using DTS.Common.Events;
using DTS.Common.SharedResource.Strings;
using DTS.Common.Utilities.Logging;
using Prism.Events;
using Prism.Events;
using Prism.Ioc;
using System;
using System.Collections.Generic;
using System.Drawing.Text;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Interop;

namespace DTS.Common.Classes.Locking
{
    public class SensorsLocking
    {
        private LockRecord[] _existingLocks = null;
        private static readonly object MyLock = new object();

        private CancellationTokenSource _cancellationTokenSource = null;
        private readonly Task _updateTask = null;
        private const int MAX_WAIT_TIME_MS = 10000;
        /// <summary>
        /// returns false if stop was not needed or failed
        /// returns true if stop was completed
        /// </summary>
        /// <returns></returns>
        private bool StopUpdating()
        {
            if (null == _cancellationTokenSource || null == _existingLocks) { return false; }
            lock (MyLock)
            {
                _cancellationTokenSource.Cancel();
                if (!_updateTask.Wait(MAX_WAIT_TIME_MS))
                {
                    APILogger.Log("Failed to stop updating locks");
                    return false;
                }
            }
            return true;
        }
        public void Unlock(bool bCheckLock, string userName, int userId)
        {
            if (!StopUpdating()) { return; }

            lock (MyLock)
            {
                if (null == _existingLocks || 0 == _existingLocks.Length) { return; }
            }
            try
            {
                FreeLocks();                
            }
            catch (Exception ex) { APILogger.Log(ex); }
        }
        private void FreeLocks()
        {
            LockRecord[] locks;
            lock (MyLock)
            {
                if (null == _existingLocks || 0 == _existingLocks.Length) { return; }
                locks = _existingLocks.ToArray();
            }
            foreach( var record in locks)
            {
                try
                {
                    LockManager.FreeLoc
                }
                catch(Exception ex) { APILogger.Log(ex); }
            }
        }
        private bool CheckLock(bool publishErrors, string userName, int userId, LockRecord lockRecord, out LockError lockError)
        {
            throw new NotImplementedException();
        }
        /// <summary>
        /// performs an immediate update of locks, publishes an error if the lock could not be updated
        /// </summary>
        /// <param name="publishErrors">whether to publish when there's an error or not</param>
        /// <returns></returns>
        private bool CheckLocks(bool publishErrors, string userName, int userId)
        {
            try
            {
                LockRecord[] records;
                lock (MyLock)
                {
                    //FB 18006 Prevent null reference exception 
                    if (_existingLocks == null || 0 == _existingLocks.Length)
                    {
                        APILogger.Log("_existingLock is null");
                        return false;
                    }
                    //create a local copy of the locks so we can update them without the lock
                    records = _existingLocks.ToArray();
                }
                var failed = new List<LockRecord>();
                var errors = new List<LockError>();
                foreach (var record in records)
                {
                    LockError lockError;
                    if (!CheckLock(publishErrors, userName, userId, record, out lockError))
                    {
                        failed.Add(record);
                        errors.Add(lockError);
                    }
                }
                if (failed.Any() && errors.Any())
                {
                    if (publishErrors)
                    {                        
                        var msg = GetErrorMessage(errors.ToArray(), records.ToArray());
                        var eventAggregator = ContainerLocator.Container.Resolve<IEventAggregator>();
                        eventAggregator.GetEvent<PageErrorEvent>().Publish(new PageErrorArg(new[] { msg }, null));                        
                    }
                    //if we failed to update ANY of them we need to wipe out our selection
                    lock (MyLock)
                    {
                        _existingLocks = new LockRecord[0];
                    }
                    WipeOutChanges();
                    return false;
                }
                return true;
            }
            catch (Exception ex)
            {
                APILogger.Log(ex);
                if (publishErrors)
                {
                    var eventAggregator = ContainerLocator.Container.Resolve<IEventAggregator>();
                    eventAggregator.GetEvent<PageErrorEvent>().Publish(new PageErrorArg(
                        new[] { $"{StringResources.FailedToUpdateLock}, {ex.Message}" }, null));
                }
                _cancellationTokenSource?.Cancel();
                lock (MyLock)
                {
                    _existingLocks = new LockRecord[0];
                }
                return false;
            }
        }
        private void WipeOutChanges()
        {
            throw new NotImplementedException();
        }
        private static string GetErrorMessage(LockError[] errors, LockRecord[] lockRecords )
        {
            StringBuilder sb = new StringBuilder(0);            

            for( var i = 0; i < errors.Length && i < lockRecords.Length; i ++)
            {
                var error = errors[i];
                var record = lockRecords[i];
                if (error.LockStolen)
                {
                    sb.AppendLine(string.Format(StringResources.LockStolen_Sensors, record.ItemKey, error.LockingUser, error.LockingMachine));
                }
                else if(error.LockLost)
                {
                    sb.AppendLine(string.Format(StringResources.LockLost_Sensors, record.ItemKey));
                }
                else
                {
                    sb.AppendLine($"{StringResources.FailedToUpdateLock} - {record.ItemKey}");
                }
            }
            return sb.ToString();
        }
        /// <summary>
        /// returns true if the lockrecord matches the sensor currently locked in this control
        /// 14340 sensor lost/locked - unlocked on sensor import
        /// </summary>
        /// <param name="lockRecord"></param>
        /// <returns></returns>
        public bool IsCurrentlyLocked(LockRecord lockRecord)
        {
            lock (MyLock)
            {
                if (null == _existingLocks) { return false; }

                return Array.Exists(_existingLocks, x => x.ItemId == lockRecord.ItemId && x.ItemCategory == lockRecord.ItemCategory);
            }
        }
    }
}