"""一致性监控（§6.7）：时序层面质量自检，每目标独立状态。

机载激光移除后无外部距离基准，飞行中只能靠自身时序一致性监控数据质量：
**只能降级、不能纠偏**（绝对精度靠地面静态验证）。匹配层面的质量（|Δy|
残差、框高一致性、代价门限）由匹配硬约束承担，本节只管时序层面。
"""

from dataclasses import dataclass
from typing import Dict, Hashable, Optional


@dataclass
class ConsistencyStatus:
    """单目标单帧一致性判定结果（§6.7）。"""

    jump_px: Optional[float]  # |D − 上次 D|；首帧无参考为 None
    abnormal: bool            # 本帧是否跳变超门限
    streak: int               # 连续异常帧数（含本帧，正常帧清零）
    confidence_degraded: bool  # streak ≥ N：置信度降级
    invalid: bool              # streak ≥ M：质量语义判无效


class ConsistencyMonitor:
    """每目标：上次视差 + 连续异常计数（§11.1 必须持久化的状态）。"""

    def __init__(self, jump_px: float, degrade_frames: int, invalid_frames: int) -> None:
        if jump_px <= 0.0:
            raise ValueError("jump_px 必须为正")
        if degrade_frames < 1:
            raise ValueError("degrade_frames 必须 ≥ 1")
        if invalid_frames < degrade_frames:
            raise ValueError("invalid_frames 必须 ≥ degrade_frames")
        self._jump_px = jump_px
        self._degrade_frames = degrade_frames
        self._invalid_frames = invalid_frames
        self._last_d: Dict[Hashable, float] = {}
        self._streak: Dict[Hashable, int] = {}

    def advance(self, key: Hashable, disparity_px: float) -> ConsistencyStatus:
        """推进目标 key 的一致性判定（配对成功帧每帧一次）。"""
        last = self._last_d.get(key)
        if last is None:
            jump: Optional[float] = None
            abnormal = False
            streak = 0
        else:
            jump = abs(disparity_px - last)
            abnormal = jump > self._jump_px
            streak = self._streak.get(key, 0) + 1 if abnormal else 0
        self._last_d[key] = disparity_px
        if streak:
            self._streak[key] = streak
        else:
            self._streak.pop(key, None)
        return ConsistencyStatus(
            jump_px=jump,
            abnormal=abnormal,
            streak=streak,
            confidence_degraded=streak >= self._degrade_frames,
            invalid=streak >= self._invalid_frames,
        )

    def streak(self, key: Hashable) -> int:
        """目标 key 当前连续异常计数。"""
        return self._streak.get(key, 0)

    def drop(self, key: Hashable) -> None:
        """清理目标 key 的状态（目标老化清理时调用）。"""
        self._last_d.pop(key, None)
        self._streak.pop(key, None)

    def clear(self) -> None:
        self._last_d.clear()
        self._streak.clear()