/* ======================================================================
The Bodington System Software License, Version 1.0
  
Copyright (c) 2001 The University of Leeds.  All rights reserved.
  
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

1.  Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.

2.  Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.

3.  The end-user documentation included with the redistribution, if any,
must include the following acknowledgement:  "This product includes
software developed by the University of Leeds
(http://www.bodington.org/)."  Alternately, this acknowledgement may
appear in the software itself, if and wherever such third-party
acknowledgements normally appear.

4.  The names "Bodington", "Nathan Bodington", "Bodington System",
"Bodington Open Source Project", and "The University of Leeds" must not be
used to endorse or promote products derived from this software without
prior written permission. For written permission, please contact
d.gardner@leeds.ac.uk.

5.  The name "Bodington" may not appear in the name of products derived
from this software without prior written permission of the University of
Leeds.

THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO,  TITLE,  THE IMPLIED WARRANTIES 
OF QUALITY  AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO 
EVENT SHALL THE UNIVERSITY OF LEEDS OR ITS CONTRIBUTORS BE LIABLE FOR 
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE 
GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
POSSIBILITY OF SUCH DAMAGE.
=========================================================

This software was originally created by the University of Leeds and may contain voluntary 
contributions from others.  For more information on the Bodington Open Source Project, please 
see http://bodington.org/

====================================================================== */

package org.bodington.xml;

import java.text.Collator;
import java.util.*;
import java.sql.*;

import org.apache.log4j.Logger;


public class XMLQuery extends java.util.Vector
	{
    
    private static Logger log = Logger.getLogger(XMLQuery.class);
    
	// if multiple sub queries, how to combine...
	public static final int COMBINE_UNION					= 0;
	public static final int COMBINE_INTERCEPT				= 1;

	// type of descent...
	public static final int RELATE_FAMILY				= 0;
	public static final int RELATE_DESCENDENT			= 1;
	public static final int RELATE_CHILD				= 2;
	// not implemented...
	public static final int RELATE_ANCESTOR		   = 3;
	public static final int RELATE_PARENT				= 4;
	
	
	private XMLRepository repository;
	private String o_table = "xml_objects";
	private String e_table = "xml_elements";
	private String a_table = "xml_attributes";
	private String c_table = "xml_cdata";
	private String w_table = "xml_words";
	
	public int combination;
	public int relationship;
	
	public Integer xml_object_id;
	public Integer reference;
	public String title_criterion;
	
	public String element_name=null;
	public boolean root_element=false;
	public String attribute_name=null;
	public String attribute_criterion=null;
	public String text_criterion=null;
	public Vector words=new Vector();
        public int word_strength=Collator.IDENTICAL;
	
	private String element_criterion;

	
	private int[] last_position;
	private static final int MAX_DEPTH=8;
	
	XMLQuery container;
	
	// package access to constructor because apps must use XMLRepository
	XMLQuery( XMLRepository rep )
		{
		repository = rep;
		o_table = rep.o_table;
		e_table = rep.e_table;
		a_table = rep.a_table;
		c_table = rep.c_table;
		w_table = rep.w_table;
		
		relationship = RELATE_DESCENDENT;
		combination = COMBINE_UNION;
		last_position = new int[MAX_DEPTH];
		for ( int i=0; i<MAX_DEPTH; i++ )
			last_position[i]=0;
		
		container=null;
		}
	
	public void addElement( XMLQuery xml_query )
		{
		super.addElement( xml_query );
		xml_query.container = this;
		}

	private XMLQuery topQuery()
		{
		XMLQuery q = this;
		while ( q.container!=null )
			q = q.container;
		return q;
		}

	public Vector getXMLObjectRecords( Connection con, Integer max )
		throws SQLException
		{
		Integer ref;
		XMLObjectRecord record;
		Vector v = new Vector();

		repository.initWordCache( con );
		
		String sql = sqlObjects();
		log.debug( sql );
		Statement st = con.createStatement();
		ResultSet results = st.executeQuery( sql );
		while ( results.next() )
			{
			ref = new Integer( results.getInt( 6 ) );
			if ( results.wasNull() )
				ref=null;
			record = new XMLObjectRecord( results.getInt( 1 ), 
													results.getInt( 2 ),
													results.getString( 3 ),
													results.getString( 4 ),
													results.getString( 5 ),
													ref );
			v.addElement( record );
			if ( max !=null && v.size() >= max.intValue() )
				break;
			}
		results.close();
		st.close();
		
		return v;
		}
	
	public Vector getXMLElementRecords( Connection con, Integer max )
		throws SQLException
		{
		Integer parent;
		XMLElementRecord record;
		Vector v = new Vector();
		
		repository.initWordCache( con );

		String sql = sqlElements();
		log.debug( sql );
		
		Statement st = con.createStatement();
		ResultSet results = st.executeQuery( sql );
		while ( results.next() )
			{
			parent = new Integer( results.getInt( 6 ) );
			if ( results.wasNull() )
				parent=null;
			record = new XMLElementRecord( results.getInt( 1 ), 
													results.getInt( 2 ),
													results.getInt( 3 ),
													results.getInt( 4 ),
													results.getString( 5 ),
													parent );
			v.addElement( record );
			if ( max !=null && v.size() >= max.intValue() )
				break;
			}
		results.close();
		st.close();
		
		return v;
		}
	
	private String sqlElements()
		throws IllegalArgumentException 
		{
		StringBuffer select = new StringBuffer();
		for ( int i=0; i<MAX_DEPTH; i++ )
			topQuery().last_position[i]=0;
		sqlSelect( select, 0, false, null );
		return select.toString();
		}

	private String sqlObjects()
		throws IllegalArgumentException 
		{
		StringBuffer select = new StringBuffer();
		for ( int i=0; i<MAX_DEPTH; i++ )
			topQuery().last_position[i]=0;
		sqlSelect( select, 0, true, null );
		return select.toString();
		}

	private String sqlTable( int depth, int position )
		{
		return "el_" + depth + "_" + position;
		}

	private String sqlFrom( int depth, int position )
		{
		return e_table + " " + sqlTable( depth, position );
		}

	private String sqlObjectTable( int depth, int position )
		{
		return "ob_" + depth + "_" + position;
		}

	private String sqlObjectFrom( int depth, int position )
		{
		return o_table + " " + sqlObjectTable( depth, position );
		}

	private String sqlTextTable( int depth, int position )
		{
		return "tx_" + depth + "_" + position;
		}

	private String sqlTextFrom( int depth, int position )
		{
		return c_table + " " + sqlTextTable( depth, position );
		}

	private String sqlWordTable( int depth, int position )
		{
		return "w_"  + depth + "_" + position;
		}

	private String sqlWordFrom( int depth, int position )
		{
		return w_table + " " + sqlWordTable( depth, position );
		}

	private String sqlAttTable( int depth, int position )
		{
		return "at_" + depth + "_" + position;
		}

	private String sqlAttFrom( int depth, int position )
		{
		return a_table + " " + sqlAttTable( depth, position );
		}

	private String sqlInsert( String expression, String ins )
		{
		StringBuffer expanded = new StringBuffer();
		for ( int i=0; i< expression.length(); i++ )
			{
			if ( expression.charAt( i ) == '?' )
				expanded.append( ins );
			else
				expanded.append( expression.charAt( i ) );
			}
		return expanded.toString();
		}


	private boolean hasCriteria()
		{
		return !( reference==null && title_criterion == null && 
		            xml_object_id == null && element_name==null &&
					attribute_name == null && attribute_criterion == null &&
					words.size() == 0 );
		}


	private void sqlSelect( StringBuffer sql, int depth, boolean objects, String sql_connection )
		throws IllegalArgumentException 
		{
		int i, position = ++topQuery().last_position[depth];
		
		int last_deeper_position;
		XMLQuery current;
		StringBuffer connect;
		Integer[] xml_token_id = new Integer[words.size()];
		int xml_token_count=0;

		if ( !hasCriteria() && size()== 0 )
			throw new IllegalArgumentException( "A query with no search criteria were specified." );
		
		//look up token ids first, include only those that exist
		for ( i=0; i<words.size(); i++ )
			{
			xml_token_id[xml_token_count] = repository.getTokenId( (String)words.elementAt( i ), word_strength );
			if ( xml_token_id[xml_token_count] != null )
				xml_token_count++;
			}
			
		// a select statement is only need if this node in the query tree
		// has search criteria
		if ( hasCriteria() )
			{
			// sort out which tables to put in query and how to join them
			sql.append( "SELECT " );
			sql.append( "DISTINCT " );
			if ( objects )
				sql.append( sqlObjectTable( depth, position ) );
			else
				sql.append( sqlTable( depth, position ) );
			sql.append( ".* FROM " );
					
			if ( objects || reference!=null || title_criterion!=null )
				{
				sql.append( sqlObjectFrom( depth, position ) );
				sql.append( ", " );
				sql.append( sqlFrom( depth, position ) );
				sql.append( ", " );
				}
			else
				{
				sql.append( sqlFrom( depth, position ) );
				sql.append( ", " );
				}

			// must include the attributes table if there is a search on it.
			if ( attribute_name !=null && attribute_criterion != null )
				{
				sql.append( sqlAttFrom( depth, position ) );
				sql.append( ", " );
				}

			// if there is a word match then word tables are
			if ( xml_token_count > 0 )
				{
				if ( xml_token_count == 1 || combination == COMBINE_UNION )
					{
					sql.append( sqlWordFrom( depth, position ) );
					sql.append( "_0, " );
					}
				else
					{
					for ( i=0; i<xml_token_count; i++ )
						{
						sql.append( sqlWordFrom( depth, position ) );
						sql.append( "_" );
						sql.append( i );
						sql.append( ", " );
						}
					}
				}

			// there will be ", " at the end so chop it off...
			sql.setLength( sql.length()-2 );
			
			// ready for where clause
			sql.append( " WHERE " );

			// first table joining expressions
			if ( objects || reference!=null || title_criterion!=null )
				{
				sql.append( this.sqlObjectTable( depth, position ) );
				sql.append( ".xml_object_id = " );
				sql.append( this.sqlTable( depth, position ) );
				sql.append( ".xml_object_id AND " );
				}

			// must include the attributes table if there is a search on it.
			if ( attribute_name !=null && attribute_criterion != null )
				{
				sql.append( sqlAttTable( depth, position ) );
				sql.append( ".xml_element_id = " );
				sql.append( sqlTable( depth, position ) );
				sql.append( ".xml_element_id AND " );
				}

			// if there is a word match then word tables are
			if ( xml_token_count > 0 )
				{
				if ( xml_token_count == 1 || combination == COMBINE_UNION )
					{
					sql.append( sqlWordTable( depth, position ) );
					sql.append( "_0.xml_element_id = " );
					sql.append( sqlTable( depth, position ) );
					sql.append( ".xml_element_id AND " );
					}
				else
					{
					for ( i=0; i<xml_token_count; i++ )
						{
						sql.append( sqlWordTable( depth, position ) );
						sql.append( "_" );
						sql.append( i );
						sql.append( ".xml_element_id = " );
						sql.append( sqlTable( depth, position ) );
						sql.append( ".xml_element_id AND " );
						}
					}
				}

			// if we already know that required tokens don't exist return
			// a query that is guaranteed to return no records.
			if ( xml_token_count != words.size() && 
						(combination == COMBINE_INTERCEPT || xml_token_count==0 ) )
				{
				sql.append( sqlTable( depth, position ) );
				sql.append( ".xml_element_id = NULL" );
				return;
				}

			// now the expressions to find the desired records
			if ( reference!=null )
				{
				sql.append( this.sqlObjectTable( depth, position ) );
				sql.append( ".reference = " );
				sql.append( reference.toString() );
				sql.append( " AND " );
				}
			if ( title_criterion!=null )
				{
				sql.append( "(" );
				sql.append( sqlInsert( title_criterion, this.sqlObjectTable( depth, position ) + ".title" ) );
				sql.append( ") AND " );
				}
			
			if ( xml_object_id != null )
			    {
				sql.append( this.sqlTable( depth, position ) );
				sql.append( ".xml_object_id = " );
				sql.append( xml_object_id.toString() );
				sql.append( " AND " );
			    }
			    
			if ( element_name!=null )
				{
				sql.append( this.sqlTable( depth, position ) );
				sql.append( ".element_name = '" );
				sql.append( element_name );
				sql.append( "'" );
				sql.append( " AND " );
				}
								
			if ( root_element )
				{
				sql.append( sqlTable( depth, position ) );
				sql.append( ".left_index = 0" );
				sql.append( " AND " );
				}

								
			if ( attribute_name !=null && attribute_criterion != null )
				{
				sql.append( this.sqlAttTable( depth, position ) + ".name = '" );
				sql.append( attribute_name );
				sql.append( "' AND (" );
				sql.append( sqlInsert( attribute_criterion, this.sqlAttTable( depth, position ) + ".value" ) );
				sql.append( ") AND " );
				}
								
			if ( xml_token_count > 0 )
				{
				if ( combination == COMBINE_UNION )
					{
					if ( xml_token_count > 1 )
						sql.append( "(" );
						
					for ( i=0; i<xml_token_count; i++ )
						{
						if ( i>0 )
							sql.append( " OR " );
                                                sql.append( "( " );
						sql.append( sqlWordTable( depth, position ) );
						sql.append( "_0.xml_token_id = " );
						sql.append( xml_token_id[i] );
                                                sql.append( " AND " );
						sql.append( sqlWordTable( depth, position ) );
						sql.append( "_0.flags <= " );
                                                sql.append( repository.strengthToWordFlag( word_strength ) );
                                                sql.append( " ) " );
						}
					
					if ( xml_token_count > 1 )
						sql.append( ")" );

					sql.append( " AND " );
					}
				else if ( combination == COMBINE_INTERCEPT )
					{
					for ( i=0; i<xml_token_count; i++ )
						{
                                                sql.append( "( " );
						sql.append( sqlWordTable( depth, position ) );
						sql.append( "_" );
						sql.append( i );
						sql.append( ".xml_token_id = " );
						sql.append( xml_token_id[i] );
                                                sql.append( " AND " );
						sql.append( sqlWordTable( depth, position ) );
						sql.append( "_" );
						sql.append( i );
						sql.append( ".flags <= " );
                                                sql.append( repository.strengthToWordFlag( word_strength ) );
                                                sql.append( " ) " );
						sql.append( " AND " );
						}
					}
				else
					throw new IllegalArgumentException( "Unknown combination operator." );
				}

			if ( text_criterion!=null )
				{
				throw new IllegalArgumentException( "Text criterion not implemented." );
				}
						

			// did containing query specify some joining SQL ?
			if ( sql_connection != null )
				sql.append( sql_connection );
			}
			
			
		if ( this.size()>1 &&
				relationship != RELATE_FAMILY && 
				relationship != RELATE_DESCENDENT && 
				relationship != RELATE_CHILD &&
				relationship != RELATE_ANCESTOR &&
				relationship != RELATE_PARENT
					)
				throw new IllegalArgumentException( "Unrecognized relationship option." );
				
		if ( hasCriteria() )
			{
			// parentheses needed if there are multiple siblings
			if ( this.size()>1 )
				sql.append( " ( " );
				
			for ( i=0; i<this.size(); i++ )
				{
				current = (XMLQuery)this.elementAt( i );

				// join to previous sibling
				if ( i>0 )
					{
					if ( combination == COMBINE_UNION )
						sql.append( " OR " );
					else if ( combination == COMBINE_INTERCEPT )
						sql.append( " AND " );
					else
						throw new IllegalArgumentException( "Unrecognized combination option." );
					}
					
				// start sub query
				sql.append( " EXISTS (" );
				
				// prepare a clause to join this query to sub query
				connect = new StringBuffer();
				// all type of relationship put the elements into the same object
				connect.append( sqlTable( depth, position ) );
				connect.append( ".xml_object_id = " );
				connect.append( sqlTable( depth+1, topQuery().last_position[depth+1]+1 ) );
				connect.append( ".xml_object_id AND " );
				// plain family relationships need no other specification
				// but descendent and child need another clause...
				if ( relationship != RELATE_FAMILY )
					{
    				if ( relationship == RELATE_DESCENDENT  )
			   		{
						connect.append( sqlTable( depth, position ) );
						connect.append( ".left_index " );
			   		connect.append( "BETWEEN " );
			   		connect.append( sqlTable( depth+1, topQuery().last_position[depth+1]+1 ) );
			   		connect.append( ".left_index AND " );
			   		connect.append( sqlTable( depth+1, topQuery().last_position[depth+1]+1 ) );
			   		connect.append( ".right_index " );
			   		}
    				else if ( relationship == RELATE_ANCESTOR  )
			   		{
						connect.append( sqlTable( depth+1, topQuery().last_position[depth+1]+1 ) );
						connect.append( ".left_index " );
			   		connect.append( "BETWEEN " );
			   		connect.append( sqlTable( depth, position ) );
			   		connect.append( ".left_index AND " );
			   		connect.append( sqlTable( depth, position ) );
			   		connect.append( ".right_index " );
			   		}
					else if ( relationship == RELATE_CHILD  )
			   		{
						connect.append( sqlTable( depth, position ) );
						connect.append( ".xml_parent_id = " );
			   		connect.append( sqlTable( depth+1, topQuery().last_position[depth+1]+1 ) );
			   		connect.append( ".xml_element_id " );
			   		}
			   	else
			   		{
						connect.append( sqlTable( depth, position ) );
			   		connect.append( ".xml_element_id = " );
			   		connect.append( sqlTable( depth+1, topQuery().last_position[depth+1]+1 ) );
						connect.append( ".xml_parent_id " );
			   		}
					connect.append( " AND " );
					}

				// insert sub query which may itself have subqueries
				current.sqlSelect( sql, depth+1, false, connect.toString() );
				
				// close sub query
				sql.append( " ) " );
				}
				
			// close parenthesis after multiple siblings
			if ( this.size()>1 )
				sql.append( " ) " );
			}
		else
			{
			for ( i=0; i<this.size(); i++ )
				{
				current = (XMLQuery)this.elementAt( i );

				// join to previous sibling
				if ( combination == COMBINE_UNION )
					{
					if ( i>0 )
						sql.append( " UNION " );
					if ( size() > 1 )
						sql.append( "(" );
					}
				else if ( combination == COMBINE_INTERCEPT )
					{
					if ( i>0 )
						sql.append( " AND EXISTS (" );
					}
				else
					throw new IllegalArgumentException( "Unrecognized combination option." );
					
				
				// prepare a clause to join this query to previous query
				if ( combination == COMBINE_UNION )
					connect=null;
				else
					{
					if ( i==0 )
						connect=null;
					else
						{
						connect = new StringBuffer();
						// all type of relationship put the elements into the same object
						if ( objects )
							{
							connect.append( sqlObjectTable( depth+1, topQuery().last_position[depth+1] ) );
							connect.append( ".xml_object_id = " );
							connect.append( sqlObjectTable( depth+1, topQuery().last_position[depth+1]+1 ) );
							connect.append( ".xml_object_id AND " );
							}
						else
							{
							connect.append( sqlTable( depth+1, topQuery().last_position[depth+1] ) );
							connect.append( ".xml_element_id = " );
							connect.append( sqlTable( depth+1, topQuery().last_position[depth+1]+1 ) );
							connect.append( ".xml_element_id AND " );
							}
						}
					}
					
				// insert sub query which may itself have subqueries
				current.sqlSelect( sql, depth+1, objects, connect!=null?connect.toString():null );
				
				// close sub query
				if ( combination == COMBINE_UNION )
					{
					if ( this.size() > 1 )
						sql.append( ")" );
					}
				}

            // anded subqueries are nested within each other
            // so they need closing
			if ( combination == COMBINE_INTERCEPT )
			    {
			    for ( i=1; i<this.size(); i++ )
    				sql.append( " ) " );
				}
			}
			
		// chop off trailing AND if there is one.
		if ( sql.substring( sql.length()-5, sql.length() ).equals( " AND " ) )
			sql.setLength( sql.length()-5 );

		}

	}