using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using NUnit.Framework;
using ShrinkEventBus;
using UnityEngine;

namespace ShrinkModFramework.Tests
{
    public sealed class ShrinkModCompositionTests
    {
        private ShrinkModFrameworkSettings _settings;
        [SetUp] public void SetUp()
        {
            ShrinkModLoader.ResetForTesting();
            _settings = ScriptableObject.CreateInstance<ShrinkModFrameworkSettings>();
            _settings.enableHarmonyPatching = false;
            _settings.verboseLogging = false;
            _settings.assemblyNamePrefixes = new[] { "ExternalFixture." };
        }
        [TearDown] public void TearDown()
        {
            ShrinkModLoader.ResetForTesting();
            UnityEngine.Object.DestroyImmediate(_settings);
        }
        private static ShrinkModInfo Info(string id, params ShrinkModDependency[] dependencies) =>
            new ShrinkModInfo(id, id, "1.2.0", 0, null, false, dependencies);
        private static ShrinkModComponentSource Source(string id, Action<ShrinkModContext> construct = null,
            params ShrinkModDependency[] dependencies) => new ShrinkModComponentSource(Info(id, dependencies), "r1",
                () => new Mod { Construct = construct });
        private static ShrinkModDependency Dep(string id, ShrinkModDependencyOrdering ordering, bool optional = true,
            string range = null) => new ShrinkModDependency(id, null, optional, ordering, range);

        [Test] public void ComposedLoad_UsesManifestOrderAndAllFourPhases_AndPublishesReadyOnce()
        {
            var phases = new List<string>(); var ready = new List<string>(); var all = 0;
            ShrinkModLoader.OnModReady += handle => { Assert.IsTrue(ShrinkModLoader.IsLoaded); ready.Add(handle.Info.ModId); };
            ShrinkModLoader.OnAllModsReady += mods => { Assert.AreEqual(2, mods.Count); all++; };
            ShrinkModComponentSource Make(string id, params ShrinkModDependency[] dependencies) =>
                new ShrinkModComponentSource(Info(id, dependencies), "r1", () => new Mod
                {
                    Construct = _ => phases.Add(id + ":construct"), Register = _ => phases.Add(id + ":register"),
                    Initialize = _ => phases.Add(id + ":initialize"), Ready = _ => phases.Add(id + ":ready")
                });
            var sources = new[] { Make("a.addon", new ShrinkModDependency("z.core", "1.0", false)), Make("z.core") };
            ShrinkModLoader.LoadComposed(_settings, sources);
            Assert.That(phases, Is.EqualTo(new[] { "z.core:construct", "z.core:register", "z.core:initialize", "z.core:ready",
                "a.addon:construct", "a.addon:register", "a.addon:initialize", "a.addon:ready" }));
            Assert.That(ready, Is.EquivalentTo(new[] { "z.core", "a.addon" }));
            ShrinkModLoader.LoadComposed(_settings, sources);
            Assert.AreEqual(2, ready.Count); Assert.AreEqual(2, all); Assert.AreEqual(8, phases.Count);
            Assert.AreEqual(2, ShrinkModLoader.LoadNewExternalMods(_settings).Count);
        }

        [Test] public void DataOnly_AllowsNullEntryAndReversibleContent()
        {
            var source = ShrinkModComponentSource.CreateDataOnly(Info("data"), "r1",
                () => new Mod { Register = ctx => ctx.RegisterContent("items", "one", "value") });
            ShrinkModLoader.LoadComposed(_settings, new[] { source, ShrinkModComponentSource.CreateDataOnly(Info("empty"), "r1") });
            Assert.IsNull(ShrinkModLoader.Mods["empty"].Instance);
            Assert.IsNull(ShrinkModLoader.Mods["data"].Info.EntryType);
            var registry = ShrinkModLoader.GetOrCreateRegistry<string>("items");
            Assert.IsTrue(registry.Contains("data:one"));
            ShrinkModLoader.LoadComposed(_settings, Array.Empty<ShrinkModComponentSource>());
            Assert.IsFalse(registry.Contains("data:one")); Assert.IsEmpty(ShrinkModLoader.Mods);
        }

        [Test] public void Wrapper_ExposesRealInstance_AndAutomaticallyAttachesAndDetachesGeneratedSubscribers()
        {
            var real = new Subscriber();
            var busKey = ShrinkBusKey.Mod("wrapped");
            var bus = EventBus.GetOrCreateBus(busKey, ShrinkBusOptions.Inline());
            var wrapperCalls = 0;
            var source = new ShrinkModComponentSource(Info("wrapped"), "r1", () => new Wrapper(real, ctx =>
            {
                wrapperCalls++; Assert.IsTrue(ctx.TryGetLoadedMod("wrapped", out var handle)); Assert.AreSame(real, handle.Instance);
            }));
            ShrinkModLoader.LoadComposed(_settings, new[] { source });
            Assert.AreSame(real, ShrinkModLoader.Mods["wrapped"].Instance);
            bus.Post(new Ping()); Assert.AreEqual(1, real.Events); Assert.AreEqual(1, wrapperCalls);
            ShrinkModLoader.LoadComposed(_settings, Array.Empty<ShrinkModComponentSource>());
            Assert.AreEqual(1, real.Detaches);
        }

        [Test] public void PublicEventAttachment_CanBeDisposedExplicitly()
        {
            var real = new Subscriber(); var key = ShrinkBusKey.Mod("manual");
            var bus = EventBus.GetOrCreateBus(key, ShrinkBusOptions.Inline());
            try
            {
                var binding = ShrinkModOptionalRuntimeIntegration.TryAttachEventBusInstance(real.GetType(), real, "manual", false);
                Assert.IsNotNull(binding); bus.Post(new Ping()); Assert.AreEqual(1, real.Events);
                binding.Dispose(); bus.Post(new Ping()); Assert.AreEqual(1, real.Events);
            }
            finally { EventBus.RemoveBus(key); }
        }

        [TestCase("[1.0,2.0)", "1.0.0", true)]
        [TestCase("[1.0,2.0)", "2.0", false)]
        [TestCase("[1.2,)", "7.0", true)]
        [TestCase("1.0", "0.9", false)]
        [TestCase("1.0", "1.0.0", true)]
        [TestCase("[1.2]", "1.2.0", true)]
        [TestCase("(,1.0],[1.2,)", "1.1", false)]
        public void Ranges_ParseAndCheckBounds(string range, string version, bool expected) =>
            Assert.AreEqual(expected, ShrinkModVersionRange.Parse(range).Contains(version));
        [TestCase("[2,1]")] [TestCase("[1,2")] [TestCase("[1,)", false)]
        public void Ranges_RejectInvalidSyntax(string range, bool invalid = true)
        {
            if (invalid) Assert.Throws<FormatException>(() => ShrinkModVersionRange.Parse(range));
            else Assert.DoesNotThrow(() => ShrinkModVersionRange.Parse(range));
        }

        [Test] public void RangeAndMissingMandatoryErrors_PreserveCurrentComposition()
        {
            ShrinkModLoader.LoadComposed(_settings, new[] { Source("core") });
            var generation = ShrinkModLoader.Mods["core"].Generation;
            var violation = Source("addon", null, Dep("core", ShrinkModDependencyOrdering.After, false, "[2,3)"));
            var error = Assert.Throws<InvalidOperationException>(() => ShrinkModLoader.LoadComposed(_settings, new[] { Source("core"), violation }));
            Assert.That(error.Message, Does.Contain("[2,3)"));
            Assert.Throws<InvalidOperationException>(() => ShrinkModLoader.LoadComposed(_settings, new[] { violation }));
            Assert.AreEqual(generation, ShrinkModLoader.Mods["core"].Generation);
        }

        [TestCase(ShrinkModDependencyOrdering.Before, "a", "z")]
        [TestCase(ShrinkModDependencyOrdering.After, "z", "a")]
        [TestCase(ShrinkModDependencyOrdering.None, "a", "z")]
        public void OptionalOrdering_OrdersPresentTargets_AndAllowsAbsentTargets(ShrinkModDependencyOrdering order, string first, string second)
        {
            var calls = new List<string>();
            var a = Source("a", _ => calls.Add("a"), Dep("z", order));
            ShrinkModLoader.LoadComposed(_settings, new[] { a, Source("z", _ => calls.Add("z")) });
            Assert.That(calls, Is.EqualTo(new[] { first, second }));
            ShrinkModLoader.LoadComposed(_settings, new[] { a });
            Assert.That(ShrinkModLoader.Mods.Keys, Is.EquivalentTo(new[] { "a" }));
        }

        [Test] public void BeforeCycles_AreRejectedBeforeLifecycle()
        {
            var a = Source("a", _ => Assert.Fail("No lifecycle before validation"), Dep("b", ShrinkModDependencyOrdering.Before));
            var b = Source("b", null, Dep("a", ShrinkModDependencyOrdering.Before));
            var error = Assert.Throws<InvalidOperationException>(() => ShrinkModLoader.LoadComposed(_settings, new[] { a, b }));
            Assert.That(error.Message, Does.Contain("Circular")); Assert.IsFalse(ShrinkModLoader.IsLoaded);
        }

        [Test] public void ChangedIncomingOrdering_RebuildsExistingTarget()
        {
            var calls = new List<string>(); var z = Source("z", _ => calls.Add("z"));
            ShrinkModLoader.LoadComposed(_settings, new[] { z }); calls.Clear();
            ShrinkModLoader.LoadComposed(_settings, new[] { z, Source("a", _ => calls.Add("a"), Dep("z", ShrinkModDependencyOrdering.Before)) });
            Assert.That(calls, Is.EqualTo(new[] { "a", "z" }));
        }

        [Test] public void FailedReplacement_RestoresPublicInstanceAndEventBinding()
        {
            var instances = new List<Subscriber>();
            var source = new ShrinkModComponentSource(Info("wrapped"), "r1", () =>
            { var real = new Subscriber(); instances.Add(real); return new Wrapper(real, null); });
            ShrinkModLoader.LoadComposed(_settings, new[] { source });
            var broken = source.WithMetadata(source.Info, "r2", () => new Mod { Initialize = _ => throw new InvalidOperationException("broken") });
            Assert.Throws<ShrinkModTransactionException>(() => ShrinkModLoader.LoadComposed(_settings, new[] { broken }));
            Assert.IsTrue(ShrinkModLoader.IsLoaded); Assert.AreEqual(2, instances.Count);
            Assert.AreEqual(1, instances[0].Detaches); Assert.AreSame(instances[1], ShrinkModLoader.Mods["wrapped"].Instance);
        }

        [Test] public void Discovery_IsPublicAuthorizedAndDeferred_WithShaRevisionAndRollback()
        {
            _settings.enableExternalDllMods = true;
            var path = Path.Combine(Path.GetTempPath(), Guid.NewGuid() + ".dll");
            try
            {
                File.Copy(Fixture("ExternalFixture.Mod.V1.dll.bytes"), path);
                Assert.IsEmpty(ShrinkModComponentDiscovery.Discover(_settings, Array.Empty<string>()));
                var source = ShrinkModComponentDiscovery.Discover(_settings, new[] { path }).Single();
                Assert.IsFalse(ShrinkModLoader.IsLoaded); Assert.IsEmpty(ShrinkModLoader.Mods);
                Assert.AreEqual(0, ShrinkModDiagnostics.CaptureExternalAssemblies(_settings).CurrentRevisionCount);
                using (var sha = System.Security.Cryptography.SHA256.Create())
                    Assert.That(source.Revision, Does.StartWith(BitConverter.ToString(sha.ComputeHash(File.ReadAllBytes(path))).Replace("-", "") + ":"));
                ShrinkModLoader.LoadComposed(_settings, new[] { source.WithMetadata(source.Info, source.Revision) });
                Assert.AreEqual(1, ShrinkModDiagnostics.CaptureExternalAssemblies(_settings).CurrentRevisionCount);
                var oldRevision = source.Revision;
                File.Copy(Fixture("ExternalFixture.Mod.V2.Failing.dll.bytes"), path, true);
                var broken = ShrinkModComponentDiscovery.Discover(_settings, new[] { path }).Single();
                Assert.Throws<ShrinkModTransactionException>(() => ShrinkModLoader.LoadComposed(_settings, new[] { broken }));
                Assert.AreEqual(oldRevision, ShrinkModCordisRuntime.Host.CurrentSources.Single().Revision);
                Assert.AreEqual("1.0.0", ShrinkModLoader.Mods["external.fixture"].Info.Version);
            }
            finally { File.Delete(path); }
        }

        [Test] public void ResolvePolicy_ReceivesRequesterNameAndAuthorizedPath_AndCanDenyCachedCandidate()
        {
            _settings.enableExternalDllMods = true;
            var path = Path.Combine(Path.GetTempPath(), "ExternalFixture.Mod." + Guid.NewGuid() + ".dll");
            try
            {
                File.Copy(Fixture("ExternalFixture.Mod.V1.dll.bytes"), path);
                ShrinkModLoader.LoadAuthorized(_settings, new[] { path });
                var name = Path.GetFileNameWithoutExtension(path);
                var args = new ResolveEventArgs(name, typeof(ShrinkModCompositionTests).Assembly);
                Assert.IsNotNull(ShrinkExternalModAssemblyLoader.OnAssemblyResolve(null, args));
                var calls = 0;
                ShrinkModLoader.AssemblyResolvePolicy = (requester, requested, candidate) =>
                { calls++; Assert.AreSame(args.RequestingAssembly, requester); Assert.AreEqual(name, requested.Name); Assert.AreEqual(path, candidate); return false; };
                Assert.IsNull(ShrinkExternalModAssemblyLoader.OnAssemblyResolve(null, args)); Assert.AreEqual(1, calls);
                Assert.IsNull(ShrinkExternalModAssemblyLoader.OnAssemblyResolve(null, new ResolveEventArgs("not.authorized")));
                Assert.AreEqual(1, calls);
                ShrinkModLoader.AssemblyResolvePolicy = (_, __, ___) => true;
                Assert.IsNotNull(ShrinkExternalModAssemblyLoader.OnAssemblyResolve(null, args));
                var state = ShrinkExternalModAssemblyLoader.CaptureState();
                state.Current.Clear();
                ShrinkExternalModAssemblyLoader.RestoreState(state);
                ShrinkModLoader.AssemblyResolvePolicy = (_, __, ___) => false;
                Assert.IsNull(ShrinkExternalModAssemblyLoader.OnAssemblyResolve(null, args));
                Assert.AreEqual(0, ShrinkModDiagnostics.CaptureExternalAssemblies(_settings).CurrentRevisionCount);
                ShrinkModLoader.AssemblyResolvePolicy = (_, __, ___) => true;
                Assert.IsNotNull(ShrinkExternalModAssemblyLoader.OnAssemblyResolve(null, args));
            }
            finally { File.Delete(path); }
        }

        [Test] public void ManifestMetadataChange_WithSameRevision_RevalidatesAndRebuilds()
        {
            var first = Source("mod");
            ShrinkModLoader.LoadComposed(_settings, new[] { first });
            var generation = ShrinkModLoader.Mods["mod"].Generation;
            var info = new ShrinkModInfo("mod", "new manifest name", "1.3", 0, null, false,
                new[] { Dep("missing.optional", ShrinkModDependencyOrdering.None) });
            ShrinkModLoader.LoadComposed(_settings, new[] { first.WithMetadata(info, first.Revision) });
            Assert.Greater(ShrinkModLoader.Mods["mod"].Generation, generation);
            Assert.AreEqual("1.3", ShrinkModLoader.Mods["mod"].Info.Version);
        }

        [Test] public void MixedBeforeAfterCycle_AndOptionalRangeViolation_AreRejected()
        {
            var a = Source("a", null, Dep("b", ShrinkModDependencyOrdering.Before));
            var b = Source("b", null, Dep("c", ShrinkModDependencyOrdering.Before));
            var c = Source("c", null, Dep("a", ShrinkModDependencyOrdering.Before));
            Assert.Throws<InvalidOperationException>(() => ShrinkModLoader.LoadComposed(_settings, new[] { a, b, c }));
            c = Source("c", null, Dep("b", ShrinkModDependencyOrdering.After), Dep("a", ShrinkModDependencyOrdering.Before));
            Assert.Throws<InvalidOperationException>(() => ShrinkModLoader.LoadComposed(_settings, new[] { a, b, c }));
            Assert.Throws<InvalidOperationException>(() => ShrinkModLoader.LoadComposed(_settings, new[]
                { Source("a", null, Dep("b", ShrinkModDependencyOrdering.None, true, "[2,3)")), Source("b") }));
        }

        [Test] public void InitialLifecycleFailure_KeepsLoaderUnloadedAndSuppressesReadyEvents()
        {
            var notifications = 0;
            ShrinkModLoader.OnModReady += _ => notifications++;
            ShrinkModLoader.OnAllModsReady += _ => notifications++;
            var source = new ShrinkModComponentSource(Info("broken"), "r1", () => new Mod
                { Ready = _ => throw new InvalidOperationException("failure") });
            Assert.Throws<ShrinkModTransactionException>(() => ShrinkModLoader.LoadComposed(_settings, new[] { source }));
            Assert.IsFalse(ShrinkModLoader.IsLoaded); Assert.IsEmpty(ShrinkModLoader.Mods); Assert.AreEqual(0, notifications);
        }

        [Test] public void AttributeRangeAndOrdering_ArePreservedByDiscovery()
        {
            _settings.assemblyNamePrefixes = new[] { typeof(AttributeMod).Assembly.GetName().Name };
            var source = ShrinkModComponentDiscovery.Discover(_settings, Array.Empty<string>())
                .Single(item => item.Info.ModId == "composition.attribute");
            var dependency = source.Info.Dependencies.Single();
            Assert.AreEqual("[1,2)", dependency.VersionRange);
            Assert.AreEqual(ShrinkModDependencyOrdering.Before, dependency.Ordering); Assert.IsTrue(dependency.Optional);
            Assert.IsFalse(ShrinkModLoader.IsLoaded);
        }

        [ShrinkMod("composition.attribute", "Attribute fixture", "1.0")]
        [ShrinkModDependency("composition.target", optional: true, VersionRange = "[1,2)", Ordering = ShrinkModDependencyOrdering.Before)]
        public sealed class AttributeMod : ShrinkModBase { }

        private static string Fixture(string name)
        {
            var package = UnityEditor.PackageManager.PackageInfo.FindForAssembly(typeof(ShrinkModCompositionTests).Assembly);
            var root = package != null ? package.resolvedPath : UnityEditor.AssetDatabase.FindAssets("ShrinkModFramework.Tests t:asmdef")
                .Select(UnityEditor.AssetDatabase.GUIDToAssetPath).Select(Path.GetDirectoryName).Select(Path.GetDirectoryName).First();
            return Path.Combine(root, "Tests", "Fixtures", name);
        }
        private class Mod : ShrinkModBase
        {
            public Action<ShrinkModContext> Construct, Register, Initialize, Ready;
            public override void OnConstruct(ShrinkModContext context) => Construct?.Invoke(context);
            public override void OnRegisterContent(ShrinkModContext context) => Register?.Invoke(context);
            public override void OnInitialize(ShrinkModContext context) => Initialize?.Invoke(context);
            public override void OnReady(ShrinkModContext context) => Ready?.Invoke(context);
        }
        private sealed class Wrapper : Mod, IShrinkModWrapper
        {
            public Wrapper(IShrinkMod real, Action<ShrinkModContext> construct) { PublicInstance = real; Construct = construct; }
            public IShrinkMod PublicInstance { get; }
        }
        private readonly struct Ping : IShrinkEvent { }
        private sealed class Subscriber : ShrinkModBase, IShrinkGeneratedSubscriber
        {
            public int Events, Detaches;
            public IDisposable AttachGenerated(IShrinkBusResolver resolver, ShrinkBusKey? defaultBus = null)
            {
                var subscription = ShrinkGeneratedBinding.Subscribe<Ping>(resolver, defaultBus, null, this,
                    _ => Events++, ShrinkEventPriority.Normal, 0, false);
                return new Lease(() => { subscription.Dispose(); Detaches++; });
            }
        }
        private sealed class Lease : IDisposable
        {
            private Action _dispose;
            public Lease(Action dispose) { _dispose = dispose; }
            public void Dispose() { var dispose = _dispose; _dispose = null; dispose?.Invoke(); }
        }
    }
}