// (c) Copyright Ascensio System SIA 2010-2022
//
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// of the GNU Affero General Public License (AGPL) version 3 as published by the Free Software
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// to the effect that Ascensio System SIA expressly excludes the warranty of non-infringement of
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// of MERCHANTABILITY or FITNESS FOR A PARTICULAR  PURPOSE. For details, see
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// 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

namespace ASC.Security.Cryptography;

[Scope]
public class EmailValidationKeyProvider
{
    public enum ValidationResult
    {
        Ok,
        Invalid,
        Expired
    }

    public TimeSpan ValidEmailKeyInterval { get; }
    public TimeSpan ValidAuthKeyInterval { get; }
    public TimeSpan ValidVisitLinkInterval { get; }

    private readonly ILogger<EmailValidationKeyProvider> _logger;
    private static readonly DateTime _from = new DateTime(2010, 01, 01, 0, 0, 0, DateTimeKind.Utc);
    private readonly MachinePseudoKeys _machinePseudoKeys;
    private readonly TenantManager _tenantManager;

    public EmailValidationKeyProvider(MachinePseudoKeys machinePseudoKeys, TenantManager tenantManager, IConfiguration configuration, ILogger<EmailValidationKeyProvider> logger)
    {
        _machinePseudoKeys = machinePseudoKeys;
        _tenantManager = tenantManager;
        if (!TimeSpan.TryParse(configuration["email:validinterval"], out var validInterval))
        {
            validInterval = TimeSpan.FromDays(7);
        }
        if (!TimeSpan.TryParse(configuration["auth:validinterval"], out var authValidInterval))
        {
            authValidInterval = TimeSpan.FromHours(1);
        }
        if (!TimeSpan.TryParse(configuration["visit:validinterval"], out var validVisitLinkInterval))
        {
            ValidVisitLinkInterval = TimeSpan.FromMinutes(15);
        }
       
        ValidEmailKeyInterval = validInterval;
        ValidAuthKeyInterval = authValidInterval;
        _logger = logger;
    }

    public string GetEmailKey(string email)
    {
        return GetEmailKey(_tenantManager.GetCurrentTenant().Id, email);
    }

    public string GetEmailKey(int tenantId, string email)
    {
        ArgumentNullOrEmptyException.ThrowIfNullOrEmpty(email);

        email = FormatEmail(tenantId, email);

        var ms = (long)(DateTime.UtcNow - _from).TotalMilliseconds;
        var hash = GetMashineHashedData(BitConverter.GetBytes(ms), Encoding.ASCII.GetBytes(email));

        return string.Format("{0}.{1}", ms, DoStringFromBytes(hash));
    }

    private string FormatEmail(int tenantId, string email)
    {
        ArgumentNullException.ThrowIfNull(email);

        try
        {
            return string.Format("{0}|{1}|{2}", email.ToLowerInvariant(), tenantId, Encoding.UTF8.GetString(_machinePseudoKeys.GetMachineConstant()));
        }
        catch (Exception e)
        {
            _logger.CriticalFormatEmail(e);

            return email.ToLowerInvariant();
        }
    }

    public ValidationResult ValidateEmailKey(string email, string key)
    {
        return ValidateEmailKey(email, key, TimeSpan.MaxValue);
    }

    public ValidationResult ValidateEmailKey(string email, string key, TimeSpan validInterval)
    {
        var result = ValidateEmailKeyInternal(email, key, validInterval);
        _logger.DebugValidationResult(result, email, key, validInterval, _tenantManager.GetCurrentTenant().Id);

        return result;
    }

    private ValidationResult ValidateEmailKeyInternal(string email, string key, TimeSpan validInterval)
    {
        ArgumentNullOrEmptyException.ThrowIfNullOrEmpty(email);
        ArgumentNullException.ThrowIfNull(key);

        email = FormatEmail(_tenantManager.GetCurrentTenant().Id, email);
        var parts = key.Split(new[] { '.' }, StringSplitOptions.RemoveEmptyEntries);
        if (parts.Length != 2)
        {
            return ValidationResult.Invalid;
        }

        if (!long.TryParse(parts[0], out var ms))
        {
            return ValidationResult.Invalid;
        }

        var hash = GetMashineHashedData(BitConverter.GetBytes(ms), Encoding.ASCII.GetBytes(email));
        var key2 = DoStringFromBytes(hash);
        var key2_good = string.Equals(parts[1], key2, StringComparison.OrdinalIgnoreCase);
        if (!key2_good)
        {
            return ValidationResult.Invalid;
        }

        var ms_current = (long)(DateTime.UtcNow - _from).TotalMilliseconds;

        return validInterval >= TimeSpan.FromMilliseconds(ms_current - ms) ? ValidationResult.Ok : ValidationResult.Expired;
    }

    internal static string DoStringFromBytes(byte[] data)
    {
        var str = Convert.ToBase64String(data);
        str = str.Replace("=", "").Replace("+", "").Replace("/", "").Replace("\\", "");

        return str.ToUpperInvariant();
    }

    internal static byte[] GetMashineHashedData(byte[] salt, byte[] data)
    {
        var alldata = new byte[salt.Length + data.Length];
        Array.Copy(data, alldata, data.Length);
        Array.Copy(salt, 0, alldata, data.Length, salt.Length);

        return Hasher.Hash(alldata, HashAlg.SHA256);
    }
}

public class EmailValidationKeyModel
{
    public string Key { get; set; }
    public EmployeeType? EmplType { get; set; }
    public string Email { get; set; }
    public Guid? UiD { get; set; }
    public ConfirmType? Type { get; set; }
    public int RoomAccess { get; set; }
    public string RoomId { get; set; }

    public void Deconstruct(out string key, out EmployeeType? emplType, out string email, out Guid? uiD, out ConfirmType? type, out int roomAccess, out string roomId)
    {
        (key, emplType, email, uiD, type, roomAccess, roomId) = (Key, EmplType, Email, UiD, Type, RoomAccess, RoomId);
    }
}