"""Bounded per-camera frame window. No copying of image tensors across the BT API."""
from collections import deque
class FrameWindow:
    def __init__(self,maximum=32):self.frames=deque(maxlen=maximum)
    def add(self,stamp,camera,path):
        if self.frames and stamp<self.frames[-1]['stamp']:self.frames.clear()
        if self.frames and stamp==self.frames[-1]['stamp']:
            views=self.frames[-1]['views']
            if camera in views or len(views)<3:views[camera]=path
        else:self.frames.append(dict(stamp=stamp,views={camera:path}))
    def since(self,after,now):
        return [dict(stamp=f['stamp'],views=dict(f['views'])) for f in self.frames if after<=f['stamp']<=now and now-f['stamp']<=10]