Let the function \( f:[0,2]\to \mathbb{R} \) be defined as where \( [t] \) denotes the greatest integer less then or equal to \( t \). Then the value of the integral \(\displaystyle \int_{0}^{2} x f(x)\,dx \) is:
\( 2e-\dfrac{1}{2} \)
\( (e-1)\!\left(e^{2}+\dfrac{1}{2}\right) \)
\( 2e-1 \)
\( 1+\dfrac{3e}{2} \)