using Newtonsoft.Json;
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.Core.ExtensionMethods;

namespace Tango.DataStore.EF
{
    public class EFDataStoreCollection : IDataStoreCollection
    {
        public string Name { get; }

        public EFDataStoreCollection(String name)
        {
            Name = name;
        }

        public void Put<T>(string key, T value)
        {
            Put(key, (object)value);
        }

        public void Put(string key, object value)
        {
            Put(key, DataStoreHelper.GetDataType(value), value);
        }

        public void Put(string key, DataType type, object value)
        {
            using (var db = ObservablesContext.CreateDefault())
            {
                var globalItem = db.GlobalDataStoreItems.FirstOrDefault(x => x.CollectionName == Name && x.Key == key);

                if (globalItem != null)
                {
                    if (globalItem.DataType != (int)type)
                    {
                        throw new InvalidOperationException("A global data store item exists with the same key, but different data type.");
                    }
                }

                DataStoreItem item = db.DataStoreItems.SingleOrDefault(x => x.CollectionName == Name && x.Key == key);

                if (item == null)
                {
                    item = new DataStoreItem();
                    db.DataStoreItems.Add(item);
                }

                item.CollectionName = Name;
                item.Key = key;
                item.DataType = (int)type;
                item.Value = EFDataStoreHelper.CreateBytes(type, value);
                item.IsSynchronized = false;
                item.LastUpdated = DateTime.UtcNow;
                item.IsDeleted = false;

                db.SaveChanges();
            }
        }

        public T Get<T>(string key)
        {
            return (T)Get(key, null);
        }

        public T Get<T>(string key, T defaultValue)
        {
            return (T)Get(key, (object)defaultValue);
        }

        public object Get(string key)
        {
            return Get(key, null);
        }

        public object Get(string key, object defaultValue)
        {
            return GetItem(key, defaultValue).Value;
        }

        public IDataStoreItem GetItem(string key)
        {
            return GetItem(key, null);
        }

        public IDataStoreItem GetItem(string key, object defaultValue)
        {
            using (var db = ObservablesContext.CreateDefault())
            {
                var item = db.DataStoreItems.SingleOrDefault(x => x.CollectionName == Name && x.Key == key && !x.IsDeleted);

                if (item == null)
                {
                    var globalItem = db.GlobalDataStoreItems.SingleOrDefault(x => x.CollectionName == Name && x.Key == key);

                    if (globalItem == null)
                    {
                        if (defaultValue == null)
                        {
                            throw new KeyNotFoundException("The specified data store key was not found.");
                        }
                        else
                        {
                            Put(key, defaultValue);
                            return GetItem(key);
                        }
                    }
                    else
                    {
                        return globalItem.ToDataStoreItem();
                    }
                }

                return item.ToDataStoreItem();
            }
        }

        public List<IDataStoreItem> GetAll()
        {
            using (var db = ObservablesContext.CreateDefault())
            {
                var localItems = db.DataStoreItems.Where(x => x.CollectionName == Name && !x.IsDeleted).ToList();
                var globalItems = db.GlobalDataStoreItems.Where(x => x.CollectionName == Name).ToList();

                foreach (var globalItem in globalItems.ToList())
                {
                    var localItem = localItems.FirstOrDefault(x => x.CollectionName == globalItem.CollectionName && x.Key == globalItem.Key);

                    if (localItem != null)
                    {
                        globalItems.Remove(globalItem);
                    }
                }

                return localItems.Select(x => x.ToDataStoreItem()).Concat(localItems.Select(x => x.ToDataStoreItem())).ToList();
            }
        }

        public List<IDataStoreItem> GetUnsynchronized()
        {
            using (var db = ObservablesContext.CreateDefault())
            {
                return db.DataStoreItems.Where(x => x.CollectionName == Name && !x.IsSynchronized).ToList().Select(x => x.ToDataStoreItem()).ToList();
            }
        }

        public void Delete(string key)
        {
            using (var db = ObservablesContext.CreateDefault())
            {
                db.Database.ExecuteSqlCommand($"DELETE FROM DATA_STORE_ITEMS WHERE COLLECTION_NAME = '{Name}' AND [KEY] = '{key}'");
            }
        }

        public void DeleteAll()
        {
            using (var db = ObservablesContext.CreateDefault())
            {
                db.Database.ExecuteSqlCommand($"DELETE FROM DATA_STORE_ITEMS WHERE COLLECTION_NAME = '{Name}'");
            }
        }

        public int Count()
        {
            using (var db = ObservablesContext.CreateDefault())
            {
                return db.DataStoreItems.Count(x => x.CollectionName == Name);
            }
        }
    }
}