import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.logging.Level;
import java.util.logging.Logger;

public class ConfusionMatrixReader {

    final static String DATAFILE_LOC = "confusion_matrix.txt";
    final private HashMap<String, Integer> confusionMatrix = new HashMap<>();
    final private HashMap<String, Integer> countMatrix = new HashMap<>();

    public ConfusionMatrixReader() {
        try {
            readConfusionMatrix();
        } catch (Exception ex) {
            Logger.getLogger(ConfusionMatrixReader.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    private void readConfusionMatrix()
            throws FileNotFoundException, IOException {
        FileInputStream fis;
        fis = new FileInputStream(DATAFILE_LOC);
        BufferedReader in = new BufferedReader(new InputStreamReader(fis));

        while (in.ready()) {
            String line = in.readLine();
            int space = line.lastIndexOf(' ');
            String keys = line.substring(0, space);
            try {
                int count = Integer.parseInt(line.substring(space + 1));
                confusionMatrix.put(keys, count);

                String key = keys.substring(0, keys.indexOf('|'));
                Integer value = countMatrix.get(key);
                if (value == null) {
                    value = 0;
                }
                countMatrix.put(key, value + count);
            } catch (NumberFormatException e) {
                System.err.println("problems with string <" + line + ">");
            }
        }
    }

    /**
     * Returns the count for the pair <error>|<correct> in the confusion matrix,
     * e.g. "c|ct" is 36
     *
     * @param error
     * @param correct
     * @return
     */
    public int getConfusionCount(String error, String correct) {
        Integer count = confusionMatrix.get(error + "|" + correct);
        return count == null ? 0 : count;
    }
}