/*
 * #!
 * Ontopia Engine
 * #-
 * Copyright (C) 2001 - 2013 The Ontopia Project
 * #-
 * Licensed 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 net.ontopia.utils;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.io.Writer;

/**
 * INTERNAL: An InputStream stream that turns a Reader into an
 * InputStream given an encoding.
 */
public class ReaderInputStream extends InputStream {
  protected Reader reader;
  protected ByteArrayOutputStream byteArrayOut;
  protected Writer writer;
  protected char[] chars;
  protected byte[] buffer;
  protected int index, length;

  public ReaderInputStream(Reader reader) {
    this.reader = reader;
    byteArrayOut = new ByteArrayOutputStream();
    writer = new OutputStreamWriter(byteArrayOut);
    chars = new char[1024];
  }

  public ReaderInputStream(Reader reader, String encoding) throws UnsupportedEncodingException {
    this.reader = reader;
    byteArrayOut = new ByteArrayOutputStream();
    writer = new OutputStreamWriter(byteArrayOut, encoding);
    chars = new char[1024];
  }

  public int read() throws IOException {
    if (index >= length)
      fillBuffer();
    if (index >= length)
      return -1;
    return 0xff & buffer[index++];
  }

  protected void fillBuffer() throws IOException {
    if (length < 0)
      return;
    int numChars = reader.read(chars);
    if (numChars < 0) {
      length = -1;
    } else {
      byteArrayOut.reset();
      writer.write(chars, 0, numChars);
      writer.flush();
      buffer = byteArrayOut.toByteArray();
      length = buffer.length;
      index = 0;
    }
  }

  public int read(byte[] data, int off, int len) throws IOException {
    if (index >= length)
      fillBuffer();
    if (index >= length)
      return -1;
    int amount = Math.min(len, length - index);
    System.arraycopy(buffer, index, data, off, amount);
    index += amount;
    return amount;
  }

  public int available() throws IOException {
    return (index < length) ? length - index :
      ((length >= 0) && reader.ready()) ? 1 : 0;
  }

  public void close() throws IOException {
    reader.close();
  }
  
}