// Copyright (c) 2017 schick Informatik


using System;
using System.Collections.Generic;
using log4net;
using bsmd.database;
using System.ServiceModel.Activation;
using System.ServiceProcess;
using System.Timers;
using System.IO;

namespace bsmd.LockingService
{

    [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
    public class LockingService : IService
    {
        private static readonly ILog _log = LogManager.GetLogger(typeof(LockingService));
        private static readonly Dictionary<Guid, LockEntry> lockDict = new Dictionary<Guid, LockEntry>();
        private static readonly Timer staleTimer = new Timer(5000); // alle 5 Sekunden prüfen
        private const int staleTimeoutSeconds = 120; // wenn sie eine Anwendung 2 Minuten nicht meldet, werden die Locks freigegeben

        static LockingService()
        {
            staleTimer.Elapsed += StaleTimer_Elapsed;
        }

        private static void StaleTimer_Elapsed(object sender, ElapsedEventArgs e)
        {
            lock (lockDict)
            {
                List<Guid> deleteList = new List<Guid>();
                foreach (Guid key in lockDict.Keys)
                    if ((DateTime.Now - lockDict[key].lockAquired).TotalSeconds > staleTimeoutSeconds)
                        deleteList.Add(key);
                foreach (Guid key in deleteList)
                {
                    _log.WarnFormat("Stale remove message core id {0}, User {1}", key, lockDict[key].userId);
                    lockDict.Remove(key);
                }
            }
        }

        private readonly ILog log = LogManager.GetLogger(typeof(LockingService));

        #region Implementation IService

        public Guid Lock(Guid messageCoreId, Guid userId)
        {
            Guid result = Guid.Empty;

            lock (lockDict)
            {
                if (!lockDict.ContainsKey(messageCoreId))
                {
                    LockEntry le = new LockEntry();
                    le.lockAquired = DateTime.Now;
                    le.userId = userId;
                    lockDict.Add(messageCoreId, le);                   
                }
                else
                {
                    if (lockDict[messageCoreId].userId == userId)
                    {
                        // this means "refresh"
                        lockDict[messageCoreId].lockAquired = DateTime.Now;                        
                    }
                    else
                    {
                        // lock taken by somebody else..
                        result = lockDict[messageCoreId].userId;
                    }
                }
            }

            return result;
        }


        public void Unlock(Guid messageCoreId, Guid userId)
        {
            lock(lockDict)
            {
                if(lockDict.ContainsKey(messageCoreId))
                {
                    if (lockDict[messageCoreId].userId == userId)
                        lockDict.Remove(messageCoreId);
                }
            }
        }

        public void LockRefresh(List<Guid> currentLocks, Guid userId)
        {
            foreach (Guid messageCoreId in currentLocks)
                this.Lock(messageCoreId, userId);
        }


        public void Log(string msg, string host, Guid userId)
        {
            log.Info(string.Format("{0} {1}:{2}", host, userId, msg));
        }

        public List<CoreLock> GetLocks()
        {
            List<CoreLock> result = new List<CoreLock>();
            lock (lockDict)
            {
                foreach (Guid messageCoreId in lockDict.Keys)
                {
                    CoreLock coreLock = new CoreLock();
                    coreLock.CoreId = messageCoreId;
                    coreLock.UserId = lockDict[messageCoreId].userId;
                    result.Add(coreLock);
                }
            }
            return result;
        }

        public ServerStatus GetStatus()
        {
            ServerStatus serverStatus = new ServerStatus();

            // Test if processes are running
            ServiceController[] services = ServiceController.GetServices();

            foreach (ServiceController serviceController in services)
            {
                switch (serviceController.ServiceName)
                {
                    case "NSW Report Generator":
                        serverStatus.Report = (int)serviceController.Status;
                        break;
                    case "NSWSendService":
                        serverStatus.Transmitter = (int)serviceController.Status;
                        break;
                    case "ExcelReadService":
                        serverStatus.Excel = (int)serviceController.Status;
                        break;

                    default:
                        break;
                }
            }

            // collect file Names
            // TODO: evtl. könnte es Sinn ergeben, wenn man diese Daten z.B. nur alle 10 Sekunden erzeugt und
            // dann allen Aufrufern liefert.

            serverStatus.IMPFiles = new List<string>();
            string impPath = Path.Combine(Properties.Settings.Default.TransmitterRoot, "IMP");
            if(Directory.Exists(impPath))
            {
                foreach(string file in Directory.GetFiles(impPath))
                    serverStatus.IMPFiles.Add(Path.GetFileNameWithoutExtension(file));
            }

            serverStatus.READYFiles = new List<string>();
            string readyPath = Path.Combine(Properties.Settings.Default.TransmitterRoot, "READY");
            if (Directory.Exists(readyPath))
            {
                foreach (string file in Directory.GetFiles(readyPath))
                    serverStatus.READYFiles.Add(Path.GetFileNameWithoutExtension(file));
            }

            serverStatus.CORRUPTFiles = new List<string>();
            string corruptPath = Path.Combine(Properties.Settings.Default.TransmitterRoot, "CORRUPT");
            if (Directory.Exists(corruptPath))
            {
                foreach (string file in Directory.GetFiles(corruptPath))
                    serverStatus.CORRUPTFiles.Add(Path.GetFileNameWithoutExtension(file));
            }

            return serverStatus;
        }

        public bool RestoreFromFile(string filename)
        {
            bool result = false;
            string readyPath = Path.Combine(Properties.Settings.Default.TransmitterRoot, "READY");
            string filePath = string.Format("{0}\\{1}.xml", readyPath, filename);
            if(File.Exists(filePath))
            {
                _log.InfoFormat("Restoring declaraction class from {0}", filePath);

                // TBD

                result = true;
            }
            else
            {
                _log.ErrorFormat("Restore file {0} does not exist", filePath);
            }

            return result;
        }


        #endregion

        #region class LockEntry

        internal class LockEntry
        {
            public DateTime lockAquired = DateTime.Now;
            public Guid userId;
        }

        #endregion

    }
}