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IBM Data Merge Utility - a template based transformation and enrichment engine
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/*
 * 
 * Copyright 2015-2017 IBM
 * Licensed 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.
 *
 */
package com.ibm.util.merge.template.directive.enrich.provider;

import com.ibm.util.merge.Config;
import com.ibm.util.merge.data.DataElement;
import com.ibm.util.merge.data.DataList;
import com.ibm.util.merge.data.DataObject;
import com.ibm.util.merge.data.DataPrimitive;
import com.ibm.util.merge.exception.Merge500;
import com.ibm.util.merge.exception.MergeException;
import com.ibm.util.merge.template.content.Content;
import com.ibm.util.merge.template.content.TagSegment;
import com.ibm.util.merge.template.directive.Enrich;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;

import javax.sql.DataSource;

/**
 * A common base clase for JNDI and JDBC Providers
 * 
 * @author Mike Storey
 *
 */
public abstract class SqlProvider implements ProviderInterface {
	protected transient DataSource jdbcSource = null;
	protected transient Connection connection = null;
	protected transient final String source;
	protected transient final String parameter;
	
	public SqlProvider(String source, String parameter) {
		this.source = source;
		this.parameter = parameter;
	}
	
	protected abstract void connect(Config config) throws MergeException;
	
	@Override
	public DataElement provide(Enrich context) throws MergeException {
		connect(context.getConfig());
		
		Content query = new Content(context.getTemplate().getWrapper(), context.getEnrichCommand(), TagSegment.ENCODE_SQL);
		query.replace(context.getTemplate().getReplaceStack(), false, context.getConfig().getNestLimit());
		DataList table = new DataList();
		ResultSet results;

		// Execute Command
		try {
			results = this.connection.
					prepareStatement(query.getValue(), ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY).
					executeQuery();
		} catch (SQLException e) {
			throw new Merge500("Invalid SQL Query " + query.getValue() + " Message:" + e.getMessage());
		}

		// Build result table.
		try {
			ResultSetMetaData meta = results.getMetaData();
			while (results.next()) {
				DataObject row = new DataObject();
				for (int column = 1; column <= meta.getColumnCount(); column++) {
					row.put(meta.getColumnName(column), new DataPrimitive(results.getString(column)));
				}
				table.add(row);
			}
			results.close();
		} catch (SQLException e) {
			throw new Merge500("SQL Exception processing results" + query );
		}
		return table;
	}

	@Override
	public void close() {
		if (this.connection != null) {
			try {
				this.connection.close();
			} catch (SQLException e) {
				// TODO Log Exception?
			}
		}
		return;
	}
}