using System.Buffers.Text;
using System.Security.Cryptography;
using IdentityShroud.Core.Messages;

namespace IdentityShroud.Core.Security.Keys.Rsa;

public class RsaProvider : IKeyProvider
{
    public bool IsPublic => true;

    public KeyData CreateKey(KeyPolicy policy)
    {
        if (policy is RsaKeyPolicy p)
        {
            using var rsa = RSA.Create(p.KeySize);
            var publicParamaters = rsa.ExportParameters(includePrivateParameters: false);
            return new KeyData(
                rsa.ExportPkcs8PrivateKey(),
                new()
                {
                    ["e"] = Base64Url.EncodeToString(publicParamaters.Exponent),
                    ["n"] = Base64Url.EncodeToString(publicParamaters.Modulus),
                });
        }

        throw new ArgumentException("Incorrect policy type", nameof(policy));
    }

    public void SetJwkParameters(Dictionary<string, string> parameters, JsonWebKey jwk)
    {
        jwk.Exponent = parameters["e"];
        jwk.Modulus = parameters["n"];
    }
}