using System;
using System.Data;
using System.Data.Common;
using System.Linq;
using System.Reflection;

namespace CSFramework.DB
{
    /// <summary>
    /// 数据转换工具,DbDataReader/DataRow转实体对象
    /// </summary>
    public static class DbTools
    {

        private static void SetValue(object obj, PropertyInfo p, string fname, object fvalue, Type fType)
        {
            object tv;

            //处理byte数组转日期，如SqlServer的Timestamp类型
            //数据类型是byte[],且对象属性类型是DateTime
            if (p.PropertyType == typeof(DateTime) && fType == typeof(byte[]))
            {
                long lo = Math.Abs(BitConverter.ToInt64((byte[])fvalue, 0));
                DateTime rt = DateTime.FromBinary(lo);
                p.SetValue(obj, rt, null);
            }
            //数组类型,单独处理
            else if (p.PropertyType.IsArray)
            {
                if (fvalue == DBNull.Value) //特殊处理DBNull类型
                    p.SetValue(obj, null, null);
                else
                    p.SetValue(obj, fvalue, null);
            }
            //bool类型，特殊处理
            else if (p.PropertyType == typeof(Boolean))
            {
                string[] bTrue = "YES,Y,T,1,TRUE".Split(',');
                string[] bFalse = "NO,N,F,0,FALSE".Split(',');

                var o = bTrue.Where(e => e.ToUpper() == fvalue.ToString().Trim().ToUpper()).FirstOrDefault();
                if (!String.IsNullOrEmpty(o))
                    p.SetValue(obj, true, null);
                else
                    p.SetValue(obj, false, null);
            }
            //处理对象数据类型
            else if (p.PropertyType == typeof(System.Object))
            {
                p.SetValue(obj, fvalue, null);
            }
            else
            {
                //普通数据类型，赋值操作
                if (fvalue == null || String.IsNullOrWhiteSpace(fvalue.ToString()))//空值
                    tv = p.PropertyType.IsValueType ? Activator.CreateInstance(p.PropertyType) : null;//值类型
                else
                    tv = System.ComponentModel.TypeDescriptor.GetConverter(p.PropertyType).ConvertFromString(fvalue.ToString());//创建对象
                p.SetValue(obj, tv, null);
            }
        }

        /// <summary>
        /// DbDataReader转换为对象实例,(字段名称优先)
        /// </summary>
        /// <typeparam name="T">对象类型</typeparam>
        /// <param name="row">DbDataReader实例</param>
        /// <returns></returns>

        public static T Convert2Object<T>(DbDataReader row) where T : new()
        {
            T obj = new T();
            Type type = typeof(T);

            string fname; object fvalue; Type fType;

            //循环记录的字段名称
            for (int i = 0; i < row.FieldCount; i++)
            {
                fname = row.GetName(i);//字段名
                fvalue = row.GetValue(i);//字段的值
                fType = row.GetFieldType(i);//字段的数据类型

                //根据字段名称获取对象的属性
                PropertyInfo p = type.GetProperty(fname, BindingFlags.Public | BindingFlags.Instance | BindingFlags.IgnoreCase);

                if (p != null) SetValue(obj, p, fname, fvalue, fType);
            }

            return obj;
        }

        /// <summary>
        /// DataRow转换为对象实例
        /// </summary>
        /// <typeparam name="T">对象类型</typeparam>
        /// <param name="row">DataRow实例</param>
        /// <returns></returns>
        public static T Convert2Object<T>(DataRow row) where T : new()
        {
            T obj = new T();
            Type type = typeof(T);

            string fname; object fvalue; Type fType;

            for (int i = 0; i < row.Table.Columns.Count; i++)
            {
                fname = row.Table.Columns[i].ColumnName;//字段名
                fvalue = row[fname];//值
                fType = row.Table.Columns[i].DataType;//字段数据类型

                PropertyInfo p = type.GetProperty(fname, BindingFlags.Public | BindingFlags.Instance | BindingFlags.IgnoreCase);

                if (p != null) SetValue(obj, p, fname, fvalue, fType);
            }

            return obj;
        }


    }
}