using System;

using System.Collections.Generic;

using System.Linq;

​

public class GenericObject

{

    public int Id { get; set; }

}

​

public class ObjectVersion

{

    public int Id { get; set; }

    public GenericObject GenericObject { get; set; }

}

​

public class ObjectDependency

{

    public string Name { get; set; }

    public ObjectVersion ObjectVersion1 { get; set; }

    public ObjectVersion ObjectVersion2 { get; set; }

}

​

public class Program

{

    public static void Main()

    {

            GenericObject go1 = new GenericObject()

            {

                Id = 1

            };

​

            GenericObject go2 = new GenericObject()

            {

                Id = 2

            };

​

            GenericObject go3 = new GenericObject()

            {

                Id = 3

            };

​

            ObjectVersion ov1 = new ObjectVersion()

            {

                Id = 1,

                GenericObject = go1

            };

​

            ObjectVersion ov2 = new ObjectVersion()

            {

                Id = 2,

                GenericObject = go2

            };

​

            ObjectVersion ov3 = new ObjectVersion()

            {

                Id = 3,

                GenericObject = go3

            };

​

            ObjectVersion ov4 = new ObjectVersion()

            {

                Id = 4,

                GenericObject = go1

            };

​

            List<ObjectDependency> dependencies = new List<ObjectDependency>();

​

            ObjectDependency d1 = new ObjectDependency()

            {

                Name = "d1",

                ObjectVersion1 = ov1,

                ObjectVersion2 = ov2

            };

            dependencies.Add(d1);

​

            ObjectDependency d2 = new ObjectDependency()

            {

                Name = "d2",

                ObjectVersion1 = ov2,

                ObjectVersion2 = ov3

            };

            dependencies.Add(d2);

​

            ObjectDependency d3 = new ObjectDependency()

            {

                Name = "d3",

                ObjectVersion1 = ov4,

                ObjectVersion2 = ov2

            };

            dependencies.Add(d3);

​

            // Get all ObjectDependencies containing ov2

            // Output:

            // d1

            // d2

            // d3

            Console.WriteLine("Get all ObjectDependencies containing ov2");

            IEnumerable<ObjectDependency> ov2Dependencies = dependencies.Where(d => d.ObjectVersion1.Id == ov2.Id || d.ObjectVersion2.Id == ov2.Id)

                .OrderBy(d => d.Name);

            foreach (ObjectDependency dependency in ov2Dependencies)

            {

                Console.WriteLine(dependency.Name);

            }

​

            // Get all ObjectVersions dependent on ov2

            // Output:

            // 1

            // 3

            // 4

            Console.WriteLine("Get all ObjectVersions dependent on ov2");

            IEnumerable<ObjectVersion> ov2AllDependentObjectVersions = dependencies.Where(d => d.ObjectVersion1.Id == ov2.Id || d.ObjectVersion2.Id == ov2.Id)

                .Select(d => d.ObjectVersion1)

                .Union(dependencies.Where(d => d.ObjectVersion1.Id == ov2.Id || d.ObjectVersion2.Id == ov2.Id)

                .Select(d => d.ObjectVersion2))

                .Where(o => o.Id != ov2.Id)

                .OrderBy(o => o.Id);

            foreach (ObjectVersion ov in ov2AllDependentObjectVersions)

            {

                Console.WriteLine(ov.Id);

            }

​

            // Get latest ObjectVersions dependent on ov2 with different GenericObject

            // Output:

            // 3

            // 4

            Console.WriteLine("Get latest ObjectVersions dependent on ov2 with different GenericObject");

            IEnumerable<ObjectVersion> ov2LatestDependentObjectVersions = dependencies.Where(d => d.ObjectVersion1.Id == ov2.Id || d.ObjectVersion2.Id == ov2.Id)

                .Select(d => d.ObjectVersion1)

                .Union(dependencies.Where(d => d.ObjectVersion1.Id == ov2.Id || d.ObjectVersion2.Id == ov2.Id)

                .Select(d => d.ObjectVersion2))

                .Where(o => o.Id != ov2.Id)

                .GroupBy(o => o.GenericObject.Id)

                .Select(g => g.OrderByDescending(o => o.Id).FirstOrDefault())

                .OrderBy(o => o.Id);

            foreach (ObjectVersion ov in ov2LatestDependentObjectVersions)

            {

                Console.WriteLine(ov.Id);

            }

​

            // Get latest ObjectDependencies containing ov2 with different GenericObject

            // Output:

            // d2

            // d3

            Console.WriteLine("Get latest ObjectDependencies containing ov2 with different GenericObject");

            IEnumerable<ObjectDependency> ov2LatestDependencies = dependencies.Where(d => d.ObjectVersion1.Id == ov2.Id || d.ObjectVersion2.Id == ov2.Id)

                .Where(x => x.ObjectVersion1.Id == ov2.Id)

                .Select(x => new

                {

                    ObjectDependency = x,

                    ObjectVersion = x.ObjectVersion2

                })

                .Union(

                    dependencies.Where(d => d.ObjectVersion1.Id == ov2.Id || d.ObjectVersion2.Id == ov2.Id)

                    .Where(x => x.ObjectVersion2.Id == ov2.Id)

                    .Select(x => new

                    {

                        ObjectDependency = x,

                        ObjectVersion = x.ObjectVersion1

                    })

                )

                .GroupBy(x => x.ObjectVersion.GenericObject.Id)

                .Select(x => x.OrderByDescending(y => y.ObjectVersion.Id).FirstOrDefault())

                .Select(x => x.ObjectDependency)

                .OrderBy(d => d.Name);

            foreach (ObjectDependency dependency in ov2LatestDependencies)

            {

                Console.WriteLine(dependency.Name);

            }

    }

}