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

namespace WebApi.Helpers
{
    public class ValidationHelper
    {
        /// <summary>
        /// 验证对象的必填字段
        /// </summary>
        /// <typeparam name="T">要验证的对象类型</typeparam>
        /// <param name="obj">要验证的对象</param>
        /// <param name="errorMessage">错误信息</param>
        /// <returns>验证是否通过</returns>
        public static bool ValidateRequired<T>(T obj, out string errorMessage)
        {
            errorMessage = string.Empty;
            if (obj == null)
            {
                errorMessage = "对象不能为空";
                return false;
            }

            var properties = typeof(T).GetProperties();
            foreach (var prop in properties)
            {
                var value = prop.GetValue(obj);
                if (value == null)
                {
                    errorMessage = $"【{prop.Name}不能为空】";
                    return false;
                }
                //else if (prop.PropertyType == typeof(int) && (int)value == 0)
                //{
                //    errorMessage = $"【{prop.Name}不能为0】";
                //    return false;
                //}
                else if (prop.PropertyType == typeof(string) && string.IsNullOrEmpty((string)value))
                {
                    errorMessage = $"【{prop.Name}不能为空】";
                    return false;
                }
                else if (prop.PropertyType == typeof(object) && (object)value == null)
                {
                    errorMessage = $"【{prop.Name}不能为空】";
                    return false;
                }
            }

            return true;
        }

        /// <summary>
        /// 验证对象的指定字段
        /// </summary>
        /// <typeparam name="T">要验证的对象类型</typeparam>
        /// <param name="obj">要验证的对象</param>
        /// <param name="propertyNames">要验证的属性名列表</param>
        /// <param name="errorMessage">错误信息</param>
        /// <returns>验证是否通过</returns>
        public static bool ValidateProperties<T>(T obj, string[] propertyNames, out string errorMessage)
        {
            errorMessage = string.Empty;
            if (obj == null)
            {
                errorMessage = "对象不能为空";
                return false;
            }

            foreach (var propName in propertyNames)
            {
                var prop = typeof(T).GetProperty(propName);
                if (prop == null) continue;

                var value = prop.GetValue(obj);
                if (value == null)
                {
                    errorMessage = $"【{propName}不能为空】";
                    return false;
                }
                //else if (prop.PropertyType == typeof(int) && (int)value == 0)
                //{
                //    errorMessage = $"【{propName}不能为0】";
                //    return false;
                //}
                else if (prop.PropertyType == typeof(string) && string.IsNullOrEmpty((string)value))
                {
                    errorMessage = $"【{propName}不能为空】";
                    return false;
                }
            }

            return true;
        }
    }
}