/*
 * 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.lucene.replicator;

import java.io.IOException;
import java.io.InputStream;

import org.apache.lucene.store.IndexInput;

/** 
 * An {@link InputStream} which wraps an {@link IndexInput}.
 * 
 * @lucene.experimental
 */
public final class IndexInputInputStream extends InputStream {
  
  private final IndexInput in;
  
  private long remaining;
  
  public IndexInputInputStream(IndexInput in) {
    this.in = in;
    remaining = in.length();
  }
  
  @Override
  public int read() throws IOException {
    if (remaining == 0) {
      return -1;
    } else {
      --remaining;
      return in.readByte();
    }
  }
  
  @Override
  public int available() throws IOException {
    return (int) in.length();
  }
  
  @Override
  public void close() throws IOException {
    in.close();
  }
  
  @Override
  public int read(byte[] b) throws IOException {
    return read(b, 0, b.length);
  }
  
  @Override
  public int read(byte[] b, int off, int len) throws IOException {
    if (remaining == 0) {
      return -1;
    }
    if (remaining < len) {
      len = (int) remaining;
    }
    in.readBytes(b, off, len);
    remaining -= len;
    return len;
  }
  
  @Override
  public long skip(long n) throws IOException {
    if (remaining == 0) {
      return -1;
    }
    if (remaining < n) {
      n = remaining;
    }
    in.seek(in.getFilePointer() + n);
    remaining -= n;
    return n;
  }
  
}