This piece is from Bach's Well Tempered Clavier. The Well Tempered Clavier consists of 24 Preludes and Fugues in every possible key, and this is the first one in C major. The entire piece consists of the same arpeggio pattern. So your right hand pattern is mostly the same: p-p-i-m-a-i-m-a.

The strategy for this type of arrangement is quite simple: to build the arpeggio use the melody, and with other notes of the backing chords you fill the "holes", i.e. rests or tied notes.