using System;
using System.Collections.Generic;
using System.Linq;
using Cysharp.Threading.Tasks;
using ShrinkContext;
using ShrinkEventBus;

namespace ShrinkModFramework
{
    /// <summary>把 IShrinkMod 四阶段生命周期映射为一个可逆 Cordis 组件。</summary>
    internal sealed class ShrinkModComponent : IShrinkComponent
    {
        private readonly ShrinkModContextHost _host;
        private readonly ShrinkModComponentSource _source;
        private readonly string[] _inject;
        private readonly string[] _provide;

        public ShrinkModComponent(ShrinkModContextHost host, ShrinkModComponentSource source)
        {
            _host = host ?? throw new ArgumentNullException(nameof(host));
            _source = source ?? throw new ArgumentNullException(nameof(source));
            _inject = source.Info.Dependencies
                .Where(dependency => !dependency.Optional)
                .Select(dependency => ShrinkModContextHost.GetModKey(dependency.ModId))
                .Distinct(StringComparer.Ordinal)
                .ToArray();
            _provide = new[] { ShrinkModContextHost.GetModKey(source.Info.ModId) };
        }

        public string Name => "shrink.mod/" + _source.Info.ModId;
        public IReadOnlyList<string> Inject => _inject;
        public IReadOnlyList<string> Provide => _provide;

        public UniTask ApplyAsync(ShrinkCtx ctx, object config)
        {
            var instance = _source.Factory();
            if (instance == null)
                throw new InvalidOperationException($"Mod factory returned null: {_source.Info.ModId}");

            var handle = new ShrinkModHandle(_source.Info, instance)
            {
                Generation = _host.NextGeneration()
            };

            ctx.Effect(
                () => _host.RegisterHandle(handle),
                () =>
                {
                    _host.UnregisterHandle(handle);
                    handle.State = ShrinkModState.Unloaded;
                });

            IDisposable harmonyLease = null;
            ctx.Effect(
                () => harmonyLease = ShrinkHarmonyPatchService.AcquirePatchesIfNeeded(
                    handle.Info, _host.EnableHarmonyPatching, _host.VerboseLogging),
                () => harmonyLease?.Dispose());

            var modContext = new ShrinkModContext(handle.Info, _host.RegistryManager,
                _host.Mods, _host.VerboseLogging, ctx);

            instance.OnConstruct(modContext);
            handle.State = ShrinkModState.Constructed;

            // 先登记归属清理，OnRegisterContent 中途失败也能撤回已注册的部分内容。
            ctx.Effect(() => { }, () => _host.RegistryManager.RemoveOwnedEntries(handle.Info.ModId));
            instance.OnRegisterContent(modContext);
            handle.State = ShrinkModState.ContentRegistered;

            IDisposable eventBinding = null;
            ctx.Effect(
                () => eventBinding = ShrinkModOptionalRuntimeIntegration.TryAttachEventBusInstance(
                    instance.GetType(), instance, handle.Info.ModId, _host.VerboseLogging),
                () =>
                {
                    eventBinding?.Dispose();
                    EventBus.RemoveBus(ShrinkBusKey.Mod(handle.Info.ModId));
                });

            // 模组网络 handler 以 ModId 为归属键，可在失败或卸载时整体撤回。
            ctx.Effect(() => { }, () => ShrinkModNetworkManager.UnregisterHandlers(handle.Info.ModId));
            instance.OnInitialize(modContext);
            handle.State = ShrinkModState.Initialized;

            instance.OnReady(modContext);
            handle.State = ShrinkModState.Ready;
            ctx.Set(_provide[0], handle);
            return UniTask.CompletedTask;
        }
    }
}