Connected.Common/Common.Numbering/NumberingOps.cs

using Connected.Entities;
using Connected.Entities.Storage;
using Connected.Interop;
using Connected.Middleware;
using Connected.ServiceModel;
using Connected.Services;

namespace Common.Numbering;
internal sealed class NumberingOps
{
	public sealed class Calculate : ServiceFunction<NumberingCalculateArgs, string>
	{
		public Calculate(IMiddlewareService middleware)
		{
			Middleware = middleware;
		}

		private IMiddlewareService Middleware { get; }

		protected override async Task<string?> OnInvoke()
		{
			foreach (var middleware in await Middleware.Query<INumberingProvider>())
			{
				if (await middleware.Invoke(Arguments) is string result && !string.IsNullOrEmpty(result))
					return result;
			}

			return null;
		}
	}

	public sealed class NextValue : ServiceFunction<NumberingCalculateArgs, string>
	{
		public NextValue(IStorageProvider storage, INumberingService numbering)
		{
			Storage = storage;
			Numbering = numbering;
		}

		private IStorageProvider Storage { get; }
		private INumberingService Numbering { get; }

		protected override async Task<string?> OnInvoke()
		{
			var result = await Prepare();

			await Storage.Open<Numbering>().Update(result, Arguments,
				async () =>
				{
					result = await Prepare();

					return result;
				},
				async (f) =>
				{
					await Task.CompletedTask;

					return f;
				});

			return result.Value;
		}

		private async Task<Numbering> Prepare()
		{
			var current = await Numbering.Select(Arguments.AsArguments<NumberingSelectArgs>());

			if (current is null)
			{
				var id = await TryInsert();

				if (id == 0)
					current = await Numbering.Select(Arguments.AsArguments<NumberingSelectArgs>());
				else
					current = await Numbering.Select(id);
			}

			if (current is null)
				throw new NullReferenceException(nameof(INumbering));

			var newValue = string.Empty;

			if (TypeConversion.TryConvert(current.Value, out long existingValue))
				newValue = existingValue++.ToString();
			else
				newValue = current.Value;

			return (Numbering)current with { Value = newValue };
		}

		private async Task<int> TryInsert()
		{
			try
			{
				return (await Storage.Open<Numbering>().Update(Arguments.AsEntity<Numbering>(State.New))).Id;
			}
			catch
			{
				return 0;
			}
		}
	}

	public sealed class SelectByEntity : ServiceFunction<NumberingSelectArgs, INumbering>
	{
		public SelectByEntity(IStorageProvider storage)
		{
			Storage = storage;
		}

		private IStorageProvider Storage { get; }

		protected override async Task<INumbering?> OnInvoke()
		{
			return await (from e in Storage.Open<Numbering>()
							  where string.Equals(e.Entity, Arguments.Entity, StringComparison.OrdinalIgnoreCase)
							  select e).AsEntity();
		}
	}

	public sealed class Select : ServiceFunction<PrimaryKeyArgs<int>, INumbering>
	{
		public Select(IStorageProvider storage)
		{
			Storage = storage;
		}

		private IStorageProvider Storage { get; }

		protected override async Task<INumbering?> OnInvoke()
		{
			return await (from e in Storage.Open<Numbering>()
							  where e.Id == Arguments.Id
							  select e).AsEntity();
		}
	}
}