import uuid as _uuid
from dataclasses import dataclass, field
from enum import Enum


class EventType(str, Enum):
    FALL = "fall"
    NO_MOTION = "no_motion"
    IMMOBILITY = "immobility"
    GHOST = "ghost"
    ZONE_WARNING = "zone_warning"
    ZONE_RESTRICTED = "zone_restricted"
    PINCH = "pinch"
    MONITORING_DEGRADED = "monitoring_degraded"
    DEVICE_FAULT = "device_fault"
    LONE_WORKER = "lone_worker"        # 2인 1조 존에 단독 작업 지속
    OVERCAPACITY = "overcapacity"      # 존 정원 초과 지속
    OVERSTAY = "overstay"              # 존 체류 상한 초과 (트랙별)


class Severity(str, Enum):
    CRITICAL = "critical"
    HIGH = "high"
    WARNING = "warning"
    INFO = "info"


_SEVERITY = {
    EventType.NO_MOTION: Severity.CRITICAL,
    EventType.GHOST: Severity.CRITICAL,
    EventType.FALL: Severity.HIGH,
    EventType.ZONE_RESTRICTED: Severity.HIGH,
    EventType.PINCH: Severity.HIGH,
    EventType.IMMOBILITY: Severity.WARNING,
    EventType.ZONE_WARNING: Severity.WARNING,
    EventType.MONITORING_DEGRADED: Severity.WARNING,
    EventType.DEVICE_FAULT: Severity.WARNING,
    # 단독 작업은 규정 위반이자 사고 시 구조 지연 요인 — 정원/체류보다 한 단계 높게.
    EventType.LONE_WORKER: Severity.HIGH,
    EventType.OVERCAPACITY: Severity.WARNING,
    EventType.OVERSTAY: Severity.WARNING,
}


def severity_for(event_type: EventType) -> Severity:
    return _SEVERITY.get(event_type, Severity.INFO)


@dataclass(frozen=True)
class Event:
    event_type: EventType
    severity: Severity
    camera_id: str
    track_id: int | None
    zone_id: str | None
    occurred_at: float
    duration_s: float
    metrics: dict
    spatial: tuple | None  # (x, y) 유령사고 등 공간 기준
    # Stable idempotency key: generated ONCE at event creation and carried unchanged through the
    # offline queue and every retry, so a POST that succeeded server-side but timed out
    # client-side is deduplicated by the server (see server IngestController) instead of stored twice.
    event_uuid: str = field(default_factory=lambda: _uuid.uuid4().hex)

    def to_payload(self, device_id: str) -> dict:
        return {
            "device_id": device_id,
            "event_uuid": self.event_uuid,
            "camera_id": self.camera_id,
            "event_type": self.event_type.value,
            "severity": self.severity.value,
            "track_id": self.track_id,
            "zone_id": self.zone_id,
            "occurred_at": self.occurred_at,
            "duration_s": round(self.duration_s, 2),
            "metrics": self.metrics,
        }