using System;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;

namespace DotNetCore.CAP.EntityFrameworkCore.Test
{
	public abstract class TestHost : IDisposable
	{
		protected IServiceCollection _services;
		private IServiceProvider _provider;
		private IServiceProvider _scopedProvider;

		public TestHost()
		{
			CreateServiceCollection();
			PreBuildServices();
			BuildServices();
			PostBuildServices();
		}

		protected IServiceProvider Provider => _scopedProvider ?? _provider;

		private void CreateServiceCollection()
		{
			var services = new ServiceCollection();

			services.AddOptions();
			services.AddLogging();

			var connectionString = ConnectionUtil.GetConnectionString();
			//services.AddSingleton(new SqlServerOptions { ConnectionString = connectionString });
			services.AddDbContext<TestDbContext>(options => options.UseSqlServer(connectionString));

			_services = services;
		}

		protected virtual void PreBuildServices()
		{
		}

		private void BuildServices()
		{
			_provider = _services.BuildServiceProvider();
		}

		protected virtual void PostBuildServices()
		{
		}

		public IDisposable CreateScope()
		{
			var scope = CreateScope(_provider);
			var loc = scope.ServiceProvider;
			_scopedProvider = loc;
			return new DelegateDisposable(() =>
			{
				if (_scopedProvider == loc)
				{
					_scopedProvider = null;
				}
				scope.Dispose();
			});
		}

		public IServiceScope CreateScope(IServiceProvider provider)
		{
			var scope = provider.GetService<IServiceScopeFactory>().CreateScope();
			return scope;
		}

		public T GetService<T>() => Provider.GetService<T>();

		public T Ensure<T>(ref T service)
			where T : class
			=> service ?? (service = GetService<T>());

		public virtual void Dispose()
		{
			(_provider as IDisposable)?.Dispose();
		}

		private class DelegateDisposable : IDisposable
		{
			private Action _dispose;

			public DelegateDisposable(Action dispose)
			{
				_dispose = dispose;
			}

			public void Dispose()
			{
				_dispose();
			}
		}
	}
}