import java.util.*;

/**
 * CWE-407 unit test for Redis acl.c defect.
 *
 * redis-0001: src/acl.c getUpcomingChannelList()
 *   list *upcoming built from new ACL channels, then checked with
 *   listSearchKey(upcoming, channel) — O(U) per original channel, O(C×U) total.
 *   Fix: build dict *upcoming_set alongside list for O(1) exact-match lookup.
 */
public class RedisTest {

    // Simulate listSearchKey approach (defect)
    static boolean isChannelInUpcomingList(List<String> upcoming, String channel) {
        for (String c : upcoming) {           // O(U) linear scan
            if (c.equals(channel)) return true;
        }
        return false;
    }

    static boolean getUpcomingChannelList_list(List<String> newChannels, List<String> originalChannels) {
        // Build upcoming list (O(U))
        List<String> upcoming = new ArrayList<>(newChannels);

        // Check each original channel against upcoming: O(C × U)
        boolean match = true;
        for (String ch : originalChannels) {
            if (!isChannelInUpcomingList(upcoming, ch)) {
                match = false;
                break;
            }
        }
        return match;
    }

    // Simulate dict/set approach (fix)
    static boolean getUpcomingChannelList_dict(List<String> newChannels, List<String> originalChannels) {
        // Build upcoming set for O(1) lookup
        Set<String> upcoming_set = new HashSet<>(newChannels);

        boolean match = true;
        for (String ch : originalChannels) {
            if (!upcoming_set.contains(ch)) {      // O(1) lookup
                match = false;
                break;
            }
        }
        return match;
    }

    static void testRedis0001() throws Exception {
        int U = 1000;   // upcoming channels (new ACL)
        int C = 1000;   // original channels to check

        List<String> newChannels = new ArrayList<>();
        for (int i = 0; i < U; i++) newChannels.add("chan:" + i);

        // original channels: 500 overlap + 500 new (forces full scan in list version)
        List<String> originalChannels = new ArrayList<>();
        for (int i = 0; i < C / 2; i++) originalChannels.add("chan:" + i);
        for (int i = 0; i < C / 2; i++) originalChannels.add("extra:" + i);

        // correctness
        boolean r1 = getUpcomingChannelList_list(newChannels, originalChannels);
        boolean r2 = getUpcomingChannelList_dict(newChannels, originalChannels);
        assert r1 == r2 : "list and dict must agree: " + r1 + " vs " + r2;

        // performance
        long t0 = System.nanoTime();
        for (int r = 0; r < 500; r++) getUpcomingChannelList_list(newChannels, originalChannels);
        long tList = System.nanoTime() - t0;

        t0 = System.nanoTime();
        for (int r = 0; r < 500; r++) getUpcomingChannelList_dict(newChannels, originalChannels);
        long tDict = System.nanoTime() - t0;

        double ratio = (double) tList / tDict;
        System.out.printf("redis-0001: list=%.3fs dict=%.3fs ratio=%.1f×%n",
                tList / 1e9, tDict / 1e9, ratio);
        assert ratio > 3 : "Expected >3× speedup, got " + ratio;
        System.out.println("PASS redis-0001");
    }

    public static void main(String[] args) throws Exception {
        testRedis0001();
        System.out.println("ALL PASS");
    }
}