How can I add a label to an arrow?
\documentclass{article}
\usepackage{tikz}
\tikzstyle{every picture}+=[remember picture]
\tikzstyle{na} = [shape=rectangle,inner sep=0pt]
\newcommand{\ptFleche}[2]{ \tikz[baseline=(#1.base)]\node[na](#1){#2}; }
\newcommand{\Fleche}[5][thick]{ \begin{tikzpicture}[overlay] \path[->,#1](#2) edge [out=#4, in=#5] (#3) ;
\end{tikzpicture} }
\begin{document}
$$f(x)=\left\{
\begin{array}{ccc}
\ptFleche{mot1}{$f_1(x)$} & ,& x\in A \\
& & \\
\ptFleche{mot3}{$f_2(x)$} & ,&x\in B
\end{array}\right .\;\;\;\;,\;\;\;\;g(x)=\left\{
\begin{array}{ccc}
\ptFleche{mot2}{$g_1(x)$} & ,&x\in C\\
& & \\
\ptFleche{mot4}{$g_2(x)$} & ,&x\in D
\end{array}\right .$$
\Fleche[blue,line width=1.0pt]{mot1}{mot4}{20}{150}
\end{document}
Drawing that I have
Drawing that I want
Any hint would be appreciation.