using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Linq.Expressions;
using DAL.Interfaces;

namespace DAL.Repositories
{
    public class RepositoryBase<T> where T : class
    {
        protected DbContext RepositoryDataContext;
        protected DbSet<T> RepositoryDbSet;


        public RepositoryBase(IFoorumDbContext dbContext)
        {
            RepositoryDataContext = dbContext as DbContext;
            if (RepositoryDataContext == null)
            {
                throw new ArgumentNullException(paramName: nameof(dbContext));
            }
            RepositoryDbSet = RepositoryDataContext.Set<T>();
            if (RepositoryDbSet == null)
            {
                throw new NullReferenceException(message: nameof(RepositoryDbSet));
            }
        }

        public T Add(T entity)
        {
            var ret = RepositoryDbSet.Add(entity);
            SaveChanges();
            return ret;
        }

        public T Update(T entity)
        {
            RepositoryDbSet.Attach(entity);
            RepositoryDataContext.Entry(entity).State = EntityState.Modified;
            return entity;
        }

        public void Delete(T entity)
        {
            RepositoryDbSet.Remove(entity);
        }

        public void Delete(Expression<Func<T, bool>> where)
        {
            IEnumerable<T> objects = RepositoryDbSet.Where<T>(where).AsEnumerable();
            foreach (T obj in objects)
                RepositoryDbSet.Remove(obj);
        }

        public T GetById(int id)
        {
            return RepositoryDbSet.Find(id);
        }

        public virtual IEnumerable<T> GetAll()
        {
            return RepositoryDbSet.ToList();
        }

        public virtual IEnumerable<T> GetMany(Expression<Func<T, bool>> where)
        {
            return RepositoryDbSet.Where(where).ToList();
        }

        public T Get(Expression<Func<T, bool>> where)
        {
            return RepositoryDbSet.Where(where).FirstOrDefault<T>();
        }
        public int SaveChanges()
        {
            return RepositoryDataContext.SaveChanges();
        }
    }
}