using System;
using System.Threading;
using Cysharp.Threading.Tasks;
using GameFramework.Event;

namespace SepCore.AsyncTask
{
    /// <summary>
    /// 异步任务辅助类，用于将事件回调转换为 UniTask
    /// </summary>
    public static class AsyncTaskHelper
    {
        /// <summary>
        /// 等待指定事件触发
        /// </summary>
        /// <typeparam name="T">事件参数类型</typeparam>
        /// <param name="eventId">事件ID</param>
        /// <param name="predicate">事件过滤条件</param>
        /// <param name="timeout">超时时间（秒），0表示不超时</param>
        /// <param name="cancellationToken">取消令牌</param>
        /// <returns>事件参数</returns>
        public static UniTask<T> WaitEventAsync<T>(
            int eventId,
            Func<T, bool> predicate = null,
            float timeout = 0f,
            CancellationToken cancellationToken = default) where T : GameEventArgs
        {
            var tcs = new UniTaskCompletionSource<T>();
            var eventComponent = global::GameEntry.Event;
            var timeoutCancellationTokenSource = timeout > 0f ? new CancellationTokenSource() : null;
            CancellationTokenRegistration cancellationRegistration = default;
            int isCompleted = 0;

            EventHandler<GameEventArgs> handler = null;
            void Cleanup(bool disposeCancellationRegistration)
            {
                eventComponent.Unsubscribe(eventId, handler);
                timeoutCancellationTokenSource?.Cancel();
                timeoutCancellationTokenSource?.Dispose();
                if (disposeCancellationRegistration)
                {
                    cancellationRegistration.Dispose();
                }
            }

            bool TryComplete(bool disposeCancellationRegistration = true)
            {
                if (Interlocked.Exchange(ref isCompleted, 1) != 0)
                {
                    return false;
                }

                Cleanup(disposeCancellationRegistration);
                return true;
            }

            handler = (_, e) =>
            {
                var args = e as T;
                if (args == null) return;

                if (predicate != null && !predicate(args)) return;

                if (TryComplete())
                {
                    tcs.TrySetResult(args);
                }
            };

            eventComponent.Subscribe(eventId, handler);

            if (cancellationToken.CanBeCanceled)
            {
                cancellationRegistration = cancellationToken.Register(() =>
                {
                    if (TryComplete(false))
                    {
                        tcs.TrySetCanceled(cancellationToken);
                    }
                });
            }

            // 超时处理
            if (timeoutCancellationTokenSource != null)
            {
                WaitTimeoutAsync(timeout, timeoutCancellationTokenSource.Token, () =>
                {
                    if (TryComplete())
                    {
                        tcs.TrySetException(new TimeoutException($"等待事件超时: {timeout}秒"));
                    }
                }).Forget();
            }

            return tcs.Task;
        }

        /// <summary>
        /// 等待成功或失败事件
        /// </summary>
        /// <typeparam name="TSuccess">成功事件参数类型</typeparam>
        /// <typeparam name="TFailure">失败事件参数类型</typeparam>
        /// <param name="successEventId">成功事件ID</param>
        /// <param name="failureEventId">失败事件ID</param>
        /// <param name="successPredicate">成功事件过滤条件</param>
        /// <param name="failurePredicate">失败事件过滤条件</param>
        /// <param name="timeout">超时时间（秒），0表示不超时</param>
        /// <param name="cancellationToken">取消令牌</param>
        /// <returns>成功事件参数</returns>
        public static UniTask<TSuccess> WaitSuccessOrFailureAsync<TSuccess, TFailure>(
            int successEventId,
            int failureEventId,
            Func<TSuccess, bool> successPredicate = null,
            Func<TFailure, bool> failurePredicate = null,
            float timeout = 0f,
            CancellationToken cancellationToken = default)
            where TSuccess : GameEventArgs
            where TFailure : GameEventArgs
        {
            var tcs = new UniTaskCompletionSource<TSuccess>();
            var eventComponent = global::GameEntry.Event;
            var timeoutCancellationTokenSource = timeout > 0f ? new CancellationTokenSource() : null;
            CancellationTokenRegistration cancellationRegistration = default;
            int isCompleted = 0;

            // 先声明两个 handler，再赋值 lambda，避免前向引用
            EventHandler<GameEventArgs> successHandler = null;
            EventHandler<GameEventArgs> failureHandler = null;
            void Cleanup(bool disposeCancellationRegistration)
            {
                eventComponent.Unsubscribe(successEventId, successHandler);
                eventComponent.Unsubscribe(failureEventId, failureHandler);
                timeoutCancellationTokenSource?.Cancel();
                timeoutCancellationTokenSource?.Dispose();
                if (disposeCancellationRegistration)
                {
                    cancellationRegistration.Dispose();
                }
            }

            bool TryComplete(bool disposeCancellationRegistration = true)
            {
                if (Interlocked.Exchange(ref isCompleted, 1) != 0)
                {
                    return false;
                }

                Cleanup(disposeCancellationRegistration);
                return true;
            }

            successHandler = (_, e) =>
            {
                var args = e as TSuccess;
                if (args == null) return;

                if (successPredicate != null && !successPredicate(args)) return;

                if (TryComplete())
                {
                    tcs.TrySetResult(args);
                }
            };

            failureHandler = (_, e) =>
            {
                var args = e as TFailure;
                if (args == null) return;

                if (failurePredicate != null && !failurePredicate(args)) return;

                if (TryComplete())
                {
                    tcs.TrySetException(new Exception($"操作失败: {args}"));
                }
            };

            eventComponent.Subscribe(successEventId, successHandler);
            eventComponent.Subscribe(failureEventId, failureHandler);

            if (cancellationToken.CanBeCanceled)
            {
                cancellationRegistration = cancellationToken.Register(() =>
                {
                    if (TryComplete(false))
                    {
                        tcs.TrySetCanceled(cancellationToken);
                    }
                });
            }

            // 超时处理
            if (timeoutCancellationTokenSource != null)
            {
                WaitTimeoutAsync(timeout, timeoutCancellationTokenSource.Token, () =>
                {
                    if (TryComplete())
                    {
                        tcs.TrySetException(new TimeoutException($"等待事件超时: {timeout}秒"));
                    }
                }).Forget();
            }

            return tcs.Task;
        }

        private static async UniTaskVoid WaitTimeoutAsync(float timeout, CancellationToken cancellationToken, Action onTimeout)
        {
            try
            {
                await UniTask.Delay(TimeSpan.FromSeconds(timeout), cancellationToken: cancellationToken);
            }
            catch (OperationCanceledException)
            {
                return;
            }

            onTimeout?.Invoke();
        }
    }
}