Connected.Framework.ServiceModel.Client/Connected.ServiceModel.Client.Data/TableStorageProvider.cs

using System.Linq.Expressions;
using System.Reflection;
using Connected.Annotations;
using Connected.Data;
using Connected.Data.Storage;
using Connected.Entities;
using Connected.Entities.Storage;
using Connected.Expressions;
using Connected.Expressions.Evaluation;
using Connected.Expressions.Query;
using Connected.Expressions.Translation;
using Connected.Interop;
using Connected.ServiceModel.Data;

namespace Connected.ServiceModel.Client.Data;

[Priority(2)]
internal class TableStorageProvider : QueryProvider, IStorageExecutor, IStorageMiddleware
{
	public TableStorageProvider(IStorageProvider storage)
	{
		Storage = storage;
	}

	private IStorageProvider Storage { get; }

	protected override object? OnExecute(Expression expression)
	{
		return CreateExecutionPlan(expression).Compile()(this);
	}

	private static Expression<Func<IStorageExecutor, object>> CreateExecutionPlan(Expression expression)
	{
		var lambda = expression as LambdaExpression;

		if (lambda is not null)
			expression = lambda.Body;

		var context = new ExpressionCompilationContext(new CqlLanguage());
		var translator = new Translator(context);
		var translation = translator.Translate(expression);
		var parameters = lambda?.Parameters;
		var provider = Resolve(expression, parameters, typeof(IStorage<>));

		if (provider is null)
		{
			var rootQueryable = Resolve(expression, parameters, typeof(IQueryable));

			provider = Expression.Property(rootQueryable, typeof(IQueryable).GetTypeInfo().GetDeclaredProperty(nameof(IQueryable.Provider)));
		}

		return ExecutionBuilder.Build(context, new CqlLinguist(context, CqlLanguage.Default, translator), translation, provider);
	}

	/// <summary>
	/// Find the expression of the specified type, either in the specified expression or parameters.
	/// </summary>
	private static Expression Resolve(Expression expression, IList<ParameterExpression> parameters, Type type)
	{
		if (parameters is not null)
		{
			var found = parameters.FirstOrDefault(p => type.IsAssignableFrom(p.Type));

			if (found is not null)
				return found;
		}

		return SubtreeResolver.Resolve(expression, type);
	}

	public IEnumerable<TResult?> Execute<TResult>(IStorageOperation operation)
		 where TResult : IEntity
	{
		var result = Storage.Open<TResult>().Query(new StorageContextArgs(operation));

		if (result.IsCompleted)
			return result.Result;

		var r = result.GetAwaiter().GetResult();

		return r;
	}

	public bool SupportsEntity(Type entityType)
	{
		return entityType.ImplementsInterface(typeof(ITableEntity<>));
	}

	public IStorageOperation CreateOperation<TEntity>(TEntity entity)
		where TEntity : IEntity
	{
		var builder = new AggregatedCommandBuilder<TEntity?>();

		if (builder.Build(entity) is not StorageOperation operation)
			throw new NullReferenceException(nameof(StorageOperation));

		return operation;
	}

	public IStorageReader<TEntity> OpenReader<TEntity>(IStorageOperation operation, IStorageConnection connection)
	{
		return new TableReader<TEntity>(operation, connection);
	}

	public IStorageWriter OpenWriter(IStorageOperation operation, IStorageConnection connection)
	{
		return new TableWriter(operation, connection);
	}

	public async Task Initialize()
	{
		await Task.CompletedTask;
	}
}