#nullable enable
using System;
using System.Collections.Generic;
using Cysharp.Threading.Tasks;
using ShrinkEventBus;

namespace ShrinkCommand.Integration
{
    public static class ShrinkCommandEventBusBridge
    {
        [ShrinkEventSubscriber(OwnerId = "shrink.command", DefaultBus = "game")]
        private sealed class CommandRequestSubscriber
        {
            [ShrinkSubscribe(Priority = ShrinkEventPriority.Lowest)]
            private UniTask OnExecuteRequest(ShrinkCommandExecuteRequestEvent eventArgs)
            {
                return HandleExecuteRequestAsync(eventArgs);
            }
        }

        private sealed class ServiceRegistration
        {
            public string ServiceName = ShrinkCommandConstants.DefaultServiceName;
            public ShrinkCommandService Service = null!;
            public IShrinkCommandSource? DefaultSource;
            public Action<ShrinkCommandExecutingInfo>? ExecutingHandler;
            public Action<ShrinkCommandExecutedInfo>? ExecutedHandler;
        }

        private static readonly object SyncRoot = new();
        private static readonly Dictionary<string, ServiceRegistration> RegisteredByName = new(StringComparer.OrdinalIgnoreCase);
        private static readonly Dictionary<ShrinkCommandService, ServiceRegistration> RegisteredByService = new();
        private static IDisposable? _requestHandlerBinding;

#if UNITY_5_3_OR_NEWER
        [UnityEngine.RuntimeInitializeOnLoadMethod(UnityEngine.RuntimeInitializeLoadType.SubsystemRegistration)]
#endif
        private static void ResetStaticState()
        {
            lock (SyncRoot)
            {
                foreach (var registration in RegisteredByService.Values)
                {
                    if (registration.ExecutingHandler != null)
                        registration.Service.OnCommandExecuting -= registration.ExecutingHandler;
                    if (registration.ExecutedHandler != null)
                        registration.Service.OnCommandExecuted -= registration.ExecutedHandler;
                }

                RegisteredByService.Clear();
                RegisteredByName.Clear();
                _requestHandlerBinding?.Dispose();
                _requestHandlerBinding = null;
            }
        }

        public static void RegisterService(
            ShrinkCommandService service,
            ShrinkCommandEventBusBridgeOptions? options = null)
        {
            if (service == null)
                throw new ArgumentNullException(nameof(service));

            EnsureInitialized();
            options ??= new ShrinkCommandEventBusBridgeOptions();

            lock (SyncRoot)
            {
                if (RegisteredByService.TryGetValue(service, out var existing))
                {
                    existing.DefaultSource = options.DefaultSource;
                    if (!string.Equals(existing.ServiceName, options.ServiceName, StringComparison.OrdinalIgnoreCase))
                    {
                        RegisteredByName.Remove(existing.ServiceName);
                        existing.ServiceName = NormalizeServiceName(options.ServiceName);
                        RegisteredByName[existing.ServiceName] = existing;
                    }

                    return;
                }

                var registration = new ServiceRegistration
                {
                    ServiceName = NormalizeServiceName(options.ServiceName),
                    Service = service,
                    DefaultSource = options.DefaultSource
                };
                registration.ExecutingHandler = info => PublishExecuting(registration, info);
                registration.ExecutedHandler = info => PublishExecuted(registration, info);
                service.OnCommandExecuting += registration.ExecutingHandler;
                service.OnCommandExecuted += registration.ExecutedHandler;
                RegisteredByService[service] = registration;
                RegisteredByName[registration.ServiceName] = registration;
            }
        }

        public static void UnregisterService(ShrinkCommandService service)
        {
            if (service == null)
                return;

            lock (SyncRoot)
            {
                if (!RegisteredByService.TryGetValue(service, out var registration))
                    return;

                if (registration.ExecutingHandler != null)
                    service.OnCommandExecuting -= registration.ExecutingHandler;
                if (registration.ExecutedHandler != null)
                    service.OnCommandExecuted -= registration.ExecutedHandler;

                RegisteredByService.Remove(service);
                RegisteredByName.Remove(registration.ServiceName);
            }
        }

        public static async UniTask<ShrinkCommandExecutionResult> RequestCommandAsync(
            string rawInput,
            IShrinkCommandSource? source = null,
            string? serviceName = null)
        {
            var requestEvent = new ShrinkCommandExecuteRequestEvent
            {
                ServiceName = NormalizeServiceName(serviceName),
                RawInput = rawInput ?? string.Empty,
                Source = source
            };

            await EventBus.PostAsync(requestEvent);
            return requestEvent.ExecutionResult ?? ShrinkCommandExecutionResult.Failure("没有命令桥处理该请求。");
        }

        private static void EnsureInitialized()
        {
            if (_requestHandlerBinding != null)
                return;

            _requestHandlerBinding = EventBus.Attach(new CommandRequestSubscriber());
        }

        private static async UniTask HandleExecuteRequestAsync(ShrinkCommandExecuteRequestEvent eventArgs)
        {
            if (eventArgs == null || eventArgs.IsHandled || eventArgs.IsCanceled)
                return;

            ServiceRegistration? registration;
            lock (SyncRoot)
            {
                RegisteredByName.TryGetValue(NormalizeServiceName(eventArgs.ServiceName), out registration);
            }

            if (registration == null)
            {
                eventArgs.IsHandled = true;
                eventArgs.ExecutionResult = ShrinkCommandExecutionResult.Failure(
                    $"未找到命令服务: {NormalizeServiceName(eventArgs.ServiceName)}");
                return;
            }

            var source = eventArgs.Source ?? registration.DefaultSource;
            if (source == null)
            {
                eventArgs.IsHandled = true;
                eventArgs.ExecutionResult = ShrinkCommandExecutionResult.Failure("命令请求缺少来源对象。");
                return;
            }

            eventArgs.ExecutionResult = await registration.Service.ExecuteAsync(source, eventArgs.RawInput);
            eventArgs.IsHandled = true;
        }

        private static void PublishExecuting(ServiceRegistration registration, ShrinkCommandExecutingInfo info)
        {
            EventBus.Post(new ShrinkCommandExecutingEvent
            {
                ServiceName = registration.ServiceName,
                RawInput = info.RawInput,
                CommandPath = info.Command.Path,
                SourceId = info.Source.SourceId,
                SourceDisplayName = info.Source.DisplayName,
                Arguments = new Dictionary<string, string>(info.Arguments, StringComparer.OrdinalIgnoreCase)
            });
        }

        private static void PublishExecuted(ServiceRegistration registration, ShrinkCommandExecutedInfo info)
        {
            var commandPath = info.Command?.Path ?? string.Empty;
            var arguments = new Dictionary<string, string>(info.Arguments, StringComparer.OrdinalIgnoreCase);
            EventBus.Post(new ShrinkCommandExecutedEvent
            {
                ServiceName = registration.ServiceName,
                RawInput = info.RawInput,
                CommandPath = commandPath,
                SourceId = info.Source.SourceId,
                SourceDisplayName = info.Source.DisplayName,
                Arguments = arguments,
                IsSuccess = info.Result.IsSuccess,
                Message = info.Result.Message
            });

            if (info.Result.IsSuccess)
                return;

            EventBus.Post(new ShrinkCommandFailedEvent
            {
                ServiceName = registration.ServiceName,
                RawInput = info.RawInput,
                CommandPath = commandPath,
                SourceId = info.Source.SourceId,
                SourceDisplayName = info.Source.DisplayName,
                Arguments = arguments,
                ErrorMessage = info.Result.Message
            });
        }

        private static string NormalizeServiceName(string? serviceName)
        {
            return string.IsNullOrWhiteSpace(serviceName) ? ShrinkCommandConstants.DefaultServiceName : serviceName.Trim();
        }
    }
}