using CC.Yi.IDAL;
using CC.Yi.Model;
using Microsoft.EntityFrameworkCore;
using System;
using System.Linq;
using System.Linq.Expressions;

namespace CC.Yi.DAL
{
    public class BaseDal<T> : IBaseDal<T> where T : class, new()
    {
        public DataContext Db;
        public BaseDal(DataContext _Db)
        {
            Db = _Db;
        }
        public IQueryable<T> GetEntities(Expression<Func<T, bool>> whereLambda)
        {
            return Db.Set<T>().Where(whereLambda).AsQueryable();
        }

        public int GetCount(Expression<Func<T, bool>> whereLambda) //统计数量
        {
            return Db.Set<T>().Where(whereLambda).Count();
        }

        public IQueryable<IGrouping<S, T>> GetGroup<S>(Expression<Func<T, bool>> whereLambda, Expression<Func<T, S>> groupByLambda) //分组
        {
            return Db.Set<T>().Where(whereLambda).GroupBy<T, S>(groupByLambda).AsQueryable();

        }



        public IQueryable<T> GetPageEntities<S>(int pageSize, int pageIndex, out int total, Expression<Func<T, bool>> whereLambda, Expression<Func<T, S>> orderByLambda, bool isAsc)
        {
            total = Db.Set<T>().Where(whereLambda).Count();
            if (isAsc)
            {
                var pageData = Db.Set<T>().Where(whereLambda)
                              .OrderBy<T, S>(orderByLambda)
                              .Skip(pageSize * (pageIndex - 1))
                              .Take(pageSize).AsQueryable();
                return pageData;
            }
            else
            {
                var pageData = Db.Set<T>().Where(whereLambda)
                                 .OrderByDescending<T, S>(orderByLambda)
                                 .Skip(pageSize * (pageIndex - 1))
                                 .Take(pageSize).AsQueryable();
                return pageData;
            }
        }

        public T Add(T entity)
        {
            Db.Set<T>().Add(entity);
            //Db.SaveChanges();
            return entity;
        }

        public bool Update(T entity)
        {
            //所有字段均修改
            Db.Entry<T>(entity).State = EntityState.Modified;
            //return Db.SaveChanges() > 0;
            return true;
        }


        public bool Delete(T entity)
        {
            Db.Entry<T>(entity).State = EntityState.Deleted;
            //return Db.SaveChanges() > 0;
            return true;
        }
        public bool Detete(int id)
        {
            var entity = Db.Set<T>().Find(id);//根据id找到实体
            Db.Set<T>().Remove(entity);//由于这里先Find找到了实体，所以这里可以用Remove标记该实体要移除（删除）。如果不是先Find到实体就需要用System.Data.Entity.EntityState.Deleted
            return true;
        }

    }
}