using DatabaseCore.Models;
using Microsoft.EntityFrameworkCore;
using ModuleTools.BindingModels;
using ModuleTools.BusinessLogics;
using ModuleTools.Enums;
using ModuleTools.Interfaces;
using ModuleTools.Models;
using ModuleTools.ViewModels;
using System;
using System.Linq;
using System.Threading.Tasks;

namespace DatabaseCore
{
	public abstract class AbstractGenerticEntityService<G, S, T, L, E> : IGenerticEntityService<G, S>
		where G : GetBindingModel
		where S : SetBindingModel
		where T : BaseEntity
		where L : ListViewModel<E>, new()
		where E : ElementViewModel
	{
		public async Task<OperationResultModel> CreateAsync(S model)
		{
			using var context = DatabaseManager.GetContext;

			var result = AdditionalCheckingWhenAdding(context, model);
			if (!result.IsSucceeded)
			{
				return result;
			}

			var exsistEntity = GetUniqueEntity(model, context);
			if (exsistEntity == null)
			{
				var entity = Mapper.MapToClass<S, T>(model, true);
				await context.Set<T>().AddAsync(entity);
				await context.SaveChangesAsync();
				return OperationResultModel.Success(Mapper.MapToClass<T, E>(entity, true));
			}
			else
			{
				if (exsistEntity.IsDeleted)
				{
					exsistEntity = Mapper.MapToClass(model, exsistEntity, true);
					exsistEntity.IsDeleted = false;
					await context.SaveChangesAsync();
					return OperationResultModel.Success(Mapper.MapToClass<T, E>(exsistEntity, true));
				}
				else
				{
					return OperationResultModel.Error("Error:", "Элемент уже существует", ResultServiceStatusCode.ExsistItem);
				}
			}
		}

		public async Task<OperationResultModel> DeleteAsync(G model)
		{
			using var context = DatabaseManager.GetContext;
			using var transaction = context.Database.BeginTransaction();
			try
			{
				var entity = await context.Set<T>().FirstOrDefaultAsync(x => x.Id == model.Id);
				if (entity == null)
				{
					return OperationResultModel.Error("Error:", "Элемент не найден", ResultServiceStatusCode.NotFound);
				}
				else if (entity.IsDeleted)
				{
					return OperationResultModel.Error("Error:", "Элемент был удален", ResultServiceStatusCode.WasDelete);
				}

				var result = AdditionalCheckingWhenDeleting(context, entity, model);
				if (!result.IsSucceeded)
				{
					return result;
				}

				entity.IsDeleted = true;
				entity.DateDelete = DateTime.Now;

				await context.SaveChangesAsync();

				AdditionalDeleting(context, entity, model);

				await transaction.CommitAsync();
			}
			catch (Exception)
			{
				await transaction.RollbackAsync();
				throw;
			}

			return OperationResultModel.Success(true);
		}

		public async Task<OperationResultModel> RestoreAsync(G model)
		{
			if (model.Id.HasValue || AdditionalCheckForSingleGet(model))
			{
				using var context = DatabaseManager.GetContext;
				var entity = model.Id.HasValue ? IncludingWhenReading(context.Set<T>().AsQueryable()).FirstOrDefault(x => x.Id == model.Id.Value)
				 : GetSingleRecord(context.Set<T>().AsQueryable(), model);
				if (entity == null)
				{
					return OperationResultModel.Error("Error:", "Элемент не найден", ResultServiceStatusCode.NotFound);
				}
				else if (!entity.IsDeleted)
				{
					return OperationResultModel.Error("Error:", "Элемент не был удален", ResultServiceStatusCode.ExsistItem);
				}
				entity.IsDeleted = false;

				await context.SaveChangesAsync();

				return OperationResultModel.Success(Mapper.MapToClass<T, E>(entity, true));
			}
			return OperationResultModel.Error("Error:", "Элемент не найден", ResultServiceStatusCode.NotFound);
		}

		public async Task<OperationResultModel> ReadAsync(G model)
		{
			int countPages = 0;
			using var context = DatabaseManager.GetContext;

			// для одной записи
			if (model.Id.HasValue || AdditionalCheckForSingleGet(model))
			{
				var entity = model.Id.HasValue ? IncludingWhenReading(context.Set<T>().AsQueryable()).FirstOrDefault(x => x.Id == model.Id.Value)
				 : GetSingleRecord(context.Set<T>().AsQueryable(), model);
				if (entity == null)
				{
					return OperationResultModel.Error("Error:", "Элемент не найден", ResultServiceStatusCode.NotFound);
				}
				if (entity.IsDeleted)
				{
					return OperationResultModel.Error("Error:", "Элемент удален", ResultServiceStatusCode.WasDelete);
				}
				return OperationResultModel.Success(Mapper.MapToClass<T, E>(entity, model.HaveRight));
			}

			var query = context.Set<T>().Where(x => !x.IsDeleted).AsQueryable();

			query = AdditionalCheckingWhenReadingList(query, model);

			query = OrderingWhenReading(query);

			query = IncludingWhenReading(query);

			return await Task.Run(() =>
			{

				if (model.PageNumber.HasValue && model.PageSize.HasValue)
				{
					countPages = (int)Math.Ceiling((double)query.Count() / model.PageSize.Value);
					query = query
								.Skip(model.PageSize.Value * model.PageNumber.Value)
								.Take(model.PageSize.Value);
				}
				var result = new L
				{
					MaxCount = countPages,
					List = query.Select(x => Mapper.MapToClass<T, E>(x, model.HaveRight)).ToList()
				};

				return OperationResultModel.Success(result);
			});
		}

		public async Task<OperationResultModel> UpdateAsync(S model)
		{
			using var context = DatabaseManager.GetContext;

			var result = AdditionalCheckingWhenUpdateing(context, model);
			if (!result.IsSucceeded)
			{
				return result;
			}

			var exsistEntity = GetUniqueEntity(model, context);
			if (exsistEntity != null)
			{
				return OperationResultModel.Error("Error:", "Существует запись с такими значениями", ResultServiceStatusCode.ExsistItem);
			}

			var entity = context.Set<T>().FirstOrDefault(x => x.Id == model.Id);
			if (entity == null)
			{
				return OperationResultModel.Error("Error:", "Элемент не найден", ResultServiceStatusCode.NotFound);
			}
			else if (entity.IsDeleted)
			{
				return OperationResultModel.Error("Error:", "Элемент был удален", ResultServiceStatusCode.WasDelete);
			}
			entity = Mapper.MapToClass(model, entity, true);

			await context.SaveChangesAsync();

			return OperationResultModel.Success(Mapper.MapToClass<T, E>(entity, true));
		}

		/// <summary>
		/// Поиск записи с уникальными значениями
		/// </summary>
		/// <param name="model"></param>
		/// <returns></returns>
		protected abstract T GetUniqueEntity(S model, DbContext context);

		/// <summary>
		/// Возможные дополнительные проверки при добавлении
		/// </summary>
		/// <param name="context"></param>
		/// <param name="model"></param>
		/// <returns></returns>
		protected abstract OperationResultModel AdditionalCheckingWhenAdding(DbContext context, S model);

		/// <summary>
		/// Возможные дополнительные проверки при удалении
		/// </summary>
		/// <param name="context"></param>
		/// <param name="model"></param>
		/// <returns></returns>
		protected abstract OperationResultModel AdditionalCheckingWhenDeleting(DbContext context, T entity, G model);

		/// <summary>
		/// Добавление дополнительных фильтров
		/// </summary>
		/// <param name="query"></param>
		/// <param name="model"></param>
		/// <returns></returns>
		protected abstract IQueryable<T> AdditionalCheckingWhenReadingList(IQueryable<T> query, G model);

		/// <summary>
		/// Возможные дополнительные проверки модели при изменении
		/// </summary>
		/// <param name="model"></param>
		protected abstract OperationResultModel AdditionalCheckingWhenUpdateing(DbContext context, S model);

		/// <summary>
		/// Дополнительные удаления зависимых сущностей
		/// </summary>
		/// <param name="model"></param>
		protected abstract void AdditionalDeleting(DbContext context, T entity, G model);

		/// <summary>
		/// Установка сортировок
		/// </summary>
		/// <param name="query"></param>
		/// <returns></returns>
		protected abstract IQueryable<T> OrderingWhenReading(IQueryable<T> query);

		/// <summary>
		/// Добавление Include
		/// </summary>
		/// <param name="query"></param>
		/// <returns></returns>
		protected abstract IQueryable<T> IncludingWhenReading(IQueryable<T> query);

		protected virtual bool AdditionalCheckForSingleGet(G model) => false;

		protected virtual T GetSingleRecord(IQueryable<T> list, G model) => null;
	}
}