#nullable enable
using System;
using System.Collections.Generic;
using System.Diagnostics;
using Cysharp.Threading.Tasks;

namespace ShrinkContext.AppAdapter.Editor
{
    public sealed class ShrinkContextBenchmarkReport
    {
        internal ShrinkContextBenchmarkReport(int unrelatedFiberCount, int reloadIterations,
            double notifyMilliseconds, long notificationDispatchCount, long notificationCandidateVisits,
            long naiveFiberVisits, int consumerApplyCount, int failureIterations,
            int restoredFailureCount, double restoreMilliseconds, long managedMemoryDeltaBytes)
        {
            UnrelatedFiberCount = unrelatedFiberCount;
            ReloadIterations = reloadIterations;
            NotifyMilliseconds = notifyMilliseconds;
            NotificationDispatchCount = notificationDispatchCount;
            NotificationCandidateVisits = notificationCandidateVisits;
            NaiveFiberVisits = naiveFiberVisits;
            ConsumerApplyCount = consumerApplyCount;
            FailureIterations = failureIterations;
            RestoredFailureCount = restoredFailureCount;
            RestoreMilliseconds = restoreMilliseconds;
            ManagedMemoryDeltaBytes = managedMemoryDeltaBytes;
        }

        public int UnrelatedFiberCount { get; }
        public int ReloadIterations { get; }
        public double NotifyMilliseconds { get; }
        public long NotificationDispatchCount { get; }
        public long NotificationCandidateVisits { get; }
        public long NaiveFiberVisits { get; }
        public int ConsumerApplyCount { get; }
        public int FailureIterations { get; }
        public int RestoredFailureCount { get; }
        public double RestoreMilliseconds { get; }
        public long ManagedMemoryDeltaBytes { get; }
    }

    /// <summary>Editor 可重复容量基准；耗时仅报告，不作为跨机器通过阈值。</summary>
    public static class ShrinkContextBenchmarkRunner
    {
        public static async UniTask<ShrinkContextBenchmarkReport> RunAsync(
            int unrelatedFiberCount = 1000, int reloadIterations = 100, int failureIterations = 25)
        {
            if (unrelatedFiberCount < 0)
                throw new ArgumentOutOfRangeException(nameof(unrelatedFiberCount));
            if (reloadIterations <= 0)
                throw new ArgumentOutOfRangeException(nameof(reloadIterations));
            if (failureIterations <= 0)
                throw new ArgumentOutOfRangeException(nameof(failureIterations));

            var memoryBefore = GC.GetTotalMemory(false);
            var runtime = new ShrinkContextRuntime();
            var targetConsumer = new BenchmarkConsumer("benchmark.target");
            runtime.Use(targetConsumer);
            for (var i = 0; i < unrelatedFiberCount; i++)
                runtime.Use(new BenchmarkConsumer("benchmark.unrelated." + i));

            var notifyStopwatch = Stopwatch.StartNew();
            for (var i = 0; i < reloadIterations; i++)
            {
                var provider = runtime.Use(new BenchmarkProvider("provider-" + i, "benchmark.target"));
                if (provider.LastError != null)
                    throw new InvalidOperationException("Benchmark provider failed.", provider.LastError);
                await runtime.RetireAsync(provider);
            }
            notifyStopwatch.Stop();

            var notifySnapshot = runtime.CaptureDiagnostic();
            var naiveFiberVisits = notifySnapshot.Notifications.DispatchCount * runtime.Fibers.Count;

            var catalog = new ShrinkComponentCatalog();
            catalog.Register("stable", () => new BenchmarkProvider("stable", "benchmark.restore"));
            catalog.Register("failing", () => new BenchmarkFailingProvider("benchmark.restore"));
            var restoreRuntime = new ShrinkContextRuntime();
            var loader = new ShrinkContextLoader(restoreRuntime, catalog);
            await loader.ApplyAsync(new[] { new ShrinkLoaderEntry("provider", "stable") });

            var restoredFailures = 0;
            var restoreStopwatch = Stopwatch.StartNew();
            for (var i = 0; i < failureIterations; i++)
            {
                try
                {
                    await loader.ApplyAsync(new[] { new ShrinkLoaderEntry("provider", "failing") });
                }
                catch (ShrinkLoaderException)
                {
                    if (loader.LastTransaction?.PreviousCompositionRestored == true &&
                        loader.TryGetFiber("provider", out var restored) &&
                        restored.State == ShrinkFiberState.Active)
                    {
                        restoredFailures++;
                    }
                }
            }
            restoreStopwatch.Stop();

            await runtime.ShutdownAsync();
            await restoreRuntime.ShutdownAsync();
            var memoryAfter = GC.GetTotalMemory(false);

            return new ShrinkContextBenchmarkReport(
                unrelatedFiberCount,
                reloadIterations,
                notifyStopwatch.Elapsed.TotalMilliseconds,
                notifySnapshot.Notifications.DispatchCount,
                notifySnapshot.Notifications.CandidateVisitCount,
                naiveFiberVisits,
                targetConsumer.ApplyCount,
                failureIterations,
                restoredFailures,
                restoreStopwatch.Elapsed.TotalMilliseconds,
                memoryAfter - memoryBefore);
        }

        private sealed class BenchmarkProvider : IShrinkComponent
        {
            private readonly string[] _provide;

            public BenchmarkProvider(string name, string key)
            {
                Name = name;
                Key = key;
                _provide = new[] { key };
            }

            public string Name { get; }
            private string Key { get; }
            public IReadOnlyList<string> Inject => Array.Empty<string>();
            public IReadOnlyList<string> Provide => _provide;

            public UniTask ApplyAsync(ShrinkCtx ctx, object? config)
            {
                ctx.Set(Key, Name);
                return UniTask.CompletedTask;
            }
        }

        private sealed class BenchmarkConsumer : IShrinkComponent
        {
            private readonly string[] _inject;

            public BenchmarkConsumer(string key)
            {
                Key = key;
                _inject = new[] { key };
            }

            private string Key { get; }
            public string Name => "consumer:" + Key;
            public int ApplyCount { get; private set; }
            public IReadOnlyList<string> Inject => _inject;
            public IReadOnlyList<string> Provide => Array.Empty<string>();

            public UniTask ApplyAsync(ShrinkCtx ctx, object? config)
            {
                ctx.Get<string>(Key);
                ApplyCount++;
                return UniTask.CompletedTask;
            }
        }

        private sealed class BenchmarkFailingProvider : IShrinkComponent
        {
            private readonly string[] _provide;

            public BenchmarkFailingProvider(string key)
            {
                Key = key;
                _provide = new[] { key };
            }

            private string Key { get; }
            public string Name => "benchmark-failing";
            public IReadOnlyList<string> Inject => Array.Empty<string>();
            public IReadOnlyList<string> Provide => _provide;

            public UniTask ApplyAsync(ShrinkCtx ctx, object? config)
            {
                ctx.Set(Key, Name);
                throw new InvalidOperationException("Expected benchmark replacement failure.");
            }
        }
    }
}