General aviation pilot reported a near miss with another aircraft while landing at a non-towered airport. The pilot maneuvered to avoid a collision then returned for landing.

Narrative

I approached VIS from the north-east; announcing my position at 10 miles out and at 2500ft. Radio traffic indicated a busy pattern using runway 30. Winds were light and variable. Runway 30 is the designated calm-wind runway at VIS. At 5 miles out; I announced my position and altitude again; and intention to overfly the airport at 2500ft (pattern altitude 1300ft MSL) and use a teardrop entry for a 45-degree entry to a left downwind for a full-stop landing on runway 30. After announcing my position overhead the runway and passing the downwind pattern; I began a descent and was about to initiate a right turn for the teardrop when I saw an aircraft on ADSB at roughly 1300ft AGL heading directly for the airport. There were no announcements from this aircraft and I picked him upon on my visual scan shortly thereafter. He did not appear aware of my presence and I positively identified the aircraft as Aircraft Y. I extended my direction of flight until he passed behind me and began my teardrop. I lost sight of him visually and assumed he had overflown the airport. I entered a standard downwind after the 45-degree entry; a normal base-leg; and a normal turn to final; with routine position announcements. On short final and approximately 100ft AGL; a local CFI who landed a few minutes earlier made a radio announcement to advise me that 'there's some guy on final for runway 12 right now'. I was able to make visual contact and saw Aircraft Y on short final; opposite direction. There had been no radio calls of any kind on the CTAF from this aircraft. I applied full power for a go-around and broke right to overfly the taxiway. I made a radio announcement of the go-around and advised the other aircraft to break right to remain clear. There was no reply and Aircraft Y made a touch-and-go on the runway while I flew opposite direction over the taxiway. Upon climb-out I advised local traffic that I was flying the upwind for closed traffic back to runway 30. After turning downwind; I saw Aircraft Y flying west from the airport opposite to the standard left base-leg. Another aircraft trying to enter the pattern needed to do a 360-degree turn to accommodate my unexpected downwind and was asking for position advisories on Aircraft Y; which I was able to give. As Aircraft Y departed to the west; all remaining aircraft landed on rwy 30 in a standard and safe fashion. After landing; I discussed the incident with the CFI who had made the timely radio call. He suspected that it might have been a student pilot from ZZZ given the aircraft type. Subsequent investigation via a flight tracker [it] appears to confirm this; showing Aircraft Y initiated and ended its flight in ZZZ. The track shows that after making touch-and-goes at ZZZ1; the aircraft proceeded directly to VIS; cut through the active traffic pattern at pattern height; and made a touch-and-go landing opposite to the prevailing traffic pattern. Had the CFI not made the timely radio call; this would have resulted in two aircraft landing opposite direction simultaneously on the same runway and potentially a head-on collision. I believe that this incident was caused by a gross disregard for standard piloting practice by the Aircraft Y pilot. While radio calls are not required at uncontrolled airfields; they are certainly expected if the aircraft is equipped with a radio. Similarly; while any runway can be used at an uncontrolled airport; this aircraft flew through an active traffic pattern; made no radio calls; and landed opposite the busy and prevailing pattern. The pilot showed a complete lack of situation awareness; failed to adhere to standard best practices; and showed no evidence of appropriate aeronautical decision making. While I do not believe that this incident should result in any action against the pilot; I do think that it merits some remedial education or at least a reminder that they are not the only aircraft in the sky. For myself; I learned several lessons. I routinely use ADSBto check for traffic in the pattern as a back-up to my visual scan; but I failed to positively identify this individual's position after he passed me. Had I been aware that he had overflown the airport and entered a left-downwind for rwy 12 (rather than flying eastward as I had assumed); I would have been better prepared for the go-around or might have flown an upwind leg at traffic-pattern altitude. Following the go-around; I was preoccupied with his position and failed to identify that another aircraft was attempting to enter the pattern via an overhead teardrop entry similar to the one I had flown. As I turned downwind; he needed to make a 360-degree turn for spacing. My situational awareness was not as strong as it could have been; although we used good communication and spacing was not a concern. I also routinely check the final approach path before turning base-to-final; in case there is traffic on final that isn't announcing itself. On this flight I learned that I also need to take time to check the *other* final approach path to ensure there isn't opposite direction traffic. In summary; I suspect that this was a student pilot with poor SA (Situational Awareness); perhaps announcing on the wrong frequency (it just occurred to me that I could have checked the ZZZ1 frequency to see if he was on it). Additional emphasis on uncontrolled field operations for primary students at this school (if our suspicion is correct) would be helpful in mitigating further incidents.