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

namespace ASPNET.StarterKit.Chart
{
	//*********************************************************************
	//
	// BarGraph Class
	//
	// This class uses GDI+ to render Bar Chart.
	//
	//*********************************************************************

	public class BarGraph : Chart
	{
		private const float _graphLegendSpacer = 15F;
		private const int	_labelFontSize = 7;
		private const int	_legendFontSize = 9;
		private const float _legendRectangleSize = 10F;
		private const float _spacer = 5F;

		// Overall related members
		private Color	_backColor;
		private string	_fontFamily;
		private string	_longestTickValue = string.Empty;	// Used to calculate max value width
		private float	_maxTickValueWidth;					// Used to calculate left offset of bar graph
		private float	_totalHeight;
		private float	_totalWidth;
		
		// Graph related members
		private float	_barWidth;
		private float	_bottomBuffer;	// Space from bottom to x axis
		private bool	_displayBarData;	
		private Color	_fontColor;
		private float	_graphHeight;		
		private float	_graphWidth;
		private float	_maxValue = 0.0f;	// = final tick value * tick count
		private float	_scaleFactor;		// = _maxValue / _graphHeight
		private float	_spaceBtwBars;	// For now same as _barWidth
		private float	_topBuffer;		// Space from top to the top of y axis
		private float	_xOrigin;			// x position where graph starts drawing
		private float	_yOrigin;			// y position where graph starts drawing
		private string	_yLabel;
		private int		_yTickCount;
		private float	_yTickValue;		// Value for each tick = _maxValue/_yTickCount

		// Legend related members
		private bool	_displayLegend;
		private float	_legendWidth;
		private string	_longestLabel = string.Empty;	// Used to calculate legend width
		private float	_maxLabelWidth = 0.0f;

		public string FontFamily {
			get{ return _fontFamily; }
			set{ _fontFamily = value; }
		}

		public Color BackgroundColor {
			set{ _backColor = value; }
		}

		public int BottomBuffer {
			set { _bottomBuffer = Convert.ToSingle(value); }
		}

		public Color FontColor {
			set{ _fontColor = value; }
		}

		public int Height {
			get{ return Convert.ToInt32(_totalHeight); }
			set{ _totalHeight = Convert.ToSingle(value); }  
		}

		public int Width {
			get{ return Convert.ToInt32(_totalWidth); }
			set{ _totalWidth = Convert.ToSingle(value); }	
		}

		public bool ShowLegend {
			get{ return _displayLegend; }
			set{ _displayLegend = value; }
		}

		public bool ShowData {
			get{ return _displayBarData; }
			set{ _displayBarData = value; }
		}
		public int TopBuffer {
			set { _topBuffer = Convert.ToSingle(value); }
		}

		public string VerticalLabel {
			get{ return _yLabel; }
			set{ _yLabel = value; }
		}

		public int VerticalTickCount {
			get{ return _yTickCount; }
			set{ _yTickCount = value; }
		}

		public BarGraph()
		{
			AssignDefaultSettings();
		}

		public BarGraph(Color bgColor)
		{
			AssignDefaultSettings();
			BackgroundColor = bgColor;
		}

		//*********************************************************************
		//
		// This method collects all data points and calculate all the necessary dimensions 
		// to draw the bar graph.  It is the method called before invoking the Draw() method.
		// labels is the x values.
		// values is the y values.
		//
		//*********************************************************************

		public void CollectDataPoints(string[] labels, string[] values)
		{
			if (labels.Length == values.Length) 
			{
				for(int i=0; i<labels.Length; i++)
				{
					float temp = Convert.ToSingle(values[i]);
					string shortLbl = MakeShortLabel(labels[i]);

					// For now put 0.0 for start position and sweep size
					DataPoints.Add(new ChartItem(shortLbl, labels[i], temp, 0.0f, 0.0f, GetColor(i)));
				
					// Find max value from data; this is only temporary _maxValue
					if (_maxValue < temp) _maxValue = temp;

					// Find the longest description
					if (_displayLegend) 
					{
						string currentLbl = labels[i] + " (" + shortLbl + ")";
						float currentWidth = CalculateImgFontWidth(currentLbl, _legendFontSize, FontFamily);
						if(_maxLabelWidth < currentWidth)
						{
							_longestLabel = currentLbl;
							_maxLabelWidth = currentWidth;
						}
					}
				}

				CalculateTickAndMax();
				CalculateGraphDimension();
				CalculateBarWidth(DataPoints.Count, _graphWidth);
				CalculateSweepValues();
			}
			else
				throw new Exception("X data count is different from Y data count");
		}
		
		//*********************************************************************
		//
		// Same as above; called when user doesn't care about the x values
		//
		//*********************************************************************

		public void CollectDataPoints(string[] values)
		{
			string[] labels = values;
			CollectDataPoints(labels, values);
		}

		//*********************************************************************
		//
		// This method returns a bar graph bitmap to the calling function.  It is called after 
		// all dimensions and data points are calculated.
		//
		//*********************************************************************

		public override Bitmap Draw()
		{
			int height = Convert.ToInt32(_totalHeight);
			int width = Convert.ToInt32(_totalWidth);

			Bitmap bmp = new Bitmap(width, height);
			
			using(Graphics graph = Graphics.FromImage(bmp))
			{
				graph.CompositingQuality = CompositingQuality.HighQuality;
				graph.SmoothingMode = SmoothingMode.AntiAlias;

				// Set the background: need to draw one pixel larger than the bitmap to cover all area
				graph.FillRectangle(new SolidBrush(_backColor), -1, -1, bmp.Width+1, bmp.Height+1);

				DrawVerticalLabelArea(graph);
				DrawBars(graph);
				DrawXLabelArea(graph);
				if (_displayLegend) DrawLegend(graph);
			}

			return bmp;
		}

		//*********************************************************************
		//
		// This method draws all the bars for the graph.
		//
		//*********************************************************************

		private void DrawBars(Graphics graph)
		{
			SolidBrush brsFont = null;
			Font valFont = null;
			StringFormat sfFormat = null;

			try 
			{
				brsFont = new SolidBrush(_fontColor);
				valFont = new Font(_fontFamily, _labelFontSize);
				sfFormat = new StringFormat();
				sfFormat.Alignment = StringAlignment.Center;
				int i = 0;

				// Draw bars and the value above each bar
				foreach(ChartItem item in DataPoints)
				{
					using(SolidBrush barBrush = new SolidBrush(item.ItemColor))
					{
						float itemY = _yOrigin + _graphHeight - item.SweepSize;

						// When drawing, all position is relative to (_xOrigin, _yOrigin)
						graph.FillRectangle(barBrush, _xOrigin + item.StartPos, itemY, _barWidth, item.SweepSize);

						// Draw data value
						if (_displayBarData)
						{
							float startX = _xOrigin + (i * (_barWidth + _spaceBtwBars));  // This draws the value on center of the bar
							float startY = itemY - 2f - valFont.Height;					  // Positioned on top of each bar by 2 pixels
							RectangleF recVal = new RectangleF(startX, startY, _barWidth + _spaceBtwBars, valFont.Height);
							graph.DrawString(item.Value.ToString("#,###.##"), valFont, brsFont, recVal, sfFormat);	
						}
						i++;
					}
				}
			}
			finally 
			{
				if (brsFont != null) brsFont.Dispose();
				if (valFont != null) valFont.Dispose();
				if (sfFormat != null) sfFormat.Dispose();
			}
		}

		//*********************************************************************
		//
		// This method draws the y label, tick marks, tick values, and the y axis.
		//
		//*********************************************************************

		private void DrawVerticalLabelArea(Graphics graph)
		{
			Font lblFont = null;
			SolidBrush brs = null;
			StringFormat lblFormat = null;
			Pen pen = null;
			StringFormat sfVLabel = null;
			
			try
			{
				lblFont = new Font(_fontFamily, _labelFontSize);
				brs = new SolidBrush(_fontColor);
				lblFormat = new StringFormat();
				pen = new Pen(_fontColor);
				sfVLabel = new StringFormat();

				lblFormat.Alignment = StringAlignment.Near;

				// Draw vertical label at the top of y-axis and place it in the middle top of y-axis
				RectangleF recVLabel = new RectangleF(0f, _yOrigin-2*_spacer-lblFont.Height, _xOrigin*2, lblFont.Height);
				sfVLabel.Alignment = StringAlignment.Center;
				graph.DrawString(_yLabel, lblFont, brs, recVLabel, sfVLabel);

				// Draw all tick values and tick marks
				for (int i=0; i<_yTickCount; i++)
				{
					float currentY = _topBuffer + (i * _yTickValue/_scaleFactor);	// Position for tick mark
					float labelY = currentY-lblFont.Height/2;						// Place label in the middle of tick
					RectangleF lblRec = new RectangleF(_spacer, labelY, _maxTickValueWidth, lblFont.Height);
				
					float currentTick = _maxValue - i*_yTickValue;					// Calculate tick value from top to bottom
					graph.DrawString(currentTick.ToString("#,###.##"), lblFont, brs, lblRec, lblFormat);	// Draw tick value  
					graph.DrawLine(pen, _xOrigin, currentY, _xOrigin - 4.0f, currentY);						// Draw tick mark
				}

				// Draw y axis
				graph.DrawLine(pen, _xOrigin, _yOrigin, _xOrigin, _yOrigin + _graphHeight);
			}
			finally
			{
				if (lblFont != null) lblFont.Dispose();
				if (brs != null) brs.Dispose();
				if (lblFormat != null) lblFormat.Dispose();
				if (pen != null) pen.Dispose();
				if (sfVLabel != null) sfVLabel.Dispose();
			}
		}

		//*********************************************************************
		//
		// This method draws x axis and all x labels
		//
		//*********************************************************************

		private void DrawXLabelArea(Graphics graph)
		{
			Font lblFont = null;
			SolidBrush brs = null;
			StringFormat lblFormat = null;
			Pen pen = null;

			try
			{
				lblFont = new Font(_fontFamily, _labelFontSize);
				brs = new SolidBrush(_fontColor);
				lblFormat = new StringFormat();
				pen = new Pen(_fontColor);

				lblFormat.Alignment = StringAlignment.Center;

				// Draw x axis
				graph.DrawLine(pen, _xOrigin, _yOrigin + _graphHeight, _xOrigin + _graphWidth, _yOrigin + _graphHeight);

				float currentX;
				float currentY = _yOrigin + _graphHeight + 2.0f;	// All x labels are drawn 2 pixels below x-axis
				float labelWidth = _barWidth + _spaceBtwBars;		// Fits exactly below the bar
				int i = 0;

				// Draw x labels
				foreach(ChartItem item in DataPoints)
				{
					currentX = _xOrigin + (i * labelWidth);
					RectangleF recLbl = new RectangleF(currentX, currentY, labelWidth, lblFont.Height);
					string lblString = _displayLegend ? item.Label : item.Description;	// Decide what to show: short or long

					graph.DrawString(lblString, lblFont, brs, recLbl, lblFormat);
					i++;
				}
			}
			finally
			{
				if (lblFont != null) lblFont.Dispose();
				if (brs != null) brs.Dispose();
				if (lblFormat != null) lblFormat.Dispose();
				if (pen != null) pen.Dispose();
			}
		}

		//*********************************************************************
		//
		// This method determines where to place the legend box.
		// It draws the legend border, legend description, and legend color code.
		//
		//*********************************************************************

		private void DrawLegend(Graphics graph)
		{
			Font lblFont = null;
			SolidBrush brs = null;
			StringFormat lblFormat = null;
			Pen pen = null;

			try
			{
				lblFont = new Font(_fontFamily, _legendFontSize);
				brs = new SolidBrush(_fontColor);
				lblFormat = new StringFormat();
				pen = new Pen(_fontColor);
				lblFormat.Alignment = StringAlignment.Near;

				// Calculate Legend drawing start point
				float startX = _xOrigin + _graphWidth + _graphLegendSpacer;
				float startY = _yOrigin;

				float xColorCode = startX + _spacer;
				float xLegendText = xColorCode + _legendRectangleSize + _spacer;
				float legendHeight = 0.0f;
				for(int i=0; i<DataPoints.Count; i++)
				{
					ChartItem point = DataPoints[i];
					string text = point.Description + " (" + point.Label + ")";
					float currentY = startY + _spacer + (i * (lblFont.Height + _spacer));
					legendHeight += lblFont.Height + _spacer;

					// Draw legend description
					graph.DrawString(text, lblFont, brs, xLegendText, currentY, lblFormat);

					// Draw color code
					graph.FillRectangle(new SolidBrush(DataPoints[i].ItemColor), xColorCode, currentY + 3f, _legendRectangleSize, _legendRectangleSize);
				}

				// Draw legend border
				graph.DrawRectangle(pen, startX, startY, _legendWidth, legendHeight + _spacer);
			}
			finally
			{
				if (lblFont != null) lblFont.Dispose();
				if (brs != null) brs.Dispose();
				if (lblFormat != null) lblFormat.Dispose();
				if (pen != null) pen.Dispose();
			}
		}

		//*********************************************************************
		//
		// This method calculates all measurement aspects of the bar graph from the given data points
		//
		//*********************************************************************

		private void CalculateGraphDimension() 
		{
			FindLongestTickValue();
			
			// Need to add another character for spacing; this is not used for drawing, just for calculation
			_longestTickValue += "0";		
			_maxTickValueWidth = CalculateImgFontWidth(_longestTickValue, _labelFontSize, FontFamily);
			float leftOffset = _spacer + _maxTickValueWidth;
			float rtOffset = 0.0f;

			if (_displayLegend) 
			{
				_legendWidth = _spacer + _legendRectangleSize + _spacer + _maxLabelWidth + _spacer;
				rtOffset = _graphLegendSpacer + _legendWidth + _spacer;
			}
			else
				rtOffset = _spacer;		// Make graph in the middle

			_graphHeight = _totalHeight - _topBuffer - _bottomBuffer;	// Buffer spaces are used to print labels
			_graphWidth = _totalWidth - leftOffset - rtOffset;
			_xOrigin = leftOffset;
			_yOrigin = _topBuffer;

			// Once the correct _maxValue is determined, then calculate _scaleFactor
			_scaleFactor = _maxValue / _graphHeight;
		}

		//*********************************************************************
		//
		// This method determines the longest tick value from the given data points.
		// The result is needed to calculate the correct graph dimension.
		//
		//*********************************************************************

		private void FindLongestTickValue()
		{
			float currentTick;
			string tickString;
			for (int i=0; i<_yTickCount; i++)
			{
				currentTick = _maxValue - i*_yTickValue;	
				tickString = currentTick.ToString("#,###.##");
				if (_longestTickValue.Length < tickString.Length)
					_longestTickValue = tickString;
			}
		}

		//*********************************************************************
		//
		// This method calculates the image width in pixel for a given text
		//
		//*********************************************************************

		private float CalculateImgFontWidth(string text, int size, string family)
		{
			Bitmap bmp = null;
			Graphics graph = null;
			Font font = null;

			try
			{
				font = new Font(family, size);

				// Calculate the size of the string.
				bmp = new Bitmap(1,1,PixelFormat.Format32bppArgb);
				graph = Graphics.FromImage(bmp);
				SizeF oSize = graph.MeasureString(text, font);
			
				return oSize.Width;
			}
			finally
			{
				if (graph != null) graph.Dispose();
				if (bmp != null) bmp.Dispose();
				if (font != null) font.Dispose();
			}
		}
		
		//*********************************************************************
		//
		// This method creates abbreviation from long description; used for making legend
		//
		//*********************************************************************

		private string MakeShortLabel(string text)
		{
			string label = text;
			if (text.Length > 2) 
			{
				int midPostition = Convert.ToInt32(Math.Floor(text.Length/2));
				label = text.Substring(0,1) + text.Substring(midPostition, 1) + text.Substring(text.Length-1,1);
			}
			return label;
		}

		//*********************************************************************
		//
		// This method calculates the max value and each tick mark value for the bar graph.
		//
		//*********************************************************************

		private void CalculateTickAndMax()
		{
			float tempMax = 0.0f;

			// Give graph some head room first about 10% of current max
			_maxValue *= 1.1f;

			if (_maxValue != 0.0f)
			{
				// Find a rounded value nearest to the current max value
				// Calculate this max first to give enough space to draw value on each bar
				double exp = Convert.ToDouble(Math.Floor(Math.Log10(_maxValue)));
				tempMax = Convert.ToSingle(Math.Ceiling(_maxValue / Math.Pow(10, exp)) * Math.Pow(10, exp));
			}
			else
				tempMax = 1.0f;

			// Once max value is calculated, tick value can be determined; tick value should be a whole number
			_yTickValue = tempMax / _yTickCount;
			double expTick = Convert.ToDouble(Math.Floor(Math.Log10(_yTickValue)));
			_yTickValue = Convert.ToSingle(Math.Ceiling(_yTickValue / Math.Pow(10, expTick)) * Math.Pow(10, expTick));

			// Re-calculate the max value with the new tick value
			_maxValue = _yTickValue * _yTickCount;
		}

		//*********************************************************************
		//
		// This method calculates the height for each bar in the graph
		//
		//*********************************************************************

		private void CalculateSweepValues()
		{
			// Called when all values and scale factor are known
			// All values calculated here are relative from (_xOrigin, _yOrigin)
			int i = 0;
			foreach(ChartItem item in DataPoints)
			{
				// This implementation does not support negative value
				if (item.Value >= 0) item.SweepSize = item.Value/_scaleFactor;
				
				// (_spaceBtwBars/2) makes half white space for the first bar
				item.StartPos = (_spaceBtwBars/2) + i * (_barWidth+_spaceBtwBars);
				i++;
			}
		}

		//*********************************************************************
		//
		// This method calculates the width for each bar in the graph
		//
		//*********************************************************************

		private void CalculateBarWidth(int dataCount, float barGraphWidth)
		{
			// White space between each bar is the same as bar width itself
			_barWidth = barGraphWidth / (dataCount * 2);  // Each bar has 1 white space 
			_spaceBtwBars = _barWidth;
		}

		//*********************************************************************
		//
		// This method assigns default value to the bar graph properties and is only 
		// called from BarGraph constructors
		//
		//*********************************************************************

		private void AssignDefaultSettings()
		{
			// default values
			_totalWidth = 700f;
			_totalHeight = 450f;
			_fontFamily = "Verdana";
			_backColor = Color.White;
			_fontColor = Color.Black;
			_topBuffer = 30f;
			_bottomBuffer = 30f;
			_yTickCount = 2;
			_displayLegend = false;
			_displayBarData = false;
		}
	}
}
