/*
    * Copyright (C) 2010, Google Inc. and others
    *
    * This program and the accompanying materials are made available under the
    * terms of the Eclipse Distribution License v. 1.0 which is available at
    * https://www.eclipse.org/org/documents/edl-v10.php.
    *
    * SPDX-License-Identifier: BSD-3-Clause
    */
  
  package org.eclipse.jgit.lib;
  
  import java.io.IOException;
  import java.io.InputStream;
  
  /**
   * Stream of data coming from an object loaded by {@link org.eclipse.jgit.lib.ObjectLoader}.
   */
  public abstract class ObjectStream extends InputStream {
  	/**
  	 * Get Git object type, see {@link Constants}.
  	 *
  	 * @return Git object type, see {@link Constants}.
  	 */
  	public abstract int getType();
  
  	/**
  	 * Get total size of object in bytes
  	 *
  	 * @return total size of object in bytes
  	 */
  	public abstract long getSize();
  
  	/**
  	 * Simple stream around the cached byte array created by a loader.
  	 * <p>
  	 * ObjectLoader implementations can use this stream type when the object's
  	 * content is small enough to be accessed as a single byte array, but the
  	 * application has still requested it in stream format.
  	 */
  	public static class SmallStream extends ObjectStream {
  		private final int type;
  
  		private final byte[] data;
  
  		private int ptr;
  
  		private int mark;
  
  		/**
  		 * Create the stream from an existing loader's cached bytes.
  		 *
  		 * @param loader
  		 *            the loader.
  		 */
  		public SmallStream(ObjectLoader loader) {
  			this(loader.getType(), loader.getCachedBytes());
  		}
  
  		/**
  		 * Create the stream from an existing byte array and type.
  		 *
  		 *@param type
  		 *            the type constant for the object.
  		 *@param data
  		 *            the fully inflated content of the object.
  		 */
  		public SmallStream(int type, byte[] data) {
  			this.type = type;
  			this.data = data;
  		}
  
  		@Override
  		public int getType() {
  			return type;
  		}
  
  		@Override
  		public long getSize() {
  			return data.length;
  		}
  
  		@Override
  		public int available() {
  			return data.length - ptr;
  		}
  
  		@Override
  		public long skip(long n) {
  			int s = (int) Math.min(available(), Math.max(0, n));
  			ptr += s;
  			return s;
  		}
  
  		@Override
  		public int read() {
  			if (ptr == data.length)
  				return -1;
  			return data[ptr++] & 0xff;
 		}
 
 		@Override
 		public int read(byte[] b, int off, int len) {
 			if (ptr == data.length)
 				return -1;
 			int n = Math.min(available(), len);
 			System.arraycopy(data, ptr, b, off, n);
 			ptr += n;
 			return n;
 		}
 
 		@Override
 		public boolean markSupported() {
 			return true;
 		}
 
 		@Override
 		public void mark(int readlimit) {
 			mark = ptr;
 		}
 
 		@Override
 		public void reset() {
 			ptr = mark;
 		}
 	}
 
 	/**
 	 * Simple filter stream around another stream.
 	 * <p>
 	 * ObjectLoader implementations can use this stream type when the object's
 	 * content is available from a standard InputStream.
 	 */
 	public static class Filter extends ObjectStream {
 		private final int type;
 
 		private final long size;
 
 		private final InputStream in;
 
 		/**
 		 * Create a filter stream for an object.
 		 *
 		 * @param type
 		 *            the type of the object.
 		 * @param size
 		 *            total size of the object, in bytes.
 		 * @param in
 		 *            stream the object's raw data is available from. This
 		 *            stream should be buffered with some reasonable amount of
 		 *            buffering.
 		 */
 		public Filter(int type, long size, InputStream in) {
 			this.type = type;
 			this.size = size;
 			this.in = in;
 		}
 
 		@Override
 		public int getType() {
 			return type;
 		}
 
 		@Override
 		public long getSize() {
 			return size;
 		}
 
 		@Override
 		public int available() throws IOException {
 			return in.available();
 		}
 
 		@Override
 		public long skip(long n) throws IOException {
 			return in.skip(n);
 		}
 
 		@Override
 		public int read() throws IOException {
 			return in.read();
 		}
 
 		@Override
 		public int read(byte[] b, int off, int len) throws IOException {
 			return in.read(b, off, len);
 		}
 
 		@Override
 		public boolean markSupported() {
 			return in.markSupported();
 		}
 
 		@Override
 		public void mark(int readlimit) {
 			in.mark(readlimit);
 		}
 
 		@Override
 		public void reset() throws IOException {
 			in.reset();
 		}
 
 		@Override
 		public void close() throws IOException {
 			in.close();
 		}
 	}
 }