/*******************************************************************************
 * Copyright (c) 2004 Actuate Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *  Actuate Corporation  - initial API and implementation
 *******************************************************************************/

package org.eclipse.birt.data.engine.impl;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.logging.Level;

import org.eclipse.birt.core.data.DataType;
import org.eclipse.birt.data.engine.api.IBaseDataSetDesign;
import org.eclipse.birt.data.engine.api.IColumnDefinition;
import org.eclipse.birt.data.engine.api.IComputedColumn;
import org.eclipse.birt.data.engine.api.IPreparedQuery;
import org.eclipse.birt.data.engine.api.IQueryDefinition;
import org.eclipse.birt.data.engine.core.DataException;
import org.eclipse.birt.data.engine.executor.DataSourceFactory;
import org.eclipse.birt.data.engine.executor.ResultClass;
import org.eclipse.birt.data.engine.executor.ResultFieldMetadata;
import org.eclipse.birt.data.engine.executor.ResultObject;
import org.eclipse.birt.data.engine.i18n.ResourceConstants;
import org.eclipse.birt.data.engine.odi.ICandidateQuery;
import org.eclipse.birt.data.engine.odi.ICustomDataSet;
import org.eclipse.birt.data.engine.odi.IDataSource;
import org.eclipse.birt.data.engine.odi.IEventHandler;
import org.eclipse.birt.data.engine.odi.IQuery;
import org.eclipse.birt.data.engine.odi.IResultClass;
import org.eclipse.birt.data.engine.odi.IResultIterator;
import org.eclipse.birt.data.engine.odi.IResultObject;

/**
 * A prepared query which uses a Script Data Source.
 */
class PreparedScriptDSQuery extends PreparedDataSourceQuery
		implements
			IPreparedQuery
{
	/**
	 * @param dataEngine
	 * @param queryDefn
	 * @param dataSetDesign
	 * @param appContext
	 * @throws DataException
	 */
	PreparedScriptDSQuery( DataEngineImpl dataEngine, IQueryDefinition queryDefn, 
			IBaseDataSetDesign dataSetDesign, Map appContext ) throws DataException
	{
		super( dataEngine, queryDefn, dataSetDesign, appContext );
		logger.logp( Level.FINER,
				PreparedScriptDSQuery.class.getName( ),
				"PreparedScriptDSQuery",
				"PreparedScriptDSQuery starts up." );
	}
		
	/*
	 * @see org.eclipse.birt.data.engine.api.IPreparedQuery#getParameterMetaData()
	 */
    public Collection getParameterMetaData() throws DataException
	{
		DataException e = new DataException( ResourceConstants.PARAMETER_METADATA_NOT_SUPPORTED );
		logger.logp( Level.FINE,
				PreparedDataSourceQuery.class.getName( ),
				"getParameterMetaData",
				"Cannot get parameter metadata for this type of data source.",
				e );
		throw e;
	}
    
    /*
     * @see org.eclipse.birt.data.engine.impl.PreparedDataSourceQuery#newExecutor()
     */
	protected QueryExecutor newExecutor()
	{
		return new ScriptDSQueryExecutor();
	}
	
	/**
	 * Concrete class of DSQueryExecutor used in PreparedScriptDSQuery
	 */
	class ScriptDSQueryExecutor extends DSQueryExecutor
	{
		private ResultClass resultClass;
		private CustomDataSet customDataSet;
		
		/*
		 * @see org.eclipse.birt.data.engine.impl.PreparedQuery.Executor#createOdiDataSource()
		 */
		protected IDataSource createOdiDataSource( )
		{
			// An empty odi data source is used for script data set
			PreparedScriptDSQuery self = PreparedScriptDSQuery.this;
			return DataSourceFactory.getFactory( )
					.getDataSource( null,
							null,
							this.dataSource.getDesign( ),
							this.dataSet.getDesign( ),
							self.queryDefn.getInputParamBindings( ),
							DataSetCacheUtil.getCacheOption( self.dataEngine.getContext( ),
									appContext ),
							DataSetCacheUtil.getCacheCount( self.dataEngine.getContext(), appContext ),
							self.dataEngine.getSession( ));
		}
	
		/*
		 * @see org.eclipse.birt.data.engine.impl.PreparedQuery.Executor#createOdiQuery()
		 */
		protected IQuery createOdiQuery()  throws DataException
		{
			assert odiDataSource != null;
			ICandidateQuery candidateQuery = odiDataSource.newCandidateQuery( );
			return candidateQuery;
		}
		
		/*
		 * @see org.eclipse.birt.data.engine.impl.PreparedQuery.Executor#populateOdiQuery()
		 */
		protected void populateOdiQuery( ) throws DataException
		{
			super.populateOdiQuery( );
			
			ICandidateQuery candidateQuery = (ICandidateQuery) odiQuery;
			assert candidateQuery != null;
			
			ScriptDataSetRuntime scriptDataSet = (ScriptDataSetRuntime) dataSet;
			List resultHints = dataSet.getResultSetHints( );
			List computedColumns = dataSet.getComputedColumns();
			List columnsList = new ArrayList( );
			
			// Resolve parameter binding
			resolveDataSetParameters( true );
			
			// If a "describe" script or handler exists and it 
			// returns true, use dynamic metadata; 
			// otherwise use static columns defined in result hint
			if ( scriptDataSet.describe() )
			{
				columnsList.addAll( scriptDataSet.getDescribedMetaData());
			}
			else
			{
				Iterator it = resultHints.iterator( );
				for ( int j = 0; it.hasNext( ); j++ )
				{
					IColumnDefinition columnDefn = (IColumnDefinition) it.next( );
					
					// All columns are declared as custom to allow as to set column value
					// at runtime
					ResultFieldMetadata columnMetaData = new ResultFieldMetadata( j + 1,
							columnDefn.getColumnName( ),
							columnDefn.getColumnName( ),
							DataType.getClass( columnDefn.getDataType( ) ),
							null /* nativeTypeName */, 
							true );
					columnsList.add( columnMetaData );
					columnMetaData.setAlias( columnDefn.getAlias( ) );
				}
			}
			
			// Add computed columns
			int count = columnsList.size();
			Iterator it = computedColumns.iterator();
			for ( int j = resultHints.size(); it.hasNext( ); j++ )
			{
			    IComputedColumn compColumn = (IComputedColumn)it.next();
			    ResultFieldMetadata columnMetaData = new ResultFieldMetadata( 
			    		++count,
						compColumn.getName(),
						compColumn.getName(),
						DataType.getClass( compColumn.getDataType() ),
						null /* nativeTypeName */, 
						true );
			    columnsList.add( columnMetaData );
			}
			
			resultClass = new ResultClass( columnsList );
		}
		
		/*
		 * @see org.eclipse.birt.data.engine.impl.PreparedQuery.Executor#prepareOdiQuery()
		 */
		protected void prepareOdiQuery(  ) throws DataException
		{
			assert odiQuery != null;
			assert resultClass != null;
			assert dataSet instanceof ScriptDataSetRuntime;
			
			ICandidateQuery candidateQuery = (ICandidateQuery) odiQuery;
			customDataSet = new CustomDataSet( );
			candidateQuery.setCandidates( customDataSet );
		}
		
		/*
		 * @see org.eclipse.birt.data.engine.impl.PreparedQuery.Executor#executeOdiQuery()
		 */
		protected IResultIterator executeOdiQuery( IEventHandler eventHandler )
				throws DataException
		{	
			// prepareOdiQuery must be called before			
			customDataSet.open();
			dataSet.afterOpen();
			ICandidateQuery candidateQuery = (ICandidateQuery) odiQuery;
			return candidateQuery.execute( eventHandler );
		}
	
		/**
		 * 
		 */
		private final class CustomDataSet implements ICustomDataSet
		{
			/*
			 * @see org.eclipse.birt.data.engine.odi.ICustomDataSet#getResultClass()
			 */
			public IResultClass getResultClass( )
			{
				return resultClass;
			}
			
			/*
			 * @see org.eclipse.birt.data.engine.odi.ICustomDataSet#open()
			 */
			public void open( ) throws DataException
			{
				((ScriptDataSetRuntime) dataSet).open();
			}
			
			/*
			 * @see org.eclipse.birt.data.engine.odi.ICustomDataSet#fetch()
			 */
			public IResultObject fetch( ) throws DataException
			{
				Object[] fields = new Object[resultClass.getFieldCount( )];
				ResultObject resultObject = new ResultObject( resultClass,
						fields );
				
				dataSet.setRowObject( resultObject, true );
				boolean evalResult = ((ScriptDataSetRuntime) dataSet).fetch();
	
				if ( ! evalResult )
					resultObject = null;
	
				return resultObject;
			}
			
			/*
			 * @see org.eclipse.birt.data.engine.odi.ICustomDataSet#close()
			 */
			public void close( ) throws DataException
			{
				( (ScriptDataSetRuntime) dataSet ).close( );
			}
		}
	}
	
}