/*

   Derby - Class TreeWalker

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to you 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.

 */
import java.io.*;
import java.sql.*;
import java.util.*;

import org.apache.derby.iapi.error.StandardException;
import org.apache.derby.iapi.reference.ContextId;
import org.apache.derby.iapi.services.context.ContextManager;
import org.apache.derby.iapi.services.sanity.SanityManager;
import org.apache.derby.iapi.sql.compile.Visitable;
import org.apache.derby.iapi.sql.compile.Visitor;
import org.apache.derby.iapi.sql.conn.LanguageConnectionContext;
import org.apache.derby.impl.jdbc.EmbedConnection;
import org.apache.derby.impl.sql.compile.QueryTreeNode;

/**
 * Little program to run the Derby parser on a text string and to print
 * the resulting abstract syntax tree produced by the parser.
 */
public  class   TreeWalker  implements  Visitor
{
    ///////////////////////////////////////////////////////////////////////////////////
    //
    // CONSTANTS
    //
    ///////////////////////////////////////////////////////////////////////////////////

    private static  final   String  DRIVER_NAME = "org.apache.derby.jdbc.EmbeddedDriver";
    private static  final   String  CONNECTION_URL = "jdbc:derby:dummy;create=true";
    private static  final   String  DERBY_DEBUG_SETTING = "derby.debug.true";
    private static  final   String  STOP_AFTER_PARSING =  "StopAfterParsing";
    private static  final   String  STOPPED_AFTER_PARSING = "42Z55";
    private static  final   String  SHUTDOWN_URL = "jdbc:derby:;shutdown=true";
    private static  final   String  INDENTATION = "    ";
    
    ///////////////////////////////////////////////////////////////////////////////////
    //
    // STATE
    //
    ///////////////////////////////////////////////////////////////////////////////////

    private PrintStream _printStream = System.out;
    private int             _depth;
    private HashSet     _visitedNodes;

    ///////////////////////////////////////////////////////////////////////////////////
    //
    // ENTRY POINT
    //
    ///////////////////////////////////////////////////////////////////////////////////

    /**
     * Entry point. Takes one argument: the string to be parsed. Along
     * the way, this program will create a dummy Derby database if it
     * doesn't already exist.
     */
    public  static  void    main( String[] args )
        throws Exception
    {
        TreeWalker   astParser = new TreeWalker();

        astParser.execute( args );
    }

    private void    execute( String[] args )
        throws Exception
    {
        System.setProperty( DERBY_DEBUG_SETTING, STOP_AFTER_PARSING );
        Class.forName( DRIVER_NAME );

        String                      text = args[ 0 ];
        Connection              conn = DriverManager.getConnection( CONNECTION_URL );
        PreparedStatement   ps = null;

        println( "Parsing:\n" + text );
        
        try {
            ps = conn.prepareStatement( text );
       }
        catch (SQLException se)
        {
            String  sqlState = se.getSQLState();

            if ( !STOPPED_AFTER_PARSING.equals( sqlState ) ) { throw se; }
        }
        
        ContextManager      contextManager = ((EmbedConnection) conn).getContextManager();
        LanguageConnectionContext   lcc = (LanguageConnectionContext) contextManager.getContext( ContextId.LANG_CONNECTION);
        QueryTreeNode       queryTree = (QueryTreeNode) lcc.getLastQueryTree();

        _depth = 0;
        _visitedNodes = new HashSet();
        visit( queryTree );

        try {
            DriverManager.getConnection( SHUTDOWN_URL );
        }
        catch (Exception e) {}
    }

    ///////////////////////////////////////////////////////////////////////////////////
    //
    // Visitor BEHAVIOR
    //
    ///////////////////////////////////////////////////////////////////////////////////

    public   Visitable visit(Visitable node) throws StandardException
    {
        if ( !_visitedNodes.contains( node ) )
        {
            _depth++;
            _visitedNodes.add( node );

            StringBuffer    buffer = new StringBuffer();

            for ( int i = 0; i < _depth; i++ ) { buffer.append( INDENTATION ); }
            buffer.append( node.getClass().getName() );

            println( buffer.toString() );

            node.accept( this );

            _depth--;
        }

        return node;
    }

    public  boolean stopTraversal() { return false; }
    public  boolean skipChildren(Visitable node) throws StandardException   { return false; }


    ///////////////////////////////////////////////////////////////////////////////////
    //
    // MINIONS
    //
    ///////////////////////////////////////////////////////////////////////////////////

    private void    println( String text )
    {
        _printStream.println( text );
    }
    
}