binomial expression with $x^r$

Question

Solve the series $$\sum_{p\ge0}\sum_{r\ge0}(1+x^{n-p+1})\left(\binom{p}{r}^2x^r\right)$$ What I am having problem here is accommodating for that $x^r$ otherwise $\sum_{r\ge0} \binom{p}{r}^2 $ is quite easily solvable by generating it from the product of $(1+x)^n$ and $(x+1)^n$ and we get the result out to be $\binom{2p}{p}$. Any insight would be helpful...