using System;

using System.Collections.Generic;

using System.Data;

using System.Reflection;

namespace CommonSD

{

    /// <summary>

    /// DataTable与实体类互相转换

    /// </summary>

    /// <typeparam name="T">实体类</typeparam>

    public class ModelHandler<T> where T : new()

    {

        #region DataTable转换成实体类

        /// <summary>

        /// 填充对象列表：用DataSet的第一个表填充实体类

        /// </summary>

        /// <param name="ds">DataSet</param>

        /// <returns></returns>

        public List<T> FillModel(DataSet ds)

        {

            if (ds == null || ds.Tables[] == null || ds.Tables[].Rows.Count == )

            {

                return null;

            }

            else

            {

                return FillModel(ds.Tables[]);

            }

        }

        /// <summary>

        /// 填充对象列表：用DataSet的第index个表填充实体类

        /// </summary>

        public List<T> FillModel(DataSet ds, int index)

        {

            if (ds == null || ds.Tables.Count <= index || ds.Tables[index].Rows.Count == )

            {

                return null;

            }

            else

            {

                return FillModel(ds.Tables[index]);

            }

        }

        /// <summary>

        /// 填充对象列表：用DataTable填充实体类

        /// </summary>

        public List<T> FillModel(DataTable dt)

        {

            if (dt == null || dt.Rows.Count == )

            {

                return null;

            }

            List<T> modelList = new List<T>();

            foreach (DataRow dr in dt.Rows)

            {

                //T model = (T)Activator.CreateInstance(typeof(T));

                T model = new T();

                for (int i = ; i < dr.Table.Columns.Count; i++)

                {

                    PropertyInfo propertyInfo = model.GetType().GetProperty(dr.Table.Columns[i].ColumnName);

                    if (propertyInfo != null && dr[i] != DBNull.Value)

                        propertyInfo.SetValue(model, dr[i], null);

                }

                modelList.Add(model);

            }

            return modelList;

        }

        /// <summary>

        /// 填充对象：用DataRow填充实体类

        /// </summary>

        public T FillModel(DataRow dr)

        {

            if (dr == null)

            {

                return default(T);

            }

            //T model = (T)Activator.CreateInstance(typeof(T));

            T model = new T();

            for (int i = ; i < dr.Table.Columns.Count; i++)

            {

                PropertyInfo propertyInfo = model.GetType().GetProperty(dr.Table.Columns[i].ColumnName);

                if (propertyInfo != null && dr[i] != DBNull.Value)

                    propertyInfo.SetValue(model, dr[i], null);

            }

            return model;

        }

        #endregion

        #region 实体类转换成DataTable

        /// <summary>

        /// 实体类转换成DataSet

        /// </summary>

        /// <param name="modelList">实体类列表</param>

        /// <returns></returns>

        public DataSet FillDataSet(List<T> modelList)

        {

            if (modelList == null || modelList.Count == )

            {

                return null;

            }

            else

            {

                DataSet ds = new DataSet();

                ds.Tables.Add(FillDataTable(modelList));

                return ds;

            }

        }

        /// <summary>

        /// 实体类转换成DataTable

        /// </summary>

        /// <param name="modelList">实体类列表</param>

        /// <returns></returns>

        public DataTable FillDataTable(List<T> modelList)

        {

            if (modelList == null || modelList.Count == )

            {

                return null;

            }

            DataTable dt = CreateData(modelList[]);

            foreach (T model in modelList)

            {

                DataRow dataRow = dt.NewRow();

                foreach (PropertyInfo propertyInfo in typeof(T).GetProperties())

                {

                    dataRow[propertyInfo.Name] = propertyInfo.GetValue(model, null);

                }

                dt.Rows.Add(dataRow);

            }

            return dt;

        }

        /// <summary>

        /// 根据实体类得到表结构

        /// </summary>

        /// <param name="model">实体类</param>

        /// <returns></returns>

        private DataTable CreateData(T model)

        {

            DataTable dataTable = new DataTable(typeof(T).Name);

            foreach (PropertyInfo propertyInfo in typeof(T).GetProperties())

            {

                dataTable.Columns.Add(new DataColumn(propertyInfo.Name, propertyInfo.PropertyType));

            }

            return dataTable;

        }

        #endregion

    }

}