using System;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Text;

namespace HRManager.CommonComponent
{
    /// <summary>
    /// 生成驗證碼圖象類
    /// </summary>
    public class ValidateCode
    {
        private const int CODELEN = 4;  //4位驗證碼
        
        public string code;             //生成的驗證碼
        public string imgFilePath ;     //生成的圖象路徑
        public string imgFileName;      //生成的圖象文件名

        /// <summary>
        /// 構造函數，得到保存圖象的路徑
        /// </summary>
        public ValidateCode(string imgFilePath)
        {
            this.imgFilePath = imgFilePath;
        }

        /// <summary>
        /// 析構函數，刪除生成的圖象文件
        /// </summary>
        ~ValidateCode()
        {
            File.Delete(this.imgFilePath+this.imgFileName);	//使用File的Delete靜態方法，刪除臨時圖象
        }

        /// <summary>
        /// 生成驗證碼圖象文件，并存儲在服務器中
        /// </summary>
        public void GenerateCodeImage()
        {
            this.GetCode();
            Bitmap img = null;
            Graphics g = null;            

            int gHeight = code.Length * 12;
            img = new Bitmap(gHeight, 25);
            g = Graphics.FromImage(img);

            g.Clear(Color.AliceBlue);                       //背景顏色            
            Font font = new Font("Arial Black", 10);        //文字字體
            SolidBrush brush = new SolidBrush(Color.Black); //文字顏色
           
            g.DrawString(this.code, font, brush, 3, 3);
            
            this.imgFileName = this.code + ".Png";
            img.Save(this.imgFilePath+this.imgFileName, ImageFormat.Png);

            g.Dispose();
            img.Dispose();
        }

        /// <summary>
        /// 生成隨即的四位字母、數字混合串
        /// </summary>
        /// <returns>四位字母、數字混合串</returns>
        public void GetCode()
        {
            char[] allChars = new char[]{
                '0','1','2','3','4','5','6','7','8','9',
                'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',
                'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'
            };
            
            Random rand = new Random();

            for (int i = 0; i < CODELEN; i++)
            {
                rand = new Random((i+1) * (int)DateTime.Now.Ticks);
                this.code+= allChars[rand.Next(allChars.Length - 1)];
            }
        }      
    }
}