/*
 *
 * (c) Copyright Ascensio System Limited 2010-2018
 *
 * This program is freeware. You can redistribute it and/or modify it under the terms of the GNU 
 * General Public License (GPL) version 3 as published by the Free Software Foundation (https://www.gnu.org/copyleft/gpl.html). 
 * In accordance with Section 7(a) of the GNU GPL 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 more details, see GNU GPL at https://www.gnu.org/copyleft/gpl.html
 *
 * You can contact Ascensio System SIA by email at sales@onlyoffice.com
 *
 * The interactive user interfaces in modified source and object code versions of ONLYOFFICE must display 
 * Appropriate Legal Notices, as required under Section 5 of the GNU GPL version 3.
 *
 * Pursuant to Section 7 § 3(b) of the GNU GPL you must retain the original ONLYOFFICE logo which contains 
 * relevant author attributions when distributing the software. If the display of the logo in its graphic 
 * form is not reasonably feasible for technical reasons, you must include the words "Powered by ONLYOFFICE" 
 * in every copy of the program you distribute. 
 * Pursuant to Section 7 § 3(e) we decline to grant you any rights under trademark law for use of our trademarks.
 *
*/


using System;
using System.Net.Sockets;
using System.Security;
using System.Threading;
using System.Threading.Tasks;
using ASC.Common.Logging;
using ASC.Common.Security.Authorizing;
using ASC.Common.Threading;
using ASC.Core;
using ASC.Web.Core.PublicResources;
using MailKit.Net.Smtp;
using MailKit.Security;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Options;
using MimeKit;
using SecurityContext = ASC.Core.SecurityContext;

namespace ASC.Api.Settings.Smtp
{
    public class SmtpOperation
    {
        public const string OWNER = "SMTPOwner";
        public const string SOURCE = "SMTPSource";
        public const string PROGRESS = "SMTPProgress";
        public const string RESULT = "SMTPResult";
        public const string ERROR = "SMTPError";
        public const string FINISHED = "SMTPFinished";

        protected DistributedTask TaskInfo { get; set; }

        protected CancellationToken CancellationToken { get; private set; }

        protected int Progress { get; private set; }

        protected string Source { get; private set; }

        protected string Status { get; set; }

        protected string Error { get; set; }

        protected int CurrentTenant { get; private set; }

        protected Guid CurrentUser { get; private set; }
        public UserManager UserManager { get; }
        public SecurityContext SecurityContext { get; }
        public TenantManager TenantManager { get; }
        public IConfiguration Configuration { get; }
        protected ILog Logger { get; private set; }

        public SmtpSettingsWrapper SmtpSettings { get; private set; }

        private readonly string messageSubject;

        private readonly string messageBody;


        public SmtpOperation(
            SmtpSettingsWrapper smtpSettings,
            int tenant,
            Guid user,
            UserManager userManager,
            SecurityContext securityContext,
            TenantManager tenantManager,
            IConfiguration configuration,
            IOptionsMonitor<ILog> options)
        {
            SmtpSettings = smtpSettings;
            CurrentTenant = tenant;
            CurrentUser = user;
            UserManager = userManager;
            SecurityContext = securityContext;
            TenantManager = tenantManager;
            Configuration = configuration;

            //todo
            //messageSubject = WebstudioNotifyPatternResource.subject_smtp_test;
            //messageBody = WebstudioNotifyPatternResource.pattern_smtp_test;

            Source = "";
            Progress = 0;
            Status = "";
            Error = "";
            Source = "";

            TaskInfo = new DistributedTask();

            Logger = options.CurrentValue;
        }

        public void RunJob(DistributedTask _, CancellationToken cancellationToken)
        {
            try
            {
                CancellationToken = cancellationToken;

                SetProgress(5, "Setup tenant");

                TenantManager.SetCurrentTenant(CurrentTenant);

                SetProgress(10, "Setup user");

                SecurityContext.AuthenticateMe(CurrentUser); //Core.Configuration.Constants.CoreSystem);

                SetProgress(15, "Find user data");

                var currentUser = UserManager.GetUsers(SecurityContext.CurrentAccount.ID);

                SetProgress(20, "Create mime message");

                var toAddress = new MailboxAddress(currentUser.UserName, currentUser.Email);

                var fromAddress = new MailboxAddress(SmtpSettings.SenderDisplayName, SmtpSettings.SenderAddress);

                var mimeMessage = new MimeMessage
                {
                    Subject = messageSubject
                };

                mimeMessage.From.Add(fromAddress);

                mimeMessage.To.Add(toAddress);

                var bodyBuilder = new BodyBuilder
                {
                    TextBody = messageBody
                };

                mimeMessage.Body = bodyBuilder.ToMessageBody();

                mimeMessage.Headers.Add("Auto-Submitted", "auto-generated");

                using var client = GetSmtpClient();
                SetProgress(40, "Connect to host");

                client.Connect(SmtpSettings.Host, SmtpSettings.Port.GetValueOrDefault(25),
                    SmtpSettings.EnableSSL ? SecureSocketOptions.Auto : SecureSocketOptions.None, cancellationToken);

                if (SmtpSettings.EnableAuth)
                {
                    SetProgress(60, "Authenticate");

                    client.Authenticate(SmtpSettings.CredentialsUserName,
                        SmtpSettings.CredentialsUserPassword, cancellationToken);
                }

                SetProgress(80, "Send test message");

                client.Send(FormatOptions.Default, mimeMessage, cancellationToken);

            }
            catch (AuthorizingException authError)
            {
                Error = Resource.ErrorAccessDenied; // "No permissions to perform this action";
                Logger.Error(Error, new SecurityException(Error, authError));
            }
            catch (AggregateException ae)
            {
                ae.Flatten().Handle(e => e is TaskCanceledException || e is OperationCanceledException);
            }
            catch (SocketException ex)
            {
                Error = ex.Message; //TODO: Add translates of ordinary cases
                Logger.Error(ex.ToString());
            }
            catch (AuthenticationException ex)
            {
                Error = ex.Message; //TODO: Add translates of ordinary cases
                Logger.Error(ex.ToString());
            }
            catch (Exception ex)
            {
                Error = ex.Message; //TODO: Add translates of ordinary cases
                Logger.Error(ex.ToString());
            }
            finally
            {
                try
                {
                    TaskInfo.SetProperty(FINISHED, true);
                    PublishTaskInfo();

                    SecurityContext.Logout();
                }
                catch (Exception ex)
                {
                    Logger.ErrorFormat("LdapOperation finalization problem. {0}", ex);
                }
            }
        }

        public SmtpClient GetSmtpClient()
        {
            var sslCertificatePermit = Configuration["mail.certificate-permit"] != null &&
                    Convert.ToBoolean(Configuration["mail.certificate-permit"]);

            return new SmtpClient
            {
                ServerCertificateValidationCallback = (sender, certificate, chain, errors) =>
                    sslCertificatePermit ||
                    MailKit.MailService.DefaultServerCertificateValidationCallback(sender, certificate, chain, errors),
                Timeout = (int)TimeSpan.FromSeconds(30).TotalMilliseconds
            };
        }

        public virtual DistributedTask GetDistributedTask()
        {
            FillDistributedTask();
            return TaskInfo;
        }

        protected virtual void FillDistributedTask()
        {
            TaskInfo.SetProperty(SOURCE, Source);
            TaskInfo.SetProperty(OWNER, CurrentTenant);
            TaskInfo.SetProperty(PROGRESS, Progress < 100 ? Progress : 100);
            TaskInfo.SetProperty(RESULT, Status);
            TaskInfo.SetProperty(ERROR, Error);
            //TaskInfo.SetProperty(PROCESSED, successProcessed);
        }

        protected int GetProgress()
        {
            return Progress;
        }

        const string PROGRESS_STRING = "Progress: {0}% {1} {2}";

        public void SetProgress(int? currentPercent = null, string currentStatus = null, string currentSource = null)
        {
            if (!currentPercent.HasValue && currentStatus == null && currentSource == null)
                return;

            if (currentPercent.HasValue)
                Progress = currentPercent.Value;

            if (currentStatus != null)
                Status = currentStatus;

            if (currentSource != null)
                Source = currentSource;

            Logger.InfoFormat(PROGRESS_STRING, Progress, Status, Source);

            PublishTaskInfo();
        }

        protected void PublishTaskInfo()
        {
            FillDistributedTask();
            TaskInfo.PublishChanges();
        }
    }
}