// (c) Copyright Ascensio System SIA 2010-2022
//
// This program is a free software product.
// You can redistribute it and/or modify it under the terms
// of the GNU Affero General Public License (AGPL) version 3 as published by the Free Software
// Foundation. In accordance with Section 7(a) of the GNU AGPL its Section 15 shall be amended
// to the effect that Ascensio System SIA expressly excludes the warranty of non-infringement of
// any third-party rights.
//
// This program is distributed WITHOUT ANY WARRANTY, without even the implied warranty
// of MERCHANTABILITY or FITNESS FOR A PARTICULAR  PURPOSE. For details, see
// the GNU AGPL at: http://www.gnu.org/licenses/agpl-3.0.html
//
// You can contact Ascensio System SIA at Lubanas st. 125a-25, Riga, Latvia, EU, LV-1021.
//
// The  interactive user interfaces in modified source and object code versions of the Program must
// display Appropriate Legal Notices, as required under Section 5 of the GNU AGPL version 3.
//
// Pursuant to Section 7(b) of the License you must retain the original Product logo when
// distributing the program. Pursuant to Section 7(e) we decline to grant you any rights under
// trademark law for use of our trademarks.
//
// All the Product's GUI elements, including illustrations and icon sets, as well as technical writing
// content are licensed under the terms of the Creative Commons Attribution-ShareAlike 4.0
// International. See the License terms at http://creativecommons.org/licenses/by-sa/4.0/legalcode

using System.Text;
using System.Text.RegularExpressions;

using SecurityContext = ASC.Core.SecurityContext;

namespace ASC.Api.Core.Auth;

[Scope]
public class BasicAuthHandler : AuthenticationHandler<AuthenticationSchemeOptions>
{
    private readonly UserManager _userManager;
    private readonly SecurityContext _securityContext;
    private readonly PasswordHasher _passwordHasher;

    public BasicAuthHandler(
        IOptionsMonitor<AuthenticationSchemeOptions> options,
        ILoggerFactory logger,
        UrlEncoder encoder,
        ISystemClock clock
        ) : base(options, logger, encoder, clock)
    {

    }

    public BasicAuthHandler(
      IOptionsMonitor<AuthenticationSchemeOptions> options,
      ILoggerFactory logger, 
      UrlEncoder encoder, 
      ISystemClock clock,
      UserManager userManager,
      SecurityContext securityContext,
      PasswordHasher passwordHasher) : this(options, logger, encoder, clock)
    {
        _userManager = userManager;
        _securityContext = securityContext;
        _passwordHasher = passwordHasher;
    }

    protected override Task<AuthenticateResult> HandleAuthenticateAsync()
    {
        Response.Headers.Add("WWW-Authenticate", "Basic");

        if (!Request.Headers.ContainsKey("Authorization"))
        {
            return Task.FromResult(AuthenticateResult.Fail("Authorization header missing."));
        }

        // Get authorization key
        var authorizationHeader = Request.Headers["Authorization"].ToString();
        var authHeaderRegex = new Regex(@"Basic (.*)");

        if (!authHeaderRegex.IsMatch(authorizationHeader))
        {
            return Task.FromResult(AuthenticateResult.Fail("Authorization code not formatted properly."));
        }

        var authBase64 = Encoding.UTF8.GetString(Convert.FromBase64String(authHeaderRegex.Replace(authorizationHeader, "$1")));
        var authSplit = authBase64.Split(Convert.ToChar(":"), 2);
        var authUsername = authSplit[0];
        var authPassword = authSplit.Length > 1 ? authSplit[1] : throw new Exception("Unable to get password");

        try
        {
            var userInfo = _userManager.GetUserByEmail(authUsername);
            var passwordHash = _passwordHasher.GetClientPassword(authPassword);

            _securityContext.AuthenticateMe(userInfo.Email, passwordHash);

        }
        catch (Exception)
        {
            return Task.FromResult(AuthenticateResult.Fail("The username or password is not correct."));
        }

        return Task.FromResult(AuthenticateResult.Success(new AuthenticationTicket(Context.User, Scheme.Name)));
    }
}