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

namespace ShrinkModFramework
{
    /// <summary>默认模组组件根；目录变更只提交完整的新组合，失败时由 Host 恢复旧组合。</summary>
    public static class ShrinkModCordisRuntime
    {
        private static ShrinkModContextHost _host;

        public static bool IsInitialized => _host != null;
        public static ShrinkModContextHost Host => _host ?? throw new InvalidOperationException(
            "ShrinkModCordisRuntime has not been initialized.");
        public static IReadOnlyDictionary<string, ShrinkModHandle> Mods =>
            _host?.Mods ?? EmptyMods;

        private static readonly IReadOnlyDictionary<string, ShrinkModHandle> EmptyMods =
            new Dictionary<string, ShrinkModHandle>();

        public static async UniTask<IReadOnlyDictionary<string, ShrinkModHandle>> ApplyDiscoveredAsync(
            ShrinkModFrameworkSettings settings = null,
            IEnumerable<string> authorizedDllPaths = null)
        {
            settings ??= ShrinkModFrameworkSettings.Instance;
            var verboseLogging = settings == null || settings.verboseLogging;
            if (_host == null)
            {
                _host = new ShrinkModContextHost(
                    settings == null || settings.enableHarmonyPatching,
                    verboseLogging);
            }

            var revisionState = ShrinkExternalModAssemblyLoader.CaptureState();
            ShrinkModNetworkManager.Configure(settings == null || settings.enableNetworkSync, verboseLogging);
            try
            {
                var authorizedPaths = authorizedDllPaths?.ToArray() ?? Array.Empty<string>();
                var sources = ShrinkModComponentDiscovery.DiscoverCurrent(
                    settings, verboseLogging, authorizedPaths);
                await _host.ApplyAsync(sources, () => ShrinkExternalModAssemblyLoader.RestoreState(revisionState));
            }
            catch
            {
                // DLL revision discovery is part of the same composition transaction:
                // a failing replacement must not make the failed assembly current.
                ShrinkExternalModAssemblyLoader.RestoreState(revisionState);
                throw;
            }

            if (verboseLogging)
                UnityEngine.Debug.Log($"[ShrinkModFramework] Cordis 模组组合已提交，共 {_host.Mods.Count} 个。");
            return _host.Mods;
        }

        /// <summary>提交宿主组合；生命周期或发现失败时恢复之前的程序集 revision 和组件。</summary>
        public static async UniTask<IReadOnlyDictionary<string, ShrinkModHandle>> ApplyComposedAsync(
            ShrinkModFrameworkSettings settings, IReadOnlyList<ShrinkModComponentSource> sources)
        {
            if (sources == null) throw new ArgumentNullException(nameof(sources));
            settings ??= ShrinkModFrameworkSettings.Instance;
            var verbose = settings != null && settings.verboseLogging;
            if (_host == null) _host = new ShrinkModContextHost(settings == null || settings.enableHarmonyPatching, verbose);
            var previous = ShrinkExternalModAssemblyLoader.CaptureState();
            try
            {
                var states = sources.Where(source => source != null && source.DiscoveryState != null)
                    .Select(source => source.DiscoveryState).Distinct().ToArray();
                var composedState = new ShrinkExternalModAssemblyLoader.RevisionState();
                foreach (var state in states)
                {
                    foreach (var pair in state.Current)
                    {
                        if (composedState.Current.TryGetValue(pair.Key, out var other) && other.Revision != pair.Value.Revision)
                            throw new InvalidOperationException($"Conflicting discovered revisions for {pair.Key}.");
                        composedState.Current[pair.Key] = pair.Value;
                    }
                    foreach (var pair in state.Known) composedState.Known[pair.Key] = pair.Value;
                }
                ShrinkExternalModAssemblyLoader.RestoreState(composedState);
                ShrinkModNetworkManager.Configure(settings == null || settings.enableNetworkSync, verbose);
                await _host.ApplyAsync(sources, () => ShrinkExternalModAssemblyLoader.RestoreState(previous));
            }
            catch
            {
                ShrinkExternalModAssemblyLoader.RestoreState(previous);
                throw;
            }
            return _host.Mods;
        }

        public static IReadOnlyShrinkModRegistry<T> GetOrCreateRegistry<T>(string name) =>
            Host.GetOrCreateRegistry<T>(name);

        internal static void ResetForDomainReload()
        {
            _host = null;
        }

        internal static void ResetForTesting()
        {
            if (_host != null)
                _host.ShutdownAsync().GetAwaiter().GetResult();
            _host = null;
        }
    }
}