#nullable enable
using System;
using System.Collections.Generic;
using System.Linq;
using Cysharp.Threading.Tasks;
using NUnit.Framework;
using ShrinkContext;

namespace ShrinkContext.Tests
{
    /// <summary>
    /// 纤程生命周期（论文算法 4、5 与元理论 4.4 的可观察行为）：
    /// 依赖驱动激活/停用、提供者替换重载、drain-before-inverse 次序、
    /// 父子级联、供给冲突、循环依赖静止、惯性链式转换、分步部分回滚、错误路径回滚。
    /// </summary>
    public class FiberLifecycleTests
    {
        private ShrinkContextRuntime _runtime = null!;

        [SetUp]
        public void SetUp()
        {
            _runtime = new ShrinkContextRuntime();
        }

        [Test]
        public void ProviderReady_ConsumerActivates()
        {
            var provider = new ProviderComponent("provider", "svc", "v1");
            var consumer = new ConsumerComponent("consumer", "svc");

            var providerFiber = _runtime.Use(provider);
            var consumerFiber = _runtime.Use(consumer);

            Assert.AreEqual(ShrinkFiberState.Active, providerFiber.State);
            Assert.AreEqual(ShrinkFiberState.Active, consumerFiber.State);
            Assert.AreEqual("v1", consumer.LastSeen);
            Assert.AreEqual(1, consumer.LoadCount);
        }

        [Test]
        public void MissingDependency_StaysInactiveThenActivatesOnLateProvider()
        {
            var consumer = new ConsumerComponent("consumer", "svc");
            var consumerFiber = _runtime.Use(consumer);

            Assert.AreEqual(ShrinkFiberState.Inactive, consumerFiber.State,
                "依赖缺失时静默保持非活动，不抛错、不加载");
            Assert.AreEqual(0, consumer.LoadCount);

            var provider = new ProviderComponent("provider", "svc", "late");
            var providerFiber = _runtime.Use(provider);

            Assert.AreEqual(ShrinkFiberState.Active, providerFiber.State);
            Assert.AreEqual(ShrinkFiberState.Active, consumerFiber.State,
                "提供者出现后依赖者被响应式激活（activating 转换）");
            Assert.AreEqual("late", consumer.LastSeen);
        }

        [Test]
        public void RetireProvider_DrainsDependentsBeforeOwnInverses()
        {
            var log = new List<string>();
            var provider = new OrderProviderComponent("provider", "svc", "v1", log);
            var consumer = new OrderConsumerComponent("consumer", "svc", log);

            var providerFiber = _runtime.Use(provider);
            var consumerFiber = _runtime.Use(consumer);

            CollectionAssert.AreEqual(new[] { "provider-effect", "consumer-load" }, log);
            Assert.AreEqual(ShrinkFiberState.Active, consumerFiber.State);

            TestAwait.Run(_runtime.RetireAsync(providerFiber));

            CollectionAssert.AreEqual(
                new[] { "provider-effect", "consumer-load", "consumer-undo", "provider-undo" },
                log,
                "依赖者必须先于提供者的逆操作完成卸载（L-Unload 守卫：drain dependents）");
            Assert.AreEqual(ShrinkFiberState.Inactive, consumerFiber.State);
            Assert.AreEqual(ShrinkFiberState.Inactive, providerFiber.State);
        }

        [Test]
        public void ProviderReplacement_ReloadsDependent()
        {
            var first = new ProviderComponent("p1", "svc", "v1");
            var consumer = new ConsumerComponent("consumer", "svc");
            var firstFiber = _runtime.Use(first);
            var consumerFiber = _runtime.Use(consumer);
            Assert.AreEqual("v1", consumer.LastSeen);

            TestAwait.Run(_runtime.RetireAsync(firstFiber));
            Assert.AreEqual(ShrinkFiberState.Inactive, consumerFiber.State);

            var second = new ProviderComponent("p2", "svc", "v2");
            var secondFiber = _runtime.Use(second);

            Assert.AreEqual(ShrinkFiberState.Active, secondFiber.State);
            Assert.AreEqual(ShrinkFiberState.Active, consumerFiber.State);
            Assert.AreEqual("v2", consumer.LastSeen);
            Assert.AreEqual(2, consumer.LoadCount, "提供者替换必须触发依赖者重载");
        }

        [Test]
        public void ProviderReplacement_SameValueStillReloads_UidSemantics()
        {
            var first = new ProviderComponent("p1", "svc", "same");
            var consumer = new ConsumerComponent("consumer", "svc");
            var firstFiber = _runtime.Use(first);
            var consumerFiber = _runtime.Use(consumer);

            TestAwait.Run(_runtime.RetireAsync(firstFiber));

            var second = new ProviderComponent("p2", "svc", "same");
            _runtime.Use(second);

            Assert.AreEqual(2, consumer.LoadCount,
                "目标按提供者 uid 而非值比较：同值不同提供者的替换也要重载（定义 46）");
            Assert.AreEqual("same", consumer.LastSeen);
        }

        [Test]
        public void ParentRetire_CascadesToChildFiber()
        {
            var parent = new ProviderComponent("parent", "parent.svc", "pv");
            var parentFiber = _runtime.Use(parent);

            var child = new ConsumerComponent("child", "parent.svc");
            var childFiber = _runtime.Use(child, null, parentFiber.Ctx);
            Assert.AreEqual(ShrinkFiberState.Active, childFiber.State);
            Assert.AreSame(parentFiber, childFiber.Parent);

            TestAwait.Run(_runtime.RetireAsync(parentFiber));

            Assert.AreEqual(ShrinkFiberState.Inactive, parentFiber.State);
            Assert.AreEqual(ShrinkFiberState.Inactive, childFiber.State,
                "父纤程卸载必须级联卸载子纤程（算法 4：实例化是父的可逆效应）");
        }

        [Test]
        public void SupplyConflict_SecondProviderFailsAndKeepsFirst()
        {
            var first = new ProviderComponent("p1", "svc", "v1");
            var firstFiber = _runtime.Use(first);
            Assert.AreEqual(ShrinkFiberState.Active, firstFiber.State);

            var second = new ProviderComponent("p2", "svc", "v2");
            var secondFiber = _runtime.Use(second);

            Assert.AreEqual(ShrinkFiberState.Inactive, secondFiber.State);
            Assert.IsInstanceOf<ShrinkSupplyConflictException>(secondFiber.LastError,
                "两个活跃纤程供给同一 realm 必须在生成阶段报错（供给不相交）");

            Assert.IsTrue(_runtime.TryGetRaw<string>(_runtime.RootContext, "svc", out var value));
            Assert.AreEqual("v1", value, "冲突失败后第一个提供者的绑定必须保持完好");
            Assert.AreEqual(ShrinkFiberState.Active, firstFiber.State);
        }

        [Test]
        public void UndeclaredSupply_FailsFiberAndLeavesNoBinding()
        {
            var fiber = _runtime.Use(new UndeclaredProviderComponent());

            Assert.AreEqual(ShrinkFiberState.Inactive, fiber.State);
            Assert.IsInstanceOf<ShrinkUndeclaredSupplyException>(fiber.LastError);
            Assert.IsFalse(_runtime.TryGetRaw<int>(_runtime.RootContext, "not-declared", out _));

            var snapshot = _runtime.CaptureDiagnostic();
            var diagnostic = snapshot.Fibers.Single(item => item.Uid == fiber.Uid);
            Assert.AreEqual(ShrinkFiberDiagnosticStatus.Failed, diagnostic.Status);
            StringAssert.Contains("not-declared", diagnostic.ErrorMessage);
        }

        [Test]
        public void DiagnosticSnapshot_ExplainsWaitingDependencyAndPotentialProvider()
        {
            var waiting = _runtime.Use(new ConsumerComponent("waiting", "svc"));
            var blockedProvider = _runtime.Use(new ProviderComponent("blocked-provider", "svc")
            {
                Inject = new[] { "missing" }
            });

            var snapshot = _runtime.CaptureDiagnostic();
            var waitingDiagnostic = snapshot.Fibers.Single(item => item.Uid == waiting.Uid);
            Assert.AreEqual(ShrinkFiberDiagnosticStatus.Waiting, waitingDiagnostic.Status);
            Assert.AreEqual(1, waitingDiagnostic.Dependencies.Count);
            Assert.IsFalse(waitingDiagnostic.Dependencies[0].IsSatisfied);
            CollectionAssert.Contains(waitingDiagnostic.Dependencies[0].PotentialProviderUids,
                blockedProvider.Uid,
                "等待链应显示声明了该键、但自身依赖未满足的潜在提供者");
        }

        [Test]
        public void NotifyIndex_VisitsOnlyConsumersOfChangedKey()
        {
            var target = new ConsumerComponent("target", "target-key");
            _runtime.Use(target);
            for (var i = 0; i < 40; i++)
                _runtime.Use(new ConsumerComponent("unrelated-" + i, "other-" + i));

            _runtime.Use(new ProviderComponent("provider", "target-key", "value"));

            var notifications = _runtime.CaptureDiagnostic().Notifications;
            Assert.AreEqual(1, notifications.LastCandidateCount,
                "notify 应从 key 倒排索引取得候选，不扫描 40 个无关 fiber");
            Assert.AreEqual(41, notifications.IndexedKeyCount);
            Assert.AreEqual("value", target.LastSeen);
        }

        [Test]
        public void CircularDependencies_BothStayInactiveWithoutError()
        {
            var a = new ProviderComponent("a", "ka") { Inject = new[] { "kb" } };
            var b = new ProviderComponent("b", "kb") { Inject = new[] { "ka" } };

            var fiberA = _runtime.Use(a);
            var fiberB = _runtime.Use(b);

            Assert.AreEqual(ShrinkFiberState.Inactive, fiberA.State);
            Assert.AreEqual(ShrinkFiberState.Inactive, fiberB.State);
            Assert.IsNull(fiberA.LastError);
            Assert.IsNull(fiberB.LastError,
                "依赖循环表现为可预测的永久非活动，而不是死锁或异常（论文 6.5）");
        }

        [Test]
        public void Inertia_MidLoadRetire_NeverActivatesAndChainsToUnload()
        {
            var gate1 = new UniTaskCompletionSource();
            var gate2 = new UniTaskCompletionSource();

            var first = new ProviderComponent("p1", "svc", "v1") { OnApply = () => gate1.Task };
            var consumer = new ConsumerComponent("consumer", "svc");

            var firstFiber = _runtime.Use(first);
            Assert.AreEqual(ShrinkFiberState.Loading, firstFiber.State);

            var consumerFiber = _runtime.Use(consumer);
            Assert.AreEqual(ShrinkFiberState.Inactive, consumerFiber.State,
                "提供者仍在装载（未 Active）时，依赖者不可见其绑定");

            // 装载中途退役：目标翻转 ⊥，但进行中的转换继续跑到惯性边界
            var retireTask = _runtime.RetireAsync(firstFiber);
            Assert.AreEqual(ShrinkFiberState.Loading, firstFiber.State,
                "惯性：已进入的转换继续运行，之后才响应新目标");

            var second = new ProviderComponent("p2", "svc", "v2") { OnApply = () => gate2.Task };
            var secondFiber = _runtime.Use(second);

            gate2.TrySetResult();
            Assert.AreEqual(ShrinkFiberState.Active, secondFiber.State);
            Assert.AreEqual(ShrinkFiberState.Active, consumerFiber.State);
            Assert.AreEqual("v2", consumer.LastSeen, "依赖者切换到新提供者");

            gate1.TrySetResult();
            TestAwait.Run(retireTask);

            Assert.AreEqual(ShrinkFiberState.Inactive, firstFiber.State);
            Assert.IsFalse(firstFiber.EverActive,
                "装载中途目标变化的组件不得进入 Active，必须链式转入卸载并回滚");
            Assert.IsNotNull(firstFiber.LastError, "旧提供者补装时撞上活跃的新提供者，按供给冲突失败");

            Assert.IsTrue(_runtime.TryGetRaw<string>(_runtime.RootContext, "svc", out var value));
            Assert.AreEqual("v2", value, "失败路径不得破坏新提供者的绑定");
            Assert.AreEqual(ShrinkFiberState.Active, consumerFiber.State);
        }

        [Test]
        public void IterativeApply_TargetChangeInterruptsAndRollsBackExecutedSteps()
        {
            var component = new IterativeComponent("iterative", "svc", 3);
            var fiber = _runtime.Use(component);
            Assert.AreEqual(ShrinkFiberState.Loading, fiber.State);

            component.Gates[0].TrySetResult();
            Assert.AreEqual(1, component.ExecutedSteps);

            // 转换仍在步进器等待中时翻转目标（不阻塞：延续由后续闸门驱动）
            var retireTask = _runtime.RetireAsync(fiber);

            // 放行第 2 步：执行完该步后，步进边界守卫发现目标已变 → 中断 + 回滚已执行步骤
            component.Gates[1].TrySetResult();
            TestAwait.Run(retireTask);

            Assert.AreEqual(2, component.ExecutedSteps, "守卫在第 3 步之前中断迭代");
            CollectionAssert.AreEqual(
                new[] { "step1", "step2", "undo2", "undo1" },
                component.Steps,
                "部分回滚：仅已执行步骤的逆操作按 LIFO 运行（定理 64 转换内中断）");
            Assert.AreEqual(ShrinkFiberState.Inactive, fiber.State);
            Assert.IsFalse(fiber.EverActive);
            Assert.IsFalse(_runtime.TryGetRaw<string>(_runtime.RootContext, "svc", out _),
                "步骤中的 set 效应必须随回滚撤回");
        }

        [Test]
        public void ApplyFailure_RollsBackPartialEffects()
        {
            var failing = new FailingComponent("failing", "svc");
            var fiber = _runtime.Use(failing);

            Assert.AreEqual(ShrinkFiberState.Inactive, fiber.State);
            Assert.IsFalse(fiber.EverActive);
            Assert.IsInstanceOf<InvalidOperationException>(fiber.LastError);
            Assert.IsFalse(_runtime.TryGetRaw<string>(_runtime.RootContext, "svc", out _),
                "apply 抛异常前注册的效应必须全部回滚（L-Raise → 卸载路径）");
        }

        [Test]
        public void DomainReset_DefaultRuntimeIsRebuilt()
        {
            ShrinkContextDefaults.ResetForTesting();
            var runtime = ShrinkContextDefaults.Default;
            runtime.Use(new ProviderComponent("p", "k", "v"));

            ShrinkContextDefaults.ResetForTesting();

            var rebuilt = ShrinkContextDefaults.Default;
            Assert.AreNotSame(runtime, rebuilt);
            Assert.AreEqual(0, rebuilt.Fibers.Count, "Domain Reload 后注册表必须为空");
        }
    }
}