black slacks, black shirt, tie, i'm not sure about the jeans that just doesn't seem fitting, however if that is all you have, i'm sure your friend would rather you wore that and came, rather than not coming at all
You're supposed to wear black or at least dark clothes at a funeral. Dark grey or blue might be okay too, but white? No way. I don't know any country in Europe where wearing white clothes at a funeral is commonly accepted. Someone will get offended for sure.
A suit, for sure. Dark colors are normal in many cultures, black being the obvious choice. White colored dress shirt - don't wear a dark suit AND a dark shirt... you'll look like a mortician. Wear a relatively plain solid colored tie, no flashy patterns and no bright colors.
Dress shoes, dark socks. Never white/light socks with dark pants and shoes. The color of your shoes should match the color of your belt. (brown or black) Brown dress shoes are hard to pull off with black suits, but it is possible - you just have to know what you're doing. Better to stick to black shoes and belt.
You're not there to impress anyone, but it's still a time to show respect. Dress the part, it's only one day.
Of course, all of this depends upon your culture, what others will be wearing, do you have to speak, will you be "greeting" people and accepting condolences, etc.