package exercise.choice;

import java.io.*;
import java.util.*;

public class ChoiceEvaluator {

    public static ChoiceEvaluation
	evaluateSubmission(ChoiceSubmission submission) {

	String studentID = submission.getStudentID();
	String exerciseID = submission.getExerciseID();
	String submissionID = submission.getSubmissionID();

	try {
	    ChoiceSolution soln = ChoiceSolution.loadSolution(exerciseID);
	    boolean[] solnChoices = soln.getCorrectChoices();
	    boolean[] subnChoices = submission.getSelectedChoices();

	    // Does the student pass?
	    boolean passed = true;
	    int numChoices = solnChoices.length;
	    for (int i = 0; i < numChoices; i++) {
		if (solnChoices[i] != subnChoices[i]) {
		    passed = false;
		    break;
		}
	    }
	    ChoiceEvaluation eval = new ChoiceEvaluation(
		studentID, exerciseID, submissionID, passed);

	    // Save the evaluation to the persistent store.
	    try { ChoiceEvaluation.saveEvaluation(eval); }
	    catch (Exception e) {
		System.err.println(
			"ChoiceEvaluator.evaluateSubmission(): " +
			"Unable to save evaluation.");
	    }

	    // Return the evaluation as feedback.
	    return eval;

	} catch (IOException e) {
	    System.err.println("ChoiceEvaluator.evaluateSubmission(): " +
			       "Failed to load a solution; returning null.");
	    return null;
	}
    }
}