// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Runtime.Serialization;
using System.Text;
 
namespace Microsoft.AspNetCore.Authentication.WsFederation;
 
public class CustomStateDataFormat : ISecureDataFormat<AuthenticationProperties>
{
    public const string ValidStateData = "ValidStateData";
 
    private string lastSavedAuthenticationProperties;
    private readonly DataContractSerializer serializer = new DataContractSerializer(typeof(AuthenticationProperties));
 
    public string Protect(AuthenticationProperties data)
    {
        lastSavedAuthenticationProperties = Serialize(data);
        return ValidStateData;
    }
 
    public string Protect(AuthenticationProperties data, string purpose)
    {
        return Protect(data);
    }
 
    public AuthenticationProperties Unprotect(string state)
    {
        return state == ValidStateData ? DeSerialize(lastSavedAuthenticationProperties) : null;
    }
 
    public AuthenticationProperties Unprotect(string protectedText, string purpose)
    {
        return Unprotect(protectedText);
    }
 
    private string Serialize(AuthenticationProperties data)
    {
        using (MemoryStream memoryStream = new MemoryStream())
        {
            serializer.WriteObject(memoryStream, data);
            memoryStream.Position = 0;
            return new StreamReader(memoryStream).ReadToEnd();
        }
    }
 
    private AuthenticationProperties DeSerialize(string state)
    {
        var stateDataAsBytes = Encoding.UTF8.GetBytes(state);
 
        using (var ms = new MemoryStream(stateDataAsBytes, false))
        {
            return (AuthenticationProperties)serializer.ReadObject(ms);
        }
    }
}