Managing references to custom counters

Question

I would like to have a precise control on references to custom counters.

For instance,

• I would like to give a reference to a series of two independent counters
• I would like to choose the formatting of the reference

I have looked around but I haven't found a solution.

Here is a MWE.

\documentclass{article}

\newcounter{counterOne}
\newcounter{counterTwo}
\renewcommand{\thecounterTwo}{\alph{counterTwo}}

\begin{document}
\refstepcounter{counterOne}
\refstepcounter{counterTwo}

\label{here} Here

It was \ref{here}.

\bigskip

I would like that it displays : It was \textbf{1.(a)}
\end{document}

---

EDIT:

I've tried David's answer but it doesn't work. Here is a MWE. Unfortunately, as I don't understand the commands used in the answer, I can't fix by myself the errors.

\documentclass{article}

\newcounter{counterOne}
\newcounter{counterTwo}
\renewcommand{\thecounterTwo}{\alph{counterTwo}}

\makeatletter
\def\labelformat#1{\expandafter\def\csname p@#1\endcsname##1}
\makeatother
\labelformat{counterTwo}{\textbf{\thecounterOne.(#1)}}

\begin{document}
\refstepcounter{counterOne}
\refstepcounter{counterTwo}

\label{here} Here

It was \ref{here}.

\bigskip

I would like that it displays : It was \textbf{1.(a)}
\end{document}

The error is

Argument of @firstofone has an extra }. \par l.23 \end{document}

Answer 1

\documentclass{article}

\newcounter{counterOne}
\newcounter{counterTwo}
\renewcommand{\thecounterTwo}{\alph{counterTwo}}

% \labelformat is defined in current latex to customise the output from \ref
% For older formats load the package \usepackage{varioref} from the core
% tools bundle which originally defined this mechanism.

\labelformat{counterTwo}{\textbf{\thecounterOne.(#1)}}

\begin{document}
\refstepcounter{counterOne}
\refstepcounter{counterTwo}

\label{here} Here

It was \ref{here}.

\bigskip

I would like that it displays : It was \textbf{1.(a)}
\end{document}