/*
 * 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.store;

import java.io.Closeable;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;

/** A {@link DataInput} wrapping a plain {@link InputStream}. */
public class InputStreamDataInput extends DataInput implements Closeable {
  private final InputStream is;

  public InputStreamDataInput(InputStream is) {
    this.is = is;
  }

  @Override
  public byte readByte() throws IOException {
    int v = is.read();
    if (v == -1) throw new EOFException();
    return (byte) v;
  }

  @Override
  public void readBytes(byte[] b, int offset, int len) throws IOException {
    while (len > 0) {
      final int cnt = is.read(b, offset, len);
      if (cnt < 0) {
        // Partially read the input, but no more data available in the stream.
        throw new EOFException();
      }
      len -= cnt;
      offset += cnt;
    }
  }

  @Override
  public void close() throws IOException {
    is.close();
  }

  @Override
  public void skipBytes(long numBytes) throws IOException {
    if (numBytes < 0) {
      throw new IllegalArgumentException("numBytes must be >= 0, got " + numBytes);
    }
    long skipped = is.skip(numBytes);
    assert skipped <= numBytes;
    if (skipped < numBytes) {
      throw new EOFException();
    }
  }
}
