//Dstl (c) Crown Copyright 2017

package uk.gov.dstl.baleen.jobs.interactions.io;

import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.function.BiConsumer;
import java.util.stream.StreamSupport;

import com.opencsv.CSVReader;

import net.sf.extjwnl.data.POS;
import uk.gov.dstl.baleen.jobs.interactions.data.InteractionDefinition;
import uk.gov.dstl.baleen.jobs.interactions.data.Word;

/**
 * Reads interactions from CSV.
 * <p>
 * This reads interaction data as written by the {@link CsvInteractionWriter}.
 */
public class CsvInteractionReader {

	private final String inputFilename;

	/**
	 * Instantiates a new CSV interaction reader.
	 *
	 * @param inputFilename
	 *            the input filename
	 */
	public CsvInteractionReader(String inputFilename) {
		this.inputFilename = inputFilename;
	}

	/**
	 * Read the CSV file and send interactions to the consumer
	 *
	 * @param consumer
	 *            the consumer (first param is the InteractionRelation and the second the list of
	 *            alternative words)
	 * @throws IOException
	 *             Signals that an I/O exception has occurred.
	 */
	public void read(BiConsumer<InteractionDefinition, Collection<String>> consumer) throws IOException {
		try(CSVReader reader = new CSVReader(new FileReader(inputFilename))){
			StreamSupport.stream(reader.spliterator(), false).forEach(r -> processRecord(r, consumer));
		}
	}

	private void processRecord(String[] r, BiConsumer<InteractionDefinition, Collection<String>> consumer){
		if (r.length < 2) {
			return;
		}

		String type = r[0];
		String subType = r[1];

		if ("Type".equalsIgnoreCase(type) && "Subtype".equalsIgnoreCase(subType)) {
			// Header, ignore
			return;
		}

		String source = getOrEmpty(r, 2);
		String target = getOrEmpty(r, 3);
		String lemma = getOrEmpty(r, 4);
		POS pos = POS.getPOSForLabel(getOrEmpty(r, 5).toLowerCase());

		if (pos == null) {
			// Can't include words without a POS
			return;
		}

		InteractionDefinition i = new InteractionDefinition(type, subType, new Word(lemma, pos), source,
				target);

		List<String> alternatives = new ArrayList<>(r.length - 6);
		for (int j = 6; j < r.length; j++) {
			String alternative = r[j].trim();
			if (!alternative.isEmpty()) {
				alternatives.add(alternative);
			}
		}

		consumer.accept(i, alternatives);
	}
	
	private String getOrEmpty(String[] array, int index){
		if(array.length < index)
			return "";
		
		return array[index];
	}
}