/*
 Wotonomy: OpenStep design patterns for pure Java applications.
 Copyright (C) 2001 Michael Powers

 This library 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 2.1 of the License, or (at your option) any later version.

 This library 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 library; if not, see http://www.gnu.org
 */
package net.wotonomy.access;

import java.lang.reflect.Constructor;

import net.wotonomy.control.EOFetchSpecification;
import net.wotonomy.control.EOQualifier;
import net.wotonomy.foundation.NSArray;
import net.wotonomy.foundation.NSDictionary;

/**
*
* @author ezamudio@nasoft.com
* @author $Author: cgruber $
* @version $Revision: 894 $
*/
public class EOSQLExpressionFactory {

	protected EOAdaptor _adaptor;
	protected Class _expressionClass;
	private Constructor _instantiator;

	public EOSQLExpressionFactory(EOAdaptor adaptor) {
		super();
		_adaptor = adaptor;
		_expressionClass = _adaptor.expressionClass();
		if (_expressionClass == null)
			throw new IllegalStateException("EOAdaptor " + _adaptor.name() + " returned null for expressionClass()");
	}

	public EOAdaptor adaptor() {
		return _adaptor;
	}

	/**
	 * Creates an instance of the adaptor's expression class,
	 * with entity assigned to it.
	 * @param entity The entity with which to initialize the expression.
	 * @return An EOSQLExpression.
	 */
	public EOSQLExpression createExpression(EOEntity entity) {
		EOSQLExpression expr = null;
		if (_instantiator == null) {
			try {
				_instantiator = _expressionClass.getConstructor(new Class[]{ EOEntity.class });
			} catch (Exception ex) {
				throw new IllegalArgumentException("The expression class " + _expressionClass.getName() + " has no constructor with an entity parameter.");
			}
		}
		try {
			expr = (EOSQLExpression)_instantiator.newInstance(new Object[]{ entity });
		} catch (Exception ex) {
			throw new IllegalArgumentException("Cannot create new expression of class " + _expressionClass.getName());
		}
		return expr;
	}

	public EOSQLExpression expressionForEntity(EOEntity entity) {
		return createExpression(entity);
	}

	public EOSQLExpression deleteStatementWithQualifier(EOQualifier qualifier, EOEntity entity) {
		EOSQLExpression expr = createExpression(entity);
		expr.prepareDeleteExpressionForQualifier(qualifier);
		return expr;
	}

	public EOSQLExpression insertStatementForRow(NSDictionary row, EOEntity entity) {
		EOSQLExpression expr = createExpression(entity);
		expr.prepareInsertExpressionWithRow(row);
		return expr;
	}

	public EOSQLExpression selectStatementForAttributes(NSArray atts, boolean lock, EOFetchSpecification fspec, EOEntity entity) {
		EOSQLExpression expr = createExpression(entity);
		expr.prepareSelectExpressionWithAttributes(atts, lock, fspec);
		return expr;
	}

	public EOSQLExpression updateStatementForRow(NSDictionary row, EOQualifier qualifier, EOEntity entity) {
		EOSQLExpression expr = createExpression(entity);
		expr.prepareUpdateExpressionWithRow(row, qualifier);
		return expr;
	}

	public EOSQLExpression expressionForString(String sql) {
		EOSQLExpression expr = null;
		try {
			expr = (EOSQLExpression)_expressionClass.newInstance();
		} catch (Exception e) {
			return null;
		}
		expr.setStatement(sql);
		return expr;
	}

	public Class expressionClass() {
		return _expressionClass;
	}

}
/*
 * $Log$
 * Revision 1.2  2006/02/16 16:47:14  cgruber
 * Move some classes in to "internal" packages and re-work imports, etc.
 *
 * Also use UnsupportedOperationExceptions where appropriate, instead of WotonomyExceptions.
 *
 * Revision 1.1  2006/02/16 13:19:57  cgruber
 * Check in all sources in eclipse-friendly maven-enabled packages.
 *
 * Revision 1.1  2003/08/13 01:04:32  chochos
 * the SQL generation classes. EOSQLExpression still needs a lot of work, but the factory is pretty much done.
 *
 */