using System.Collections.Generic;
using System.Linq;
using UnityEngine;

namespace AibisDream.SaveSystem
{
    /// <summary>
    /// 运行时登记全部 <see cref="ISnapshotProvider"/>。
    /// Capture/Restore 时按 <see cref="ISnapshotProvider.RestoreOrder"/> 迭代；
    /// 不使用「谁注册了谁才存」的隐式行为，RequiredForCapture 用于显式校验。
    /// </summary>
    public static class SnapshotRegistry
    {
        private static readonly Dictionary<string, ISnapshotProvider> Providers = new();

        /// <summary>注册 provider；同 SaveId 后者覆盖前者。</summary>
        public static void Register(ISnapshotProvider provider)
        {
            if (provider == null) return;
            Providers[provider.SaveId] = provider;
        }

        public static void Unregister(string saveId)
        {
            Providers.Remove(saveId);
        }

        public static bool TryGet(string saveId, out ISnapshotProvider provider)
        {
            return Providers.TryGetValue(saveId, out provider);
        }

        /// <summary>按 RestoreOrder 升序返回，供还原流水线使用。</summary>
        public static IReadOnlyList<ISnapshotProvider> GetOrderedProviders()
        {
            return Providers.Values.OrderBy(p => p.RestoreOrder).ToList();
        }

        /// <summary>
        /// 校验 <see cref="SnapshotProviderIds.RequiredForCapture"/>；
        /// 缺失时 <c>LogWarning</c> 但不阻断 Capture。
        /// </summary>
        public static void ValidateRequiredProviders()
        {
            foreach (var saveId in SnapshotProviderIds.RequiredForCapture)
            {
                if (!Providers.ContainsKey(saveId))
                {
                    Debug.LogWarning($"[SnapshotRegistry] 缺少快照 provider: {saveId}");
                }
            }
        }
    }
}