using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Web;

namespace Common
{
  public class Identify
  {
    public static void DrawIdentifyCode(string strIdentifyCode, int intFgNoise, int intBgNoise)
    {
      if (strIdentifyCode == null || strIdentifyCode.Trim() == string.Empty)
        return;
      Bitmap bitmap = new Bitmap((int) Math.Ceiling((double) strIdentifyCode.Length * 12.5), 20);
      Graphics graphics = Graphics.FromImage((Image) bitmap);
      try
      {
        Random random = new Random();
        graphics.Clear(Color.White);
        for (int index = 0; index < intBgNoise; ++index)
        {
          int x1 = random.Next(bitmap.Width);
          int x2 = random.Next(bitmap.Width);
          int y1 = random.Next(bitmap.Height);
          int y2 = random.Next(bitmap.Height);
          graphics.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
        }
        Font font = new Font("Arial", 12f, FontStyle.Bold | FontStyle.Italic);
        LinearGradientBrush linearGradientBrush = new LinearGradientBrush(new Rectangle(0, 0, bitmap.Width, bitmap.Height), Color.Blue, Color.DarkRed, 1.2f, true);
        graphics.DrawString(strIdentifyCode, font, (Brush) linearGradientBrush, 2f, 2f);
        for (int index = 0; index < intFgNoise; ++index)
        {
          int x = random.Next(bitmap.Width);
          int y = random.Next(bitmap.Height);
          bitmap.SetPixel(x, y, Color.FromArgb(random.Next()));
        }
        graphics.DrawRectangle(new Pen(Color.Silver), 0, 0, bitmap.Width - 1, bitmap.Height - 1);
        MemoryStream memoryStream = new MemoryStream();
        bitmap.Save((Stream) memoryStream, ImageFormat.Gif);
        HttpContext.Current.Response.ClearContent();
        HttpContext.Current.Response.ContentType = "image/Gif";
        HttpContext.Current.Response.BinaryWrite(memoryStream.ToArray());
      }
      finally
      {
        graphics.Dispose();
        bitmap.Dispose();
      }
    }

    public static string IdentifyCode(int intLength)
    {
      string str = string.Empty;
      Random random = new Random();
      for (int index = 0; index < intLength; ++index)
      {
        int num = random.Next();
        char ch = num % 2 != 0 ? (char) (65U + (uint) (ushort) (num % 26)) : (char) (48U + (uint) (ushort) (num % 10));
        str += ch.ToString();
      }
      return str;
    }
  }
}