using System;

using System.Reflection;

using System.Collections.Generic;

using Newtonsoft.Json;

​

[AttributeUsage(AttributeTargets.Property)]

public abstract class DataMaskAttribute : Attribute

{

    public string VaultIdentifier { get; private set; }

​

    public DataMaskAttribute(string vaultIdentifier)

    {

        VaultIdentifier = vaultIdentifier ?? throw new ArgumentNullException($"Must pass {nameof(vaultIdentifier)} to {nameof(DataMaskAttribute)}");

    }

}

​

public interface IStringMask

{

    public string Mask(string src);

}

​

public abstract class StringMaskBase : DataMaskAttribute, IStringMask

{

    protected StringMaskBase(string vaultIdentifier) : base(vaultIdentifier)

    {

    }

​

    public abstract string Mask(string src);

}

​

public class StaticStringMask : StringMaskBase

{

    public static readonly string DefaultValue = "<redacted>";

​

    private readonly string _value;

​

    public StaticStringMask(string vaultIdentifier) : base(vaultIdentifier)

    {

        _value = DefaultValue;

    }

​

    public StaticStringMask(string vaultIdentifier, string value) : base(vaultIdentifier)

    {

        _value = value ?? DefaultValue;

    }

​

    public override string Mask(string src)

    {

        return _value;

    }

}

​

public class Person

{

    [StaticStringMask("ssn")]

    public string SSN { get; set; }

    [StaticStringMask("name", "***")]

    public string Name { get; set; }

}

​

public class Program

{

    public static void Main()

    {

        var p = new Person

        {

            Name = "bob"

        };

        var props = p.GetType().GetProperties();

        foreach (PropertyInfo propInfo in props)

        {

            if (propInfo.CanRead)

            {

                dynamic masker = propInfo.GetCustomAttribute<DataMaskAttribute>();

                dynamic unmaskedValue = propInfo.GetValue(p);

                dynamic maskedValue = masker.Mask(unmaskedValue);

                Console.WriteLine($"mask class: {masker.GetType()}");

                Console.WriteLine($"unmasked value: {unmaskedValue}");

                Console.WriteLine($"masked value: {maskedValue}");

                Console.WriteLine();

            }

         }

    }

}