/*
    * 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.vfs2.provider.http;
  
  import java.io.DataInputStream;
  import java.io.FilterInputStream;
  import java.io.IOException;
  import java.net.HttpURLConnection;
  
  import org.apache.commons.httpclient.methods.GetMethod;
  import org.apache.commons.vfs2.FileSystemException;
  import org.apache.commons.vfs2.provider.AbstractRandomAccessStreamContent;
  import org.apache.commons.vfs2.util.MonitorInputStream;
  import org.apache.commons.vfs2.util.RandomAccessMode;
  
  /**
   * RandomAccess content using HTTP.
   */
  final class HttpRandomAccessContent<FS extends HttpFileSystem> extends AbstractRandomAccessStreamContent {
  
      protected long filePointer;
  
      private final HttpFileObject<FS> fileObject;
      private final HttpFileSystem fileSystem;
  
      private DataInputStream dataInputStream;
      private MonitorInputStream monitorInputStream;
  
      HttpRandomAccessContent(final HttpFileObject<FS> fileObject, final RandomAccessMode mode) {
          super(mode);
  
          this.fileObject = fileObject;
          fileSystem = (HttpFileSystem) this.fileObject.getFileSystem();
      }
  
      @Override
      public void close() throws IOException {
          if (dataInputStream != null) {
              dataInputStream.close();
              dataInputStream = null;
              monitorInputStream = null;
          }
      }
  
      @Override
      protected DataInputStream getDataInputStream() throws IOException {
          if (dataInputStream != null) {
              return dataInputStream;
          }
  
          final GetMethod getMethod = new GetMethod();
          fileObject.setupMethod(getMethod);
          getMethod.setRequestHeader("Range", "bytes=" + filePointer + "-");
          final int status = fileSystem.getClient().executeMethod(getMethod);
          if (status != HttpURLConnection.HTTP_PARTIAL && status != HttpURLConnection.HTTP_OK) {
              throw new FileSystemException("vfs.provider.http/get-range.error", fileObject.getName(),
                      Long.valueOf(filePointer), Integer.valueOf(status));
          }
  
          monitorInputStream = new HttpFileObject.HttpInputStream(getMethod);
          // If the range request was ignored
          if (status == HttpURLConnection.HTTP_OK) {
              final long skipped = monitorInputStream.skip(filePointer);
              if (skipped != filePointer) {
                  throw new FileSystemException("vfs.provider.http/get-range.error", fileObject.getName(),
                          Long.valueOf(filePointer), Integer.valueOf(status));
              }
          }
          dataInputStream = new DataInputStream(new FilterInputStream(monitorInputStream) {
              @Override
              public int read() throws IOException {
                  final int ret = super.read();
                  if (ret > -1) {
                      filePointer++;
                  }
                  return ret;
              }
  
              @Override
              public int read(final byte[] b) throws IOException {
                  final int ret = super.read(b);
                  if (ret > -1) {
                      filePointer += ret;
                  }
                  return ret;
             }
 
             @Override
             public int read(final byte[] b, final int off, final int len) throws IOException {
                 final int ret = super.read(b, off, len);
                 if (ret > -1) {
                     filePointer += ret;
                 }
                 return ret;
             }
         });
 
         return dataInputStream;
     }
 
     @Override
     public long getFilePointer() throws IOException {
         return filePointer;
     }
 
     @Override
     public long length() throws IOException {
         return fileObject.getContent().getSize();
     }
 
     @Override
     public void seek(final long pos) throws IOException {
         if (pos == filePointer) {
             // no change
             return;
         }
 
         if (pos < 0) {
             throw new FileSystemException("vfs.provider/random-access-invalid-position.error", Long.valueOf(pos));
         }
         if (dataInputStream != null) {
             close();
         }
 
         filePointer = pos;
     }
 }