/*-------------------------------------------------------------------------
 *
 * PGLOInputStream.java
 *     This class encapsulates InputStream and provides support for loading
 *     large files into bytea fields.
 *
 * Copyright (c) 2003, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *	  $Header
 *
 *-------------------------------------------------------------------------
 */
package org.postgresql.util;

import java.io.*;
import org.postgresql.core.BaseConnection;
import org.postgresql.largeobject.*;

public class PGLOInputStream
{
	protected BaseConnection connection;        // The connection who created us
	private java.io.InputStream stream;
	private int LOlength;
	private int LOoid;
	private LargeObject lob;
	boolean isMaterialized;

	/*
	 * Constructor
	 * @param stream The InputStream with data to load into the bytea
	 * @param length The (maximum) length of the data to read from the file
	 */
	public PGLOInputStream(BaseConnection connection, java.io.InputStream stream, int length)
	{
		this.connection = connection;
		this.stream = stream;
		this.LOlength = length;
		lob = null;
		LOoid = 0; /* Invalid Oid */
		isMaterialized = false;
	}

	/*
	 * Creates a staging area (a PostgreSQL LO)
	 * and reads the data into it.
	 */
	public void materialize() throws java.sql.SQLException
	{
		LargeObjectManager lom = connection.getLargeObjectAPI();
		LOoid = lom.create();
System.out.println("LOoid=" + LOoid);
		lob = lom.open(LOoid);
		
		// Copy the file into the LO	
		OutputStream los = lob.getOutputStream();
System.out.println("los=" + los);
		try
		{
			// could be buffered, but then the OutputStream returned by LargeObject
			// is buffered internally anyhow, so there would be no performance
			// boost gained, if anything it would be worse!
			int c = stream.read();
			int p = 0;
			while (c > -1 && p < LOlength)
			{
				los.write(c);
				c = stream.read();
				p++;
			}
			los.close();
		}
		catch (IOException se)
		{
			throw new PSQLException("postgresql.unusual", se);
		}
		// lob is closed by the stream so don't call lob.close()
		// lob.close();
		
		isMaterialized = true;
	}

	/*
	 * Deletes (unlink) the staging area (a PostgreSQL LO).
	 */
	public void dematerialize() throws java.sql.SQLException
	{
		LargeObjectManager lom = connection.getLargeObjectAPI();
		lom.delete(LOoid);
		LOoid = 0; /* Invalid Oid */
		isMaterialized = false;
	}

	/*
	 * Overides Object
	 */
	public String toString()
	{
		return "loread( lo_open(" + LOoid + ", x'60000'::INTEGER), " + LOlength + " )";
	}
}