Air carrier Flight Attendant reported a gate agent suddenly opened the main cabin door upon arrival while Flight Attendant's arm was around the arming handle.

Narrative

Upon arrival to PLS; air stairs (ramp) was connected and gate agent knocked on the Main Cabin Door (MCD); I gave the thumbs up and was about to crack the door per SOP; when gate agent suddenly; dangerously; and very rapidly; flung open the MCD in my face. The right side of my body was right next to the MCD and my right arm around the arming handle. I quickly jumped back away from the door to avoid getting injured but this was SO DANGEROUS!!! Apparently island countries rush the arrival and the opening of the MCD due to certain time constraints they are given. I don't know what these are but this is SO dangerous and brought about the rushing of this CSR to get my MCD open while almost breaking my arm in the process. Please not only advise PLS of this as this main individual is always receiving air carrier flights and I do not want this to happen again to another FA. This is also the same airport where a maintenance worker tried to open the MCD on another flight of mine; almost deploying the emergency slide and ultimately injuring the purser for that flight in the process.