local function levenshtein(str1, str2)
    local len1 = string.len(str1)
    local len2 = string.len(str2)
    local matrix = {}
    local cost = 0

    -- quick cut-offs to save time
    if (len1 == 0) then
        return len2
    elseif (len2 == 0) then
        return len1
    elseif (str1 == str2) then
        return 0
    end

    -- initialise the base matrix values
    for i = 0, len1, 1 do
        matrix[i] = {}
        matrix[i][0] = i
    end
    for j = 0, len2, 1 do
        matrix[0][j] = j
    end

    -- actual Levenshtein algorithm
    for i = 1, len1, 1 do
        for j = 1, len2, 1 do
            if (str1:byte(i) == str2:byte(j)) then
                cost = 0
            else
                cost = 1
            end

            matrix[i][j] = math.min(matrix[i - 1][j] + 1, matrix[i][j - 1] + 1, matrix[i - 1][j - 1] + cost)
        end
    end

    -- return the last value - this is the Levenshtein distance
    return matrix[len1][len2]
end

return levenshtein