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/**
 * eobjects.org MetaModel
 * Copyright (C) 2010 eobjects.org
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * 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 distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.eobjects.metamodel.jdbc.dialects;

import java.text.DateFormat;
import java.util.Date;

import org.eobjects.metamodel.jdbc.JdbcDataContext;
import org.eobjects.metamodel.query.FilterItem;
import org.eobjects.metamodel.query.OperatorType;
import org.eobjects.metamodel.query.Query;
import org.eobjects.metamodel.query.SelectClause;
import org.eobjects.metamodel.query.SelectItem;
import org.eobjects.metamodel.schema.Column;
import org.eobjects.metamodel.util.DateUtils;

public class SQLServerQueryRewriter extends DefaultQueryRewriter {

    public SQLServerQueryRewriter(JdbcDataContext dataContext) {
        super(dataContext);
    }

    @Override
    public boolean isMaxRowsSupported() {
        return true;
    }

    /**
     * SQL server expects the fully qualified column name, including schema, in
     * select items.
     */
    @Override
    public boolean isSchemaIncludedInColumnPaths() {
        return true;
    }

    @Override
    protected String rewriteSelectClause(Query query, SelectClause selectClause) {
        String result = super.rewriteSelectClause(query, selectClause);

        Integer maxRows = query.getMaxRows();
        if (maxRows != null) {
            if (query.getSelectClause().isDistinct()) {
                result = "SELECT DISTINCT TOP " + maxRows + " " + result.substring("SELECT DISTINCT ".length());
            } else {
                result = "SELECT TOP " + maxRows + " " + result.substring("SELECT ".length());
            }
        }

        return result;
    }

    @Override
    public String rewriteFilterItem(FilterItem item) {
        if (item.isCompoundFilter()) {
            return super.rewriteFilterItem(item);
        }

        final SelectItem selectItem = item.getSelectItem();
        final Object operand = item.getOperand();
        final OperatorType operator = item.getOperator();

        if (selectItem == null || operand == null || operator == null) {
            return super.rewriteFilterItem(item);
        }

        final Column column = selectItem.getColumn();
        if (column == null) {
            return super.rewriteFilterItem(item);
        }

        if (operand instanceof Date) {
            final String nativeType = column.getNativeType();
            if ("TIMESTAMP".equalsIgnoreCase(nativeType) || "DATETIME".equalsIgnoreCase(nativeType)) {
                final StringBuilder sb = new StringBuilder();
                sb.append(selectItem.getSameQueryAlias(true));

                FilterItem.appendOperator(sb, operand, operator);

                final Date date = (Date) operand;

                final DateFormat format = DateUtils.createDateFormat("yyyy-MM-dd HH:mm:ss");
                final String dateTimeValue = "CAST('" + format.format(date) + "' AS DATETIME)";

                sb.append(dateTimeValue);
                return sb.toString();
            }
        }
        return super.rewriteFilterItem(item);
    }
}