/*
    * ====================================================================
    * 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.hc.core5.http2.impl.io;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.ArrayDeque;
  import java.util.Queue;
  
  class MultiByteArrayInputStream extends InputStream {
  
      private final Queue<byte[]> bufs;
      private byte[] current;
      private int pos;
  
      public MultiByteArrayInputStream(final byte[]... bufs) {
          super();
          this.bufs = new ArrayDeque<>();
          for (final byte[] buf: bufs) {
              if (buf.length > 0) {
                  this.bufs.add(buf);
              }
          }
      }
  
      private void advance() {
          if (this.current != null) {
              if (this.pos >= this.current.length) {
                  this.current = null;
              }
          }
          if (this.current == null) {
              this.current = this.bufs.poll();
              this.pos = 0;
          }
      }
  
      @Override
      public int read() throws IOException {
          advance();
          if (this.current == null) {
              return -1;
          }
          return this.current[this.pos++];
      }
  
      @Override
      public int read(final byte b[], final int off, final int len) throws IOException {
          if (b == null) {
              throw new NullPointerException();
          } else if ((off < 0) || (off > b.length) || (len < 0) ||
                 ((off + len) > b.length) || ((off + len) < 0)) {
              throw new IndexOutOfBoundsException();
          }
          advance();
          if (this.current == null) {
              return -1;
          }
          final int chunk = Math.min(this.current.length - this.pos, len);
          if (chunk <= 0) {
              return 0;
          }
          System.arraycopy(this.current, this.pos, b, off, chunk);
          this.pos += chunk;
          return chunk;
      }
  
      @Override
      public long skip(final long n) {
          advance();
          final int chunk = Math.min(this.current.length - this.pos, (int) n);
          if (chunk <= 0) {
              return 0;
          }
         this.pos += chunk;
         return chunk;
     }
 
     @Override
     public int available() {
         advance();
         return this.current != null ? this.current.length - this.pos : 0;
     }
 
     @Override
     public boolean markSupported() {
         return false;
     }
 
 }