using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;
using AutoMapper;
using Microsoft.EntityFrameworkCore.Query;
using xCommons.Extensions;
using xDataService.Interfaces;
using xModels.Base;
using xModels.Dtos;

namespace xDataService.Providers
{
    /// <summary>
    /// a Base Repository Service Implementation which Use a Repository Patterns Implementatin 
    /// and provides Data Manipulation Methods using Dtos instead of Entities ...
    /// 
    /// it can be use of following Repository Patterns Implementation:
    /// <see cref="XBaseEFRepository"/>>
    /// <see cref="XBaseMongoRepository"/>>
    /// <see cref="XBaseInMemoryRepository"/>>
    /// </summary>
    /// <typeparam name="TEntity"></typeparam>
    /// <typeparam name="TDto"></typeparam>
    /// <typeparam name="TKey"></typeparam>
    public abstract class XBaseRepositoryService<TEntity, TDto, TKey> : IXBaseRepositoryService<TEntity, TDto, TKey>
    where TEntity : XBaseEntity<TKey>
    where TDto : XBaseEntityDto<TKey>
    {
        //
        #region Properties ...
        /// <summary>
        /// Mapper Instance ...
        /// </summary>
        public IMapper Mapper { get; }

        /// <summary>
        /// Repository Implementation for Data Manipulations ...
        /// </summary>
        public IXBaseRepository<TEntity, TKey> Repository { get; }

        /// <summary>
        /// Mapping Profile Configuration ...
        /// 
        /// this Configuration used for Mapping TEntity to Dto and reverse ...
        /// default mapping prepared on Constructing time, other custom maps
        /// must handled manually if required ...
        /// </summary>
        public MapperConfiguration MapperConfiguration { get; }
        #endregion

        //
        #region Constructor ...
        public XBaseRepositoryService(
            IXBaseRepository<TEntity, TKey> repository,
            IEnumerable<Profile> mapperProfiles = null
        )
        {
            //
            Repository = repository;

            //
            // Preparing Mapping Configurations ...
            MapperConfiguration = new MapperConfiguration(cfg =>
            {
                //
                // Add Default Profiles ...

                //
                // Entity To Dto ...
                cfg.CreateMap<TEntity, TDto>()
                    .ForMember(dest => dest.Deleted, opt => opt.Ignore());
                cfg.CreateMap<XQueryResult<TEntity>, XQueryResult<TDto>>();

                //
                // Dto to Entity ...
                cfg.CreateMap<TDto, TEntity>()
                    .ForMember(dest => dest.Deleted, opt => opt.Ignore());
                cfg.CreateMap<XQueryResult<TDto>, XQueryResult<TEntity>>();

                //
                // Add Provided Profiles if Provided ...
                // if Same Profiles Provided, here resolved ...
                if (!mapperProfiles.IsNull() &&
                    mapperProfiles.HasChild())
                {
                    cfg.AddProfiles(mapperProfiles);
                }
            });

            //
            // Make Mapper Instance using prepared Configuration ...
            Mapper = MapperConfiguration.CreateMapper();
        }
        #endregion

        //
        #region Actions ...
        //
        #region Add ...
        /// <summary>
        /// add a new Dto ...
        /// </summary>
        /// <param name="item"></param>
        /// <param name="saveChanges"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<TDto> AddAsync(
            TDto item,
            bool saveChanges = true,
            CancellationToken cancellationToken = default
        )
        {
            //
            TDto result = null;

            //
            // Validate ...
            bool isValid = !item.IsNull();
            if (!isValid)
            {
                return result;
            }

            //
            try
            {
                //
                var entity = Mapper.Map<TEntity>(item);

                //
                entity = await Repository.AddAsync(
                    item: entity,
                    saveChanges: saveChanges,
                    cancellationToken: cancellationToken
                );

                //
                result = Mapper.Map<TDto>(entity);
            }
            catch
            { }

            //
            return result;
        }

        /// <summary>
        /// add or update a Dto (add if not exists/update if exists) ...
        /// </summary>
        /// <param name="item"></param>
        /// <param name="saveChanges"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<TDto> AddOrUpdateAsync(
            TDto item,
            bool saveChanges = true,
            CancellationToken cancellationToken = default
        )
        {
            //
            TDto result = null;

            //
            // Validate ...
            bool isValid = !item.IsNull();
            if (!isValid)
            {
                return result;
            }

            //
            try
            {
                //
                var entity = Mapper.Map<TEntity>(item);

                //
                entity = await Repository.AddOrUpdateAsync(
                    item: entity,
                    saveChanges: saveChanges,
                    cancellationToken: cancellationToken
                );

                //
                result = Mapper.Map<TDto>(entity);
            }
            catch
            { }

            //
            return result;
        }

        /// <summary>
        /// add a range of new Dtos ...
        /// </summary>
        /// <param name="items"></param>
        /// <param name="saveChanges"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task AddRangeAsync(
            IEnumerable<TDto> items,
            bool saveChanges = true,
            CancellationToken cancellationToken = default
        )
        {
            //
            TDto result = null;

            //
            // Validate ...
            bool isValid =
                !items.IsNull() &&
                items.HasChild();
            if (!isValid)
            {
                return;
            }

            //
            try
            {
                //
                var entities = Mapper.Map<IEnumerable<TEntity>>(items);

                //
                await Repository.AddRangeAsync(
                    items: entities,
                    saveChanges: saveChanges,
                    cancellationToken: cancellationToken
                );
            }
            catch
            { }
        }
        #endregion

        //
        #region Update ...
        /// <summary>
        /// Update an Dto values ...
        /// </summary>
        /// <param name="id"></param>
        /// <param name="item"></param>
        /// <param name="saveChanges"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<TDto> UpdateAsync(
            TKey id,
            TDto item,
            bool saveChanges = true,
            CancellationToken cancellationToken = default
        )
        {
            //
            TDto result = null;

            //
            try
            {
                //
                var entity = Mapper.Map<TEntity>(item);

                //
                entity = await Repository.UpdateAsync(
                    id: item.Id,
                    item: entity,
                    saveChanges: saveChanges,
                    cancellationToken: cancellationToken
                );

                //
                result = Mapper.Map<TDto>(entity);
            }
            catch
            { }

            //
            return result;
        }

        /// <summary>
        /// Update a range of Dtos ...
        /// </summary>
        /// <param name="items"></param>
        /// <param name="saveChanges"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<bool> UpdateRangeAsync(
            IEnumerable<TDto> items,
            bool saveChanges = true,
            CancellationToken cancellationToken = default
        )
        {
            //
            // Validate ...
            var result =
                !items.IsNull() &&
                items.HasChild();
            if (!result)
            {
                return result;
            }

            //
            try
            {
                //
                var entitis = Mapper.Map<IEnumerable<TEntity>>(items);

                //
                result = await Repository.UpdateRangeAsync(
                    items: entitis,
                    saveChanges: saveChanges,
                    cancellationToken: cancellationToken
                );
            }
            catch
            {
                result = false;
            }

            //
            return result;
        }
        #endregion

        //
        #region Remove ...
        /// <summary>
        /// remove an Dto by it's Id ...
        /// </summary>
        /// <param name="id"></param>
        /// <param name="softDelete"></param>
        /// <param name="saveChanges"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<TDto> RemoveAsync(
            TKey id,
            bool softDelete = true,
            bool saveChanges = true,
            CancellationToken cancellationToken = default
        )
        {
            //
            TDto result = null;

            //
            try
            {
                //
                var entity = await Repository.RemoveAsync(
                    id: id,
                    softDelete: softDelete,
                    saveChanges: saveChanges,
                    cancellationToken: cancellationToken
                );

                //
                result = Mapper.Map<TDto>(entity);
            }
            catch
            { }

            //
            return result;
        }

        /// <summary>
        /// remove an Dto ...
        /// </summary>
        /// <param name="item"></param>
        /// <param name="softDelete"></param>
        /// <param name="saveChanges"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<TDto> RemoveAsync(
            TDto item,
            bool softDelete = true,
            bool saveChanges = true,
            CancellationToken cancellationToken = default
        )
        {
            //
            TDto result = null;

            //
            try
            {
                //
                var entity = Mapper.Map<TEntity>(item);

                //
                entity = await Repository.RemoveAsync(
                    item: entity,
                    softDelete: softDelete,
                    saveChanges: saveChanges,
                    cancellationToken: cancellationToken
                );

                //
                result = Mapper.Map<TDto>(entity);
            }
            catch
            { }

            //
            return result;
        }

        /// <summary>
        /// remove a range of exists Dtos ...
        /// </summary>
        /// <param name="items"></param>
        /// <param name="softDelete"></param>
        /// <param name="saveChanges"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task RemoveRangeAsync(
            IEnumerable<TDto> items,
            bool softDelete = true,
            bool saveChanges = true,
            CancellationToken cancellationToken = default
        )
        {
            //
            // Validate ...
            var isValid =
                !items.IsNull() &&
                items.HasChild();
            if (!isValid)
            {
                return;
            }

            //
            var entities = Mapper.Map<IEnumerable<TEntity>>(items);

            //
            try
            {
                //
                await Repository.RemoveRangeAsync(
                    items: entities,
                    softDelete: softDelete,
                    saveChanges: saveChanges,
                    cancellationToken: cancellationToken
                );
            }
            catch
            { }
        }
        #endregion

        //
        #region Count ...
        /// <summary>
        /// count all exists Dtos ...
        /// </summary>
        /// <param name="ignoreSoftDeleteds"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<int> CountAsync(
            bool ignoreSoftDeleteds = true,
            CancellationToken cancellationToken = default
        )
        {
            //
            var result = await Repository.CountAsync(
                cancellationToken: cancellationToken,
                ignoreSoftDeleteds: ignoreSoftDeleteds
            );

            //
            return result;
        }

        /// <summary>
        /// count all exists Entities Pages by providing page size ...
        /// </summary>
        /// <param name="pageSize"></param>
        /// <param name="totalItems"></param>
        /// <param name="ignoreSoftDeleteds"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<int> PagesCountAsync(
            int pageSize,
            int? totalItems = null,
            bool ignoreSoftDeleteds = true,
            CancellationToken cancellationToken = default
        )
        {
            //
            var result = await Repository.PagesCountAsync(
                pageSize: pageSize,
                totalItems: totalItems,
                cancellationToken: cancellationToken,
                ignoreSoftDeleteds: ignoreSoftDeleteds
            );

            //
            return result;
        }
        #endregion

        //
        #region Exists ...
        /// <summary>
        /// Check a Dto exists or not ...
        /// </summary>
        /// <param name="id"></param>
        /// <param name="ignoreSoftDeleteds"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<bool> IsExistsAsync(
            TKey id,
            bool ignoreSoftDeleteds = true,
            CancellationToken cancellationToken = default
        )
        {
            //
            var result = await Repository.IsExistsAsync(
                id: id,
                cancellationToken: cancellationToken,
                ignoreSoftDeleteds: ignoreSoftDeleteds
            );

            //
            return result;
        }
        #endregion

        //
        #region Retrieve ...
        /// <summary>
        /// retrieve an Dto by it's Id ...
        /// </summary>
        /// <param name="id"></param>
        /// <param name="ignoreSoftDeleteds"></param>
        /// <param name="includeBuilder"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<TDto> GetAsync(
            TKey id,
            bool ignoreSoftDeleteds = true,
            Func<IQueryable<TEntity>, IIncludableQueryable<TEntity, object>> includeBuilder = null,
            CancellationToken cancellationToken = default
        )
        {
            //
            TDto result = null;

            //
            try
            {
                //
                var entity = await Repository.GetAsync(
                    id: id,
                    includeBuilder: includeBuilder,
                    cancellationToken: cancellationToken,
                    ignoreSoftDeleteds: ignoreSoftDeleteds
                );

                //
                result = Mapper.Map<TDto>(entity);
            }
            catch
            { }

            //
            return result;
        }

        /// <summary>
        /// retrieve all exists Dtos ...
        /// </summary>
        /// <param name="ignoreSoftDeleteds"></param>
        /// <param name="orderBuilder"></param>
        /// <param name="includeBuilder"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<IEnumerable<TDto>> GetAllAsync(
            bool ignoreSoftDeleteds = true,
            Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBuilder = null,
            Func<IQueryable<TEntity>, IIncludableQueryable<TEntity, object>> includeBuilder = null,
            CancellationToken cancellationToken = default
        )
        {
            //
            IEnumerable<TDto> result = Enumerable.Empty<TDto>();

            //
            try
            {
                //
                var entities = await Repository.GetAllAsync(
                    orderBuilder: orderBuilder,
                    includeBuilder: includeBuilder,
                    cancellationToken: cancellationToken,
                    ignoreSoftDeleteds: ignoreSoftDeleteds
                );

                //
                result = Mapper.Map<IEnumerable<TDto>>(entities);
            }
            catch
            { }

            //
            return result;
        }

        /// <summary>
        /// retrieve all exists Dtos
        /// as Async Enumerable ...
        /// </summary>
        /// <param name="ignoreSoftDeleteds"></param>
        /// <param name="orderBuilder"></param>
        /// <param name="includeBuilder"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async IAsyncEnumerable<TDto> GetAllAsAsyncEnumerable(
            bool ignoreSoftDeleteds = true,
            Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBuilder = null,
            Func<IQueryable<TEntity>, IIncludableQueryable<TEntity, object>> includeBuilder = null,
            [EnumeratorCancellation] CancellationToken cancellationToken = default
        )
        {
            //
            var entityEnumerable = Repository.GetAllAsAsyncEnumerable(
                orderBuilder: orderBuilder,
                includeBuilder: includeBuilder,
                ignoreSoftDeleteds: ignoreSoftDeleteds
            );
            await foreach (var entity in entityEnumerable)
            {
                //
                if (cancellationToken.IsCancellationRequested)
                {
                    yield break;
                }

                //
                var dto = Mapper.Map<TDto>(entity);
                yield return dto;
            }
        }

        /// <summary>
        /// find an Dto by providing a Conditional Expression ...
        /// </summary>
        /// <param name="predicate"></param>
        /// <param name="ignoreSoftDeleteds"></param>
        /// <param name="includeBuilder"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<TDto> FindOneAsync(
            Expression<Func<TEntity, bool>> predicate,
            bool ignoreSoftDeleteds = true,
            Func<IQueryable<TEntity>, IIncludableQueryable<TEntity, object>> includeBuilder = null,
            CancellationToken cancellationToken = default
        )
        {
            //
            TDto result = null;

            //
            try
            {
                //
                var entity = await Repository.FindOneAsync(
                    predicate: predicate,
                    includeBuilder: includeBuilder,
                    cancellationToken: cancellationToken,
                    ignoreSoftDeleteds: ignoreSoftDeleteds
                );

                //
                result = Mapper.Map<TDto>(entity);
            }
            catch
            { }

            //
            return result;
        }

        /// <summary>
        /// find a collection of Dtos by proving a Conditional Expression ...
        /// </summary>
        /// <param name="predicate"></param>
        /// <param name="ignoreSoftDeleteds"></param>
        /// <param name="orderBuilder"></param>
        /// <param name="includeBuilder"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<IEnumerable<TDto>> FindManyAsync(
            Expression<Func<TEntity, bool>> predicate,
            bool ignoreSoftDeleteds = true,
            Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBuilder = null,
            Func<IQueryable<TEntity>, IIncludableQueryable<TEntity, object>> includeBuilder = null,
            CancellationToken cancellationToken = default
        )
        {
            //
            IEnumerable<TDto> result = Enumerable.Empty<TDto>();

            //
            try
            {
                //
                var entities = await Repository.FindManyAsync(
                    predicate: predicate,
                    orderBuilder: orderBuilder,
                    includeBuilder: includeBuilder,
                    cancellationToken: cancellationToken,
                    ignoreSoftDeleteds: ignoreSoftDeleteds
                );

                //
                result = Mapper.Map<IEnumerable<TDto>>(entities);
            }
            catch
            { }

            //
            return result;
        }

        /// <summary>
        /// retrieve Dtos based on XQuery Pagination structure ...
        /// </summary>
        /// <param name="query"></param>
        /// <param name="ignoreSoftDeleteds"></param>
        /// <param name="predicate"></param>
        /// <param name="orderBuilder"></param>
        /// <param name="includeBuilder"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<XQueryResult<TDto>> QueryAsync(
            XQuery query,
            bool ignoreSoftDeleteds = true,
            Expression<Func<TEntity, bool>> predicate = null,
            Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBuilder = null,
            Func<IQueryable<TEntity>, IIncludableQueryable<TEntity, object>> includeBuilder = null,
            CancellationToken cancellationToken = default
        )
        {
            //
            XQueryResult<TDto> result = null;

            //
            try
            {
                //
                var entityResult = await Repository.QueryAsync(
                    query: query,
                    predicate: predicate,
                    orderBuilder: orderBuilder,
                    includeBuilder: includeBuilder,
                    cancellationToken: cancellationToken,
                    ignoreSoftDeleteds: ignoreSoftDeleteds
                );

                //
                result = Mapper.Map<XQueryResult<TDto>>(entityResult);
            }
            catch
            { }

            //
            return result;
        }
        #endregion

        public virtual void Dispose()
        { }
        #endregion
    }
}