I think it is genuine Longines movement BUT there appears to be parts from at least 2 other watches. The serial number of 10M which is about 1955. This is a 1920s style watch. The Gold Longines logo also appears to be from a 1950s watch that has been glued on to the enamel dial.
It has problems, it appears to be a marriage of parts seperated by decades. The case may also not have been Longines to begin with, so stay away from it.