GFramework/GFramework.Core/StateManagement/StoreBuilder.cs

using GFramework.Core.Abstractions.StateManagement;

namespace GFramework.Core.StateManagement;

/// <summary>
///     Store 构建器的默认实现。
///     该类型用于在 Store 创建之前集中配置比较器、reducer 和中间件，适合模块安装和测试工厂场景。
/// </summary>
/// <typeparam name="TState">状态树的根状态类型。</typeparam>
public sealed class StoreBuilder<TState> : IStoreBuilder<TState>
{
    /// <summary>
    ///     延迟应用到 Store 的配置操作列表。
    ///     采用延迟配置而不是直接缓存 reducer 适配器，可复用 Store 自身的注册和验证逻辑。
    /// </summary>
    private readonly List<Action<Store<TState>>> _configurators = [];

    /// <summary>
    ///     action 匹配策略。
    ///     默认使用精确类型匹配，只有在明确需要复用基类/接口 action 层次时才切换为多态匹配。
    /// </summary>
    private StoreActionMatchingMode _actionMatchingMode = StoreActionMatchingMode.ExactTypeOnly;

    /// <summary>
    ///     状态比较器。
    /// </summary>
    private IEqualityComparer<TState>? _comparer;

    /// <summary>
    ///     历史缓冲区容量。
    ///     默认值为 0，表示不记录撤销/重做历史，以维持最轻量的运行时开销。
    /// </summary>
    private int _historyCapacity;

    /// <summary>
    ///     添加一个 Store 中间件。
    /// </summary>
    /// <param name="middleware">要添加的中间件。</param>
    /// <returns>当前构建器实例。</returns>
    public IStoreBuilder<TState> UseMiddleware(IStoreMiddleware<TState> middleware)
    {
        ArgumentNullException.ThrowIfNull(middleware);
        _configurators.Add(store => store.UseMiddleware(middleware));
        return this;
    }

    /// <summary>
    ///     基于给定初始状态创建一个新的 Store。
    /// </summary>
    /// <param name="initialState">Store 的初始状态。</param>
    /// <returns>已应用当前构建器配置的 Store 实例。</returns>
    public IStore<TState> Build(TState initialState)
    {
        var store = new Store<TState>(initialState, _comparer, _historyCapacity, _actionMatchingMode);
        foreach (var configurator in _configurators)
        {
            configurator(store);
        }

        return store;
    }

    /// <summary>
    ///     配置历史缓冲区容量。
    /// </summary>
    /// <param name="historyCapacity">历史缓冲区容量；0 表示禁用历史记录。</param>
    /// <returns>当前构建器实例。</returns>
    /// <exception cref="ArgumentOutOfRangeException">当 <paramref name="historyCapacity"/> 小于 0 时抛出。</exception>
    public IStoreBuilder<TState> WithHistoryCapacity(int historyCapacity)
    {
        if (historyCapacity < 0)
        {
            throw new ArgumentOutOfRangeException(nameof(historyCapacity), historyCapacity,
                "History capacity cannot be negative.");
        }

        _historyCapacity = historyCapacity;
        return this;
    }

    /// <summary>
    ///     配置 action 匹配策略。
    /// </summary>
    /// <param name="actionMatchingMode">要使用的匹配策略。</param>
    /// <returns>当前构建器实例。</returns>
    public IStoreBuilder<TState> WithActionMatching(StoreActionMatchingMode actionMatchingMode)
    {
        _actionMatchingMode = actionMatchingMode;
        return this;
    }

    /// <summary>
    ///     配置状态比较器。
    /// </summary>
    /// <param name="comparer">状态比较器。</param>
    /// <returns>当前构建器实例。</returns>
    public IStoreBuilder<TState> WithComparer(IEqualityComparer<TState> comparer)
    {
        _comparer = comparer ?? throw new ArgumentNullException(nameof(comparer));
        return this;
    }

    /// <summary>
    ///     使用委托快速添加一个 reducer。
    /// </summary>
    /// <typeparam name="TAction">当前 reducer 处理的 action 类型。</typeparam>
    /// <param name="reducer">执行归约的委托。</param>
    /// <returns>当前构建器实例。</returns>
    public IStoreBuilder<TState> AddReducer<TAction>(Func<TState, TAction, TState> reducer)
    {
        ArgumentNullException.ThrowIfNull(reducer);
        _configurators.Add(store => store.RegisterReducer(reducer));
        return this;
    }

    /// <summary>
    ///     添加一个强类型 reducer。
    /// </summary>
    /// <typeparam name="TAction">当前 reducer 处理的 action 类型。</typeparam>
    /// <param name="reducer">要添加的 reducer。</param>
    /// <returns>当前构建器实例。</returns>
    public IStoreBuilder<TState> AddReducer<TAction>(IReducer<TState, TAction> reducer)
    {
        ArgumentNullException.ThrowIfNull(reducer);
        _configurators.Add(store => store.RegisterReducer(reducer));
        return this;
    }
}