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 *    Please make sure that third-party modules and libraries are used
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 *     or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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 *
 */

package com.openexchange.conversion.engine.internal;

import static com.openexchange.conversion.engine.internal.ConversionEngineRegistry.getInstance;
import java.io.InputStream;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import com.openexchange.conversion.ConversionService;
import com.openexchange.conversion.Data;
import com.openexchange.conversion.DataArguments;
import com.openexchange.conversion.DataException;
import com.openexchange.conversion.DataExceptionCodes;
import com.openexchange.conversion.DataHandler;
import com.openexchange.conversion.DataSource;
import com.openexchange.conversion.SimpleData;
import com.openexchange.session.Session;

/**
 * {@link ConversionServiceImpl} - Implementation of {@link ConversionService}.
 * 
 * @author <a href="mailto:thorben.betten@open-xchange.com">Thorben Betten</a>
 */
public final class ConversionServiceImpl implements ConversionService {

    /**
     * Initializes a new {@link ConversionServiceImpl}
     */
    public ConversionServiceImpl() {
        super();
    }

    public DataHandler getDataHandler(final String identifier) {
        return getInstance().getDataHandler(identifier);
    }

    public DataSource getDataSource(final String identifier) {
        return getInstance().getDataSource(identifier);
    }

    public Object convert(final String dataSourceIdentifier, final DataArguments dataSourceArguments, final String dataHandlerIdentifier, final DataArguments dataHandlerArguments, final Session session) throws DataException {
        final DataSource dataSource = lookUpAndCheckDataSource(dataSourceIdentifier, dataSourceArguments);
        final DataHandler dataHandler = lookUpAndCheckDataHandler(dataHandlerIdentifier, dataHandlerArguments);
        /*
         * Check for matching type
         */
        final Class<?> type = findMatchingType(dataSource, dataHandler);
        if (type == null) {
            throw DataExceptionCodes.NO_MATCHING_TYPE.create(dataSourceIdentifier, dataHandlerIdentifier);
        }
        /*
         * Get data from data source
         */
        final Data<?> data = dataSource.getData(type, dataSourceArguments, session);
        /*
         * ... and feed it to data handler
         */
        return dataHandler.processData(data, dataHandlerArguments, session);
    }

    public Object convert(final InputStream inputStream, final String dataHandlerIdentifier, final DataArguments dataHandlerArguments, final Session session) throws DataException {
        final DataHandler dataHandler = lookUpAndCheckDataHandler(dataHandlerIdentifier, dataHandlerArguments);
        /*
         * Check for input stream support
         */
        if (!new HashSet<Class<?>>(Arrays.asList(dataHandler.getTypes())).contains(InputStream.class)) {
            throw DataExceptionCodes.NO_MATCHING_TYPE.create(InputStream.class.getName(), dataHandlerIdentifier);
        }
        /*
         * Feed input stream to data handler
         */
        return dataHandler.processData(new SimpleData<InputStream>(inputStream), dataHandlerArguments, session);
    }

    private static DataSource lookUpAndCheckDataSource(final String dataSourceID, final DataArguments dataSourceArguments) throws DataException {
        final DataSource dataSource = getInstance().getDataSource(dataSourceID);
        if (dataSource == null) {
            throw DataExceptionCodes.UNKNOWN_DATA_SOURCE.create(dataSourceID);
        }
        final String[] args = dataSource.getRequiredArguments();
        for (final String arg : args) {
            if (!dataSourceArguments.containsKey(arg)) {
                throw DataExceptionCodes.MISSING_ARGUMENT.create(arg);
            }
        }
        return dataSource;
    }

    private static DataHandler lookUpAndCheckDataHandler(final String dataHandlerID, final DataArguments dataHandlerArguments) throws DataException {
        final DataHandler dataHandler = getInstance().getDataHandler(dataHandlerID);
        if (dataHandler == null) {
            throw DataExceptionCodes.UNKNOWN_DATA_HANDLER.create(dataHandlerID);
        }
        final String[] args = dataHandler.getRequiredArguments();
        for (final String arg : args) {
            if (!dataHandlerArguments.containsKey(arg)) {
                throw DataExceptionCodes.MISSING_ARGUMENT.create(arg);
            }
        }
        return dataHandler;
    }

    private static Class<?> findMatchingType(final DataSource dataSource, final DataHandler dataHandler) {
        final Class<?>[] dataSourceTypes = dataSource.getTypes();
        final Set<Class<?>> dataHandlerTypes = new HashSet<Class<?>>(Arrays.asList(dataHandler.getTypes()));
        /*
         * Find matching type
         */
        Class<?> type = null;
        for (int i = 0; i < dataSourceTypes.length && type == null; i++) {
            if (dataHandlerTypes.contains(dataSourceTypes[i])) {
                type = dataSourceTypes[i];
            }
        }
        return type;
    }

}
