/*
 * Copyright (c) 2023 Proton AG
 *
 * This file is part of ProtonVPN.
 *
 * ProtonVPN is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * ProtonVPN is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with ProtonVPN.  If not, see <https://www.gnu.org/licenses/>.
 */

using System;
using System.Text;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Signers;
using Org.BouncyCastle.Security;
using ProtonVPN.Crypto.Contracts;

namespace ProtonVPN.Crypto;

public class Ed25519SignatureValidator : IEd25519SignatureValidator
{
    public bool IsValid(string data, string base64Signature, string base64PublicKey)
    {
        AsymmetricKeyParameter publicKey = PublicKeyFactory.CreateKey(Convert.FromBase64String(base64PublicKey));
        Ed25519Signer validator = GetSignatureValidator(publicKey, data);
        return validator.VerifySignature(Convert.FromBase64String(base64Signature));
    }

    private Ed25519Signer GetSignatureValidator(AsymmetricKeyParameter publicKey, string data)
    {
        Ed25519Signer validator = new();
        validator.Init(false, publicKey);
        validator.BlockUpdate(Encoding.ASCII.GetBytes(data), 0, data.Length);
        return validator;
    }
}