/*
 * Jooby https://jooby.io
 * Apache License Version 2.0 https://jooby.io/LICENSE.txt
 * Copyright 2014 Edgar Espina
 */
package io.jooby.internal.jetty;

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

import io.jooby.StatusCode;
import io.jooby.exception.StatusCodeException;

public class LimitedInputStream extends FilterInputStream {
  /** The maximum size of an item, in bytes. */
  private long maxSize;

  /** The current number of bytes. */
  private long count;

  /**
   * Creates a new instance.
   *
   * @param pIn The input stream, which shall be limited.
   * @param maxSize The limit; no more than this number of bytes shall be returned by the source
   *     stream.
   */
  public LimitedInputStream(InputStream pIn, long maxSize) {
    super(pIn);
    this.maxSize = maxSize;
  }

  /** Called to check, whether the input streams limit is reached. */
  private void checkLimit() {
    if (count > maxSize) {
      throw new StatusCodeException(StatusCode.REQUEST_ENTITY_TOO_LARGE);
    }
  }

  /**
   * Reads the next byte of data from this input stream. The value byte is returned as an <code>int
   * </code> in the range <code>0</code> to <code>255</code>. If no byte is available because the
   * end of the stream has been reached, the value <code>-1</code> is returned. This method blocks
   * until input data is available, the end of the stream is detected, or an exception is thrown.
   *
   * <p>This method simply performs <code>in.read()</code> and returns the result.
   *
   * @return the next byte of data, or <code>-1</code> if the end of the stream is reached.
   * @exception IOException if an I/O error occurs.
   * @see java.io.FilterInputStream#in
   */
  public int read() throws IOException {
    int res = super.read();
    if (res != -1) {
      count += 1;
      checkLimit();
    }
    return res;
  }

  /**
   * Reads up to <code>len</code> bytes of data from this input stream into an array of bytes. If
   * <code>len</code> is not zero, the method blocks until some input is available; otherwise, no
   * bytes are read and <code>0</code> is returned.
   *
   * <p>This method simply performs <code>in.read(b, off, len)</code> and returns the result.
   *
   * @param b the buffer into which the data is read.
   * @param off The start offset in the destination array <code>b</code>.
   * @param len the maximum number of bytes read.
   * @return the total number of bytes read into the buffer, or <code>-1</code> if there is no more
   *     data because the end of the stream has been reached.
   * @exception NullPointerException If <code>b</code> is <code>null</code>.
   * @exception IndexOutOfBoundsException If <code>off</code> is negative, <code>len</code> is
   *     negative, or <code>len</code> is greater than <code>b.length - off</code>
   * @exception IOException if an I/O error occurs.
   * @see java.io.FilterInputStream#in
   */
  public int read(byte[] b, int off, int len) throws IOException {
    int res = super.read(b, off, len);
    if (res > 0) {
      count += res;
      checkLimit();
    }
    return res;
  }
}
