/*************************************************************************
 * ModernUO                                                              *
 * Copyright 2019-2020 - ModernUO Development Team                       *
 * Email: hi@modernuo.com                                                *
 * File: AccountSecurity.cs                                              *
 *                                                                       *
 * This program 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.                                   *
 *                                                                       *
 * You should have received a copy of the GNU General Public License     *
 * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 *************************************************************************/

using System;

namespace Server.Accounting.Security
{
    public enum PasswordProtectionAlgorithm
    {
        // Obsolete algorithms from RunUO. These are not secure!
        // They are included for password upgrades only.
        None,
        MD5,
        SHA1,

        // Supported algorithms
        SHA2, // ServUO compatibility
        PBKDF2,
        Argon2 // Recommended algorithm for real security.
    }

    public static class AccountSecurity
    {
        public static PasswordProtectionAlgorithm CurrentAlgorithm { get; set; }

        public static IPasswordProtection CurrentPasswordProtection => GetPasswordProtection(CurrentAlgorithm);

        public static void Configure()
        {
            CurrentAlgorithm =
                ServerConfiguration.GetOrUpdateSetting(
                    "accountSecurity.encryptionAlgorithm",
                    PasswordProtectionAlgorithm.Argon2
                );

            if (CurrentAlgorithm < PasswordProtectionAlgorithm.SHA2)
            {
                throw new Exception($"Security: {CurrentAlgorithm} is obsolete and not secure. Do not use it.");
            }
        }

        public static IPasswordProtection GetPasswordProtection(PasswordProtectionAlgorithm algorithm)
        {
            var passwordProtection = algorithm switch
            {
                PasswordProtectionAlgorithm.MD5    => MD5PasswordProtection.Instance,
                PasswordProtectionAlgorithm.SHA1   => SHA1PasswordProtection.Instance,
                PasswordProtectionAlgorithm.SHA2   => SHA2PasswordProtection.Instance,
                PasswordProtectionAlgorithm.PBKDF2 => PBKDF2PasswordProtection.Instance,
                PasswordProtectionAlgorithm.Argon2 => Argon2PasswordProtection.Instance,
                PasswordProtectionAlgorithm.None   => throw new Exception("Do not use PasswordProtectionAlgorithm.None"),
                _                                  => throw new Exception("No algorithm")
            };

            return passwordProtection;
        }
    }
}