/*
    * Copyright 2002,2004 The Apache Software Foundation.
    *
    * 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.apache.commons.jelly.tags.util;
  
  import java.io.BufferedReader;
  import java.io.File;
  import java.io.FileNotFoundException;
  import java.io.FileReader;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.UnsupportedEncodingException;
  import java.io.Reader;
  
  import org.apache.commons.jelly.JellyTagException;
  import org.apache.commons.jelly.MissingAttributeException;
  import org.apache.commons.jelly.TagSupport;
  import org.apache.commons.jelly.XMLOutput;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  /***
   * A tag which loads text from a file or URI into a Jelly variable.
   *
   * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
   * @version $Revision: 155420 $
   */
  public class LoadTextTag extends TagSupport {
  
      /*** The Log to which logging calls will be made. */
      private static final Log log = LogFactory.getLog(LoadTextTag.class);
  
      private String var;
      private File file;
      private String uri;
      private String encoding;
  
      public LoadTextTag() {
      }
  
      // Tag interface
      //-------------------------------------------------------------------------
      public void doTag(XMLOutput output) throws MissingAttributeException, JellyTagException {
          if (var == null) {
              throw new MissingAttributeException("var");
          }
          if (file == null && uri == null) {
              throw new JellyTagException( "This tag must have a 'file' or 'uri' specified" );
          }
          
          InputStream in = null;
          if (file != null) {
              if (! file.exists()) {
                  throw new JellyTagException( "The file: " + file + " does not exist" );
              }
  
              try {
                  in = new FileInputStream(file);
              } catch (FileNotFoundException e) {
                  throw new JellyTagException("could not find the file",e);
              }
          }
          else {
              in = context.getResourceAsStream(uri);
              if (in == null) {
                  throw new JellyTagException( "Could not find uri: " + uri );
              }
          }
  
          Reader reader = null;
          if (encoding != null) {
              try {
                  reader = new InputStreamReader(in, encoding);
              } catch (UnsupportedEncodingException e) {
                  throw new JellyTagException("unsupported encoding",e);
              }
          } else {
              reader = new InputStreamReader(in);
          }
  
          String text = null;
  
          try {
              text = loadText(reader);
         }
         catch (IOException e) {
             throw new JellyTagException(e);
         }
 
         context.setVariable(var, text);
     }
 
     // Properties
     //-------------------------------------------------------------------------
 
     /***
      * Sets the name of the variable which will be exported with the text value of the
      * given file.
      */
     public void setVar(String var) {
         this.var = var;
     }
     /***
      * Returns the file.
      * @return File
      */
     public File getFile() {
         return file;
     }
 
     /***
      * Returns the uri.
      * @return String
      */
     public String getUri() {
         return uri;
     }
 
     /***
      * Returns the var.
      * @return String
      */
     public String getVar() {
         return var;
     }
 
     /***
      * Sets the file to be parsed as text
      */
     public void setFile(File file) {
         this.file = file;
     }
 
     /***
      * Sets the encoding to use to read the file
      */
     public void setEncoding(String encoding) {
         this.encoding = encoding;
     }
 
     /***
      * Sets the uri to be parsed as text.
      * This can be an absolute URL or a relative or absolute URI
      * from this Jelly script or the root context.
      */
     public void setUri(String uri) {
         this.uri = uri;
     }
 
     /*** Returns the encoding set.
     * @return the encoding set with {@link #setEncoding(String)}
       */
     public String getEncoding() {
         return encoding;
     }
 
 
     // Implementation methods
     //-------------------------------------------------------------------------
 
     /***
      * Loads all the text from the given Reader
      */
     protected String loadText(Reader reader) throws IOException {
         StringBuffer buffer = new StringBuffer();
 
         // @todo its probably more efficient to use a fixed char[] buffer instead
         try {
             BufferedReader bufferedReader = new BufferedReader(reader);
             while (true) {
                 String line = bufferedReader.readLine();
                 if (line == null) {
                     break;
                 }
                 else {
                     buffer.append(line);
                     buffer.append('\n');
                 }
             }
             return buffer.toString();
         }
         finally {
             try {
                 reader.close();
             }
             catch (Exception e) {
                 log.error( "Caught exception closing Reader: " + e, e);
             }
         }
     }
 }