using System;
using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using xCommons.Extensions;
using xEventService.Configuration;
using xEventService.Constants;
using xEventService.Interfaces;
using xEventService.Models;
using xEventService.Providers;

namespace xEventService.DI {
    public static partial class XDIHelperExtension {
        /// <summary>
        /// Extract EventService Configurations ...
        /// </summary>
        /// <param name="source"></param>
        /// <returns></returns>
        public static XEventServiceConfiguration GetXEventServiceConfigurations (this IConfiguration source) {
            //
            var configSection = source
                .GetSection (ConfigurationNodeNames.EVENT_SERVICE_NODE_NAME);
            var result = configSection.Get<XEventServiceConfiguration> ();

            //
            return result;
        }

        /// <summary>
        /// Register Event Service Configurations ...
        /// </summary>
        /// <param name="services"></param>
        /// <param name="configuration"></param>
        public static void AddXEventServiceConfigurations (
            this IServiceCollection services,
            IConfiguration configuration
        ) {
            //
            var config = configuration.GetXEventServiceConfigurations ();
            services.AddXEventServiceConfigurations (config);
        }

        /// <summary>
        /// Register Event Service Configurations ...
        /// </summary>
        /// <param name="services"></param>
        /// <param name="configuration"></param>
        public static void AddXEventServiceConfigurations (
            this IServiceCollection services,
            XEventServiceConfiguration configuration
        ) {
            //
            services.AddSingleton<XEventServiceConfiguration> (configuration);
        }

        /// <summary>
        /// Register Event Service ...
        /// </summary>
        /// <param name="services"></param>
        /// <param name="configuration"></param>
        public static void AddXEventService (
            this IServiceCollection services,
            IConfiguration configuration
        ) {
            //
            // Check Configuration Registered ...
            var config = services.GetRegisteredService<XEventServiceConfiguration> ();
            if (config.IsNull ()) {
                //
                Console.WriteLine ($"XEventService: there is no provided XEventServiceConfiguration, using default ...");

                //
                // Register Default Configuration ...
                services.AddXEventServiceConfigurations (configuration);
            }

            //
            // Register IXEventBus ...
            var serviceBas = services.GetRegisteredService<IXEventBus> ();
            if (serviceBas.IsNull ()) {
                services.AddSingleton<IXEventBus, XEventBus> ();
            }
        }

        /// <summary>
        /// Register an Event Handler ...
        /// </summary>
        /// <param name="services"></param>
        /// <param name="lifetime"></param>
        /// <typeparam name="TEvent"></typeparam>
        /// <typeparam name="THandler"></typeparam>
        /// <returns></returns>
        public static void AddXEventHandler<TEvent, THandler> (
            this IServiceCollection services,
            ServiceLifetime lifetime = ServiceLifetime.Transient
        )
        where TEvent : XEvent
        where THandler : IXEventHandler<TEvent> {
            //
            services.Add (new ServiceDescriptor (
                serviceType: typeof (THandler),
                implementationType: typeof (THandler),
                lifetime: lifetime
            ));

            //
            services.Add (new ServiceDescriptor (
                serviceType: typeof (IXEventHandler<TEvent>),
                implementationType: typeof (THandler),
                lifetime: lifetime
            ));
        }

        /// <summary>
        /// Subscribe to specific Event ...
        /// </summary>
        /// <param name="app"></param>
        /// <typeparam name="TEvent"></typeparam>
        /// <typeparam name="THandler"></typeparam>
        /// <returns></returns>
        public static void XEventSubscribe<TEvent, THandler> (
            this IApplicationBuilder app,
            bool toExchange = true
        )
        where TEvent : XEvent
        where THandler : IXEventHandler<TEvent> {
            //
            var eventName = typeof (TEvent).Name;

            //
            // Retrieve EventBus from IOC ...
            var eventBus = app.ApplicationServices.GetRequiredService<IXEventBus> ();

            //
            // Subscribe to Event Handler ...
            var isSubscribed = eventBus.Subscribe<TEvent, THandler> ();
            Console.WriteLine ($"XEventService: Event Handler subscription result: {eventName} => {isSubscribed} ...");
        }
    }
}