSContentResolver cannot add other ContentResolvers");
      }
  
      /** {@inheritDoc} */
      public byte[] getContent(final String key) { 
          String normalizedKey = key;
          if (normalizedKey.startsWith(FILE_URL_PREFIX)) {
              normalizedKey = normalizedKey.substring(FILE_URL_PREFIX.length());
          }
  
          File file = new File(normalizedKey);
          if (file.exists()) {
              try {
                  return FileUtils.readFileToByteArray(file);
              } catch (final IOException e) {
                  LOG.info(e.getMessage(), e);
              }
          } else {
              file = new File(getRootFolder(), normalizedKey);
              if (file.exists()) {
                  try {
                      return FileUtils.readFileToByteArray(file);
                  } catch (final IOException e) {
                      LOG.info(e.getMessage(), e);
                  }
              }
          }
          return null;
      }
  
  
      /**
       * @param key The Settings4j Key.
       * @param value The value to Store.
       * @throws IOException if an error occured.
       */
      public void setContent(final String key, final byte[] value) throws IOException {
  
          final String normalizedKey;
          if (key.startsWith(FILE_URL_PREFIX)) {
              normalizedKey = key.substring(FILE_URL_PREFIX.length());
          } else {
              normalizedKey = key;
          }
  
          File file;
  
          if (normalizedKey.startsWith("/")) {
              // Unix-Root
              file = new File(normalizedKey);
          } else if (normalizedKey.indexOf(':') >= 0) {
             // Windows-Root
             file = new File(normalizedKey);
         } else {
             file = new File(getRootFolder(), normalizedKey);
         }
         LOG.debug("Store content in: {}", file.getAbsolutePath());
 
         FileUtils.writeByteArrayToFile(file, value);
     }
 
     /**
      * return the root of this FileSystem ContenResolver.
      * <p>
      * if no one is set, the "." will be returned.
      * 
      * @return the root of this FileSystem ContenResolver.
      */
     public File getRootFolder() {
         if (rootFolder == null) {
             rootFolder = new File(".");
             LOG.info("FSContentResolver.rootFolder is null. " //
                 + "The RootPath Folder will be used: " + rootFolder.getAbsolutePath());
         }
         return rootFolder;
     }
 
     /**
      * @param rootFolderPath the root folder Path.
      */
     public void setRootFolderPath(final String rootFolderPath) {
         final File newRootFolder = new File(rootFolderPath);
         if (!newRootFolder.exists()) {
             try {
                 FileUtils.forceMkdir(newRootFolder);
                 rootFolder = newRootFolder;
                 LOG.info("Set RootPath for FSConntentResolver: {}", newRootFolder.getAbsolutePath());
             } catch (final IOException e) {
                 LOG.warn("cannot create rootFolder: {}!", rootFolderPath);
             }
         } else {
             rootFolder = newRootFolder;
         }
     }
 }