using System;
using System.Collections.Generic;
using System.Data.Common;
using System.Reflection;
using Microsoft.EntityFrameworkCore;

namespace Hncore.Infrastructure.EF
{
    public static class Sql
    {
        /// <summary>
        /// 执行Reader
        /// </summary>
        /// <param name="dbContext"></param>
        /// <param name="sql"></param>
        /// <param name="action"></param>
        public static void Reader(this DbContext dbContext, string sql, Action<DbDataReader> action)
        {
            var conn = dbContext.Database.GetDbConnection();

            try
            {
                conn.Open();

                using (var command = conn.CreateCommand())
                {
                    string query = sql;

                    command.CommandText = query;

                    using (DbDataReader reader = command.ExecuteReader())
                    {
                        if (reader.HasRows)
                        {
                            while (reader.Read())
                            {
                                action(reader);
                            }
                        }
                    }
                }
            }
            finally
            {
                conn.Close();
            }
        }

        /// <summary>
        /// 执行Query
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="dbContext"></param>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static List<T> SqlQuery<T>(this DbContext dbContext, string sql)
        {
            List<T> list = new List<T>();

            var conn = dbContext.Database.GetDbConnection();

            try
            {
                conn.Open();

                using (var command = conn.CreateCommand())
                {
                    string query = sql;

                    command.CommandText = query;

                    using (DbDataReader reader = command.ExecuteReader())
                    {
                        if (reader.HasRows)
                        {
                            list = reader.ReaderToList<T>();
                        }
                    }
                }
            }
            finally
            {
                conn.Close();
            }


            return list;
        }

        /// <summary>
        /// 执行Sql命令
        /// </summary>
        /// <param name="dbContext"></param>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static int ExecuteSql(this DbContext dbContext, string sql)
        {
            var conn = dbContext.Database.GetDbConnection();
            int rowAffected = 0;
            try
            {
                conn.Open();

                using (var command = conn.CreateCommand())
                {
                    command.CommandText = sql;
                    rowAffected = command.ExecuteNonQuery();
                }
            }
            finally
            {
                conn.Close();
            }

            return rowAffected;
        }

        /// <summary>
        /// DataReader转泛型
        /// </summary>
        /// <typeparam name="T">传入的实体类</typeparam>
        /// <param name="objReader">DataReader对象</param>
        /// <returns></returns>
        public static List<T> ReaderToList<T>(this DbDataReader objReader)
        {
            using (objReader)
            {
                List<T> list = new List<T>();

                //获取传入的数据类型
                Type modelType = typeof(T);

                //遍历DataReader对象
                while (objReader.Read())
                {
                    //使用与指定参数匹配最高的构造函数，来创建指定类型的实例
                    T model = Activator.CreateInstance<T>();
                    for (int i = 0; i < objReader.FieldCount; i++)
                    {
                        //判断字段值是否为空或不存在的值
                        if (!IsNullOrDBNull(objReader[i]))
                        {
                            //匹配字段名
                            PropertyInfo pi = modelType.GetProperty(objReader.GetName(i),
                                BindingFlags.GetProperty | BindingFlags.Public | BindingFlags.Instance |
                                BindingFlags.IgnoreCase);
                            if (pi != null)
                            {
                                //绑定实体对象中同名的字段  
                                pi.SetValue(model, CheckType(objReader[i], pi.PropertyType), null);
                            }
                        }
                    }

                    list.Add(model);
                }

                return list;
            }
        }

        /// <summary>
        /// 判断指定对象是否是有效值
        /// </summary>
        /// <param name="obj"></param>
        /// <returns></returns>
        private static bool IsNullOrDBNull(object obj)
        {
            return (obj == null || (obj is DBNull)) ? true : false;
        }

        /// <summary>
        /// 对可空类型进行判断转换
        /// </summary>
        /// <param name="value">DataReader字段的值</param>
        /// <param name="conversionType">该字段的类型</param>
        /// <returns></returns>
        private static object CheckType(object value, Type conversionType)
        {
            if (conversionType.IsGenericType && conversionType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
            {
                if (value == null)
                    return null;
                System.ComponentModel.NullableConverter nullableConverter =
                    new System.ComponentModel.NullableConverter(conversionType);
                conversionType = nullableConverter.UnderlyingType;
            }

            if (typeof(System.Enum).IsAssignableFrom(conversionType))
            {
                return Enum.Parse(conversionType, value.ToString());
            }
            return Convert.ChangeType(value, conversionType);
        }
    }
}