using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;
using PlixP.Extentions;
using PlixP.Models;
using PlixP.Repositories.Contracts;

namespace PlixP.Repositories
{
    public class BaseRepository<T> : IBaseRepository<T>
        where T : Entity
    {
        protected readonly PlixContext DbContext;
        public DbSet<T> Entities { get; }
        public virtual IQueryable<T> Table => Entities.Where(e => e.IsRemoved == false);
        public virtual IQueryable<T> TableNoTracking => Entities.AsNoTracking().Where(e => e.IsRemoved == false);

        public BaseRepository(PlixContext dbContext)
        {
            DbContext = dbContext;
            Entities = DbContext.Set<T>(); // City => Cities
        }

        #region Async Method
        public virtual async Task<T> GetByIdAsync(CancellationToken cancellationToken, params object[] ids)
        {
            
            var entity = await Entities.FindAsync(ids, cancellationToken);
            DbContext.Entry(entity).State = EntityState.Detached;
            return entity;

        }

        public virtual async Task AddAsync(T entity, CancellationToken cancellationToken, bool saveNow = true)
        {
            Assert.NotNull(entity, nameof(entity));
            entity.CreationDate = DateTime.Now;
            await Entities.AddAsync(entity, cancellationToken).ConfigureAwait(false);
            if (saveNow)
                await DbContext.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
        }

        public virtual async Task AddRangeAsync(IEnumerable<T> entities, CancellationToken cancellationToken, bool saveNow = true)
        {
            Assert.NotNull(entities, nameof(entities));
            await Entities.AddRangeAsync(entities, cancellationToken).ConfigureAwait(false);
            if (saveNow)
                await DbContext.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
        }

        public virtual async Task UpdateAsync(T entity, CancellationToken cancellationToken, bool saveNow = true)
        {
            Assert.NotNull(entity, nameof(entity));
            DbContext.Entry(entity).State = EntityState.Detached;
            await DbContext.SaveChangesAsync(cancellationToken);
            //DbContext.Entry(entity).State = EntityState.Modified;
            DbContext.Update(entity);
            //DbContext.Entry(entity).CurrentValues.SetValues(entity);
            if (saveNow)
                await DbContext.SaveChangesAsync(cancellationToken);
        }

        public virtual async Task UpdateRangeAsync(IEnumerable<T> entities, CancellationToken cancellationToken, bool saveNow = true)
        {
            Assert.NotNull(entities, nameof(entities));
            Entities.UpdateRange(entities);
            if (saveNow)
                await DbContext.SaveChangesAsync(cancellationToken);
        }

        public virtual async Task DeleteAsync(T entity, CancellationToken cancellationToken, bool saveNow = true)
        {
            Assert.NotNull(entity, nameof(entity));
            entity.IsRemoved = true;
            Entities.Update(entity);
            if (saveNow)
                await DbContext.SaveChangesAsync(cancellationToken);
        }

        public async Task HardDeleteAsync(T entity, CancellationToken cancellationToken, bool saveNow = true)
        {
            Assert.NotNull(entity, nameof(entity));
            Entities.Remove(entity);
            if (saveNow)
                await DbContext.SaveChangesAsync(cancellationToken);
        }

        public virtual async Task DeleteRangeAsync(IEnumerable<T> entities, CancellationToken cancellationToken, bool saveNow = true)
        {
            Assert.NotNull(entities, nameof(entities));
            foreach (var apiEntity in entities)
            {
                apiEntity.IsRemoved = true;
                Entities.Update(apiEntity);
            }
            if (saveNow)
                await DbContext.SaveChangesAsync(cancellationToken);
        }
        #endregion

        #region Sync Methods
        public virtual T GetById(params object[] ids)
        {
            var ent = Entities.Find(ids);
            Detach(ent);
            return ent;
        }

        public virtual void Add(T entity, bool saveNow = true)
        {
            Assert.NotNull(entity, nameof(entity));
            Entities.Add(entity);
            if (saveNow)
                DbContext.SaveChanges();
        }

        public virtual void AddRange(IEnumerable<T> entities, bool saveNow = true)
        {
            Assert.NotNull(entities, nameof(entities));
            Entities.AddRange(entities);
            if (saveNow)
                DbContext.SaveChanges();
        }

        public virtual void Update(T entity, bool saveNow = true)
        {
            Assert.NotNull(entity, nameof(entity));
            Detach(entity);
            Entities.Update(entity);
            DbContext.SaveChanges();
        }

        public virtual void UpdateRange(IEnumerable<T> entities, bool saveNow = true)
        {
            Assert.NotNull(entities, nameof(entities));
            Entities.UpdateRange(entities);
            if (saveNow)
                DbContext.SaveChanges();
        }

        public virtual void Delete(T entity, bool saveNow = true)
        {
            Assert.NotNull(entity, nameof(entity));
            Entities.Remove(entity);
            if (saveNow)
                DbContext.SaveChanges();
        }

        public virtual void DeleteRange(IEnumerable<T> entities, bool saveNow = true)
        {
            Assert.NotNull(entities, nameof(entities));
            Entities.RemoveRange(entities);
            if (saveNow)
                DbContext.SaveChanges();
        }
        #endregion

        #region Attach & Detach
        public virtual void Detach(T entity)
        {
            Assert.NotNull(entity, nameof(entity));
            var entry = DbContext.Entry(entity);
            if (entry != null)
                entry.State = EntityState.Detached;
        }

        public virtual void Attach(T entity)
        {
            Assert.NotNull(entity, nameof(entity));
            if (DbContext.Entry(entity).State == EntityState.Detached)
                Entities.Attach(entity);
        }
        #endregion

        #region Explicit Loading
        public virtual async Task LoadCollectionAsync<TProperty>(T entity, Expression<Func<T, IEnumerable<TProperty>>> collectionProperty, CancellationToken cancellationToken)
            where TProperty : class
        {
            Attach(entity);

            var collection = DbContext.Entry(entity).Collection(collectionProperty);
            if (!collection.IsLoaded)
                await collection.LoadAsync(cancellationToken).ConfigureAwait(false);
        }

        public virtual void LoadCollection<TProperty>(T entity, Expression<Func<T, IEnumerable<TProperty>>> collectionProperty)
            where TProperty : class
        {
            Attach(entity);
            var collection = DbContext.Entry(entity).Collection(collectionProperty);
            if (!collection.IsLoaded)
                collection.Load();
        }

        public virtual async Task LoadReferenceAsync<TProperty>(T entity, Expression<Func<T, TProperty>> referenceProperty, CancellationToken cancellationToken)
            where TProperty : class
        {
            Attach(entity);
            var reference = DbContext.Entry(entity).Reference(referenceProperty);
            if (!reference.IsLoaded)
                await reference.LoadAsync(cancellationToken).ConfigureAwait(false);
        }

        public virtual void LoadReference<TProperty>(T entity, Expression<Func<T, TProperty>> referenceProperty)
            where TProperty : class
        {
            Attach(entity);
            var reference = DbContext.Entry(entity).Reference(referenceProperty);
            if (!reference.IsLoaded)
                reference.Load();
        }
        #endregion

    }
}