oscilloscope - How to connect 230V 50Hz to arduino analog input

I want to use my arduino to make a simple mains power line voltage wave oscilloscope.
questions:
1. how to connect the mains power line (230V, 50Hz) to the arduino safely and efficient (I think a simple resistor voltage divider wouldn't cut it here)?
2. can i use serial communication to get this data in real time to the PC and then do some analysis in processing or some other software (maybe a simple labview analyzing the serial data because I'm familiar with this)?

any links for documentation would be highly appreciated, 10x guys ;)