using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.BL;
using Tango.BL.Entities;
using Tango.FSE.BL.CacheEntities;
using Tango.FSE.Web.Messages;

namespace Tango.FSE.BL.Services
{
    public class MachineEventsService : FSEServiceBase
    {
        private const string EVENT_TYPES_COLLECTION = "EventTypes";
        private MemoryCacheDictionary<String, CachedEventType> _eventTypesCache;

        public MachineEventsService()
        {
            _eventTypesCache = MemoryCache.GetOrCreateCache<String, CachedEventType>(EVENT_TYPES_COLLECTION);
        }

        public Task<List<EventType>> GetAllEventTypes()
        {
            return DataResolver<List<EventType>>.Builder.New()
                .ConfigureCascade(DataResolverNode.InMemoryCache, DataResolverNode.Web, DataResolverNode.Online, DataResolverNode.DiskCache)
                .InMemoryCache((context) =>
                {
                    var eventTypes = _eventTypesCache
                    .ToList()
                    .Select(x => x.ToObservable())
                    .ToList();

                    if (eventTypes.Count == 0)
                    {
                        throw new IndexOutOfRangeException("The memory cache did contain any event types.");
                    }

                    return eventTypes;
                })
                .Web((context) =>
                {
                    var eventTypes = WebClient.GetEventTypes(new GetEventTypesRequest()).GetAwaiter().GetResult().EventTypes.Select(x => x.ToObservable()).ToList();

                    List<CachedEventType> cachedEventTypes = new List<CachedEventType>();

                    try
                    {
                        foreach (var eventType in eventTypes)
                        {
                            var cachedEventType = CachedEventType.FromObservable<CachedEventType>(eventType);
                            _eventTypesCache.Put(cachedEventType.Guid, cachedEventType);
                        }
                    }
                    catch (Exception ex)
                    {
                        LogManager.Log(ex, "Error caching event types on memory.");
                    }

                    try
                    {
                        using (var cache = DiskCache.CreateContext())
                        {
                            var collection = cache.Database.GetCollection<CachedEventType>(EVENT_TYPES_COLLECTION);

                            foreach (var cachedEventType in cachedEventTypes)
                            {
                                collection.Upsert(cachedEventType);
                            }
                        }
                    }
                    catch (Exception ex)
                    {
                        LogManager.Log(ex, "Error caching event types to disk.");
                    }

                    return eventTypes;
                })
                .Online((context) =>
                {
                    using (ObservablesContext db = ObservablesContext.CreateDefault())
                    {
                        var eventTypes = db.EventTypes.ToList();

                        List<CachedEventType> cachedEventTypes = new List<CachedEventType>();

                        try
                        {
                            foreach (var eventType in eventTypes)
                            {
                                var cachedEventType = CachedEventType.FromObservable<CachedEventType>(eventType);
                                _eventTypesCache.Put(cachedEventType.Guid, cachedEventType);
                            }
                        }
                        catch (Exception ex)
                        {
                            LogManager.Log(ex, "Error caching event types on memory.");
                        }

                        try
                        {
                            using (var cache = DiskCache.CreateContext())
                            {
                                var collection = cache.Database.GetCollection<CachedEventType>(EVENT_TYPES_COLLECTION);

                                foreach (var cachedEventType in cachedEventTypes)
                                {
                                    collection.Upsert(cachedEventType);
                                }
                            }
                        }
                        catch (Exception ex)
                        {
                            LogManager.Log(ex, "Error caching event types to disk.");
                        }

                        return eventTypes;
                    }
                })
                .DiskCache((context) =>
                {
                    using (var cache = DiskCache.CreateContext())
                    {
                        var collection = cache.Database.GetCollection<CachedEventType>(EVENT_TYPES_COLLECTION);
                        var cachedEventTypes = collection.FindAll().ToList();

                        foreach (var cachedEventType in cachedEventTypes)
                        {
                            _eventTypesCache.Put(cachedEventType.Guid, cachedEventType);
                        }

                        return cachedEventTypes.Select(x => x.ToObservable()).ToList();
                    }
                })
                .BuildExecuteAsync();
        }
    }
}