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

namespace BoYuan.Framework.Uitility.Extensions
{
    public static class DataTableExtensions
    {
        /// <summary>
        /// Linq匿名对象集合转成DataTable
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="query">The query.</param>
        /// <returns></returns>
        public static DataTable ToDataTable<T>(this IEnumerable<T> query)
        {
            var props = typeof(T).GetProperties();
            var dt = new DataTable();
            dt.Columns.AddRange(props.Select(p => new DataColumn(p.Name, p.PropertyType)).ToArray());
            if (query.Any())
            {
                for (int i = 0; i < query.Count(); i++)
                {
                    ArrayList tempList = new ArrayList();
                    foreach (PropertyInfo pi in props)
                    {
                        object obj = pi.GetValue(query.ElementAt(i), null);
                        tempList.Add(obj);
                    }
                    object[] array = tempList.ToArray();
                    dt.LoadDataRow(array, true);
                }
            }
            return dt;
        }

        /// <summary>
        /// DataTable转List
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="dt"></param>
        /// <returns></returns>
        public static IList<T> DtToList<T>(this DataTable dt) where T : new()
        {
            // 定义集合    
            IList<T> ts = new List<T>();

            // 获得此模型的类型   
            Type type = typeof(T);
            string tempName = "";
            T t;
            PropertyInfo[] propertys;
            foreach (DataRow dr in dt.Rows)
            {
                t= new T();
                // 获得此模型的公共属性      
                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)
                            pi.SetValue(t, value, null);
                    }
                }
                ts.Add(t);
            }
            return ts;

        }


        /// <summary>
        /// DataRow对象转换成Object<T>对象
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="row"></param>
        /// <returns></returns>
        public static T DataRowToObject<T>(this DataRow row)
        {
            T obj = default(T);
            if (row != null)
            {
                obj = Activator.CreateInstance<T>();

                foreach (DataColumn column in row.Table.Columns)
                {
                    PropertyInfo prop = obj.GetType().GetProperty(column.ColumnName);
                    try
                    {
                        object value = row[column.ColumnName];
                        prop.SetValue(obj, value);
                    }
                    catch (Exception ex)
                    {
                        throw ex;
                    }
                }
            }
            return obj;
        }

        /// <summary>
        /// 将DataRow[]转换成DataTable
        /// </summary>
        /// <param name="rows"></param>
        /// <returns></returns>
        public static DataTable ToDataTable(this DataRow[] rows)
        {
            if (rows == null || rows.Length == 0) return null;
            DataTable tmp = rows[0].Table.Clone();  // 复制DataRow的表结构  
            foreach (DataRow row in rows)
                tmp.Rows.Add(row.ItemArray);  // 将DataRow添加到DataTable中  
            return tmp;
        }
        
    }
}