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/*
 * The MIT License
 *
 *   Copyright (c) 2014, benas ([email protected])
 *
 *   Permission is hereby granted, free of charge, to any person obtaining a copy
 *   of this software and associated documentation files (the "Software"), to deal
 *   in the Software without restriction, including without limitation the rights
 *   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *   copies of the Software, and to permit persons to whom the Software is
 *   furnished to do so, subject to the following conditions:
 *
 *   The above copyright notice and this permission notice shall be included in
 *   all copies or substantial portions of the Software.
 *
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *   THE SOFTWARE.
 */

package io.github.benas.easybatch.jdbc;

import io.github.benas.easybatch.core.api.Record;
import io.github.benas.easybatch.core.api.RecordMapper;
import io.github.benas.easybatch.core.mapper.ObjectMapper;

import java.sql.ResultSet;

/**
 * A {@link io.github.benas.easybatch.core.api.RecordMapper} that maps database rows to domain objects.
 *
 * @param  the target domain object type.
 *
 * @author benas ([email protected])
 */
public class JdbcRecordMapper implements RecordMapper {

    /**
     * The object mapper.
     */
    private ObjectMapper objectMapper;

    /**
     * Constructs a default JdbcRecordMapper instance. Column names will be fetched from the jdbc result set meta data
     * and set to fields with the same name of the target object.
     * @param recordClass the target domain object class
     */
    public JdbcRecordMapper(final Class recordClass) {
        objectMapper = new ObjectMapper(recordClass);
    }

    /**
     * Constructs a JdbcRecordMapper instance.
     * @param recordClass the target domain object class
     * @param fieldsMapping a String array representing fields name of the target object in the same order as in the jdbc record.
     */
    public JdbcRecordMapper(final Class recordClass, final String[] fieldsMapping) {
        objectMapper = new ObjectMapper(recordClass, fieldsMapping);
    }

    @Override
    public T mapRecord(final Record record) throws Exception {
        JdbcRecord jdbcRecord = (JdbcRecord) record;
        ResultSet resultSet = jdbcRecord.getRawContent();
        int columnCount = resultSet.getMetaData().getColumnCount();

        // if fields mapping is not specified, retrieve it from the result set meta data (done only once)
        if (objectMapper.getHeadersMapping() == null) {
            String[] fieldsMapping = new String[columnCount];
            for (int i = 1; i < columnCount + 1; i++) {
                fieldsMapping[i - 1] = resultSet.getMetaData().getColumnLabel(i).toLowerCase();
            }
            objectMapper.setHeadersMapping(fieldsMapping);
        }

        // get result set data and map it to domain object instance
        String[] fieldsContents = new String[columnCount];
        for (int i = 1; i < columnCount + 1; i++) {
            fieldsContents[i - 1] = resultSet.getString(i);
        }
        return objectMapper.mapObject(fieldsContents);
    }

}