Find all functions $f$ defined over real numbers to real numbers such that $f(f(y))+f(x-y)=f(xf(y)-x)$
My attempt: Set $x=y=0$ to get $f(f(0))=0$. It will be very helpful if I will able to find $f(0)$ but I failed to find it. I tried to check the injectivity of $f$ but wasn't able to check it.
Please help me.