import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * Test for libopenshot-0001: CWE-407 display_classes filter in ObjectDetection
 * uses std::vector<std::string> + std::find inside a per-frame detection loop.
 *
 * Pattern (src/effects/ObjectDetection.cpp, GetFrame + GetPropertiesJSON):
 *   for (int i = 0; i < detections.boxes.size(); i++) {
 *       std::find(display_classes.begin(), display_classes.end(), className)
 *   }
 *
 * Complexity: O(D * C) per frame, D=detections, C=|display_classes|.
 * Fix: use std::unordered_set<std::string>; membership drops to O(1).
 *
 * Compile and run (no build tool required):
 *   javac defects/libopenshot-0001/unit/LibOpenshotObjectDetectionTest.java \
 *         -d /tmp/libopenshot-0001
 *   java -cp /tmp/libopenshot-0001 LibOpenshotObjectDetectionTest
 */
public class LibOpenshotObjectDetectionTest {

    private static int passed = 0;
    private static int failed = 0;

    // --- Defective: linear scan per detection ---

    static boolean isDisplayedDefective(List<String> displayClasses, String className) {
        if (displayClasses.isEmpty()) return true;
        // O(C) linear scan — defect site
        for (String s : displayClasses) {
            if (s.equals(className)) return true;
        }
        return false;
    }

    static int renderFrameDefective(List<String> displayClasses, List<String> detections) {
        int rendered = 0;
        for (String cls : detections) {
            if (isDisplayedDefective(displayClasses, cls)) rendered++;
        }
        return rendered;
    }

    // --- Fixed: O(1) hash set membership ---

    static boolean isDisplayedFixed(Set<String> displayClasses, String className) {
        if (displayClasses.isEmpty()) return true;
        return displayClasses.contains(className);  // O(1)
    }

    static int renderFrameFixed(Set<String> displayClasses, List<String> detections) {
        int rendered = 0;
        for (String cls : detections) {
            if (isDisplayedFixed(displayClasses, cls)) rendered++;
        }
        return rendered;
    }

    // --- Helpers ---

    static List<String> buildDetections(int count, String[] classPool) {
        List<String> out = new ArrayList<>(count);
        for (int i = 0; i < count; i++) {
            out.add(classPool[i % classPool.length]);
        }
        return out;
    }

    static List<String> buildFilterList(int size) {
        List<String> out = new ArrayList<>(size);
        for (int i = 0; i < size; i++) out.add("class" + i);
        return out;
    }

    static Set<String> buildFilterSet(int size) {
        Set<String> out = new HashSet<>(size * 2);
        for (int i = 0; i < size; i++) out.add("class" + i);
        return out;
    }

    // --- Tests ---

    static void testEmptyFilterShowsAll() {
        List<String> detections = List.of("person", "car", "dog");
        int defectiveResult = renderFrameDefective(new ArrayList<>(), detections);
        int fixedResult     = renderFrameFixed(new HashSet<>(), detections);
        check("empty filter: defective shows all detections", defectiveResult == 3);
        check("empty filter: fixed shows all detections",     fixedResult == 3);
    }

    static void testFilterExcludes() {
        List<String> filterList = List.of("person", "car");
        Set<String>  filterSet  = new HashSet<>(filterList);
        List<String> detections = List.of("person", "car", "dog", "cat", "person");
        int defectiveResult = renderFrameDefective(filterList, detections);
        int fixedResult     = renderFrameFixed(filterSet, detections);
        check("filter excludes: defective result correct (3)", defectiveResult == 3);
        check("filter excludes: fixed result correct (3)",     fixedResult == 3);
    }

    static void testFilterAllExcluded() {
        List<String> filterList = List.of("bird");
        Set<String>  filterSet  = new HashSet<>(filterList);
        List<String> detections = List.of("person", "car", "dog");
        int defectiveResult = renderFrameDefective(filterList, detections);
        int fixedResult     = renderFrameFixed(filterSet, detections);
        check("all excluded: defective shows 0", defectiveResult == 0);
        check("all excluded: fixed shows 0",     fixedResult == 0);
    }

    static void testPerformanceRatio() {
        // D=50 detections, C=40 filter classes — simulate 30 fps for 60 seconds = 1800 frames
        String[] classPool = new String[10];
        for (int i = 0; i < 10; i++) classPool[i] = "class" + i;
        List<String> detections = buildDetections(50, classPool);
        List<String> filterList = buildFilterList(40);
        Set<String>  filterSet  = buildFilterSet(40);

        int frames = 1800;

        long t0 = System.nanoTime();
        for (int f = 0; f < frames; f++) renderFrameDefective(filterList, detections);
        long defectiveNs = System.nanoTime() - t0;

        t0 = System.nanoTime();
        for (int f = 0; f < frames; f++) renderFrameFixed(filterSet, detections);
        long fixedNs = System.nanoTime() - t0;

        double ratio = (double) defectiveNs / fixedNs;
        System.out.printf("  [perf] defective=%.1fms fixed=%.1fms ratio=%.1fx%n",
            defectiveNs / 1e6, fixedNs / 1e6, ratio);
        check("fixed path is at least 1.5x faster than defective (D=50, C=40, 1800 frames)",
              ratio >= 1.5);
    }

    static void testResultsMatchAcrossImplementations() {
        // Results must be identical regardless of implementation
        String[] classPool = {"person", "car", "dog", "cat", "bird", "truck"};
        List<String> detections = buildDetections(30, classPool);
        List<String> filterList = List.of("person", "car", "truck");
        Set<String>  filterSet  = new HashSet<>(filterList);

        int defectiveResult = renderFrameDefective(filterList, detections);
        int fixedResult     = renderFrameFixed(filterSet, detections);
        check("results match between defective and fixed implementations",
              defectiveResult == fixedResult);
    }

    // --- Harness ---

    static void check(String desc, boolean cond) {
        if (cond) {
            System.out.println("  PASS: " + desc);
            passed++;
        } else {
            System.out.println("  FAIL: " + desc);
            failed++;
        }
    }

    public static void main(String[] args) {
        System.out.println("=== LibOpenshotObjectDetectionTest (libopenshot-0001, CWE-407) ===\n");

        testEmptyFilterShowsAll();
        testFilterExcludes();
        testFilterAllExcluded();
        testResultsMatchAcrossImplementations();
        testPerformanceRatio();

        System.out.println("\n--- " + passed + " passed, " + failed + " failed ---");
        if (failed > 0) System.exit(1);
    }
}