using NUnit.Framework;
using VMdemo.Core;
using VMdemo.Simulation;

namespace VMdemo.Tests.EditMode
{
    public class Step6StatsCollectorTests
    {
        [Test]
        public void StatsCollector_Reset_ClearsAllCountersAndRates()
        {
            var stats = new StatsCollector();
            stats.RecordAccess(tlbHit: true, pageTableHit: false, pageFault: false, cost: 1);
            stats.RecordAccess(tlbHit: false, pageTableHit: false, pageFault: true, cost: 104);

            stats.Reset();

            Assert.That(stats.TotalAccess, Is.EqualTo(0));
            Assert.That(stats.TlbHit, Is.EqualTo(0));
            Assert.That(stats.PageTableHit, Is.EqualTo(0));
            Assert.That(stats.PageFault, Is.EqualTo(0));
            Assert.That(stats.TotalCost, Is.EqualTo(0L));
            Assert.That(stats.TlbHitRate, Is.EqualTo(0.0));
            Assert.That(stats.PageTableHitRate, Is.EqualTo(0.0));
            Assert.That(stats.AvgCost, Is.EqualTo(0.0));
        }

        [Test]
        public void StatsCollector_CalculateCost_FollowsMvpCostModel()
        {
            var stats = new StatsCollector();

            Assert.That(stats.CalculateCost(tlbHit: true, pageTableHit: false, pageFault: false, pageFaultPenalty: 100), Is.EqualTo(1));
            Assert.That(stats.CalculateCost(tlbHit: false, pageTableHit: true, pageFault: false, pageFaultPenalty: 100), Is.EqualTo(4));
            Assert.That(stats.CalculateCost(tlbHit: false, pageTableHit: false, pageFault: true, pageFaultPenalty: 100), Is.EqualTo(104));
        }

        [Test]
        public void StatsCollector_RecordAccess_AggregatesCountersRatesAndAverage()
        {
            var stats = new StatsCollector();

            stats.RecordAccess(tlbHit: true, pageTableHit: false, pageFault: false, cost: 1);
            stats.RecordAccess(tlbHit: false, pageTableHit: true, pageFault: false, cost: 4);
            stats.RecordAccess(tlbHit: false, pageTableHit: false, pageFault: true, cost: 104);

            Assert.That(stats.TotalAccess, Is.EqualTo(3));
            Assert.That(stats.TlbHit, Is.EqualTo(1));
            Assert.That(stats.PageTableHit, Is.EqualTo(1));
            Assert.That(stats.PageFault, Is.EqualTo(1));
            Assert.That(stats.TotalCost, Is.EqualTo(109L));
            Assert.That(stats.TlbHitRate, Is.EqualTo(1.0 / 3.0).Within(1e-12));
            Assert.That(stats.PageTableHitRate, Is.EqualTo(1.0 / 3.0).Within(1e-12));
            Assert.That(stats.AvgCost, Is.EqualTo(109.0 / 3.0).Within(1e-12));
        }

        [Test]
        public void TranslatorEngine_StepOnce_ToFinalize_UpdatesStatsAndCurrentCost()
        {
            var engine = CreateEngine(pageFaultPenalty: 120, seed: 31);
            engine.SetNextVirtualAddress(0x0000_1234UL);

            while (!engine.StepOnce())
            {
            }

            Assert.That(engine.State.CurrentRound, Is.EqualTo(1));
            Assert.That(engine.State.IsPageFault, Is.True);
            Assert.That(engine.State.CurrentCost, Is.EqualTo(124));
            Assert.That(engine.Stats.TotalAccess, Is.EqualTo(1));
            Assert.That(engine.Stats.PageFault, Is.EqualTo(1));
            Assert.That(engine.Stats.TotalCost, Is.EqualTo(124L));
            Assert.That(engine.Stats.AvgCost, Is.EqualTo(124.0));
        }

        [Test]
        public void TranslatorEngine_RunOneAccess_TracksBatchSummaryWithMixedPaths()
        {
            var engine = CreateEngine(pageFaultPenalty: 100, seed: 41);
            const ulong va = 0x0000_5678UL;

            var first = engine.RunOneAccess(va); // page fault
            var second = engine.RunOneAccess(va); // tlb hit

            engine.TlbCache.Clear();
            var third = engine.RunOneAccess(va); // page table hit

            Assert.IsTrue(first.PageFault);
            Assert.IsTrue(second.TlbHit);
            Assert.IsTrue(third.PageTableHit);

            Assert.That(engine.Stats.TotalAccess, Is.EqualTo(3));
            Assert.That(engine.Stats.TlbHit, Is.EqualTo(1));
            Assert.That(engine.Stats.PageTableHit, Is.EqualTo(1));
            Assert.That(engine.Stats.PageFault, Is.EqualTo(1));
            Assert.That(engine.Stats.TotalCost, Is.EqualTo(109L));
            Assert.That(engine.Stats.TlbHitRate, Is.EqualTo(1.0 / 3.0).Within(1e-12));
            Assert.That(engine.Stats.PageTableHitRate, Is.EqualTo(1.0 / 3.0).Within(1e-12));
            Assert.That(engine.Stats.AvgCost, Is.EqualTo(109.0 / 3.0).Within(1e-12));
        }

        [Test]
        public void TranslatorEngine_Reset_ClearsStats()
        {
            var engine = CreateEngine(pageFaultPenalty: 100, seed: 51);
            engine.RunOneAccess(0x0000_9ABCUL);
            Assert.That(engine.Stats.TotalAccess, Is.EqualTo(1));

            engine.Reset();

            Assert.That(engine.Stats.TotalAccess, Is.EqualTo(0));
            Assert.That(engine.Stats.TlbHit, Is.EqualTo(0));
            Assert.That(engine.Stats.PageTableHit, Is.EqualTo(0));
            Assert.That(engine.Stats.PageFault, Is.EqualTo(0));
            Assert.That(engine.Stats.TotalCost, Is.EqualTo(0L));
            Assert.That(engine.Stats.AvgCost, Is.EqualTo(0.0));
            Assert.That(engine.State.CurrentCost, Is.EqualTo(0));
        }

        private static TranslatorEngine CreateEngine(int pageFaultPenalty, int seed)
        {
            var config = new SimulationConfig
            {
                vaBits = 24,
                pageSizeKB = 4,
                physicalMemoryMB = 1,
                tlbEntries = 4,
                accessCount = 20,
                pageFaultPenalty = pageFaultPenalty
            };

            return new TranslatorEngine(config, seed);
        }
    }
}