#include "CRSMUtil.hpp"

namespace Util {
    int damerauLevenshteinDistance(const QString& s1, const QString& s2)
    {
        int length1 = s1.length();
        int length2 = s2.length();
        int d[length1+1][length2+1];

        int i;
        int j;
        int cost;

        for(i = 0; i <= length1; i++)
        {
            d[i][0] = i;
        }
        for(j = 0; j <= length2; j++)
        {
            d[0][j] = j;
        }
        for (i = 0; i < length1;i++)
        {
            for(j = 0; j < length2; j++)
            {
                if(s1[i] == s2[j])
                {
                    cost = 0;
                }
                else
                {
                    cost = 1;
                }
                d[i+1][j+1] = std::min({
                    d[i][j+1] + 1, // delete
                    d[i+1][j] + 1, // insert
                    d[i][j] + cost // substitution
                });
                if((i > 0) && (j > 0) && (s1[i] == s2[j-1]) && (s1[i-1] == s2[j]))
                {
                    d[i+1][j+1] = std::min(
                        d[i+1][j+1],
                        d[i-1][j-1] + cost   // transposition
                    );
                }
            }
        }
        return d[length1][length2];
    }
}