using gehGassiApp.Core.Interfaces;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using gehGassiApp.Domain.Dogs;
using gehGassiApp.Core.Data;
using gehGassiApp.Core.Interfaces.Synchronization;

namespace gehGassiApp.Core.Services
{
    /// <summary>
    /// Service der die Verwaltung von Hunderassen realisiert
    /// </summary>
    public class DogRaceService : ServiceBase<DogRace>, IDogRaceService
    {
        private readonly ICommunicationService _communicationService;
        private readonly ISyncInfoPullService _syncInfoPullService;

        /// <summary>
        /// Erstellt eine Instanz
        /// </summary>
        /// <param name="unitOfWork">Instanz eines IUnitOfWork</param>
        /// <param name="communicationService">Instanz eines ICommunicationService</param>
        /// <param name="syncInfoPullService">Instanz eines ISyncInfoPullService</param>
        public DogRaceService(IUnitOfWork unitOfWork, ICommunicationService communicationService, ISyncInfoPullService syncInfoPullService) : base(unitOfWork)
        {
            _communicationService = communicationService;
            _syncInfoPullService = syncInfoPullService;
        }

        /// <summary>
        /// Gibt eine Entität anhand der eindeutigen Id zurück
        /// </summary>
        /// <param name="id">Id der Entität</param>
        /// <param name="noTracking">Gibt an ob NoTRacking verwendet werden soll. Es werden keine Entitäten im EF-Speicher gehalten</param>
        /// <returns>Entität oder null, wenn nicht gefunden</returns>
        public override DogRace Get(object id, bool noTracking = true)
        {
            return Repository.SingleOrDefault(c => c.Id == id.ToString(), noTracking);
        }

        /// <summary>
        /// Gibt eine Entität anhand der eindeutigen Id zurück
        /// </summary>
        /// <param name="id">Id der Entität</param>
        /// <param name="noTracking">Gibt an ob NoTRacking verwendet werden soll. Es werden keine Entitäten im EF-Speicher gehalten</param>
        /// <returns>Entität oder null, wenn nicht gefunden</returns>
        public override async Task<DogRace> GetAsync(object id, bool noTracking = true)
        {
            return await Repository.SingleOrDefaultAsync(c => c.Id == id.ToString(), noTracking).ConfigureAwait(false);
        }

        /// <summary>
        /// Gibt eine Liste der Hunderassen zurück.
        /// Entweder von der DB oder vom Server
        /// </summary>
        /// <param name="accessToken">Aktuelles Accesstoken</param>
        /// <param name="language">Gewünschte Sprache</param>
        /// <param name="token">CancellationToken</param>
        /// <returns>Liste der Hunderassen</returns>
        public async Task<List<DogRace>> GetRacesAsync(string language, string accessToken, CancellationToken token)
        {
            //Zuerst DB
            var localRaces = await Repository.FindAsync(c => c.Deleted == false, noTracking: true).ConfigureAwait(false);
            if (localRaces != null && localRaces.Any())
                return localRaces.Where(c => c.Deleted == false).OrderBy(c => c.Name).ToList();
            else
            {
                //Dann wenn lokal nicht verfügbar immer online...
                var isConnected = await _communicationService.IsConnected();
                //isConnected = false;
                if (isConnected)
                {
                    var racesResult = await _communicationService.GetDogRacesAsync(null, language, accessToken, token);
                    if (racesResult.Success)
                    {
                        var result = await HandleChangesAsync(racesResult.Value);
                        if (result.LastUpdate != null)
                            await _syncInfoPullService.AddOrUpddateAsync(nameof(DogRace), result.LastUpdate.Value).ConfigureAwait(false);
                        return racesResult.Value.Where(c => c.Deleted == false).OrderBy(c => c.Name).ToList();
                    }
                }
            }
            //Keine Daten online, keine offline
            return new List<DogRace>();
        }

        /// <summary>
        /// Gibt eine Hunderasse zurück.
        /// Entweder von der DB oder vom Server
        /// </summary>
        /// <param name="id">Id der Hunderasse</param>
        /// <param name="language">Gewünschte Sprache</param>
        /// <param name="accessToken">Aktuelles Accesstoken</param>
        /// <param name="token">CancellationToken</param>
        /// <returns>Hunderasse oder null, wenn nicht gefunden</returns>
        public async Task<DogRace> GetRaceAsync(string id, string language, string accessToken, CancellationToken token)
        {
            var localRace = await Repository.FirstOrDefaultAsync(c => c.Deleted == false && c.Id == id, noTracking: true).ConfigureAwait(false);
            if (localRace == null)
            {
                //Dann wenn lokal nicht verfügbar immer online...
                var isConnected = await _communicationService.IsConnected();
                //isConnected = false;
                if (isConnected)
                {
                    var racesResult = await _communicationService.GetDogRaceAsync(id, language, accessToken, token);
                    if (racesResult.Success)
                    {
                        return racesResult.Value;
                    }
                }
            }

            return localRace;
        }

        #region Pull-Push Implementation

        /// <summary>
        /// Holen der Daten vom lokalen Speicher die noch nicht synchronisiert wurden und senden an den Server
        /// </summary>
        /// <param name="accessToken">Aktuelles Accesstoken</param>
        /// <param name="token">CancellationToken</param>
        /// <returns>Task</returns>
        public async Task<SyncResult<DogRace>> PushAsync(string accessToken, CancellationToken token)
        {
            var result = new SyncResult<DogRace>();

            //Es gibt hier kein Push!
            await Task.Delay(1);

            return result;
        }

        /// <summary>
        /// Holen der letzten Daten vom Server und Synchronisieren mit den lokalen Daten
        /// </summary>
        /// <param name="language">Sprache</param>
        /// <param name="accessToken">Aktuelles Accesstoken</param>
        /// <param name="token">CancellationToken</param>
        /// <returns>Task</returns>
        public async Task<SyncResult<DogRace>> PullAsync(string language, string accessToken, CancellationToken token)
        {
            var result = new SyncResult<DogRace>();

            var isConnected = await _communicationService.IsConnected();

            if (isConnected)
            {
                //Zuerst lezte Aktivität holen...
                DateTimeOffset? lastUpdate = null;
                var lastSyncInfo = await _syncInfoPullService.GetAsync(nameof(DogRace));
                if (lastSyncInfo != null)
                    lastUpdate = lastSyncInfo.LastUpdate;

                var ctsQuery = new CancellationTokenSource(Common.Constants.PushPullTimeout);
                var racesResult = await _communicationService.GetDogRacesAsync(lastUpdate, language, accessToken, token);
                if (racesResult.Success)
                {
                    result = await HandleChangesAsync(racesResult.Value);
                    if (result.LastUpdate != null)
                        await _syncInfoPullService.AddOrUpddateAsync(nameof(DogRace), result.LastUpdate.Value).ConfigureAwait(false);
                }

                result.LastUpdate ??= lastUpdate;
            }

            return result;
        }

        #endregion

        #region Private

        /// <summary>
        /// Behandeln der Liste von Hunderassen wenn welche vom Online-Store geholt werden.
        /// </summary>
        /// <param name="races">Liste der Hunderassen</param>
        /// <returns>Task</returns>
        private async Task<SyncResult<DogRace>> HandleChangesAsync(List<DogRace> races)
        {
            var result = new SyncResult<DogRace>();

            //Je Rasse durchgehen ob was gemacht werden soll
            foreach (var race in races)
            {
                var localRace = await Repository.FirstOrDefaultAsync(c => c.Id == race.Id, false);
                if (localRace != null && localRace.UpdatedAt < race.UpdatedAt)
                {
                    if (localRace.UpdatedAt >= race.UpdatedAt)
                    {
                        if (result.LastUpdate == null || result.LastUpdate < localRace.UpdatedAt)
                            result.LastUpdate = localRace.UpdatedAt;
                        continue;
                    }

                    var deleted = localRace.Deleted == false && race.Deleted;

                    localRace.Version = race.Version;
                    localRace.UpdatedAt = race.UpdatedAt;
                    localRace.Deleted = race.Deleted;
                    localRace.Name = race.Name;
                    localRace.Description = race.Description;
                    localRace.Age = race.Age;
                    localRace.SizeAndWeight = race.SizeAndWeight;
                    localRace.Personality = race.Personality;
                    localRace.Coexistence = race.Coexistence;
                    localRace.Care = race.Care;
                    localRace.Decision = race.Decision;
                    localRace.Photo = race.Photo;
                    localRace.Created = race.Created;

                    if (result.LastUpdate == null || result.LastUpdate < localRace.UpdatedAt)
                        result.LastUpdate = localRace.UpdatedAt;
                    if (!deleted)
                        result.Updated.Add(localRace);
                    else
                        result.Deleted.Add(localRace);
                    Repository.Update(localRace);
                }

                if (localRace == null)
                {
                    localRace = new DogRace()
                    {
                        Id = race.Id,
                        Version = race.Version,
                        UpdatedAt = race.UpdatedAt,
                        Deleted = race.Deleted,
                        Name = race.Name,
                        Description = race.Description,
                        Age = race.Age,
                        SizeAndWeight = race.SizeAndWeight,
                        Personality = race.Personality,
                        Coexistence = race.Coexistence,
                        Care = race.Care,
                        Decision = race.Decision,
                        Photo = race.Photo,
                        Created = race.Created
                    };

                    Repository.Add(localRace);

                    if (result.LastUpdate == null || result.LastUpdate < localRace.UpdatedAt)
                        result.LastUpdate = localRace.UpdatedAt;
                    result.Added.Add(localRace);
                }
            }

            if (result.HasChanges)
            {
                try
                {
                    await CommitAsync().ConfigureAwait(false);
                }
                catch (Exception ex)
                {
                    var err = ex.Message;
                }
            }

            return result;
        }

        #endregion
    }
}