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[]))
            {
                var lo = Math.Abs(BitConverter.ToInt64((byte[])fvalue, 0));
                var 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(bool))
            {
                var bTrue = "YES,Y,T,1,TRUE".Split(',');
                var 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(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()
        {
            var obj = new T();
            var type = typeof(T);

            string fname;
            object fvalue;
            Type fType;

            //循环记录的字段名称
            for (var 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
                var 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()
        {
            var obj = new T();
            var type = typeof(T);

            string fname;
            object fvalue;
            Type fType;

            for (var 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

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

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

            return obj;
        }
    }
}