package tudelft.mentalhealth.motivatepersisting;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

/**
 * Table 3: Mean nr. of statements in a given answer per situation, defined by
 * PCL score and Trust. This is a singleton as we have only 1 fixed table
 * backing this, to avoid repeated loading of the table.
 */
public class MeanNrStatements {

	private Map<Situation, Double> meanNrStatements = new HashMap<>();
	private static MeanNrStatements instance;

	private MeanNrStatements() {
		readTable();
	}

	/**
	 * @return the whole table, immutable
	 */
	public Map<Situation, Double> getTable() {
		return Collections.unmodifiableMap(meanNrStatements);
	}

	/**
	 * @return the instance of the MeanNrStatements.
	 * @throws IOException
	 */
	public static MeanNrStatements instance() {
		if (instance == null) {
			instance = new MeanNrStatements();
		}
		return instance;
	}

	@Override
	public String toString() {
		return meanNrStatements.toString();
	}

	/**
	 * 
	 * @param situation the {@link Situation} of the patient.
	 * @return the average (mean) number of statements in the situation
	 */
	public Double getMean(Situation situation) {
		return meanNrStatements.get(situation);
	}

	private void readTable() {
		InputStream is = MeanNrStatements.class
				.getResourceAsStream("MeanNrStatements.csv");

		BufferedReader reader = new BufferedReader(new InputStreamReader(is));
		reader.lines().forEach(line -> addLine(line));

	}

	private void addLine(String line) {
		String[] values = line.split(",");
		PclTrend pcl = PclTrend.valueOf(values[0]);
		Trust trust = Trust.valueOf(values[1]);
		Double mean = Double.valueOf(values[2]);
		meanNrStatements.put(new Situation(pcl, trust), mean);
	}
}