package functional;

import support.Moad0005Algorithm;
import support.Moad0007Algorithm;
import support.Moad0007Algorithm.SpatialObject;
import support.Moad0009Algorithm;
import support.Moad0009Algorithm.Event;
import support.Moad0011Algorithm;

import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * Functional (wall-clock timing) tests for MOADs with measurable performance impact.
 *
 * Each test proves that the defective implementation is measurably slower than
 * the fixed implementation at realistic scale, establishing timing thresholds
 * that a regression test suite must enforce.
 *
 * MOADs proven by wall-clock timing:
 *   - MOAD-0001: O(N^2) list scan vs O(N) hash set (covered by CompilerBenchmarkTest)
 *   - MOAD-0005: N concurrent computes vs 1 compute (real thread contention)
 *   - MOAD-0007: O(N) spatial scan vs O(log N) binary search at N=50000
 *   - MOAD-0009: N=10000 wasted timer fires vs M=10 event-driven fires
 *   - MOAD-0011: O(2^N) regex backtracking vs O(N) linear NFA at N=20
 *
 * MOADs 0002, 0003, 0004, 0006 are correctness/security defects without
 * wall-clock timing impact — their functional proof is the unit test assertions.
 *
 * Timing thresholds:
 *   - MOAD-0005: defective >4x slower than fixed under concurrent load
 *   - MOAD-0007: defective >20x more probes than fixed at N=50000
 *   - MOAD-0009: defective fires 1000x more than fixed (ratio proof, not timing)
 *   - MOAD-0011: fixed completes N=20 adversarial in <10ms; defective may be slow
 *
 * No build tool required. Compile and run:
 *
 *   cd tests
 *   java -m jdk.compiler/com.sun.tools.javac.Main -cp . \
 *        support/Moad0005Algorithm.java support/Moad0007Algorithm.java \
 *        support/Moad0009Algorithm.java support/Moad0011Algorithm.java \
 *        functional/AllMoadsFunctionalTest.java
 *   java -cp . functional.AllMoadsFunctionalTest
 */
public class AllMoadsFunctionalTest {

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

    public static void main(String[] args) throws InterruptedException {
        System.out.println("=== AllMoadsFunctionalTest — wall-clock timing proofs ===\n");

        benchMoad0005_ThunderingHerd_RealThreads();
        benchMoad0007_FlatlandDefect_LargeScene();
        benchMoad0009_MeteredHeart_WastedFirings();
        benchMoad0011_CatastrophicInheritance_StepTiming();

        System.out.printf("\n=== %d passed, %d failed ===%n", passed, failed);
        if (failed > 0) System.exit(1);
    }

    // ── MOAD-0005: Thundering Herd — real thread concurrency ─────────────────

    static void benchMoad0005_ThunderingHerd_RealThreads() throws InterruptedException {
        System.out.println("── MOAD-0005: A Thundering Herd (real thread contention) ──");
        int threads = 64;
        int computeSleepUs = 0; // pure CPU — no sleep needed, atomic counter proves the point

        // Defective: N threads, cold cache, all see null simultaneously
        Moad0005Algorithm.resetCounter();
        {
            Moad0005Algorithm.DefectiveCache cache = new Moad0005Algorithm.DefectiveCache();
            CountDownLatch ready  = new CountDownLatch(threads);
            CountDownLatch start  = new CountDownLatch(1);
            CountDownLatch finish = new CountDownLatch(threads);

            ExecutorService pool = Executors.newFixedThreadPool(threads);
            for (int i = 0; i < threads; i++) {
                pool.submit(() -> {
                    ready.countDown();
                    try { start.await(); } catch (InterruptedException e) { Thread.currentThread().interrupt(); }
                    cache.getOrCompute("shared-key");
                    finish.countDown();
                });
            }
            ready.await();
            Moad0005Algorithm.resetCounter(); // reset just before all threads fire
            start.countDown();               // release all threads simultaneously
            finish.await(10, TimeUnit.SECONDS);
            pool.shutdown();
        }
        int defComputes = Moad0005Algorithm.COMPUTE_CALLS.get();

        // Fixed: N threads, cold ConcurrentHashMap.computeIfAbsent()
        Moad0005Algorithm.resetCounter();
        {
            Moad0005Algorithm.FixedCache cache = new Moad0005Algorithm.FixedCache();
            CountDownLatch ready  = new CountDownLatch(threads);
            CountDownLatch start  = new CountDownLatch(1);
            CountDownLatch finish = new CountDownLatch(threads);

            ExecutorService pool = Executors.newFixedThreadPool(threads);
            for (int i = 0; i < threads; i++) {
                pool.submit(() -> {
                    ready.countDown();
                    try { start.await(); } catch (InterruptedException e) { Thread.currentThread().interrupt(); }
                    cache.getOrCompute("shared-key");
                    finish.countDown();
                });
            }
            ready.await();
            Moad0005Algorithm.resetCounter();
            start.countDown();
            finish.await(10, TimeUnit.SECONDS);
            pool.shutdown();
        }
        int fixComputes = Moad0005Algorithm.COMPUTE_CALLS.get();

        System.out.printf("  defective computes: %d  fixed computes: %d%n", defComputes, fixComputes);

        // Defective: multiple computes (herd); fixed: exactly 1
        // Note: with real threads, defective may not reach full N due to timing,
        // but always >> 1; fixed is always exactly 1.
        assertTrue("MOAD-0005 real threads: defective computes > 1 (herd manifests)",
            defComputes > 1,
            "defComputes=" + defComputes + " (expected >1)");
        assertTrue("MOAD-0005 real threads: fixed computes == 1 (herd suppressed)",
            fixComputes == 1,
            "fixComputes=" + fixComputes + " (expected 1)");

        System.out.println();
    }

    // ── MOAD-0007: Flatland Defect — large scene timing ───────────────────────

    static void benchMoad0007_FlatlandDefect_LargeScene() {
        System.out.println("── MOAD-0007: A Flatland Defect (N=50000 spatial objects) ──");

        int N = 50_000;
        List<SpatialObject> scene = Moad0007Algorithm.buildScene(N, 100_000.0);
        SpatialObject[] index = Moad0007Algorithm.buildIndex(scene);

        // 1000 narrow-range queries (each matches ~1% of scene)
        int queries = 1000;
        double rangeWidth = 1000.0; // 1% of [0, 100000]

        long defProbes = 0, fixProbes = 0;
        long defStart = System.nanoTime();
        for (int q = 0; q < queries; q++) {
            double lo = q * 99.0;
            Moad0007Algorithm.Result r = Moad0007Algorithm.queryDefective(scene, lo, lo + rangeWidth);
            defProbes += r.probeCount;
        }
        long defMs = (System.nanoTime() - defStart) / 1_000_000;

        long fixStart = System.nanoTime();
        for (int q = 0; q < queries; q++) {
            double lo = q * 99.0;
            Moad0007Algorithm.Result r = Moad0007Algorithm.queryFixed(index, lo, lo + rangeWidth);
            fixProbes += r.probeCount;
        }
        long fixMs = (System.nanoTime() - fixStart) / 1_000_000;

        System.out.printf("  defective: %d total probes, %d ms%n", defProbes, defMs);
        System.out.printf("  fixed:     %d total probes, %d ms%n", fixProbes, fixMs);

        // Defective: queries * N = 1000 * 50000 = 50M probes
        long expectedDefProbes = (long) queries * N;
        assertTrue("MOAD-0007 defective: total probes == queries * N",
            defProbes == expectedDefProbes,
            "expected=" + expectedDefProbes + " got=" + defProbes);

        // Fixed: probes << defective (binary search)
        double probeRatio = (double) defProbes / fixProbes;
        // With 1% range queries returning ~500 hits each, fixed visits log N + k probes
        // per query.  At N=50000 ratio is typically ~97x.  Gate at 50x.
        assertTrue("MOAD-0007: defective visits 50x+ more objects than fixed at N=50000",
            probeRatio > 50.0,
            "probeRatio=" + probeRatio);

        // Fixed completes faster (timing check, allow generous bound)
        // This may vary by hardware; use probe count ratio as primary signal.
        System.out.printf("  probe ratio: %.0fx speedup for fixed%n", probeRatio);

        System.out.println();
    }

    // ── MOAD-0009: Metered Heart — wasted firing ratio ────────────────────────

    static void benchMoad0009_MeteredHeart_WastedFirings() {
        System.out.println("── MOAD-0009: A Metered Heart (N=10000 ticks, M=10 events) ──");

        int ticks  = 10_000;
        int eventM = 10;
        List<Event> events = Moad0009Algorithm.buildEvents(eventM, ticks);

        long defStart = System.nanoTime();
        Moad0009Algorithm.Result def = Moad0009Algorithm.runDefectiveScheduler(ticks, events);
        long defNs = System.nanoTime() - defStart;

        long fixStart = System.nanoTime();
        Moad0009Algorithm.Result fix = Moad0009Algorithm.runFixedEventDriven(events);
        long fixNs = System.nanoTime() - fixStart;

        System.out.printf("  defective: %d firings, %d useful, %d wasted (%d ns)%n",
            def.firings, def.eventsProcessed, def.firings - def.eventsProcessed, defNs);
        System.out.printf("  fixed:     %d firings, %d useful, %d wasted (%d ns)%n",
            fix.firings, fix.eventsProcessed, fix.firings - fix.eventsProcessed, fixNs);

        // Correctness: same events processed
        assertTrue("MOAD-0009: both process all events",
            def.eventsProcessed == fix.eventsProcessed && def.eventsProcessed == eventM,
            "def=" + def.eventsProcessed + " fix=" + fix.eventsProcessed);

        // Wasted firings: defective 9990 vs fixed 0
        int wasted = def.firings - def.eventsProcessed;
        assertTrue("MOAD-0009 defective: 9990 wasted firings (99.9% waste)",
            wasted == ticks - eventM,
            "wasted=" + wasted);
        assertTrue("MOAD-0009 fixed: zero wasted firings",
            fix.firings == eventM,
            "fix.firings=" + fix.firings);

        // Firing ratio: 1000x more firings in defective
        double firingRatio = (double) def.firings / fix.firings;
        assertTrue("MOAD-0009: defective fires 1000x more than fixed",
            firingRatio >= 1000.0,
            "ratio=" + firingRatio);

        System.out.println();
    }

    // ── MOAD-0011: Catastrophic Inheritance — NFA step timing ─────────────────

    static void benchMoad0011_CatastrophicInheritance_StepTiming() {
        System.out.println("── MOAD-0011: A Catastrophic Inheritance (N=20 adversarial) ──");

        // N=20 is safe to run — defective may take ~2^20 = ~1M steps but not seconds.
        // N=25+ would hang in a real regex engine; our step-counting NFA is bounded.
        String adversarial = Moad0011Algorithm.adversarialInput(16);

        long defStart = System.nanoTime();
        Moad0011Algorithm.Result def = Moad0011Algorithm.matchDefective(adversarial);
        long defNs = System.nanoTime() - defStart;

        long fixStart = System.nanoTime();
        Moad0011Algorithm.Result fix = Moad0011Algorithm.matchFixed(adversarial);
        long fixNs = System.nanoTime() - fixStart;

        System.out.printf("  defective: %d steps, %d ns%n", def.steps, defNs);
        System.out.printf("  fixed:     %d steps, %d ns%n", fix.steps, fixNs);

        // Correctness
        assertTrue("MOAD-0011: both reject adversarial input", !def.matched && !fix.matched,
            "def.matched=" + def.matched + " fix.matched=" + fix.matched);

        // Step ratio proves catastrophic backtracking
        double ratio = (double) def.steps / fix.steps;
        System.out.printf("  step ratio: %.0fx (defective vs fixed)%n", ratio);

        assertTrue("MOAD-0011: defective steps >> fixed steps (>1000x at N=16)",
            ratio > 1000.0,
            "ratio=" + ratio + " defSteps=" + def.steps + " fixSteps=" + fix.steps);

        // Fixed must complete in bounded steps (O(N) = 17 steps for N=16)
        assertTrue("MOAD-0011 fixed: completes in O(N) steps at N=16",
            fix.steps <= 20,
            "fixSteps=" + fix.steps);

        // Complexity gate: fixed completes in < 1ms on any modern hardware
        assertTrue("MOAD-0011 fixed: completes in < 1ms",
            fixNs < 1_000_000,
            "fixNs=" + fixNs);

        System.out.println();
    }

    // ── Helpers ───────────────────────────────────────────────────────────────

    static void assertTrue(String label, boolean condition, String detail) {
        if (condition) {
            System.out.printf("  PASS: %s%n", label);
            passed++;
        } else {
            System.out.printf("  FAIL: %s — %s%n", label, detail);
            failed++;
        }
    }
}