package unit;

import java.util.*;

/**
 * artemis-0001: ActiveMQ Artemis BindingsImpl idsToAckList List.contains O(N×M) → HashSet O(N+M)
 *
 * In BindingsImpl.routeFromCluster() (BindingsImpl.java:639):
 *
 *   List<Long> idsToAckList = new ArrayList<>();   // built from HDR_ROUTE_TO_ACK_IDS
 *   while (buff.hasRemaining()) {
 *       long bindingID = buff.getLong();
 *       if (idsToAckList.contains(bindingID)) {    // O(M) per binding — CWE-407
 *           binding.routeWithAck(...);
 *       } else {
 *           binding.route(...);
 *       }
 *   }
 *
 * N = binding IDs in the message, M = ack IDs.
 * Total: O(N×M) per cluster message delivery.
 *
 * Fix: Set<Long> idsToAckSet = new HashSet<>() — O(1) lookup.
 *
 * UNDF: assigned by generate_undf.py
 * Severity: MEDIUM
 */
public class Artemis0001BindingsTest {

    static long cmpOps = 0;

    // SLOW: List.contains — O(M) per binding
    static void routeSlow(long[] bindingIds, List<Long> idsToAckList,
                          long[] routeCount, long[] routeWithAckCount) {
        for (long bindingId : bindingIds) {
            boolean shouldAck = false;
            for (Long id : idsToAckList) {
                cmpOps++;
                if (id == bindingId) { shouldAck = true; break; }
            }
            if (shouldAck) routeWithAckCount[0]++;
            else routeCount[0]++;
        }
    }

    // FAST: Set.contains — O(1) per binding
    static void routeFast(long[] bindingIds, Set<Long> idsToAckSet,
                          long[] routeCount, long[] routeWithAckCount, long[] fastOps) {
        for (long bindingId : bindingIds) {
            fastOps[0]++;  // O(1) hash lookup
            if (idsToAckSet.contains(bindingId)) routeWithAckCount[0]++;
            else routeCount[0]++;
        }
    }

    public static void main(String[] args) {
        int N = 100;  // binding IDs per message
        int M = 50;   // ack IDs per message
        int MSG_COUNT = 1000;  // messages per benchmark run

        // Build test data: binding IDs 0..N-1, ack IDs N/2..N/2+M-1 (overlap)
        long[] bindingIds = new long[N];
        for (int i = 0; i < N; i++) bindingIds[i] = i;

        List<Long> slowAckList = new ArrayList<>();
        Set<Long> fastAckSet = new HashSet<>();
        for (int i = N / 2; i < N / 2 + M; i++) {
            slowAckList.add((long) i);
            fastAckSet.add((long) i);
        }

        // Verify correctness
        long[] slowRoute = {0}, slowAck = {0};
        long[] fastRoute = {0}, fastAck = {0};
        long[] fastOps = {0};
        routeSlow(bindingIds, slowAckList, slowRoute, slowAck);
        routeFast(bindingIds, fastAckSet, fastRoute, fastAck, fastOps);

        if (slowRoute[0] != fastRoute[0] || slowAck[0] != fastAck[0]) {
            System.err.printf("FAIL: route slow=%d fast=%d; ack slow=%d fast=%d%n",
                    slowRoute[0], fastRoute[0], slowAck[0], fastAck[0]);
            System.exit(1);
        }

        // Benchmark
        cmpOps = 0;
        for (int m = 0; m < MSG_COUNT; m++) {
            long[] r = {0}, a = {0};
            routeSlow(bindingIds, slowAckList, r, a);
        }
        long slowCmp = cmpOps;
        fastOps[0] = 0;
        for (int m = 0; m < MSG_COUNT; m++) {
            long[] r = {0}, a = {0};
            routeFast(bindingIds, fastAckSet, r, a, fastOps);
        }

        double ratio = (double) slowCmp / Math.max(fastOps[0], 1);
        System.out.printf("artemis-0001 BindingsImpl: SLOW=%d cmpOps, FAST~=%d ops, ratio=%.1fx%n",
                slowCmp, fastOps[0], ratio);

        if (ratio < 5.0) {
            System.err.printf("FAIL: ratio %.1f < 5x%n", ratio);
            System.exit(1);
        }
        System.out.println("PASS");
    }
}