using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Reflection;
using System.Text;
using NewLife.Linq;
using NewLife.Reflection;
using XCode.Configuration;
using NewLife.Log;

namespace XCode.Common
{
    /// <summary>助手类</summary>
    static class Helper
    {
        public static Boolean IsIntType(Type type)
        {
            TypeCode code = Type.GetTypeCode(type);
            switch (code)
            {
                case TypeCode.Int16:
                case TypeCode.Int32:
                case TypeCode.Int64:
                case TypeCode.UInt16:
                case TypeCode.UInt32:
                case TypeCode.UInt64:
                    return true;
                default:
                    break;
            }

            return false;
        }

        /// <summary>指定键是否为空。一般业务系统设计不允许主键为空，包括自增的0和字符串的空</summary>
        /// <param name="key"></param>
        /// <returns></returns>
        public static Boolean IsNullKey(Object key)
        {
            if (key == null) return true;

            Type type = key.GetType();

            //由于key的实际类型是由类型推倒而来，所以必须根据实际传入的参数类型分别进行装箱操作
            //如果不根据类型分别进行会导致类型转换失败抛出异常
            switch (Type.GetTypeCode(type))
            {
                case TypeCode.Int16: return ((Int16)key) <= 0;
                case TypeCode.Int32: return ((Int32)key) <= 0;
                case TypeCode.Int64: return ((Int64)key) <= 0;
                case TypeCode.UInt16: return ((UInt16)key) <= 0;
                case TypeCode.UInt32: return ((UInt32)key) <= 0;
                case TypeCode.UInt64: return ((UInt64)key) <= 0;
                case TypeCode.String: return String.IsNullOrEmpty((String)key);
                default: break;
            }

            if (type == typeof(Guid)) return ((Guid)key) == Guid.Empty;
            if (type == typeof(Byte[])) return ((Byte[])key).Length <= 0;

            return false;
        }

        /// <summary>是否空主键的实体</summary>
        /// <param name="entity"></param>
        /// <returns></returns>
        public static Boolean IsEntityNullKey(IEntity entity)
        {
            IEntityOperate eop = EntityFactory.CreateOperate(entity.GetType());
            foreach (var item in eop.Fields)
            {
                if ((item.PrimaryKey || item.IsIdentity) && IsNullKey(entity[item.Name])) return true;
            }

            //List<FieldItem> pks = eop.Fields.Where(e => e.PrimaryKey).ToList();
            //if (pks != null && pks.Count > 0)
            //{
            //    foreach (FieldItem item in pks)
            //    {
            //        // 任何一个不为空，则表明整体不为空
            //        if (!IsNullKey(entity[item.Name])) return false;
            //    }
            //    return true;
            //}

            //FieldItem field = eop.Fields.FirstOrDefault(e => e.IsIdentity);
            //if (field.IsIdentity)
            //{
            //    return IsNullKey(entity[field.Name]);
            //}

            return false;
        }

        /// <summary>获取调用者</summary>
        /// <returns></returns>
        public static String GetCaller(Int32 maxNum = 10)
        {
            return XTrace.GetCaller(2, maxNum, "<-");
            //var st = new StackTrace(2, true);
            //var sb = new StringBuilder();
            //int count = Math.Min(maxNum, st.FrameCount);
            //Type last = null;
            //var asm = Assembly.GetEntryAssembly();
            //var entry = asm == null ? null : asm.EntryPoint;
            //for (int i = 0; i < count; i++)
            //{
            //    var sf = st.GetFrame(i);
            //    var method = sf.GetMethod();

            //    var name = method.ToString();
            //    // 去掉前面的返回类型
            //    if (name.Contains(" ")) name = name.Substring(name.IndexOf(" ") + 1);

            //    var type = method.DeclaringType ?? method.ReflectedType;
            //    if (type != null && type != last)
            //        sb.AppendFormat("{0}.{1}", TypeX.Create(type).Name, name);
            //    else
            //        sb.AppendFormat("{0}", name);

            //    if (i < count - 1) sb.Append("<-");

            //    last = type;

            //    // 如果到达了入口点，可以结束了
            //    if (method == entry) break;
            //}
            //return sb.ToString();
        }
    }
}