using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Threading;
using System.Diagnostics;
using System.Timers;
using System.Globalization;
using System.IO.Compression;
using System.Linq;

namespace SafeMobileLib
{
    public class LOGS
    {
        public static bool active = true;
        public static int expirationDays = 7;
        private const int maxLogHours = 4;
        private static int procID;
        private static InterthreadMessageQueue<string> msgQueue;
        private static InterthreadMessageQueue<string> msgQueue_Error;
        System.Timers.Timer aTimer;

        private static string path = "";

        public static Boolean WRITE_LOGS = false;
        public static String logFileName = "";


        public LOGS(string _path = "")
        {
            if (!WRITE_LOGS)
                return;

            logFileName = String.Format("{0:yyyyMMdd_HHmm}.{1}", DateTime.Now, "log");

            try
            {
                path = _path;
                Process currentProcess = Process.GetCurrentProcess();
                procID = currentProcess.Id;

                msgQueue = new InterthreadMessageQueue<string>();
                msgQueue_Error = new InterthreadMessageQueue<string>();
                aTimer = new System.Timers.Timer();
                aTimer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
                // Set the Interval to 10 seconds.
                aTimer.Interval = 5000;
                aTimer.Enabled = true;
            }
            catch (Exception ex)
            {
                Console.WriteLine("Could not StartLOG!!!");
            }
        }

        public static void LOG(string msg)
        {
            if (!WRITE_LOGS)
                return;



            //add to log file
            try
            {
                if (msgQueue != null && active)
                {
                    msg = String.Format("[### {0:H:mm:ss} ###] {1}", DateTime.Now, msg);
                    msgQueue.PostItem(msg);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("####LOG:  Could not print debug information ####\n" + ex.ToString());
            }
        }

        public static void LOG_Error(string msg)
        {
            if (!WRITE_LOGS)
                return;

            //add to log file
            try
            {
                if (msgQueue_Error != null && active)
                {
                    msg = String.Format("[### {0:H:mm:ss} ###] {1}", DateTime.Now, msg);
                    msgQueue_Error.PostItem(msg);
                    msgQueue.PostItem(msg);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("####LOG_Error:  Could not print debug information ####\n" + ex.ToString());
            }
        }

        private long numberOfRunningTasks = 0;
        private object lockProcess = new object();
        private void OnTimedEvent(object source, ElapsedEventArgs e)
        {
            if (!WRITE_LOGS)
                return;

            // check if other previous tick is still running and exit if required
            bool shouldExit = false;
            lock (lockProcess)
            {
                if (numberOfRunningTasks > 0)
                    shouldExit = true;
            }

            if (shouldExit)
                return;


            try
            {
                string dirPath = "";
                if (path == "")
                    dirPath = Environment.CurrentDirectory +
                           Path.DirectorySeparatorChar + "Logs";
                else
                    dirPath = path +
                        Path.DirectorySeparatorChar + "Logs";

                if (!Directory.Exists(dirPath))
                {
                    Directory.CreateDirectory(dirPath);
                }
              
                ProcessLogs(dirPath, logFileName, msgQueue);
                

                //maintenace
                Maintenace(dirPath, logFileName);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }

        }

        private void ProcessLogs(string dirPath, string name, InterthreadMessageQueue<string> msgQueue)
        {
            lock (lockProcess)
            {
                numberOfRunningTasks++;
            }

            string filePath = "";

            if (WRITE_LOGS)
            {
                filePath = dirPath + Path.DirectorySeparatorChar + name;

                if (!File.Exists(filePath))
                {
                    using (System.IO.FileStream fs = System.IO.File.Create(filePath))
                    {
                        Byte[] info = new UTF8Encoding(true).GetBytes(DateTime.UtcNow.ToString() + "\n");
                        // Add some information to the file.
                        fs.Write(info, 0, info.Length);
                    }
                    Console.WriteLine("Creating new file!!! path:" + filePath);
                }
            }
            try
            {
                if (msgQueue != null)
                {
                    using (StreamWriter file = new System.IO.StreamWriter(filePath, true))
                    {
                        string line = msgQueue.GetItem(100);
                        while (line != default(string))
                        {
                            if (WRITE_LOGS)
                                file.WriteLine(line);

                            line = msgQueue.GetItem(100);
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                lock (lockProcess)
                {
                    numberOfRunningTasks = 0;
                }
            }
        }

        private void Maintenace(string dirPath, string filename)
        {
            if (!WRITE_LOGS)
                return;

            string filePath = dirPath + Path.DirectorySeparatorChar + filename;
            DateTime dateCreated;
            DateTime.TryParseExact(filename.Substring(0, filename.Length - 4), "yyyyMMdd_HHmm", null,
                                   DateTimeStyles.None, out dateCreated);

            DateTime dtNow = DateTime.Now;
            TimeSpan ts_sub = dtNow.Subtract(dateCreated);

            if (ts_sub.TotalHours > maxLogHours)
            {
                logFileName = String.Format("{0:yyyyMMdd_HHmm}.{1}", DateTime.Now, "log");
                //process normal logs
                ProcessLogs(dirPath, logFileName, msgQueue);
                Thread.Sleep(1000);

                // compress old file
                using (ZipArchive zip = ZipFile.Open("Logs\\" + filename.Replace(".log", "") + ".zip", ZipArchiveMode.Create))
                {
                    ZipArchiveEntry zae = zip.CreateEntryFromFile(filePath, filename);

                    if (zae != null)
                        // delete the txt log file because it was archived
                        File.Delete(filePath);
                }

                // delete zip archives if older than xx days
                if (expirationDays > 0)
                    Directory.GetFiles(dirPath)
                        .Select(f => new FileInfo(f))
                        .Where(f => f.CreationTime < DateTime.Now.AddDays((-1) * expirationDays))
                        .ToList()
                        .ForEach(f => f.Delete());
            }
        }

        private void RemoveOlder(string dirPath, int days)
        {
            if (!WRITE_LOGS)
                return;

            string[] filePaths = Directory.GetFiles(dirPath);
            for (int i = 0; i < filePaths.Length; i++)
            {
                try
                {
                    if (!File.Exists(filePaths[i]))
                        continue;
                    if (filePaths[i].Contains("current") || filePaths[i].Contains("error"))
                        continue;

                    DateTime dateCreated;
                    DateTime.TryParseExact(filePaths[i].Substring(0, filePaths[i].Length - 4), "yyyyMMdd_HHmm", null,
                                           DateTimeStyles.None, out dateCreated);

                    DateTime dtNow = DateTime.Now;

                    TimeSpan ts_sub = dtNow.Subtract(dateCreated);
                    if (ts_sub.TotalDays > 7)
                    {
                        if (File.Exists(filePaths[i]))
                        {
                            File.Delete(filePaths[i]);
                        }
                    }
                }
                catch (Exception ex)
                {
                    Utils.WriteLine("Error in RemoveOlder :" + ex.ToString());
                }
            }
        }
    }
}