/*
 * Copyright 2004 The Apache Software Foundation
 * 
 * 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.
 */

using System;

namespace Lucene.Net.Store
{
	
	/// <summary>Base implementation class for buffered {@link IndexOutput}. </summary>
	public abstract class BufferedIndexOutput:IndexOutput
	{
		internal const int BUFFER_SIZE = 1024;
		
		private byte[] buffer = new byte[BUFFER_SIZE];
		private long bufferStart = 0; // position in file of buffer
		private int bufferPosition = 0; // position in buffer
		
		/// <summary>Writes a single byte.</summary>
		/// <seealso cref="IndexInput.ReadByte()">
		/// </seealso>
		public override void  WriteByte(byte b)
		{
			if (bufferPosition >= BUFFER_SIZE)
				Flush();
			buffer[bufferPosition++] = b;
		}
		
		/// <summary>Writes an array of bytes.</summary>
		/// <param name="b">the bytes to write
		/// </param>
		/// <param name="length">the number of bytes to write
		/// </param>
		/// <seealso cref="IndexInput.ReadBytes(byte[],int,int)">
		/// </seealso>
		public override void  WriteBytes(byte[] b, int length)
		{
			for (int i = 0; i < length; i++)
				WriteByte(b[i]);
		}
		
		/// <summary>Forces any buffered output to be written. </summary>
		public override void  Flush()
		{
			FlushBuffer(buffer, bufferPosition);
			bufferStart += bufferPosition;
			bufferPosition = 0;
		}
		
		/// <summary>Expert: implements buffer write.  Writes bytes at the current position in
		/// the output.
		/// </summary>
		/// <param name="b">the bytes to write
		/// </param>
		/// <param name="len">the number of bytes to write
		/// </param>
		public abstract void  FlushBuffer(byte[] b, int len);
		
		/// <summary>Closes this stream to further operations. </summary>
		public override void  Close()
		{
			Flush();
		}
		
		/// <summary>Returns the current position in this file, where the next write will
		/// occur.
		/// </summary>
		/// <seealso cref="Seek(long)">
		/// </seealso>
		public override long GetFilePointer()
		{
			return bufferStart + bufferPosition;
		}
		
		/// <summary>Sets current position in this file, where the next write will occur.</summary>
		/// <seealso cref="GetFilePointer()">
		/// </seealso>
		public override void  Seek(long pos)
		{
			Flush();
			bufferStart = pos;
		}
		
		/// <summary>The number of bytes in the file. </summary>
		public abstract override long Length();
	}
}