#region PDFsharp Charting - A .NET charting library based on PDFsharp
//
// Authors:
//   Niklas Schneider (mailto:Niklas.Schneider@pdfsharp.com)
//
// Copyright (c) 2005-2008 empira Software GmbH, Cologne (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;

namespace PdfSharp.Charting.Renderers
{
  /// <summary>
  /// Represents the base class for all Y axis renderer.
  /// </summary>
  internal abstract class YAxisRenderer : AxisRenderer
  {
    /// <summary>
    /// Initializes a new instance of the YAxisRenderer class with the specified renderer parameters.
    /// </summary>
    internal YAxisRenderer(RendererParameters parms)
      : base(parms)
    { }

    /// <summary>
    /// Calculates optimal minimum/maximum scale and minor/major tick based on yMin and yMax.
    /// </summary>
    protected void FineTuneYAxis(AxisRendererInfo rendererInfo, double yMin, double yMax)
    {
      if (yMin == double.MaxValue && yMax == double.MinValue)
      {
        // No series data given.
        yMin = 0.0f;
        yMax = 0.9f;
      }

      if (yMin == yMax)
      {
        if (yMin == 0)
          yMax = 0.9f;
        else if (yMin < 0)
          yMax = 0;
        else if (yMin > 0)
          yMax = yMin + 1;
      }

      // If the ratio between yMax to yMin is more than 1.2, the smallest number will be set too zero.
      // It's Excel's behaviour.
      if (yMin != 0)
      {
        if (yMin < 0 && yMax < 0)
        {
          if (yMin / yMax >= 1.2)
            yMax = 0;
        }
        else if (yMax / yMin >= 1.2)
          yMin = 0;
      }

      double deltaYRaw = yMax - yMin;

      int digits = (int)(Math.Log(deltaYRaw, 10) + 1);
      double normed = deltaYRaw / Math.Pow(10, digits) * 10;

      double normedStepWidth = 1;
      if (normed < 2)
        normedStepWidth = 0.2f;
      else if (normed < 5)
        normedStepWidth = 0.5f;

      AxisRendererInfo yari = rendererInfo;
      double stepWidth = normedStepWidth * Math.Pow(10.0, digits - 1.0);
      if (yari.axis == null || double.IsNaN(yari.axis.majorTick))
        yari.MajorTick = stepWidth;
      else
        yari.MajorTick = yari.axis.majorTick;

      double roundFactor = stepWidth * 0.5;
      if (yari.axis == null || double.IsNaN(yari.axis.minimumScale))
      {
        double signumMin = (yMin != 0) ? yMin / Math.Abs(yMin) : 0;
        yari.MinimumScale = (int)(Math.Abs((yMin - roundFactor) / stepWidth) - (1 * signumMin)) * stepWidth * signumMin;
      }
      else
        yari.MinimumScale = yari.axis.minimumScale;

      if (yari.axis == null || double.IsNaN(yari.axis.maximumScale))
      {
        double signumMax = (yMax != 0) ? yMax / Math.Abs(yMax) : 0;
        yari.MaximumScale = (int)(Math.Abs((yMax + roundFactor) / stepWidth) + (1 * signumMax)) * stepWidth * signumMax;
      }
      else
        yari.MaximumScale = yari.axis.maximumScale;

      if (yari.axis == null || double.IsNaN(yari.axis.minorTick))
        yari.MinorTick = yari.MajorTick / 5;
      else
        yari.MinorTick = yari.axis.minorTick;
    }

    /// <summary>
    /// Returns the default tick labels format string.
    /// </summary>
    protected override string GetDefaultTickLabelsFormat()
    {
      return "0.0";
    }
  }
}
