import java.util.*;

/**
 * CWE-407 unit tests for RabbitMQ rabbit_fifo.erl defects.
 *
 * rabbitmq-0001: deps/rabbit/src/rabbit_fifo.erl maybe_queue_consumer()
 *   priority_queue:member(Key, ServiceQueue) — O(C) linear scan per message dispatch.
 *   Called from update_or_remove_con after checkout_one pops the consumer;
 *   the consumer is NEVER in SQ1 at that point — the scan is 100% wasted work.
 *   Fix: maintain a shadow map #{consumer_key => true} for O(1) maps:is_key().
 *
 * rabbitmq-0002: deps/rabbit/src/rabbit_queue_consumers.erl is_blocked()
 *   priority_queue:member(Consumer, BlockedConsumers) — O(B) per delivery attempt
 *   in single-active-consumer mode.
 *   Fix: shadow set #{consumer => true} in #cr{} for O(1) maps:is_key().
 */
public class RabbitMQTest {

    // --- rabbitmq-0001 ---
    // Benchmark the core operation: O(C) scan vs O(1) map lookup for member check.
    // In the post-checkout path the consumer is NEVER in the service queue —
    // the scan always does a full traversal and returns false (100% wasted).

    static boolean pqMember_scan(List<Integer> pq, int key) {
        for (int k : pq) {    // O(C) — defect: full scan, always false post-checkout
            if (k == key) return true;
        }
        return false;
    }

    static boolean pqMember_map(Set<Integer> sqSet, int key) {
        return sqSet.contains(key);   // O(1) — fix
    }

    static void testRabbitMQ0001() throws Exception {
        int C = 500;   // consumers in service queue
        List<Integer> sq = new ArrayList<>(C);
        Set<Integer> sqSet = new HashSet<>(C);
        for (int i = 1; i <= C; i++) { sq.add(i); sqSet.add(i); }

        // The post-checkout consumer key (0) is NOT in the queue — always false
        int popped = 0;

        assert !pqMember_scan(sq, popped) : "popped consumer must not be in SQ";
        assert !pqMember_map(sqSet, popped) : "popped consumer must not be in SQ";

        // performance: simulate MSG dispatch cycles — member check fires once per message
        int MSG = 500_000;
        long t0 = System.nanoTime();
        for (int m = 0; m < MSG; m++) pqMember_scan(sq, popped);
        long tScan = System.nanoTime() - t0;

        t0 = System.nanoTime();
        for (int m = 0; m < MSG; m++) pqMember_map(sqSet, popped);
        long tMap = System.nanoTime() - t0;

        double ratio = (double) tScan / tMap;
        System.out.printf("rabbitmq-0001: scan=%.3fs map=%.3fs ratio=%.1f×%n",
                tScan / 1e9, tMap / 1e9, ratio);
        assert ratio > 10 : "Expected >10× speedup, got " + ratio;
        System.out.println("PASS rabbitmq-0001");
    }

    // --- rabbitmq-0002 ---

    static boolean isBlocked_pqMember(List<Integer> blocked, int consumer) {
        return blocked.contains(consumer);    // O(B) — defect
    }

    static boolean isBlocked_mapKey(Set<Integer> blockedSet, int consumer) {
        return blockedSet.contains(consumer); // O(1) — fix
    }

    static void testRabbitMQ0002() throws Exception {
        int B = 300;   // blocked consumers (high-prefetch setup)
        int MSG = 100_000;

        List<Integer> blocked = new ArrayList<>(B);
        Set<Integer> blockedSet = new HashSet<>(B);
        for (int i = 0; i < B; i++) { blocked.add(i); blockedSet.add(i); }

        // target near end (worst case)
        int target = B - 1;

        // correctness
        assert isBlocked_pqMember(blocked, target) == isBlocked_mapKey(blockedSet, target);
        assert !isBlocked_pqMember(blocked, B + 99) && !isBlocked_mapKey(blockedSet, B + 99);

        long t0 = System.nanoTime();
        for (int r = 0; r < MSG; r++) isBlocked_pqMember(blocked, target);
        long tMember = System.nanoTime() - t0;

        t0 = System.nanoTime();
        for (int r = 0; r < MSG; r++) isBlocked_mapKey(blockedSet, target);
        long tMap = System.nanoTime() - t0;

        double ratio = (double) tMember / tMap;
        System.out.printf("rabbitmq-0002: member=%.3fs map=%.3fs ratio=%.1f×%n",
                tMember / 1e9, tMap / 1e9, ratio);
        assert ratio > 5 : "Expected >5× speedup, got " + ratio;
        System.out.println("PASS rabbitmq-0002");
    }

    public static void main(String[] args) throws Exception {
        testRabbitMQ0001();
        testRabbitMQ0002();
        System.out.println("ALL PASS");
    }
}