using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Data;
using System.Reflection;
using System.Collections;

namespace Common.Model
{
    /// <summary>    
    /// 实体转换辅助类    
    /// </summary>    
    public class ModelConvertHelper<T> where T : new()
    {
        public static IList<T> ConvertToModel(DataTable dt,bool IsDateTimeEmpty = false)
        {
            // 定义集合    
            IList<T> ts = new List<T>();

            // 获得此模型的类型   
            Type type = typeof(T);
            string tempName = "";

            foreach (DataRow dr in dt.Rows)
            {
                T t = new T();
                // 获得此模型的公共属性      
                PropertyInfo[] propertys = t.GetType().GetProperties();
                foreach (PropertyInfo pi in propertys)
                {
                    tempName = pi.Name;  // 检查DataTable是否包含此列    

                    if (dt.Columns.Contains(tempName))
                    {
                        // 判断此属性是否有Setter      
                        if (!pi.CanWrite) continue;

                        object value = dr[tempName];
                        if (value != DBNull.Value)
                        {
                            //加一重if判断，如果属性值是int32类型的，就进行一次强制转换
                            if (pi.GetMethod.ReturnParameter.ParameterType.Name == "Int32")
                            {
                                value = Convert.ToInt32(value);
                            } 
                            pi.SetValue(t, value, null);
                        }
                        if (IsDateTimeEmpty)
                        {
                            if (pi.PropertyType.ToString() == "System.DateTime")
                            {
                                if (value.ToString() == DateTime.MinValue.ToString())
                                {
                                    pi.SetValue(t, value, null);
                                }
                            }
                        }
                    }
                }
                ts.Add(t);
            }
            return ts;
        }

        /// <summary>
        /// list转datatable
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="collection"></param>
        /// <returns></returns>
        public DataTable ListToDt<T>(IEnumerable<T> collection)
        {
            var props = typeof(T).GetProperties();
            var dt = new DataTable();
            dt.Columns.AddRange(props.Select(p => new DataColumn(p.Name, p.PropertyType)).ToArray());
            if (collection.Count() > 0)
            {
                for (int i = 0; i < collection.Count(); i++)
                {
                    ArrayList tempList = new ArrayList();
                    foreach (PropertyInfo pi in props)
                    {
                        object obj = pi.GetValue(collection.ElementAt(i), null);
                        tempList.Add(obj);
                    }
                    object[] array = tempList.ToArray();
                    dt.LoadDataRow(array, true);
                }
            }
            return dt;
        }
    }

}