/*
 *  eXist SQL Module Extension GetJNDIConnectionFunction
 *  Copyright (C) 2008-09 Adam Retter <adam@exist-db.org>
 *  www.adamretter.co.uk
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *  $Id$
 */

package org.exist.xquery.modules.sql;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import org.exist.dom.QName;
import org.exist.xquery.BasicFunction;
import org.exist.xquery.Cardinality;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.IntegerValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;

import java.sql.Connection;

import javax.naming.Context;
import javax.naming.InitialContext;

import javax.sql.DataSource;


/**
 * eXist SQL Module Extension GetJNDIConnectionFunction.
 *
 * <p>Get a connection to a SQL Database via JNDI</p>
 *
 * @author   Adam Retter <adam@exist-db.org>
 * @author   Loren Cahlander
 * @version  1.2
 * @see      org.exist.xquery.BasicFunction#BasicFunction(org.exist.xquery.XQueryContext, org.exist.xquery.FunctionSignature)
 * @serial   2008-05-19
 */
public class GetJNDIConnectionFunction extends BasicFunction
{
    @SuppressWarnings( "unused" )
    private static final Logger             logger     = LogManager.getLogger( GetJNDIConnectionFunction.class );

    public final static FunctionSignature[] signatures = {
			new FunctionSignature(
					new QName("get-jndi-connection", SQLModule.NAMESPACE_URI, SQLModule.PREFIX),
					"Opens a connection to a SQL Database.",
					new SequenceType[] { 
						new FunctionParameterSequenceType("jndi-name", Type.STRING, Cardinality.EXACTLY_ONE, "The JNDI name")
					},
					new FunctionParameterSequenceType("handle", Type.LONG, Cardinality.ZERO_OR_ONE, "an xs:long representing the connection handle")),

			new FunctionSignature(
					new QName("get-jndi-connection", SQLModule.NAMESPACE_URI, SQLModule.PREFIX),
					"Opens a connection to a SQL Database.",
					new SequenceType[] { 
						new FunctionParameterSequenceType("jndi-name", Type.STRING, Cardinality.EXACTLY_ONE, "The JNDI name"),
						new FunctionParameterSequenceType("username", Type.STRING, Cardinality.EXACTLY_ONE, "The username"),
						new FunctionParameterSequenceType("password", Type.STRING, Cardinality.EXACTLY_ONE, "The password") 
					}, 
					new FunctionParameterSequenceType("handle", Type.LONG, Cardinality.ZERO_OR_ONE, "an xs:long representing the connection handle")) 
    };


    /**
     * GetJNDIConnectionFunction Constructor.
     *
     * @param  context    The Context of the calling XQuery
     * @param  signature  DOCUMENT ME!
     */
    public GetJNDIConnectionFunction( XQueryContext context, FunctionSignature signature )
    {
        super( context, signature );
    }

    /**
     * evaluate the call to the xquery get-jndi-connection() function, it is really the main entry point of this class.
     *
     * @param   args             arguments from the get-jndi-connection() function call
     * @param   contextSequence  the Context Sequence to operate on (not used here internally!)
     *
     * @return  A xs:long representing a handle to the connection
     *
     * @throws  XPathException  DOCUMENT ME!
     *
     * @see     org.exist.xquery.BasicFunction#eval(org.exist.xquery.value.Sequence[], org.exist.xquery.value.Sequence)
     */
    public Sequence eval( Sequence[] args, Sequence contextSequence ) throws XPathException
    {
        // was a JNDI name specified?
        if( args[0].isEmpty() ) {
            return( Sequence.EMPTY_SEQUENCE );
        }

        try {
            Connection con      = null;

            // get the JNDI source
            String     jndiName = args[0].getStringValue();
            Context    ctx      = new InitialContext();
            DataSource ds       = (DataSource)ctx.lookup( jndiName );

            // try and get the connection
            if( args.length == 1 ) {
                con = ds.getConnection();
            }

            if( args.length == 3 ) {
                String jndiUser     = args[1].getStringValue();
                String jndiPassword = args[2].getStringValue();

                con = ds.getConnection( jndiUser, jndiPassword );
            }

            // store the connection and return the uid handle of the connection
            return( new IntegerValue( SQLModule.storeConnection( context, con ) ) );
        }
        catch( Exception e ) {
            throw( new XPathException( this, e.getMessage() ) );
        }
    }
}