namespace PendingEmails
{
    using System;
    using System.Collections.Generic;
    using System.Data.SqlClient;
    using System.IO;
    using System.Linq;
    using System.Net.Mail;
    using System.Threading;
    using System.Timers;
    using SystemTimersTimer = System.Timers.Timer;

    class Program
    {
        static readonly SystemTimersTimer timer = new SystemTimersTimer();
        static string logfile = $@"C:\Temp\PendingEmails\emailversand_{DateTime.Now:yyyyMMdd}.txt";
        static string connectionString = "Server=SLASQL01.emea.sensus.net; Database=Auftrag; User ID=ServiceParingfile; Password=ServiceParingfile;";

        static void Main()
        {
            try
            {
                timer.AutoReset = true;
                timer.Interval = 300_000;
                timer.Elapsed += Timer_Elapsed;

                while (true)
                {
                    Timer_Elapsed(null, null);
                    timer.Start();
                    var awaiter = new ManualResetEventSlim();
                    awaiter.Wait();
                    timer.Stop();
                }
            }
            catch (Exception e)
            {
                Console.WriteLine($"{Environment.NewLine}{e}{Environment.NewLine}");
                File.AppendAllText(logfile, $"{Environment.NewLine}{e}{Environment.NewLine}");
            }
            
        }

        private static void Timer_Elapsed(object _, ElapsedEventArgs _1)
        {
            logfile = $@"C:\Temp\PendingEmails\emailversand_{DateTime.Now:yyyyMMdd}.txt";

            Console.WriteLine($"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] PREPEARING EMAILS TO SEND ...");
            File.AppendAllText(logfile, $"[{DateTime.Now:yyyy-MM-dd HH:mm:ss}] PREPEARING EMAILS TO SEND ... {Environment.NewLine}");

            using (var connection = new SqlConnection(connectionString))
            {
                connection.Open();

                var updated = new List<int>();

                using (var command = connection.CreateCommand())
                {
                    command.CommandText = @"
                        SELECT [Sender]
                             , [Subject]
                             , [Body]
                             , [Recipients]
                             , [CC]
                             , [Id]
                          FROM [Messages]
                         WHERE [StationNr] >= 2000 
                           AND [OutDate]   IS NULL
                         ORDER BY [InDate] DESC";

                    using (var reader = command.ExecuteReader())
                    {
                        while (reader.Read())
                        {
                            try
                            {
                                var email = new MailMessage();

                                email.From = new MailAddress("Stoyan.Zlatev@xylem.com");
                                email.Subject = $"{reader.GetValue(1)}";
                                email.Body = $"{reader.GetValue(2)}";

                                $"{reader.GetValue(3)}"
                                    .Split(new[] { ',', ' ' }, StringSplitOptions.RemoveEmptyEntries)
                                    .Select(x => new MailAddress(x))
                                    .ToList()
                                    .ForEach(email.To.Add);

                                $"{reader.GetValue(4)}"
                                    .Split(new[] { ',', ' ' }, StringSplitOptions.RemoveEmptyEntries)
                                    .Select(x => new MailAddress(x))
                                    .ToList()
                                    .ForEach(email.CC.Add);

                                email.CC.Add(new MailAddress("Stoyan.Zlatev@xylem.com"));

                                if (SendEmail(email))
                                {
                                    updated.Add(reader.GetInt32(5));
                                }
                            }
                            catch (Exception e)
                            {
                                File.AppendAllText(logfile, $"{Environment.NewLine}{e}{Environment.NewLine}");
                            }
                        }
                    }
                }

                if (updated.Count > 0)
                {
                    try
                    {
                        File.AppendAllText(logfile, $"UPDATEING: {string.Join(", ", updated)}{Environment.NewLine}");

                        using (var command = connection.CreateCommand())
                        {
                            command.CommandText = $@"
                                UPDATE [Messages] 
                                   SET [OutDate] = GETDATE() 
                                 WHERE [Id] IN ({string.Join(", ", updated)})";

                            command.ExecuteNonQuery();
                        }
                    }
                    catch (Exception e)
                    {
                        File.AppendAllText(logfile, $"{Environment.NewLine}{e}{Environment.NewLine}");
                    }
                }
                else
                {
                    File.AppendAllText(logfile, $"... NO PENDING EMAILS FOUND {Environment.NewLine}");
                }
            }
        }

        private static bool SendEmail(MailMessage email)
        {
            try
            {
                using (var smtpClient = new SmtpClient("smtp.xylem.com", 587))
                {
                    smtpClient.Timeout = 5000;
                    smtpClient.UseDefaultCredentials = true;
                    smtpClient.Send(email);
                }

                return true;
            }
            catch (Exception e)
            {
                File.AppendAllText(logfile, $"{Environment.NewLine}{e}{Environment.NewLine}");
            }

            return false;
        }
    }
}