How to get the current window horizontal padding?

Question

Today I wrote this little utility function to resize my current window to a comfortable width:

-- Resizes the current window to the maximum required width
function M.resize_window()
    local padding = 7
    local lines_count = vim.api.nvim_buf_line_count(0)
    local lines = vim.api.nvim_buf_get_lines(0, 0, lines_count, false)

    local longerLine = 0
    for _, line in ipairs(lines) do
        local new_len = string.len(line) or 0
        if new_len > longerLine then
            longerLine = new_len
        end
    end
    local cmd = (longerLine + padding) .. "wincmd |"
    vim.api.nvim_command(cmd)
end

As you can see, I just hardcoded some padding to a value of 7. Any way to know what value should I put as padding instead of that fixed 7 ? I guess this has to do with decorations like line-numbers, relative numbers and that stuff.