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

namespace DPumpHydr.WinFrmUI.WenSkin.DLL
{
    public static class DataTableList
    {
        public static List<T> ConvertToModel<T>(this DataTable dt) where T : new()
        {
            // 定义集合    
            List<T> ts = new List<T>();
            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)
                {
                    string tempName = pi.Name;
                    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, ConvertTo(value, pi.PropertyType), null);
                        }
                    }
                }
                ts.Add(t);
            }
            return ts;
        }
        private static object ConvertTo(object convertibleValue, Type type)
        {
            if (!type.IsGenericType)
            {
                return Convert.ChangeType(convertibleValue, type);
            }
            else
            {
                Type genericTypeDefinition = type.GetGenericTypeDefinition();
                if (genericTypeDefinition == typeof(Nullable<>))
                {
                    return Convert.ChangeType(convertibleValue, Nullable.GetUnderlyingType(type));
                }
            }
            throw new InvalidCastException(string.Format("Invalid cast from type \"{0}\" to type \"{1}\".", convertibleValue.GetType().FullName, type.FullName));
        }

        /// <summary>
        /// list to datatable
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="collection"></param>
        /// <returns></returns>
        public static DataTable ToDataTable<T>(this IEnumerable<T> collection)
        {
            var props = typeof(T).GetProperties();
            var dt = new DataTable();


            var columns = props.Select(p =>
            {
                var t = p.PropertyType;
                if (t.IsGenericType && t.GetGenericTypeDefinition() == typeof(Nullable<>))
                {
                    t = t.GetGenericArguments()[0];
                }
                return new DataColumn(p.Name, t);
            }).ToArray();
            dt.Columns.AddRange(columns);
            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;
        }
        /// <summary>
        /// list to datatable  格式转换为string类
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="collection"></param>
        /// <returns></returns>
        public static DataTable ToDataTableType<T>(this IEnumerable<T> collection)
        {
            var props = typeof(T).GetProperties();
            var dt = new DataTable();
            dt.Columns.AddRange(props.Select(p => new DataColumn(p.Name)).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;
        }
    }
}