Question regarding double integrals

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Regarding the Buffon's needle case for long needles of length $ l>t, $ (the distance between the parallel lines on the floor), we need to solve the integral $$ \int_{\theta=0}^{\frac{\pi}{2}} \int_{x=0}^{m(\theta)} \frac{4}{t\pi}\,dx\,d\theta $$ where $m(\theta) $ is the minimum between $(l/2)\sin\theta$ and $t/2 $. My question is how do I calculate the integral where the limit is a minimum of two numbers of which either can be greater than the other?