using GFramework.Core.Abstractions.Property;
using GFramework.Core.Abstractions.StateManagement;
using GFramework.Core.Extensions;
using GFramework.Core.Property;
using GFramework.Core.StateManagement;

namespace GFramework.Core.Tests.StateManagement;

/// <summary>
///     Store 状态管理能力的单元测试。
///     这些测试覆盖集中式状态容器的核心职责：状态归约、订阅通知、选择器桥接和诊断行为。
/// </summary>
[TestFixture]
public class StoreTests
{
    /// <summary>
    ///     测试 Store 在创建后能够暴露初始状态。
    /// </summary>
    [Test]
    public void State_Should_Return_Initial_State()
    {
        var store = CreateStore(new CounterState(1, "Player"));

        Assert.That(store.State.Count, Is.EqualTo(1));
        Assert.That(store.State.Name, Is.EqualTo("Player"));
    }

    /// <summary>
    ///     测试 Dispatch 能够执行 reducer 并向订阅者广播新状态。
    /// </summary>
    [Test]
    public void Dispatch_Should_Update_State_And_Notify_Subscribers()
    {
        var store = CreateStore();
        var receivedStates = new List<CounterState>();

        store.Subscribe(receivedStates.Add);

        store.Dispatch(new IncrementAction(2));

        Assert.That(store.State.Count, Is.EqualTo(2));
        Assert.That(receivedStates.Count, Is.EqualTo(1));
        Assert.That(receivedStates[0].Count, Is.EqualTo(2));
    }

    /// <summary>
    ///     测试当 reducer 返回逻辑相等状态时不会触发通知。
    /// </summary>
    [Test]
    public void Dispatch_Should_Not_Notify_When_State_Does_Not_Change()
    {
        var store = CreateStore();
        var notifyCount = 0;

        store.Subscribe(_ => notifyCount++);

        store.Dispatch(new RenameAction("Player"));

        Assert.That(store.State.Name, Is.EqualTo("Player"));
        Assert.That(notifyCount, Is.EqualTo(0));
    }

    /// <summary>
    ///     测试同一 action 类型的多个 reducer 会按注册顺序执行。
    /// </summary>
    [Test]
    public void Dispatch_Should_Run_Multiple_Reducers_In_Registration_Order()
    {
        var store = CreateStore();
        store.RegisterReducer<IncrementAction>((state, action) =>
            state with { Count = state.Count + action.Amount * 10 });

        store.Dispatch(new IncrementAction(1));

        Assert.That(store.State.Count, Is.EqualTo(11));
    }

    /// <summary>
    ///     测试 SubscribeWithInitValue 会立即回放当前状态并继续接收后续变化。
    /// </summary>
    [Test]
    public void SubscribeWithInitValue_Should_Replay_Current_State_And_Future_Changes()
    {
        var store = CreateStore(new CounterState(5, "Player"));
        var receivedCounts = new List<int>();

        store.SubscribeWithInitValue(state => receivedCounts.Add(state.Count));
        store.Dispatch(new IncrementAction(3));

        Assert.That(receivedCounts, Is.EqualTo(new[] { 5, 8 }));
    }

    /// <summary>
    ///     测试注销订阅后不会再收到后续通知。
    /// </summary>
    [Test]
    public void UnRegister_Handle_Should_Stop_Future_Notifications()
    {
        var store = CreateStore();
        var notifyCount = 0;

        var unRegister = store.Subscribe(_ => notifyCount++);
        store.Dispatch(new IncrementAction(1));
        unRegister.UnRegister();
        store.Dispatch(new IncrementAction(1));

        Assert.That(notifyCount, Is.EqualTo(1));
    }

    /// <summary>
    ///     测试选择器仅在所选状态片段变化时触发通知。
    /// </summary>
    [Test]
    public void Select_Should_Only_Notify_When_Selected_Slice_Changes()
    {
        var store = CreateStore();
        var selectedCounts = new List<int>();
        var selection = store.Select(state => state.Count);

        selection.Register(selectedCounts.Add);

        store.Dispatch(new RenameAction("Renamed"));
        store.Dispatch(new IncrementAction(2));

        Assert.That(selectedCounts, Is.EqualTo(new[] { 2 }));
    }

    /// <summary>
    ///     测试选择器支持自定义比较器，从而抑制无意义的局部状态通知。
    /// </summary>
    [Test]
    public void Select_Should_Respect_Custom_Selected_Value_Comparer()
    {
        var store = CreateStore();
        var selectedCounts = new List<int>();
        var selection = store.Select(
            state => state.Count,
            new TensBucketEqualityComparer());

        selection.Register(selectedCounts.Add);

        store.Dispatch(new IncrementAction(5));
        store.Dispatch(new IncrementAction(6));

        Assert.That(selectedCounts, Is.EqualTo(new[] { 11 }));
    }

    /// <summary>
    ///     测试 ToBindableProperty 可桥接到现有 BindableProperty 风格用法，并与旧属性系统共存。
    /// </summary>
    [Test]
    public void ToBindableProperty_Should_Work_With_Existing_BindableProperty_Pattern()
    {
        var store = CreateStore();
        var mirror = new BindableProperty<int>(0);
        IReadonlyBindableProperty<int> bindableProperty = store.ToBindableProperty(state => state.Count);

        bindableProperty.Register(value => mirror.Value = value);
        store.Dispatch(new IncrementAction(3));

        Assert.That(mirror.Value, Is.EqualTo(3));
    }

    /// <summary>
    ///     测试 IStateSelector 接口重载能够复用显式选择逻辑。
    /// </summary>
    [Test]
    public void Select_With_IStateSelector_Should_Project_Selected_Value()
    {
        var store = CreateStore();
        var selection = store.Select(new CounterNameSelector());

        Assert.That(selection.Value, Is.EqualTo("Player"));
    }

    /// <summary>
    ///     测试 Store 在中间件内部发生同一实例的嵌套分发时会抛出异常。
    /// </summary>
    [Test]
    public void Dispatch_Should_Throw_When_Nested_Dispatch_Happens_On_Same_Store()
    {
        var store = CreateStore();
        store.UseMiddleware(new NestedDispatchMiddleware(store));

        Assert.That(
            () => store.Dispatch(new IncrementAction(1)),
            Throws.InvalidOperationException.With.Message.Contain("Nested dispatch"));
    }

    /// <summary>
    ///     测试中间件链执行顺序和 Store 诊断信息更新。
    /// </summary>
    [Test]
    public void Dispatch_Should_Run_Middlewares_In_Order_And_Update_Diagnostics()
    {
        var store = CreateStore();
        var logs = new List<string>();

        store.UseMiddleware(new RecordingMiddleware(logs, "first"));
        store.UseMiddleware(new RecordingMiddleware(logs, "second"));

        store.Dispatch(new IncrementAction(2));

        Assert.That(logs, Is.EqualTo(new[]
        {
            "first:before",
            "second:before",
            "second:after",
            "first:after"
        }));

        Assert.That(store.LastActionType, Is.EqualTo(typeof(IncrementAction)));
        Assert.That(store.LastStateChangedAt, Is.Not.Null);
        Assert.That(store.LastDispatchRecord, Is.Not.Null);
        Assert.That(store.LastDispatchRecord!.HasStateChanged, Is.True);
        Assert.That(store.LastDispatchRecord.NextState.Count, Is.EqualTo(2));
    }

    /// <summary>
    ///     测试未命中的 action 仍会记录诊断信息，但不会改变状态。
    /// </summary>
    [Test]
    public void Dispatch_Without_Matching_Reducer_Should_Update_Record_Without_Changing_State()
    {
        var store = CreateStore();

        store.Dispatch(new NoopAction());

        Assert.That(store.State.Count, Is.EqualTo(0));
        Assert.That(store.LastActionType, Is.EqualTo(typeof(NoopAction)));
        Assert.That(store.LastDispatchRecord, Is.Not.Null);
        Assert.That(store.LastDispatchRecord!.HasStateChanged, Is.False);
        Assert.That(store.LastStateChangedAt, Is.Null);
    }

    /// <summary>
    ///     创建一个带有基础 reducer 的测试 Store。
    /// </summary>
    /// <param name="initialState">可选初始状态。</param>
    /// <returns>已配置基础 reducer 的 Store 实例。</returns>
    private static Store<CounterState> CreateStore(CounterState? initialState = null)
    {
        var store = new Store<CounterState>(initialState ?? new CounterState(0, "Player"));
        store.RegisterReducer<IncrementAction>((state, action) => state with { Count = state.Count + action.Amount });
        store.RegisterReducer<RenameAction>((state, action) => state with { Name = action.Name });
        return store;
    }

    /// <summary>
    ///     用于测试的计数器状态。
    ///     使用 record 保持逻辑不可变语义，便于 Store 基于状态快照进行比较和断言。
    /// </summary>
    /// <param name="Count">当前计数值。</param>
    /// <param name="Name">当前名称。</param>
    private sealed record CounterState(int Count, string Name);

    /// <summary>
    ///     表示增加计数的 action。
    /// </summary>
    /// <param name="Amount">要增加的数量。</param>
    private sealed record IncrementAction(int Amount);

    /// <summary>
    ///     表示修改名称的 action。
    /// </summary>
    /// <param name="Name">新的名称。</param>
    private sealed record RenameAction(string Name);

    /// <summary>
    ///     表示没有匹配 reducer 的 action，用于验证无变更分发路径。
    /// </summary>
    private sealed record NoopAction;

    /// <summary>
    ///     显式选择器实现，用于验证 IStateSelector 重载。
    /// </summary>
    private sealed class CounterNameSelector : IStateSelector<CounterState, string>
    {
        /// <summary>
        ///     从状态中选择名称字段。
        /// </summary>
        /// <param name="state">完整状态。</param>
        /// <returns>名称字段。</returns>
        public string Select(CounterState state)
        {
            return state.Name;
        }
    }

    /// <summary>
    ///     将计数值按十位分桶比较的测试比较器。
    ///     该比较器用于验证选择器只在局部状态“语义变化”时才触发通知。
    /// </summary>
    private sealed class TensBucketEqualityComparer : IEqualityComparer<int>
    {
        /// <summary>
        ///     判断两个值是否落在同一个十位分桶中。
        /// </summary>
        /// <param name="x">左侧值。</param>
        /// <param name="y">右侧值。</param>
        /// <returns>若位于同一分桶则返回 <see langword="true"/>，否则返回 <see langword="false"/>。</returns>
        public bool Equals(int x, int y)
        {
            return x / 10 == y / 10;
        }

        /// <summary>
        ///     返回基于十位分桶的哈希码。
        /// </summary>
        /// <param name="obj">目标值。</param>
        /// <returns>分桶哈希码。</returns>
        public int GetHashCode(int obj)
        {
            return obj / 10;
        }
    }

    /// <summary>
    ///     记录中间件调用顺序的测试中间件。
    /// </summary>
    private sealed class RecordingMiddleware(List<string> logs, string name) : IStoreMiddleware<CounterState>
    {
        /// <summary>
        ///     记录当前中间件在分发前后的调用顺序。
        /// </summary>
        /// <param name="context">当前分发上下文。</param>
        /// <param name="next">后续处理节点。</param>
        public void Invoke(StoreDispatchContext<CounterState> context, Action next)
        {
            logs.Add($"{name}:before");
            next();
            logs.Add($"{name}:after");
        }
    }

    /// <summary>
    ///     在中间件阶段尝试二次分发的测试中间件，用于验证重入保护。
    /// </summary>
    private sealed class NestedDispatchMiddleware(Store<CounterState> store) : IStoreMiddleware<CounterState>
    {
        /// <summary>
        ///     标记是否已经触发过一次嵌套分发，避免因测试实现本身导致无限递归。
        /// </summary>
        private bool _hasTriggered;

        /// <summary>
        ///     在第一次进入中间件时执行嵌套分发。
        /// </summary>
        /// <param name="context">当前分发上下文。</param>
        /// <param name="next">后续处理节点。</param>
        public void Invoke(StoreDispatchContext<CounterState> context, Action next)
        {
            if (!_hasTriggered)
            {
                _hasTriggered = true;
                store.Dispatch(new IncrementAction(1));
            }

            next();
        }
    }
}