package main.rice.node;

// TODO: implement the PyBoolNode class here

package main.rice.concisegen;

import main.rice.test.TestCase;
import main.rice.test.TestResults;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * Generates a minimal (concise) set of test cases that covers all failing implementations,
 * using a greedy set cover algorithm.
 */
public class ConciseSetGenerator {

    /**
     * Returns a minimal set of test cases that catches all buggy implementations using
     * a greedy set cover algorithm. Does not mutate the input TestResults object.
     *
     * @param results the test results containing all cases and coverage info
     * @return a set of test cases that covers all failing implementations
     */
    public static Set<TestCase> setCover(TestResults results) {
        List<Set<Integer>> caseToFiles = results.getCaseToFiles();
        Set<Integer> wrongSet = results.getWrongSet();

        // Work on a copy so we don't mutate wrongSet
        Set<Integer> uncovered = new HashSet<>(wrongSet);

        Set<TestCase> cover = new HashSet<>();

        while (!uncovered.isEmpty()) {
            int bestIdx = -1;
            int bestCount = -1;

            for (int i = 0; i < caseToFiles.size(); i++) {
                Set<Integer> files = caseToFiles.get(i);
                // Count how many uncovered files this test case catches
                int count = 0;
                for (Integer f : files) {
                    if (uncovered.contains(f)) {
                        count++;
                    }
                }
                // Pick the first test case that strictly improves the count
                if (count > bestCount) {
                    bestCount = count;
                    bestIdx = i;
                }
            }

            if (bestIdx == -1 || bestCount == 0) {
                break;
            }

            cover.add(results.getTestCase(bestIdx));
            // Remove files covered by chosen test case (modifies only our working copy)
            uncovered.removeAll(caseToFiles.get(bestIdx));
        }

        return cover;
    }
}