package uk.ac.starlink.ttools.task;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import uk.ac.starlink.task.Environment;
import uk.ac.starlink.task.Parameter;
import uk.ac.starlink.task.TaskException;
import uk.ac.starlink.ttools.mode.ProcessingMode;

/**
 * MapperTask which has a single input table.
 *
 * @author   Mark Taylor
 * @since    14 Sep 2006
 */
public abstract class SingleMapperTask extends ConsumerTask {

    private final InputTableParameter inTableParam_;
    private final FilterParameter inFilterParam_;

    /**
     * Constructor.
     *
     * @param   purpose  one-line description of the purpose of the task
     * @param   outMode  processing mode which determines the destination of
     *          the processed table
     * @param   useOutFilter allow specification of filters for output table
     * @param   useInFilter  allow specification of filters for input table
     */
    public SingleMapperTask( String purpose, ProcessingMode outMode, 
                             boolean useOutFilter, boolean useInFilter ) {
        super( purpose, outMode, useOutFilter );
        List<Parameter<?>> paramList = new ArrayList<Parameter<?>>();

        /* Input table parameter. */
        inTableParam_ = new InputTableParameter( "in" );
        inTableParam_.setPosition( 1 );
        inTableParam_.setUsage( "<table>" );
        inTableParam_.setPrompt( "Location of input table" );
        paramList.add( inTableParam_.getFormatParameter() );
        paramList.add( inTableParam_.getStreamParameter() );
        paramList.add( inTableParam_ );

        /* Input filter parameter. */
        if ( useInFilter ) {
            inFilterParam_ = new FilterParameter( "icmd" );
            inFilterParam_.setTableDescription( "the input table",
                                                inTableParam_, Boolean.TRUE );
            paramList.add( inFilterParam_ );
        }
        else {
            inFilterParam_ = null;
        }

        getParameterList().addAll( 0, paramList );
    }

    /**
     * Returns an object provides which provides the (possibly filtered)
     * input table.
     *
     * @param   env  execution environment
     * @return  input table producer
     */
    protected TableProducer createInputProducer( Environment env )
            throws TaskException {
        return createProducer( env, inFilterParam_, inTableParam_ );
    }
}
