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

namespace Common
{
    public class ModelConvertHelper<T> where T : new()
    {
        public static IList<T> DataTableToModel(DataTable dt)
        {
            // 定义集合    
            IList<T> ts = new List<T>();

            // 获得此模型的类型   
            Type type = typeof(T);
            string tempName = "";

            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)
                { 
                    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;
        }

        public static IList<T> DataRowToModel(DataRow[] rows) 
        {
            // 定义集合    
            IList<T> ts = new List<T>();

            // 获得此模型的类型   
            Type type = typeof(T);
            string tempName = "";

            foreach (DataRow dr in 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)
                {
                    tempName = pi.Name;  // 检查DataTable是否包含此列 

                    if (rows[0].Table.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;
        }

        public static IList<T> DataSetToModel(DataSet ds, int tableIndex)
        {
            if (ds == null || ds.Tables.Count <= 0 || tableIndex < 0)
                return null;
            DataTable dt = ds.Tables[tableIndex];          
            return DataTableToModel(dt);
        }

        public static IList<T> DataReaderToModel(IDataReader dr)
        {
            List<T> result;
            try
            {
                List<string> field = new List<string>(dr.FieldCount);
                for (int i = 0; i < dr.FieldCount; i++)
                {
                    field.Add(dr.GetName(i).ToLower());
                }
                List<T> list = new List<T>();
                while (dr.Read())
                {
                    T model = Activator.CreateInstance<T>();
                    PropertyInfo[] properties = model.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.GetProperty);
                    for (int j = 0; j < properties.Length; j++)
                    {
                        PropertyInfo property = properties[j];
                        if (field.Contains(property.Name.ToLower()))
                        {
                            if (!IsNullOrDBNull(dr[property.Name]))
                            {
                                property.SetValue(model, HackType(dr[property.Name], property.PropertyType), null);
                            }
                        }
                    }
                    list.Add(model);
                }
                result = list;
            }
            finally
            {
                if (dr != null)
                {
                    dr.Dispose();
                }
            }
            return result;
        }

        public static T ReaderToModel(IDataReader dr)
        {
            T result;
            try
            {
                try
                {
                    if (dr.Read())  
                    {
                        List<string> list = new List<string>(dr.FieldCount);
                        for (int i = 0; i < dr.FieldCount; i++)
                        {
                            list.Add(dr.GetName(i).ToLower());
                        }
                        T model = Activator.CreateInstance<T>();
                        PropertyInfo[] properties = model.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.GetProperty);
                        for (int j = 0; j < properties.Length; j++)
                        {
                            PropertyInfo pi = properties[j];
                            if (list.Contains(pi.Name.ToLower()))
                            {
                                if (!IsNullOrDBNull(dr[pi.Name]))
                                {
                                    pi.SetValue(model, HackType(dr[pi.Name], pi.PropertyType), null);
                                }
                            }
                        }
                        result = model;
                        return result;
                    }
                }
                finally
                {
                    if (dr != null)
                    {
                        dr.Dispose();
                    }
                }
                result = default(T);
            }
            catch (Exception ex)
            {
                throw ex;
            }
            return result;
        }

        private static object HackType(object value, Type conversionType)
        {
            object result;
            if (conversionType.IsGenericType && conversionType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
            {
                if (value == null)
                {
                    result = null;
                    return result;
                }
                NullableConverter nullableConverter = new NullableConverter(conversionType);
                conversionType = nullableConverter.UnderlyingType;
            }
            result = Convert.ChangeType(value, conversionType);
            return result;
        }
        private static bool IsNullOrDBNull(object obj)
        {
            return obj is DBNull || string.IsNullOrEmpty(obj.ToString());
        }
    }
}