From e99748addca417ae66b3a83cbe69ffa9f4aa7d8c Mon Sep 17 00:00:00 2001
From: Hassan Habib <hassanhabib@live.com>
Date: Tue, 28 Feb 2023 13:27:40 -0800
Subject: [PATCH] POC: Working Prototype

---
 .../Clients/Extensions/ClientTests.cs         | 37 +++++++++
 .../Extensions/ODataEnumerableClient.cs       | 78 +++++++++++++++++++
 .../OExpressions/OExpressionService.cs        |  3 +-
 3 files changed, 117 insertions(+), 1 deletion(-)
 create mode 100644 OData.Neo.Core.Tests.Unit/Clients/Extensions/ClientTests.cs
 create mode 100644 OData.Neo.Core/Clients/Extensions/ODataEnumerableClient.cs

diff --git a/OData.Neo.Core.Tests.Unit/Clients/Extensions/ClientTests.cs b/OData.Neo.Core.Tests.Unit/Clients/Extensions/ClientTests.cs
new file mode 100644
index 0000000..8018567
--- /dev/null
+++ b/OData.Neo.Core.Tests.Unit/Clients/Extensions/ClientTests.cs
@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using OData.Neo.Core.Clients.Extensions;
+using Xunit;
+
+namespace OData.Neo.Core.Tests.Unit.Clients.Extensions
+{
+    public class ClientTests
+    {
+        [Fact]
+        public async Task ShouldFilterStudent()
+        {
+            // given
+            var students = new List<Student>
+            {
+                new Student { Id = Guid.NewGuid(), Name = "John" },
+                new Student { Id = Guid.NewGuid(), Name = "Mary" },
+                new Student { Id = Guid.NewGuid(), Name = "Peter" }
+            }.AsQueryable();
+
+            var filteredStuff = 
+                await students.ApplyODataQueryAsync(
+                    "$select=Name");
+
+            Assert.True(true);
+        }
+
+        public class Student
+        {
+            public Guid Id { get; set; }
+            public string Name { get; set; }
+        }
+    }
+}
diff --git a/OData.Neo.Core/Clients/Extensions/ODataEnumerableClient.cs b/OData.Neo.Core/Clients/Extensions/ODataEnumerableClient.cs
new file mode 100644
index 0000000..62be6f6
--- /dev/null
+++ b/OData.Neo.Core/Clients/Extensions/ODataEnumerableClient.cs
@@ -0,0 +1,78 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Reflection;
+using System.Text;
+using System.Threading.Tasks;
+using OData.Neo.Core.Brokers.Expressions;
+using OData.Neo.Core.Brokers.SqlQueries;
+using OData.Neo.Core.Services.Coordinations.OQueries;
+using OData.Neo.Core.Services.Foundations.OExpressions;
+using OData.Neo.Core.Services.Foundations.OQueries;
+using OData.Neo.Core.Services.Foundations.OSqls;
+using OData.Neo.Core.Services.Foundations.OTokenizations;
+using OData.Neo.Core.Services.Foundations.Projections;
+using OData.Neo.Core.Services.Foundations.Tokenizations;
+using OData.Neo.Core.Services.Orchestrations.OQueries;
+using OData.Neo.Core.Services.Orchestrations.OTokenizations;
+
+namespace OData.Neo.Core.Clients.Extensions
+{
+    public static class ODataEnumerableClient
+    {
+        public static async ValueTask<IQueryable> ApplyODataQueryAsync<T>(
+            this IQueryable<T> queryable,
+            string odataQuery) where T : class
+        {
+            var otokenizationService = new OTokenizationService();
+            var projectionService = new ProjectionService();
+            var tokenizationService = new TokenizationService();
+
+            var oTokenizationOrchestrationService =
+                new OTokenizationOrchestrationService(
+                    tokenizationService,
+                    projectionService,
+                    otokenizationService);
+
+            var expressionBroker = new ExpressionBroker();
+            var sqlQueryBroker = new SqlQueryBroker<T>();
+
+            var oExpressionService = new OExpressionService(expressionBroker);
+            var oQueryService = new OQueryService(sqlQueryBroker);
+            var oSqlService = new OSqlService(sqlQueryBroker);
+
+            var oQueryOrchestrationService =
+                new OQueryOrchestrationService(
+                    oExpressionService,
+                    oQueryService,
+                    oSqlService);
+
+            var oQueryCoordinationService = new OQueryCoordinationService(
+                oTokenizationOrchestrationService,
+                oQueryOrchestrationService);
+
+            Expression oQueryExpression =
+                await oQueryCoordinationService
+                    .ProcessOQueryAsync<T>(odataQuery);
+
+            return Execute(queryable, oQueryExpression);
+        }
+
+        public static IQueryable Execute<T>(IQueryable<T> sources, Expression exp)
+        {
+            MethodCallExpression call = exp as MethodCallExpression;
+
+            //  Select(...)
+            MethodInfo methodInfo = call.Method;
+
+            UnaryExpression unary = call.Arguments[1] as UnaryExpression;
+
+            LambdaExpression lambda = unary.Operand as LambdaExpression;
+
+            // Delegate delegateFunc = lambda.Compile();
+
+            return methodInfo.Invoke(null, new object[] { sources, lambda }) as IQueryable;
+        }
+    }
+}
diff --git a/OData.Neo.Core/Services/Foundations/OExpressions/OExpressionService.cs b/OData.Neo.Core/Services/Foundations/OExpressions/OExpressionService.cs
index 6d69079..218cddd 100644
--- a/OData.Neo.Core/Services/Foundations/OExpressions/OExpressionService.cs
+++ b/OData.Neo.Core/Services/Foundations/OExpressions/OExpressionService.cs
@@ -44,7 +44,8 @@ private string CovertToLinqExp(OToken token)
                 {
                     string properties = string.Join(
                         separator: ",",
-                        values: child.Children.Select(child => $"obj.{child.RawValue}"));
+                        values: child.Children.Where(c => c.ProjectedType == Models.ProjectedTokens.ProjectedTokenType.Property)
+                            .Select(c => $"obj.{c.RawValue}"));
 
                     stringBuilder.Append($"Select(obj => new {{{properties}}})");
                 }