id like to creat a pgf plot for overleaf from the below : $$P_{2}(\eta) = \begin{cases} \frac{1}{48} (-1 + \eta)^3 (-1 - 3 \eta + 9 \eta^2 + 3 \eta^3) & \text{if } 0 \leq \eta < \sqrt{2}-1 \\ -\frac{\eta^2\left(-1\ +\ \eta\ \left(2\ +\ \eta ight) ight)^2\left(6\ +\ \eta\ \left(-8\ +\ \eta\ \left(-17\ +\ \eta\ \left(20\ +\ 3\ \left(-2\ +\ \eta ight)^2\eta ight) ight) ight) ight)}{48\ \left(-1\ +\ \eta^2 ight)^3}\\ - \frac{1}{48} \ \frac{(1 - 3\eta^2)^4}{(-1 + \eta^2)^3} & \text{if }\sqrt{2}-1 \leq \eta < \frac{1}{\sqrt{3}} \\ -\frac{1}{48} (-1 + \eta)^3 (-1 - 3\eta + 9\eta^2 + 3\eta^3) & \text{if } \frac{1}{\sqrt{3}} \leq \eta \leq 1 \end{cases}$$