"""
Module 2: 偏航系统异常检测

算法: IsolationForest
  - 替代原 DBSCAN，原生支持 fit/predict 分离
  - 日推理数据量小时 DBSCAN 聚类不稳定，IF 更鲁棒
  - 自带 anomaly score，支持按严重程度排序

子检测器:
  A. StaticYawDetector   - 静态偏航角 (yaw_ang) 异常检测
  B. CableTwistDetector  - 扭缆角度 (twist_ang) 异常检测
"""
import numpy as np
import pandas as pd
from sklearn.ensemble import IsolationForest
from sklearn.preprocessing import StandardScaler
import joblib
from pathlib import Path

from config import (
    COL_YAW_ANG, COL_TWIST_ANG,
    ISO_CONTAMINATION, ISO_RANDOM_STATE, ISO_N_ESTIMATORS,
)


# ── A. 静态偏航检测器 ──────────────────────────────────────────────────────────

class StaticYawDetector:
    """
    特征: yaw_ang、短窗口滚动均值/标准差（2小时）、长窗口滚动均值（12小时）。
    短窗口捕捉瞬时偏离，长窗口捕捉持续慢漂移。
    IsolationForest 检测偏航角持续偏离正常分布的异常。
    """
    WINDOW_SHORT = 12   # 10min采样 × 12 ≈ 2小时
    WINDOW_LONG  = 72   # 10min采样 × 72 ≈ 12小时

    def __init__(self, contamination: float = ISO_CONTAMINATION):
        self.scaler = StandardScaler()
        self.model = IsolationForest(
            n_estimators=ISO_N_ESTIMATORS,
            contamination=contamination,
            random_state=ISO_RANDOM_STATE,
        )

    def _features(self, df: pd.DataFrame) -> pd.DataFrame:
        s = df[COL_YAW_ANG].copy()
        feat = pd.DataFrame({
            "yaw_ang":        s,
            "roll_mean_short": s.rolling(self.WINDOW_SHORT, min_periods=1).mean(),
            "roll_std_short":  s.rolling(self.WINDOW_SHORT, min_periods=1).std().fillna(0),
            "roll_mean_long":  s.rolling(self.WINDOW_LONG,  min_periods=1).mean(),
        }, index=df.index)
        return feat.dropna(subset=["yaw_ang"])

    def fit(self, df: pd.DataFrame) -> "StaticYawDetector":
        feat = self._features(df)
        if feat.empty:
            raise ValueError("偏航特征为空，检查 yaw_ang 测点")
        X = self.scaler.fit_transform(feat)
        self.model.fit(X)
        return self

    def predict(self, df: pd.DataFrame) -> pd.DataFrame:
        out  = pd.DataFrame({"anomaly": False, "score": np.nan}, index=df.index)
        feat = self._features(df)
        if feat.empty:
            return out
        X = self.scaler.transform(feat)
        out.loc[feat.index, "anomaly"] = self.model.predict(X) == -1
        out.loc[feat.index, "score"]   = self.model.score_samples(X)
        return out

    def save(self, path: Path):
        joblib.dump(self, path)

    @classmethod
    def load(cls, path: Path) -> "StaticYawDetector":
        return joblib.load(path)


# ── B. 扭缆角度检测器 ──────────────────────────────────────────────────────────

class CableTwistDetector:
    """
    特征: twist_ang、绝对值、变化率。
    IsolationForest 检测扭缆角度异常偏离。
    """
    def __init__(self, contamination: float = ISO_CONTAMINATION):
        self.scaler = StandardScaler()
        self.model = IsolationForest(
            n_estimators=ISO_N_ESTIMATORS,
            contamination=contamination,
            random_state=ISO_RANDOM_STATE,
        )

    def _features(self, df: pd.DataFrame) -> pd.DataFrame:
        s = df[COL_TWIST_ANG].copy()
        feat = pd.DataFrame({
            "twist_ang": s,
            "abs_twist": s.abs(),
            "delta":     s.diff().fillna(0),
        }, index=df.index)
        return feat.dropna(subset=["twist_ang"])

    def fit(self, df: pd.DataFrame) -> "CableTwistDetector":
        feat = self._features(df)
        if feat.empty:
            raise ValueError("扭缆特征为空，检查 twist_ang 测点")
        X = self.scaler.fit_transform(feat)
        self.model.fit(X)
        return self

    def predict(self, df: pd.DataFrame) -> pd.DataFrame:
        out  = pd.DataFrame({"anomaly": False, "score": np.nan}, index=df.index)
        feat = self._features(df)
        if feat.empty:
            return out
        X = self.scaler.transform(feat)
        out.loc[feat.index, "anomaly"] = self.model.predict(X) == -1
        out.loc[feat.index, "score"]   = self.model.score_samples(X)
        return out

    def save(self, path: Path):
        joblib.dump(self, path)

    @classmethod
    def load(cls, path: Path) -> "CableTwistDetector":
        return joblib.load(path)