using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Configuration;
using Grpc.Net.Client;
using MagicOnion.Client;
using System;
using System.Linq;
using System.Threading.Tasks;

namespace DysonNetwork.Shared.Etcd
{
    public static class EtcdServiceExtensions
    {
        public static IServiceCollection AddEtcdService(this IServiceCollection services, IConfiguration configuration)
        {
            var connectionString = configuration["ConnectionStrings:Etcd"];
            if (connectionString is null) throw new ArgumentNullException(nameof(connectionString));
            services.AddSingleton<IEtcdService>(new EtcdService(connectionString!));
            return services;
        }

        public static IServiceCollection AddRemoteService<TService>(this IServiceCollection services)
            where TService : class, MagicOnion.IService<TService>
        {
            services.AddSingleton<TService>(serviceProvider =>
            {
                var etcdService = serviceProvider.GetRequiredService<IEtcdService>();
                var serviceName = typeof(TService).Name.TrimStart('I'); // Convention: IMyService -> MyService

                // Synchronously wait for service discovery (or handle asynchronously if preferred)
                var endpoints = etcdService.DiscoverServicesAsync(serviceName).GetAwaiter().GetResult();

                if (endpoints.Count == 0)
                    throw new InvalidOperationException($"No endpoints found for MagicOnion service: {serviceName}");

                // For simplicity, use the first discovered endpoint
                var endpoint = endpoints.First();

                var channel = GrpcChannel.ForAddress(endpoint);
                return MagicOnionClient.Create<TService>(channel);
            });
            
            return services;
        }
    }
}