using Microsoft.Extensions.DependencyInjection;
using System;

namespace DigitalData.Core.Legacy.Client
{
    public static class ServiceFactory
    {
        private static readonly IServiceCollection _services = new ServiceCollection();
        private static readonly Lazy<IServiceProvider> _lazyProvider = new Lazy<IServiceProvider>(Build);

        public static IServiceCollection Services => !_lazyProvider.IsValueCreated
            ? _services
            : throw new InvalidOperationException(
                "Service provider has already been created. " +
                "Further modifications to the service collection are not allowed. " +
                "This is to ensure that the dependency injection container remains in a consistent state.");

        private static IServiceProvider Build() => _services.BuildServiceProvider();

        public static T Provide<T>() => _lazyProvider.Value.GetRequiredService<T>();

        public static HttpClientService<TOptions> ProvideHttpClientService<TOptions>()
            where TOptions : HttpClientOptions
            => _lazyProvider.Value.GetRequiredService<HttpClientService<TOptions>>();
    }
}