rokojori_action_library/Runtime/Text/Levenshtein.cs

using Godot;

using Rokojori.Extensions;
namespace Rokojori;

public class LevenshteinFuzzyMatch
{
  public int lowestDistance;
  public int index;
}

public class LevenshteinDistance
{   
  protected static int[,] GetMatrix( int aLength, int bLength )
  {
    var matrix = new int[ aLength + 1, bLength + 1];


    for ( var i = 0; i <= aLength; i++ )
    {
      matrix[ i, 0 ] = i;
    }

    for ( var j = 0; j <= bLength; j++ )
    {
      matrix[ 0, j ] = j;
    }

    return matrix;
  }

  public static LevenshteinFuzzyMatch ComputeFuzzyMatch( string value, string matcher )
  {
    var result = new LevenshteinFuzzyMatch();

    if ( matcher.Length >= value.Length )
    {
      result.index = 0;
      result.lowestDistance = LevenshteinDistance.Compute( value, matcher );
      
    }
    else
    {
      var offsets = value.Length - matcher.Length;

      for ( var i = 0; i < offsets; i++ )
      {
        var subValue = value.Substring( i, matcher.Length );
        var distance = LevenshteinDistance.Compute( subValue, matcher );

        if ( i == 0 )
        {
          result.index = 0;
          result.lowestDistance = distance;
          continue;
        }

        if ( distance < result.lowestDistance )
        {
          result.index = i;
          result.lowestDistance = distance;
        }
        
      }
    }


    return result;
  }


  public static int Compute( string a, string b )
  {
    var aLength = a.Length;
    var bLength = b.Length;

    if ( aLength == 0 ) { return bLength; }
    if ( bLength == 0 ) { return aLength; }

    var evaluationMatrix = LevenshteinDistance.GetMatrix( aLength, bLength );        
      
    for ( var i = 1; i <= aLength; i++ )
    {          
      for ( var j = 1; j <= bLength; j++ )
      {            
        var isSame = b[ j - 1 ] == a[ i - 1 ];

        var isDifferentCost = isSame ? 0 : 1;

        var insertionCost    = evaluationMatrix[ i - 1, j ] + 1;
        var deletionCost     = evaluationMatrix[ i , j - 1 ] + 1;
        var substitutionCost = evaluationMatrix[ i - 1, j - 1 ] + isDifferentCost;
          
        evaluationMatrix[ i , j ] = Mathf.Min( Mathf.Min( insertionCost, deletionCost ), substitutionCost );
      }
    }
      
    return evaluationMatrix[ aLength, bLength ];
  }
}