using AsbCloudApp.Services;
using AsbCloudDb.Model;
using Mapster;
using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace AsbCloudInfrastructure.Repository
{
#nullable enable
    /// <summary>
    /// CRUD сервис для работы с БД
    /// </summary>
    /// <typeparam name="TDto"></typeparam>
    /// <typeparam name="TEntity"></typeparam>
    public class CrudServiceBase<TDto, TEntity> : ICrudService<TDto>
        where TDto : AsbCloudApp.Data.IId
        where TEntity : class, IId
    {
        protected readonly IAsbCloudDbContext dbContext;
        protected readonly DbSet<TEntity> dbSet;
        protected readonly Func<IQueryable<TEntity>> GetQuery;

        public CrudServiceBase(IAsbCloudDbContext context)
        {
            dbContext = context;
            dbSet = context.Set<TEntity>();
            GetQuery = () => dbSet;
        }

        public CrudServiceBase(IAsbCloudDbContext dbContext, ISet<string> includes)
        {
            this.dbContext = dbContext;
            dbSet = dbContext.Set<TEntity>();

            GetQuery = () =>
            {
                IQueryable<TEntity> query = dbSet;
                foreach (var include in includes)
                    query = query.Include(include);
                return query;
            };
        }

        public CrudServiceBase(IAsbCloudDbContext context, Func<DbSet<TEntity>, IQueryable<TEntity>> makeQuery)
        {
            dbContext = context;
            dbSet = context.Set<TEntity>();
            GetQuery = () => makeQuery(dbSet);
        }

        /// <inheritdoc/>
        public virtual async Task<IEnumerable<TDto>> GetAllAsync(CancellationToken token = default)
        {
            var entities = await GetQuery()
                //.OrderBy(e => e.Id)
                .AsNoTracking()
                .ToListAsync(token)
                .ConfigureAwait(false);
            var dtos = entities.Select(Convert).ToList();
            return dtos;
        }

        /// <inheritdoc/>
        public virtual async Task<TDto?> GetOrDefaultAsync(int id, CancellationToken token = default)
        {
            var entity = await GetQuery()
                .AsNoTracking()
                .FirstOrDefaultAsync(e => e.Id == id, token)
                .ConfigureAwait(false);
            if (entity == default)
                return default;
            var dto = Convert(entity);
            return dto;
        }       

        /// <inheritdoc/>
        public virtual TDto? GetOrDefault(int id)
        {
            var entity = GetQuery()
                .AsNoTracking()
                .FirstOrDefault(e => e.Id == id);
            if (entity == default)
                return default;
            var dto = Convert(entity);
            return dto;
        }

        /// <inheritdoc/>
        public virtual async Task<int> InsertAsync(TDto item, CancellationToken token = default)
        {
            var entity = Convert(item);
            entity.Id = 0;
            var entry = dbSet.Add(entity);
            await dbContext.SaveChangesAsync(token);
            entry.State = EntityState.Detached;
            return entity.Id;
        }

        /// <inheritdoc/>
        public virtual async Task<int> InsertRangeAsync(IEnumerable<TDto> items, CancellationToken token = default)
        {
            if (!items.Any())
                return 0;
            var entities = items.Select(i =>
            {
                var entity = Convert(i);
                entity.Id = 0;
                return entity;
            });
            var entries = new List<Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry>(items.Count());
            foreach (var entity in entities)
            {
                var entry = dbSet.Add(entity);
                entries.Add(entry);
            }
            var affected = await dbContext.SaveChangesAsync(token);
            entries.ForEach(e => e.State = EntityState.Detached);
            return affected;
        }

        /// <inheritdoc/>
        public virtual async Task<int> UpdateAsync(TDto item, CancellationToken token = default)
        {
            var existingEntity = await dbSet
                .AsNoTracking()
                .FirstOrDefaultAsync(e => e.Id == item.Id, token)
                .ConfigureAwait(false);

            if (existingEntity is null)
                return ICrudService<TDto>.ErrorIdNotFound;

            var entity = Convert(item);
            var entry = dbSet.Update(entity);
            await dbContext.SaveChangesAsync(token);
            entry.State = EntityState.Detached;
            return entry.Entity.Id;
        }

        public virtual async Task<int> UpdateRangeAsync(IEnumerable<TDto> dtos, CancellationToken token)
        {
            var ids = dtos.Select(d => d.Id);
            var existingEntities = await dbSet
                .AsNoTracking()
                .Where(d => ids.Contains(d.Id))
                .Select(d => d.Id)
                .ToListAsync(token)
                .ConfigureAwait(false);

            if (ids.Count() > existingEntities.Count)
                return ICrudService<TDto>.ErrorIdNotFound;

            foreach (var dto in dtos)
            {
                var entity = Convert(dto);
                var entry = dbSet.Update(entity);
            }

            var affected = await dbContext.SaveChangesAsync(token);
            return affected;
        }

        /// <inheritdoc/>
        public virtual Task<int> DeleteAsync(int id, CancellationToken token = default)
        {
            var entity = dbSet
                .AsNoTracking()
                .FirstOrDefault(e => e.Id == id);
            if (entity == default)
                return Task.FromResult(ICrudService<TDto>.ErrorIdNotFound);
            var entry = dbSet.Remove(entity);
            var affected = dbContext.SaveChangesAsync(token);
            entry.State = EntityState.Detached;
            return affected;
        }

        protected virtual TDto Convert(TEntity src) => src.Adapt<TDto>();

        protected virtual TEntity Convert(TDto src) => src.Adapt<TEntity>();
    }
#nullable disable
}