using System;

using System.Collections.Generic;

using System.Linq;

public class Module 

{

    public String module_name;

    public Module(string name) 

    {

        module_name = name;

    }

}

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Program p = new Program();

        p.CurrentCode();

    }

​

    // The following is the currecnt code and is definitively incorrect

    // Mistakes -

    // 1. to compare if two lists contain the same elements, .Equals can not be used.  '.Equals' checks if two objects are the same or not. In here there are 2 different list objects which may contain the same elements

    // 2. Because of the 1, the first if statement is always false and the else if statement will always be true resulting in exception being thrown

    public void CurrentCode()

    {

        var existingModules = new List<Module>() { new Module("module1"), new Module("module2") };

        var newModules = new List<Module>() { new Module("newModule") };

​

        var newModuleNames = newModules.Select(n1 => n1.module_name); // This creates a new List of strings that contain the names of modules

​

        var difference = existingModules.Where(n => !newModuleNames.Contains(n.module_name)); // difference is a list that contains those existing modules that are not in newModules.

​

        if (difference.Equals(existingModules)) // This condition check is always going to be false because .Equals checks for equality of reference and not whether the two lists are identical.

        {

            ;

            // Commenting out following code due to missing pieces.

            //var modules = ModuleValidator.Validate(body.properties.modules, db.MaxFlash != 0);

            //db.SetModules(modules);

        }

        else if (!difference.Equals(newModules)) // This condition check is also always false(same reason as above, but because of ! condition, this if statement will always be true

        {

            throw new Exception("immutable property");

        }

    }

​

    // The following code is better (still may not be correct)

    // It correctly checks whether the two lists contain the same elements or not by using the AreSame method. Check this method below.

    public void Bettercode() 

    {

        var existingModules = new List<Module>() { new Module("module1"), new Module("module2") };

        var newModules = new List<Module>() { new Module("newModule") };

​

        var newModuleNames = newModules.Select(n1 => n1.module_name); // This creates a new List of strings that contain the names of modules

​

        var difference = existingModules.Where(n => !newModuleNames.Contains(n.module_name)); // difference is a list that contains those existing modules that are not in newModules.

​

        if (AreSame(difference, existingModules)) // This condition will check if the collection difference and existingModules are identical.

        {

            // If new Modules only contains elements that are not in existing Modules, then the following code will execute.

            int a = 1;

            // Commenting out following code due to missing pieces.

            //var modules = ModuleValidator.Validate(body.properties.modules, db.MaxFlash != 0);

            //db.SetModules(modules);

        }

        else if (!AreSame(difference, newModules)) // This condition will check if collections differnce and newModules are not identical.

        {

            // this condition still seems wrong as it always seem to be true.

            throw new Exception("immutable property");

        }

    }

​

    //Method that checks whether the first collection contains the same members as second collection.

    public bool AreSame(IEnumerable<Module> first, IEnumerable<Module> second)

    {

        var areEqual = first.OrderBy(i => i.module_name).SequenceEqual(second.OrderBy(i => i.module_name));

        return areEqual;

    }

}