Cottage Wall Movement/damage - How and Solution

I am considering purchasing a cottage but noticed that on one exterior wall of the cottage, it appears to have moved approx one inch outwards at the top of the wall ie. small gap where the wall meets the ceiling. This was noticed in a couple rooms inside and on the same wall - the seperation runs for approx 16 ft in the middle of a 45ft wall. Also noticed outside in the same area, looks like there is bowing out at the end of the roof line. Cannot determine issues from looking in the attic other than some bowing mostly on the opposite side of the roof. Was this caused by a one time snow event or should I be concerned - has the snow forced the roof down, putting pressure, forcing the wall out? What is the repair to ensure the outter wall does not move any further, and what are the risks if nothing is done?

thank you,

Al