using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace OrpaonEMS.App.Com
{
    /// <summary>
    /// 处理数据类型转换，数制转换、编码转换相关的类
    /// </summary>    
    public sealed class ConvertHelper
    {
        #region 补足位数
        /// <summary>
        /// 指定字符串的固定长度，如果字符串小于固定长度，
        /// 则在字符串的前面补足零，可设置的固定长度最大为9位
        /// </summary>
        /// <param name="text">原始字符串</param>
        /// <param name="limitedLength">字符串的固定长度</param>
        public static string RepairZero(string text, int limitedLength)
        {
            //补足0的字符串
            string temp = "";

            //补足0
            for (int i = 0; i < limitedLength - text.Length; i++)
            {
                temp += "0";
            }

            //连接text
            temp += text;

            //返回补足0的字符串
            return temp;
        }
        #endregion

        #region 各进制数间转换

        /// <summary>
        /// 实现各进制数间的转换。
        /// </summary>
        /// <param name="value">要转换的值,即原值</param>
        /// <param name="from">原值的进制,只能是2,8,10,16四个值。</param>
        /// <param name="to">要转换到的目标进制，只能是2,8,10,16四个值。</param>
        /// <returns>转换失败返回“0”</returns>
        /// <example>
        /// ConvertBase("15",10,16); 表示将十进制数15转换为16进制的数。
        /// </example>
        public static string ConvertBase(string value, int from, int to)
        {
            try
            {
                int intValue = Convert.ToInt32(value, from);     //先转成10进制
                string result = Convert.ToString(intValue, to);  //再转成目标进制

                if (to == 2)
                {
                    result = result.PadLeft(8, '0');
                }

                return result;
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex);
                return "0";
            }
        }

        #endregion

        #region 使用指定字符集将string转换成byte[]
        /// <summary>
        /// 使用指定字符集将string转换成byte[]
        /// </summary>
        /// <param name="text">要转换的字符串</param>
        /// <param name="encoding">字符编码</param>
        public static byte[] StringToBytes(string text, Encoding encoding)
        {
            return encoding.GetBytes(text);
        }
        #endregion

        #region byte[]转string

        /// <summary>
        /// 使用指定字符集将byte[]转换成string
        /// </summary>
        /// <param name="bytes">要转换的字节数组</param>
        /// <param name="encoding">字符编码</param>
        public static string BytesToString(byte[] bytes, Encoding encoding)
        {
            return encoding.GetString(bytes);
        }

        /// <summary>
        /// 从字节数组生成字符串;
        /// </summary>
        /// <param name="buffer"></param>
        /// <returns></returns>
        public string GetBufferStr(byte[] buffer)
        {
            //byte SEP = 0xB3 /*分隔符|*/;

            string result = "";
            for (int i = 0; i < buffer.Length; i++)
            {
                switch (buffer[i])
                {
                    //case SEP:
                    //    result += "|";
                    //    break;
                    default:
                        string str = (char)buffer[i] + "";
                        if (!string.IsNullOrEmpty(str))
                        {
                            result += str;
                        }
                        break;
                }
            }

            return result;
        }

        #endregion

        #region 将byte[]转换成int
        /// <summary>
        /// 将byte[]转换成int
        /// </summary>
        /// <param name="data">需要转换成整数的byte数组</param>
        public static int BytesToInt32(byte[] data)
        {
            //如果传入的字节数组长度小于4,则返回0
            if (data.Length < 4)
            {
                return 0;
            }

            //定义要返回的整数
            int num = 0;

            //如果传入的字节数组长度大于4,需要进行处理
            if (data.Length >= 4)
            {
                //创建一个临时缓冲区
                byte[] tempBuffer = new byte[4];

                //将传入的字节数组的前4个字节复制到临时缓冲区
                Buffer.BlockCopy(data, 0, tempBuffer, 0, 4);

                //将临时缓冲区的值转换成整数，并赋给num
                num = BitConverter.ToInt32(tempBuffer, 0);
            }

            //返回整数
            return num;
        }
        #endregion

        #region struct和byte[]互转

        public static byte[] StructToBytes(object structObj)
        {
            int size = Marshal.SizeOf(structObj);
            IntPtr buffer = Marshal.AllocHGlobal(size);
            try
            {
                Marshal.StructureToPtr(structObj, buffer, false);
                byte[] bytes = new byte[size];
                Marshal.Copy(buffer, bytes, 0, size);
                return bytes;
            }
            finally
            {
                Marshal.FreeHGlobal(buffer);
            }
        }

        public static T BytesToStruct<T>(byte[] data)
        {
            IntPtr buffer = Marshal.AllocHGlobal(data.Length);
            try
            {
                Marshal.Copy(data, 0, buffer, data.Length);
                return Marshal.PtrToStructure<T>(buffer);
            }
            finally
            {
                Marshal.FreeHGlobal(buffer);
            }
        }

        #endregion

        /// <summary>
        /// 通用类型转换
        /// http://www.dzwebs.net/4343.html
        /// </summary>
        /// <param name="value">值</param>
        /// <param name="type">类型</param>
        /// <returns>object</returns>
        public static object ChangeType(object value, Type type)
        {
            if (value == null && type.IsGenericType) return Activator.CreateInstance(type);
            if (value == null) return null;
            if (type == value.GetType()) return value;
            if (type.IsEnum)
            {
                if (value is string)
                    return Enum.Parse(type, value as string);
                else
                    return Enum.ToObject(type, value);
            }

            if (!type.IsInterface && type.IsGenericType)
            {
                Type innerType = type.GetGenericArguments()[0];
                object innerValue = ChangeType(value, innerType);
                return Activator.CreateInstance(type, new object[] { innerValue });
            }

            if (value is string && type == typeof(Guid)) return new Guid(value as string);
            if (value is string && type == typeof(Version)) return new Version(value as string);

            //自定义类转换会在这句返回;
            if (!(value is IConvertible)) return value;

            return Convert.ChangeType(value, type);
        }
    }
}