//
//  ========================================================================
//  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.http;

import java.io.IOException;

import org.eclipse.jetty.io.JBuffer;
import org.eclipse.jetty.io.Buffers;
import org.eclipse.jetty.io.BufferUtil;
import org.eclipse.jetty.io.EndPoint;
import org.eclipse.jetty.io.EofException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/* ------------------------------------------------------------ */
/**
 * Abstract Generator. Builds HTTP Messages.
 *
 * Currently this class uses a system parameter "jetty.direct.writers" to control
 * two optional writer to byte conversions. buffer.writers=true will probably be
 * faster, but will consume more memory.   This option is just for testing and tuning.
 *
 */
abstract class AbstractGenerator
{
	private static final Logger LOG = LoggerFactory.getLogger(AbstractGenerator.class);

	public static final boolean LAST=true;
	public static final boolean MORE=false;

	// states
	final static int STATE_HEADER = 0;
	final static int STATE_CONTENT = 2;
	final static int STATE_FLUSHING = 3;
	final static int STATE_END = 4;

	// data

	final Buffers _buffers; // source of buffers
	final EndPoint _endp;

	int _state = STATE_HEADER;

	int _status = 0;
	int _version = HttpVersions.HTTP_1_1_ORDINAL;
	JBuffer _reason;
	JBuffer _method;
	String _uri;

	long _contentWritten = 0;
	long _contentLength = HttpTokens.UNKNOWN_CONTENT;
	boolean _last = false;
	boolean _head = false;
	boolean _noContent = false;
	Boolean _persistent = null;

	JBuffer _header; // JBuffer for HTTP header (and maybe small _content)
	JBuffer _buffer; // JBuffer for copy of passed _content
	JBuffer _content; // JBuffer passed to addContent


	/* ------------------------------------------------------------------------------- */
	/**
	 * Constructor.
	 *
	 * @param buffers buffer pool
	 * @param io the end point
	 */
	AbstractGenerator(Buffers buffers, EndPoint io)
	{
		this._buffers = buffers;
		this._endp = io;
	}

	/* ------------------------------------------------------------ */
	/**
	 * Add content.
	 * 
	 * @param content
	 * @param last
	 * @throws IllegalArgumentException if <code>content</code> is {@link JBuffer#isImmutable immutable}.
	 * @throws IllegalStateException If the request is not expecting any more content,
	 *   or if the buffers are full and cannot be flushed.
	 * @throws IOException if there is a problem flushing the buffers.
	 */
	public abstract void addContent(JBuffer content, boolean last) throws IOException;

	abstract boolean isRequest();

	public final boolean isOpen()
	{
		return _endp.isOpen();
	}

	public final void resetBuffer()
	{
		if(_state>=STATE_FLUSHING)
			throw new IllegalStateException("Flushed");

		_last = false;
		_persistent = null;
		_contentWritten = 0;
		_contentLength = HttpTokens.UNKNOWN_CONTENT;
		_content=null;
		if (_buffer!=null)
			_buffer.clear();
	}

	/* ------------------------------------------------------------ */
	/**
	 * @return Returns the contentBufferSize.
	 */
	public final int getContentBufferSize()
	{
		if (_buffer==null)
			_buffer = _buffers.getBuffer();
		return _buffer.capacity();
	}

	public final JBuffer getUncheckedBuffer()
	{
		return _buffer;
	}

	public final boolean isComplete()
	{
		return _state == STATE_END;
	}

	public final boolean isIdle()
	{
		return _state == STATE_HEADER && _method==null && _status==0;
	}

	public final boolean isCommitted()
	{
		return _state != STATE_HEADER;
	}

	public final void setContentLength(long value)
	{
		if (value<0)
			_contentLength=HttpTokens.UNKNOWN_CONTENT;
		else
			_contentLength=value;
	}

	public final void setHead(boolean head)
	{
		_head = head;
	}

	/* ------------------------------------------------------------ */
	/**
	 * @return <code>false</code> if the connection should be closed after a request has been read,
	 * <code>true</code> if it should be used for additional requests.
	 */
	public final boolean isPersistent()
	{
		return _persistent!=null
		?_persistent.booleanValue()
		:(isRequest()?true:_version>HttpVersions.HTTP_1_0_ORDINAL);
	}

	public final void setPersistent(boolean persistent)
	{
		_persistent = persistent;
	}

	/* ------------------------------------------------------------ */
	/**
	 * @param version The version of the client the response is being sent to (NB. Not the version
	 *            in the response, which is the version of the server).
	 */
	public final void setVersion(int version)
	{
		if (_state != STATE_HEADER)
			throw new IllegalStateException("STATE!=START "+_state);
		_version = version;
		if (_version==HttpVersions.HTTP_0_9_ORDINAL && _method!=null)
			_noContent=true;
	}

	/* ------------------------------------------------------------ */
	/**
	 * @param status The status code to send.
	 * @param reason the status message to send.
	 */
	public final void setResponse(int status, String reason)
	{
		if (_state != STATE_HEADER) throw new IllegalStateException("STATE!=START");
		_method=null;
		_status = status;
		if (reason!=null)
		{
			int len=reason.length();

			// TODO don't hard code
			if (len>1024)
				len=1024;
			_reason = BufferUtil.newBuffer(len);
			for (int i=0;i<len;i++)
			{
				char ch = reason.charAt(i);
				if (ch!='\r'&&ch!='\n')
					_reason.put((byte)ch);
				else
					_reason.put((byte)' ');
			}
		}
	}

	public final void completeUncheckedAddContent()
	{
		if (_noContent)
		{
			if(_buffer!=null)
				_buffer.clear();
		}
		else
		{
			_contentWritten+=_buffer.remaining();
			if (_head)
				_buffer.clear();
		}
	}

	public boolean isBufferFull()
	{
		if (_buffer != null && _buffer.space()==0)
		{
			if (_buffer.remaining()==0)
				_buffer.compact();
			return _buffer.space()==0;
		}

		return _content!=null && _content.remaining()>0;
	}

	public final boolean isWritten()
	{
		return _contentWritten>0;
	}

	public final boolean isAllContentWritten()
	{
		return _contentLength>=0 && _contentWritten>=_contentLength;
	}

	public abstract void completeHeader(HttpFields fields, boolean allContentAdded) throws IOException;

	/* ------------------------------------------------------------ */
	/**
	 * Complete the message.
	 *
	 * @throws IOException
	 */
	public void complete() throws IOException
	{
		if (_state == STATE_HEADER)
		{
			throw new IllegalStateException("State==HEADER");
		}

		if (_contentLength >= 0 && _contentLength != _contentWritten && !_head)
		{
			if (LOG.isDebugEnabled())
				LOG.debug("ContentLength written=="+_contentWritten+" != contentLength=="+_contentLength);
			_persistent = false;
		}
	}

	public abstract int flushBuffer() throws IOException;


	public final void flush(long maxIdleTime) throws IOException
	{
		// block until everything is flushed
		long now=System.currentTimeMillis();
		long end=now+maxIdleTime;
		JBuffer content = _content;
		JBuffer buffer = _buffer;
		if (content!=null && content.remaining()>0 || buffer!=null && buffer.remaining()>0 || isBufferFull())
		{
			flushBuffer();

			while (now<end && (content!=null && content.remaining()>0 ||buffer!=null && buffer.remaining()>0) && _endp.isOpen()&& !_endp.isOutputShutdown())
			{
				blockForOutput(end-now);
				now=System.currentTimeMillis();
			}
		}
	}

	/* ------------------------------------------------------------ */
	/**
	 * Utility method to send an error response. If the builder is not committed, this call is
	 * equivalent to a setResponse, addContent and complete call.
	 *
	 * @param code The error code
	 * @param reason The error reason
	 * @param content Contents of the error page
	 * @param close True if the connection should be closed
	 * @throws IOException if there is a problem flushing the response
	 */
	public final void sendError(int code, String reason, String content, boolean close) throws IOException
	{
		if (close)
			_persistent=false;
		if (isCommitted())
		{
			LOG.debug("sendError on committed: {} {}",code,reason);
		}
		else
		{
			LOG.debug("sendError: {} {}",code,reason);
			setResponse(code, reason);
			if (content != null)
			{
				completeHeader(null, false);
				addContent(BufferUtil.wrap(content), LAST);
			}
			else if (code>=400)
			{
				completeHeader(null, false);
				addContent(BufferUtil.wrap("Error: "+(reason==null?(""+code):reason)), LAST);
			}
			else
			{
				completeHeader(null, true);
			}
			complete();
		}
	}

	public final long getContentWritten()
	{
		return _contentWritten;
	}


	public final void blockForOutput(long maxIdleTime) throws IOException
	{
		if (_endp.isBlocking())
		{
			try
			{
				flushBuffer();
			}
			catch(IOException e)
			{
				_endp.close();
				throw e;
			}
		}
		else
		{
			if (!_endp.blockWritable(maxIdleTime))
			{
				_endp.close();
				throw new EofException("timeout");
			}

			flushBuffer();
		}
	}

}