#nullable enable
using System;
using System.Collections.Generic;
using Cysharp.Threading.Tasks;
using ShrinkApp;
using ShrinkContext;
using ShrinkDataSaver;

namespace ShrinkDataSaver.Integration.App
{
    /// <summary>
    /// ShrinkDataSaver 的原生 Cordis 组件（阶段 3）：
    /// - 提供 <c>shrink.service.datasaver</c> 余效应键（门面服务）；
    /// - 初始化为前向；停用时的终止动作为最终落盘设置（补偿式收尾：
    ///   存档写入本身跨会话持久，不可严格求逆，以 flush 保证一致性，见论文 6.1 扣留与补偿）；
    /// - 与经典 ShrinkDataSaverAppInstaller（ModuleId "shrink.datasaver"）二选一使用。
    /// </summary>
    public sealed class ShrinkDataSaverAppComponent : IShrinkComponent
    {
        public const string ServiceKey = "shrink.service.datasaver";
        public const string ModuleKey = "app.module.shrink.datasaver";

        private static readonly string[] ProvideKeys = { ModuleKey, ServiceKey };
        private readonly ShrinkDataSaverRuntimeConfig? _runtimeConfig;

        public ShrinkDataSaverAppComponent()
        {
        }

        public ShrinkDataSaverAppComponent(ShrinkDataSaverRuntimeConfig? runtimeConfig)
        {
            _runtimeConfig = runtimeConfig;
        }

        public string Name => "shrink.datasaver";

        public IReadOnlyList<string> Inject => Array.Empty<string>();

        public IReadOnlyList<string> Provide => ProvideKeys;

        public UniTask ApplyAsync(ShrinkCtx ctx, object? config)
        {
            ShrinkAppServices? appServices = null;
            var runtimeConfig = _runtimeConfig ?? CreateDefaultRuntimeConfig();
            if (config is ShrinkDataSaverAppModuleConfig moduleConfig)
            {
                appServices = moduleConfig.Services;
                if (moduleConfig.RuntimeConfig != null)
                    runtimeConfig = moduleConfig.RuntimeConfig;
            }
            else if (config is ShrinkAppServices services)
            {
                appServices = services;
            }

            ShrinkDataSaverRuntime.Initialize(runtimeConfig);
            var facade = new ShrinkDataSaverService();
            ctx.Set(ServiceKey, facade, new ShrinkDataSaverAccessPolicy(facade));
            ctx.Set(ModuleKey, Name);

            if (appServices != null)
            {
                appServices.Register(facade);
                ctx.EffectInverse(() =>
                {
                    appServices.TryUnregister(facade);
                    return UniTask.CompletedTask;
                });
            }

            ctx.EffectInverse(async () =>
            {
                await ShrinkSettings.SaveAsync();
            });
            return UniTask.CompletedTask;
        }

        private static ShrinkDataSaverRuntimeConfig CreateDefaultRuntimeConfig()
        {
            // 编辑器/EditMode 环境下 DontDestroyOnLoad 会抛异常，驱动只在播放模式常驻
            return new ShrinkDataSaverRuntimeConfig
            {
#if UNITY_5_3_OR_NEWER
                DontDestroyOnLoadDriver = UnityEngine.Application.isPlaying
#else
                DontDestroyOnLoadDriver = false
#endif
            };
        }
    }
}