// --------------------------------------------------------------------------------------------------------------------

 // <copyright file="FractionHelper.cs" company="OxyPlot">

 //   The MIT License (MIT)

 //

 //   Copyright (c) 2012 Oystein Bjorke

 //

 //   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.

 // </copyright>

 // <summary>

 //   Generates fraction strings from double values.

 // </summary>

 // --------------------------------------------------------------------------------------------------------------------

 namespace OxyPlot

 {

     using System;

     using System.Globalization;

     /// <summary>

     /// Provides functionality to generate fraction strings from double values.

     /// </summary>

     /// <remarks>

     /// Examples: "3/4", "PI/2"

     /// </remarks>

     public static class FractionHelper

     {

         /// <summary>

         /// Converts a double to a fraction string.

         /// </summary>

         /// <param name="value">

         /// The value.

         /// </param>

         /// <param name="unit">

         /// The unit.

         /// </param>

         /// <param name="unitSymbol">

         /// The unit symbol.

         /// </param>

         /// <param name="eps">

         /// The tolerance.

         /// </param>

         /// <param name="formatProvider">

         /// The format Provider.

         /// </param>

         /// <returns>

         /// The convert to fraction string.

         /// </returns>

         public static string ConvertToFractionString(

             double value,

             double unit = 1,

             string unitSymbol = null,

             double eps = 1e-6,

             IFormatProvider formatProvider = null)

         {

             if (Math.Abs(value) < eps)

             {

                 return "0";

             }

             // ½, ⅝, ¾

             value /= unit;

             // int whole = (int)(value - (int) value);

             // int N = 10000;

             // int frac = (int) ((value - whole)*N);

             // var d = GCF(N,frac);

             for (int d = 1; d <= 64; d++)

             {

                 double n = value * d;

                 var ni = (int)Math.Round(n);

                 if (Math.Abs(n - ni) < eps)

                 {

                     string nis = unitSymbol == null || ni != 1 ? ni.ToString(CultureInfo.InvariantCulture) : string.Empty;

                     if (d == 1)

                     {

                         return string.Format("{0}{1}", nis, unitSymbol);

                     }

                     return string.Format("{0}{1}/{2}", nis, unitSymbol, d);

                 }

             }

             return string.Format(formatProvider ?? CultureInfo.CurrentCulture, "{0}{1}", value, unitSymbol);

         }

         /// <summary>

         /// Finds the greates common divisor.

         /// </summary>

         /// <param name="a">

         /// The a.

         /// </param>

         /// <param name="b">

         /// The b.

         /// </param>

         /// <returns>

         /// The gcd.

         /// </returns>

         public static int gcd(int a, int b)

         {

             if (b == 0)

             {

                 return a;

             }

             return gcd(b, a % b);

         }

         /// <summary>

         /// Finds the greatest common factor.

         /// </summary>

         /// <param name="x">

         /// The x.

         /// </param>

         /// <param name="y">

         /// The y.

         /// </param>

         /// <returns>

         /// The gcf.

         /// </returns>

         private static int GCF(int x, int y)

         {

             x = Math.Abs(x);

             y = Math.Abs(y);

             int z;

             do

             {

                 z = x % y;

                 if (z == 0)

                 {

                     return y;

                 }

                 x = y;

                 y = z;

             }

             while (true);

         }

     }

 }