from dataclasses import dataclass

from edge.tracking import Track
from edge.models import L_ANKLE, R_ANKLE


def point_in_polygon(x: float, y: float, poly: list[tuple[float, float]]) -> bool:
    inside = False
    n = len(poly)
    j = n - 1
    for i in range(n):
        xi, yi = poly[i]
        xj, yj = poly[j]
        if ((yi > y) != (yj > y)) and (x < (xj - xi) * (y - yi) / ((yj - yi) or 1e-9) + xi):
            inside = not inside
        j = i
    return inside


@dataclass(frozen=True)
class Zone:
    zone_id: str
    level: str  # "warning" | "restricted"
    polygon: list  # list[tuple[float,float]]


@dataclass
class ZoneConfig:
    debounce_s: float = 0.75


class ZoneIntrusionDetector:
    def __init__(self, zones: list[Zone], cfg: ZoneConfig):
        self.zones = zones
        self.cfg = cfg
        self._inside_since: dict[tuple[int, str], float] = {}
        self._fired: set[tuple[int, str]] = set()

    def forget(self, track_id: int) -> None:
        self._inside_since = {k: v for k, v in self._inside_since.items() if k[0] != track_id}
        self._fired = {k for k in self._fired if k[0] != track_id}

    def _foot(self, track: Track, frame_wh=None) -> tuple[float, float]:
        kps = track.latest.keypoints
        a, b = kps[L_ANKLE], kps[R_ANKLE]
        fx, fy = (a.x + b.x) / 2, (a.y + b.y) / 2
        # Zones are stored NORMALIZED (0..1 of the image) by the dashboard, which stretches the
        # camera snapshot to a fixed canvas. The foot is camera-native pixels, so normalize it
        # by the frame size to compare in the same space — otherwise every zone is misplaced
        # (a zone drawn at image-centre would be checked against a raw pixel like 480, matching
        # nothing on a 1280-wide frame). frame_wh=None keeps raw coords for unit tests that
        # supply their own matching space.
        if frame_wh:
            w, h = frame_wh
            if w > 0 and h > 0:
                fx, fy = fx / w, fy / h
        return (fx, fy)

    def active_zone_ids(self, track_id: int) -> set:
        return {z for (tid, z) in self._inside_since if tid == track_id}

    def update(self, track: Track, now: float, frame_wh=None) -> list[dict]:
        fx, fy = self._foot(track, frame_wh)
        out = []
        for zone in self.zones:
            key = (track.track_id, zone.zone_id)
            if point_in_polygon(fx, fy, zone.polygon):
                start = self._inside_since.setdefault(key, now)
                if now - start >= self.cfg.debounce_s and key not in self._fired:
                    self._fired.add(key)
                    out.append({"zone_id": zone.zone_id, "level": zone.level})
            else:
                self._inside_since.pop(key, None)
                self._fired.discard(key)
        return out