using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.BL;
using Tango.BL.Builders;
using Tango.BL.DTO;
using Tango.BL.Entities;
using Tango.Core.Threading;
using Tango.FSE.BL.CacheEntities;
using Z.EntityFramework.Plus;
using Z.EntityFramework.Extensions;
using Tango.BL.Enumerations;
using Tango.Settings;
using Tango.FSE.Web.Messages;

namespace Tango.FSE.BL.Services
{
    /// <summary>
    /// Represents the machines CRUD API for retrieving and updating machines.
    /// </summary>
    /// <seealso cref="Tango.FSE.BL.FSEServiceBase" />
    public class MachinesService : FSEServiceBase
    {
        private const string MACHINES_COLLECTION = "Machines";
        private const string FULL_MACHINES_COLLECTION = "Machines_Full";
        private bool _fullMachinesCachePerformed;

        private MemoryCacheDictionary<String, CachedMachine> _machinesCache;
        private MemoryCacheDictionary<String, CachedMachine> _machinesCacheFull;

        /// <summary>
        /// Initializes a new instance of the <see cref="MachinesService"/> class.
        /// </summary>
        public MachinesService()
        {
            _machinesCache = MemoryCache.GetOrCreateCache<String, CachedMachine>(MACHINES_COLLECTION);
            _machinesCacheFull = MemoryCache.GetOrCreateCache<String, CachedMachine>(FULL_MACHINES_COLLECTION);
        }

        /// <summary>
        /// Gets a machine by the specified serial number.
        /// A machine that exists outside of the current user organization will not be retrieved.
        /// The machine will be retrieved along with it's organization only.
        /// Once a machine retrieved successfully, it will be cached on disk and on memory.
        /// The resolver behavior is In-Memory first, then Online, then Disk.
        /// </summary>
        /// <param name="serialNumber">The serial number.</param>
        /// <returns></returns>
        public Task<Machine> GetMachine(String serialNumber)
        {
            bool allowAll = CurrentUser.HasPermission(Permissions.FSE_ConnectAnyMachine);

            return DataResolver<Machine>.Builder.New()
                .ConfigureCascade(DataResolverNode.InMemoryCache, DataResolverNode.Web, DataResolverNode.Online, DataResolverNode.DiskCache)
                .InMemoryCache((context) =>
                {
                    return _machinesCache.Get(serialNumber).ToObservable();
                })
                .Web((context) =>
                {
                    var response = WebClient.GetMachine(new GetMachineRequest()
                    {
                        AllowAllMachines = allowAll,
                        OrganizationGuid = CurrentUser.OrganizationGuid,
                        SerialNumber = serialNumber
                    }).GetAwaiter().GetResult();

                    if (response.Machine != null)
                    {
                        var machine = response.Machine.ToObservable();

                        LogManager.Log("Machine retrieved successfully. Caching machine...");

                        var cachedMachine = CachedMachine.FromObservable<CachedMachine>(machine);

                        //Store in memory cache.
                        _machinesCache.Put(serialNumber, cachedMachine);

                        //Store disk cache.
                        try
                        {
                            using (var cache = DiskCache.CreateContext())
                            {
                                cache.Database.GetCollection<CachedMachine>(MACHINES_COLLECTION).Upsert(cachedMachine);
                            }
                        }
                        catch (Exception ex)
                        {
                            LogManager.Log(ex, "Error caching machine on disk.");
                        }

                        return machine;
                    }

                    throw new ArgumentOutOfRangeException($"Could not locate machine with serial number '{serialNumber}' using the remote server.");
                })
                .Online((context) =>
                {
                    using (ObservablesContext db = ObservablesContext.CreateDefault())
                    {
                        var machine = new MachineBuilder(db)
                        .Set(x => (allowAll || x.OrganizationGuid == CurrentUser.OrganizationGuid) && x.SerialNumber == serialNumber)
                        .WithOrganization()
                        .Build();

                        if (machine != null)
                        {
                            LogManager.Log("Machine retrieved successfully. Caching machine...");

                            var cachedMachine = CachedMachine.FromObservable<CachedMachine>(machine);

                            //Store in memory cache.
                            _machinesCache.Put(serialNumber, cachedMachine);

                            //Store disk cache.
                            try
                            {
                                using (var cache = DiskCache.CreateContext())
                                {
                                    cache.Database.GetCollection<CachedMachine>(MACHINES_COLLECTION).Upsert(cachedMachine);
                                }
                            }
                            catch (Exception ex)
                            {
                                LogManager.Log(ex, "Error caching machine on disk.");
                            }

                            return machine;
                        }

                        throw new ArgumentOutOfRangeException($"Could not locate machine with serial number '{serialNumber}' on the remote database.");
                    }
                })
                .DiskCache((context) =>
                {
                    using (var cache = DiskCache.CreateContext())
                    {
                        var cachedMachine = cache.Database.GetCollection<CachedMachine>(MACHINES_COLLECTION).FindOne(x => x.SerialNumber == serialNumber && (allowAll || x.OrganizationGuid == CurrentUser.OrganizationGuid));

                        //Store in memory cache.
                        _machinesCache.Put(serialNumber, cachedMachine);

                        return cachedMachine.ToObservable();
                    }
                })
                .BuildExecuteAsync();
        }

        /// <summary>
        /// Gets a machine by the specified serial number along with all it's associated entities like
        /// Organization, configuration, hardware version, machine version, spools calibration and color calibration.
        /// Once a machine is retrieved it will be cached on disk and in memory.
        /// If the specified machine does not exists within the current user organization it will not be retrieved.
        /// The resolver behavior is In-Memory first, then Online, then Disk.
        /// On the first call to this method, a process of fully caching all the current user organization machines starts in the background.
        /// </summary>
        /// <param name="serialNumber">The serial number.</param>
        /// <returns></returns>
        public Task<Machine> GetMachineFull(String serialNumber)
        {
            return GetMachineFull(serialNumber, true);
        }

        private Task<Machine> GetMachineFull(String serialNumber, bool enableLogs)
        {
            bool allowAll = CurrentUser.HasPermission(Permissions.FSE_ConnectAnyMachine);

            return DataResolver<Machine>.Builder.New()
                    .EnableLogs(enableLogs)
                    .ConfigureCascade(DataResolverNode.InMemoryCache, DataResolverNode.Web, DataResolverNode.Online, DataResolverNode.DiskCache)
                    .InMemoryCache((context) =>
                    {
                        return _machinesCacheFull.Get(serialNumber).ToObservable();
                    })
                    .Web((context) =>
                    {
                        var response = WebClient.GetMachine(new GetMachineRequest()
                        {
                            AllowAllMachines = allowAll,
                            OrganizationGuid = CurrentUser.OrganizationGuid,
                            SerialNumber = serialNumber,
                            GetExtendedInfo = true
                        }).GetAwaiter().GetResult();

                        if (response.Machine != null)
                        {
                            var machine = response.Machine.ToObservable();

                            if (enableLogs) LogManager.Log("Machine retrieved successfully. Caching machine on disk and in memory...");

                            var cachedMachine = CachedMachine.FromObservable<CachedMachine>(machine);

                            //Store in memory cache.
                            _machinesCacheFull.Put(serialNumber, cachedMachine);

                            //Store disk cache.
                            try
                            {
                                using (var cache = DiskCache.CreateContext())
                                {
                                    cache.Database.GetCollection<CachedMachine>(FULL_MACHINES_COLLECTION).Upsert(cachedMachine);
                                }
                            }
                            catch (Exception ex)
                            {
                                LogManager.Log(ex, $"Error caching machine '{serialNumber}' on disk.");
                            }

                            return machine;
                        }
                        else
                        {
                            throw new ArgumentOutOfRangeException($"Could not locate machine with serial number '{serialNumber}' on the remote database.");
                        }
                    })
                    .Online((context) =>
                    {
                        using (ObservablesContext db = ObservablesContext.CreateDefault())
                        {
                            var machine = new MachineBuilder(db)
                            .Set(x => (allowAll || x.OrganizationGuid == CurrentUser.OrganizationGuid) && x.SerialNumber == serialNumber)
                            .WithOrganization()
                            .WithVersion()
                            .WithSpools()
                            .WithCats()
                            .WithConfiguration().Build();

                            if (machine != null)
                            {
                                if (enableLogs) LogManager.Log("Machine retrieved successfully. Caching machine on disk and in memory...");

                                var cachedMachine = CachedMachine.FromObservable<CachedMachine>(machine);

                                //Store in memory cache.
                                _machinesCacheFull.Put(serialNumber, cachedMachine);

                                //Store disk cache.
                                try
                                {
                                    using (var cache = DiskCache.CreateContext())
                                    {
                                        cache.Database.GetCollection<CachedMachine>(FULL_MACHINES_COLLECTION).Upsert(cachedMachine);
                                    }
                                }
                                catch (Exception ex)
                                {
                                    LogManager.Log(ex, $"Error caching machine '{serialNumber}' on disk.");
                                }

                                if (SettingsManager.Default.GetOrCreate<ServicesSettings>().PerformFullOrganizationMachinesCaching)
                                {
                                    if (!_fullMachinesCachePerformed)
                                    {
                                        _fullMachinesCachePerformed = true;

                                        //Continue loading the rest of the machines on a separate thread...
                                        ThreadFactory.StartNew(() =>
                                        {

                                            LogManager.Log("Starting caching entire organization machines on disk and in memory...");

                                            var serials = new List<String>();

                                            using (ObservablesContext d = ObservablesContext.CreateDefault())
                                            {
                                                serials = d.Machines.Where(x => x.OrganizationGuid == CurrentUser.OrganizationGuid).Select(x => x.SerialNumber).ToList();
                                            }

                                            foreach (var serial in serials)
                                            {
                                                try
                                                {
                                                    var fm = GetMachineFull(serial, false).Result;
                                                }
                                                catch (Exception ex)
                                                {
                                                    LogManager.Log(ex, $"Error occurred while trying to cache machine '{serial}' in the background. Skipping...");
                                                }
                                            }

                                            LogManager.Log("Full organization machines cache completed.");
                                        });
                                    }
                                }

                                return machine;
                            }
                            else
                            {
                                throw new ArgumentOutOfRangeException($"Could not locate machine with serial number '{serialNumber}' on the remote database.");
                            }
                        }
                    })
                    .DiskCache((context) =>
                    {
                        using (var cache = DiskCache.CreateContext())
                        {
                            var cachedMachine = cache.Database.GetCollection<CachedMachine>(FULL_MACHINES_COLLECTION).FindOne(x => x.SerialNumber == serialNumber && x.OrganizationGuid == CurrentUser.OrganizationGuid);

                            if (cachedMachine == null)
                            {
                                throw new KeyNotFoundException("The machine entity could not be found on the remote server or local cache.\nPlease check your Internet connection and try again.");
                            }

                            //Store in memory cache.
                            _machinesCacheFull.Put(serialNumber, cachedMachine);

                            return cachedMachine.ToObservable();
                        }
                    })
                    .BuildExecuteAsync();
        }

        /// <summary>
        /// Gets the current user organization's machines.
        /// Once this method is called, all machines will be cached.
        /// The resolver behavior is In-Memory first, then Online, then Disk.
        /// </summary>
        /// <returns></returns>
        public Task<List<Machine>> GetAllMachines()
        {
            bool allowAll = CurrentUser.HasPermission(Permissions.FSE_ConnectAnyMachine);

            return DataResolver<List<Machine>>.Builder.New()
                .ConfigureCascade(DataResolverNode.InMemoryCache, DataResolverNode.Web, DataResolverNode.Online, DataResolverNode.DiskCache)
                .InMemoryCache((context) =>
                {
                    var machines = _machinesCache
                    .ToList()
                    .Where(x => allowAll || x.OrganizationGuid == CurrentUser.OrganizationGuid)
                    .Select(x => x.ToObservable())
                    .ToList();

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

                    return machines;
                })
                .Web((context) => 
                {
                    var response = WebClient.GetAllMachines(new GetAllMachinesRequest()
                    {
                        AllowAllMachines = allowAll,
                        OrganizationGuid = CurrentUser.OrganizationGuid,
                    }).GetAwaiter().GetResult();

                    var machines = response.Machines.Select(x => x.ToObservable()).ToList();

                    List<CachedMachine> cachedMachines = new List<CachedMachine>();

                    foreach (var machine in machines)
                    {
                        try
                        {
                            var cachedMachine = CachedMachine.FromObservable<CachedMachine>(machine);
                            cachedMachines.Add(cachedMachine);
                        }
                        catch (Exception ex)
                        {
                            LogManager.Log(ex, $"Error creating cached machine (partial) '{machine.SerialNumber}'.");
                        }
                    }

                    try
                    {
                        foreach (var cachedMachine in cachedMachines)
                        {
                            _machinesCache.Put(cachedMachine.SerialNumber, cachedMachine);
                        }
                    }
                    catch (Exception ex)
                    {
                        LogManager.Log(ex, "Error caching machines (partial) to memory.");
                    }

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

                            foreach (var cachedMachine in cachedMachines)
                            {
                                try
                                {
                                    collection.Upsert(cachedMachine);
                                }
                                catch (Exception ex)
                                {
                                    LogManager.Log(ex, $"Error caching machine '{cachedMachine.SerialNumber}' (partial) to disk.");
                                }
                            }
                        }
                    }
                    catch (Exception ex)
                    {
                        LogManager.Log(ex, "Error caching machines (partial) to disk.");
                    }


                    return machines;
                })
                .Online((context) =>
                {
                    using (ObservablesContext db = ObservablesContext.CreateDefault())
                    {
                        var machines = db.Machines.Where(x => allowAll || x.OrganizationGuid == CurrentUser.OrganizationGuid).Include(x => x.Organization).ToList();

                        List<CachedMachine> cachedMachines = new List<CachedMachine>();

                        foreach (var machine in machines)
                        {
                            try
                            {
                                var cachedMachine = CachedMachine.FromObservable<CachedMachine>(machine);
                                cachedMachines.Add(cachedMachine);
                            }
                            catch (Exception ex)
                            {
                                LogManager.Log(ex, $"Error creating cached machine (partial) '{machine.SerialNumber}'.");
                            }
                        }

                        try
                        {
                            foreach (var cachedMachine in cachedMachines)
                            {
                                _machinesCache.Put(cachedMachine.SerialNumber, cachedMachine);
                            }
                        }
                        catch (Exception ex)
                        {
                            LogManager.Log(ex, "Error caching machines (partial) to memory.");
                        }

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

                                foreach (var cachedMachine in cachedMachines)
                                {
                                    try
                                    {
                                        collection.Upsert(cachedMachine);
                                    }
                                    catch (Exception ex)
                                    {
                                        LogManager.Log(ex, $"Error caching machine '{cachedMachine.SerialNumber}' (partial) to disk.");
                                    }
                                }
                            }
                        }
                        catch (Exception ex)
                        {
                            LogManager.Log(ex, "Error caching machines (partial) to disk.");
                        }

                        return machines;
                    }
                })
                .DiskCache((context) =>
                {
                    using (var cache = DiskCache.CreateContext())
                    {
                        var collection = cache.Database.GetCollection<CachedMachine>(MACHINES_COLLECTION);

                        var cachedMachines = collection
                        .Find(x => allowAll || x.OrganizationGuid == CurrentUser.OrganizationGuid)
                        .ToList();

                        foreach (var cachedMachine in cachedMachines)
                        {
                            _machinesCache.Put(cachedMachine.SerialNumber, cachedMachine);
                        }

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

        /// <summary>
        /// Updates the specified machine.
        /// </summary>
        /// <param name="machine">The machine.</param>
        /// <returns></returns>
        /// <exception cref="InternetConnectionException"></exception>
        public async Task<Machine> UpdateMachine(Machine machine)
        {
            throw new NotImplementedException();

            if (ConnectivityProvider.IsOnline)
            {
                using (var db = ObservablesContext.CreateDefault())
                {
                    await db.SingleUpdateAsync(machine); //Update using Z EF Extensions (no problem with out of context entity!)...
                    return machine;
                }
            }
            else
            {
                throw new InternetConnectionException();
            }
        }
    }
}