using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;

namespace Subtext.Web.Controls.Captcha
{
    public class CaptchaImage : IDisposable
    {
		/// <summary>
		/// Initializes a new instance of the <see cref="CaptchaImage"/> class.
		/// </summary>
        public CaptchaImage()
        {
            this.random = new Random();
            this.FontWarp = FontWarpFactor.Low;
            this.Width = 180;
            this.Height = 50;
		}

		#region Disposable Pattern
		/// <summary>
		/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
		/// </summary>
		public virtual void Dispose()
        {
            GC.SuppressFinalize(this);
            this.Dispose(true);
        }

		/// <summary>
		/// Disposes the Captcha image.
		/// </summary>
		/// <param name="disposing">if set to <c>true</c> [disposing].</param>
        public virtual void Dispose(bool disposing)
        {
            if (disposing)
            {
                this.Image.Dispose();
            }
        }

		/// <summary>
		/// Releases unmanaged resources and performs other cleanup operations before the
		/// <see cref="CaptchaImage"/> is reclaimed by garbage collection.
		/// </summary>
        ~CaptchaImage()
        {
            this.Dispose(false);
		}
		#endregion
    	
    	/// <summary>
    	/// Generates a new Captcha image.
    	/// </summary>
		public void GenerateImage()
        {
            this.image = this.GenerateImagePrivate();
        }

        private Bitmap GenerateImagePrivate()
        {
            Font font;
            Bitmap bitmap = new Bitmap(this.width, this.height, PixelFormat.Format32bppArgb);
			using (Graphics graphics = Graphics.FromImage(bitmap))
			{
				graphics.SmoothingMode = SmoothingMode.AntiAlias;
				RectangleF rectF = new RectangleF(0f, 0f, this.width, this.height);
				Rectangle rect = new Rectangle(0, 0, this.width, this.height);
				HatchBrush smallConfettiBrush = new HatchBrush(HatchStyle.SmallConfetti, Color.LightGray, Color.White);
				graphics.FillRectangle(smallConfettiBrush, rect);
				float previousWidth = 0f;
				float size = Convert.ToInt32((this.height * 0.8));
				while (true)
				{
					font = new System.Drawing.Font(this.fontFamilyName, size, FontStyle.Bold);
					SizeF textSize = graphics.MeasureString(this.Text, font);
					if (textSize.Width <= this.width)
					{
						break;
					}
					if (previousWidth > 0f)
					{
						int estimatedSize = Convert.ToInt32(((textSize.Width - this.width) / (previousWidth - textSize.Width)));
						if (estimatedSize > 0)
						{
							size -= estimatedSize;
						}
						else
						{
							size -= 1f;
						}
					}
					else
					{
						size -= 1f;
					}
					previousWidth = textSize.Width;
				}
				size += 4f;
				
				font = new System.Drawing.Font(this.fontFamilyName, size, FontStyle.Bold);
				StringFormat format = new StringFormat();
				format.Alignment = StringAlignment.Center;
				format.LineAlignment = StringAlignment.Center;
				
				GraphicsPath textPath = new GraphicsPath();
				textPath.AddString(this.Text, font.FontFamily, (int)font.Style, font.Size, rect, format);
				if (this.FontWarp != FontWarpFactor.None)
				{
					int warpDivisor = 0;
					switch (this._fontWarp)
					{
						case FontWarpFactor.Low:
							warpDivisor = 6;
							break;

						case FontWarpFactor.Medium:
							warpDivisor = 5;
							break;

						case FontWarpFactor.High:
							warpDivisor = 4;
							break;

						case FontWarpFactor.Extreme:
							warpDivisor = 3;
							break;
					}
					int heightRange = Convert.ToInt32((((double)rect.Height) / ((double)warpDivisor)));
					int widthRange = Convert.ToInt32((((double)rect.Width) / ((double)warpDivisor)));
					PointF point1 = this.RandomPoint(0, widthRange, 0, heightRange);
					PointF point2 = this.RandomPoint(rect.Width - (widthRange - Convert.ToInt32(point1.X)), rect.Width, 0, heightRange);
					PointF point3 = this.RandomPoint(0, widthRange, rect.Height - (heightRange - Convert.ToInt32(point1.Y)), rect.Height);
					PointF point4 = this.RandomPoint(rect.Width - (widthRange - Convert.ToInt32(point3.X)), rect.Width, rect.Height - (heightRange - Convert.ToInt32(point2.Y)), rect.Height);
					PointF[] points = new PointF[] { point1, point2, point3, point4 };
					Matrix matrix = new Matrix();
					matrix.Translate(0f, 0f);
					textPath.Warp(points, rectF, matrix, WarpMode.Perspective, 0f);
				}
				HatchBrush largeConfettiBrush = new HatchBrush(HatchStyle.LargeConfetti, Color.LightGray, Color.DarkGray);
				graphics.FillPath(largeConfettiBrush, textPath);
				
				int maxDimension = Math.Max(rect.Width, rect.Height);
				int steps = Convert.ToInt32((((double)(rect.Width * rect.Height)) / 30));
				for (int i = 0; i <= steps; i++)
				{
					graphics.FillEllipse(largeConfettiBrush, this.random.Next(rect.Width), this.random.Next(rect.Height), this.random.Next(Convert.ToInt32((((double)maxDimension) / 50))), this.random.Next(Convert.ToInt32((((double)maxDimension) / 50))));
				}
				font.Dispose();
				largeConfettiBrush.Dispose();
				graphics.Dispose();
			}
            return bitmap;
        }

        private PointF RandomPoint(int xmin, int xmax, int ymin, int ymax)
        {
            return new PointF(this.random.Next(xmin, xmax), this.random.Next(ymin, ymax));
        }

        public string Font
        {
            get
            {
                return this.fontFamilyName;
            }
            set
            {
				try
				{
					using (System.Drawing.Font font1 = new System.Drawing.Font(value, 12f))
					{
						this.fontFamilyName = value;
						font1.Dispose();
					}
				}catch(Exception)
				{
					this.fontFamilyName = FontFamily.GenericSerif.Name;
				}
            }
        }

		/// <summary>
		/// Amount of random waping to apply to rendered text.
		/// </summary>
		/// <value>The font warp.</value>
        public FontWarpFactor FontWarp
        {
            get
            {
                return this._fontWarp;
            }
            set
            {
                this._fontWarp = value;
            }
        }

		/// <summary>
		/// Height of the Captcha image in pixels.
		/// </summary>
        public int Height
        {
            get
            {
                return this.height;
            }
            set
            {
                if (value <= 30)
                {
                    throw new ArgumentOutOfRangeException("height", value, "height must be greater than 30.");
                }
                this.height = value;
            }
        }

		/// <summary>
		/// Gets the captcha image to display based on the current property 
		/// values.  Will render the image if it hasn't been rendered yet.
		/// </summary>
		/// <value>The image.</value>
        public Bitmap Image
        {
            get
            {
                if (this.image == null)
                {
                    this.image = this.GenerateImagePrivate();
                }
                return this.image;
            }
        }

    	/// <summary>
    	/// Width of the Captcha image in pixels.
    	/// </summary>
        public int Width
        {
            get
            {
                return this.width;
            }
            set
            {
                if (value <= 60)
                {
                    throw new ArgumentOutOfRangeException("width", value, "width must be greater than 60.");
                }
                this.width = value;
            }
        }

		/// <summary>
		/// Gets or sets the text to render (warped of course).
		/// </summary>
		/// <value>The text.</value>
    	public string Text
    	{
    		get { return this.text; }
    		set { this.text = value; }
    	}

    	string text;

        private FontWarpFactor _fontWarp;
        private Bitmap image;
        private int height;
        private int width;
        private Random random;
        private string fontFamilyName;       

        public enum FontWarpFactor
        {
            None,
            Low,
            Medium,
            High,
            Extreme
        }
    }
}