package at.gv.egovernment.moa.spss.util;

import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.math.BigDecimal;

public class FilteredOutputStream extends BufferedOutputStream {
	private BigDecimal from = null;
	private BigDecimal to = null;
	private BigDecimal counter = new BigDecimal("0");
	BigDecimal one = new BigDecimal("1");
	
	public FilteredOutputStream(OutputStream innerStream, 
			int bufferSize, BigDecimal from, 
			BigDecimal to) {
		super(innerStream, bufferSize);
		this.from = from;
		this.to = to;
	}

	@Override
	public synchronized void write(int b) throws IOException {
		if(!inRange(counter)) {
			super.write(b);
		}
		counter = counter.add(one);
	}

	@Override
	public synchronized void write(byte[] b, int off, int len) throws IOException {
		this.filteredWrite(b, off, len);
	}

	@Override
	public synchronized void flush() throws IOException {
		super.flush();
	}

	@Override
	public void write(byte[] b) throws IOException {
		if(b != null) {
			this.filteredWrite(b, 0, b.length);
		}
	}

	@Override
	public void close() throws IOException {
		super.close();
	}
	
	private synchronized void filteredWrite(byte[] b, int off, int len) throws IOException {
		for(int i = 0; i < len; i++) {
			if(!inRange(counter)) {
				super.write(b[off+i]);
			}
			counter = counter.add(one);
		}
	}
	
	private boolean inRange(BigDecimal counter) {
		  if ( (from == null) || (to == null))
			  return false;
		  
		  int compare = counter.compareTo(from);
		  if (compare == -1)
			  return false;
		  else {
			  compare = counter.compareTo(to);
			  if (compare == 1)
				  return false;
			  else
				  return true;
		  }
	  }
}