using LFlow.InternalEventBus.Interface;
using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using System.Collections.Concurrent;
using System.Reflection;

namespace LFlow.InternalEventBus
{

    public static class InternalEventBusExtensions
    {
        private static readonly ConcurrentDictionary<Type, IInternalEventSubscriber> _eventSubscribers = new();
        private static readonly ConcurrentBag<Type> _eventSubscriberTypes = [];
        /// <summary>
        /// 添加事件订阅服务
        /// </summary>
        /// <param name="services"></param>
        /// <param name="assemblies"></param>
        public static void AddInternalEventBus(this IServiceCollection services, List<Assembly> assemblies)
        {
            assemblies?.ForEach(assembly =>
            {
                var types = assembly.GetTypes().ToList();
                foreach (var type in types)
                {
                    if (type.GetInterface(nameof(IInternalEventSubscriber)) != null)
                    {
                        services.AddSingleton(type);
                        _eventSubscriberTypes.Add(type);
                    }
                }
            });
        }
        /// <summary>
        /// 构建事件对象列表
        /// </summary>
        /// <param name="app"></param>
        private static void BuildInternalEventBusServiceProvider(this IApplicationBuilder app)
        {
            var serviceProvider = app.ApplicationServices;
            _eventSubscriberTypes.ToList().ForEach(type =>
            {
                if (serviceProvider.GetService(type) is IInternalEventSubscriber subscriber)
                    _eventSubscribers.TryAdd(type, subscriber);
            });
        }
        /// <summary>
        /// 启用内部事件
        /// </summary>
        /// <param name="app"></param>
        public static void UseInternalEventBus(this IApplicationBuilder app)
        {
            // build serviceProvider and eventSubscribers
            app.BuildInternalEventBusServiceProvider();
            // sort by priority
            var orderedSubscribers = _eventSubscribers.Values.OrderBy(t => t?.Priority ?? 0).ToList();
            orderedSubscribers.ForEach(subscriber =>
            {
                if (subscriber is IInternalEventSubscriber eventSubscriber)
                {
                    InternalEventBus.Register(eventSubscriber.EventName, eventSubscriber);
                }
            });
        }
    }
}