"""阈值智能推荐 API

2026-09-11 (project-20260911-threshold-fix) 修复：
    推荐值必须与后端解析器（app.utils.threshold_parser）语法一致 —— 原实现给黄灯/适中型
    生成区间/文字标签（`52.33~107.67`、`偏离55%`），用户点“自动建议”填入后保存即静默失效。
    现在统一生成可解析表达式：标量比较（支持负数）/ 闭区间 `A~B` / 多条件 `C1|C2`。
"""
from fastapi import APIRouter, Depends, Query
from sqlalchemy.orm import Session
from app.database import get_db
from app.auth_middleware import require_auth, require_role
from app.models import KPIDefinition, KPIValue, OperationLog
from app.utils.threshold_parser import THRESHOLD_HELP, is_valid_threshold
from typing import Any, Optional
import json

router = APIRouter(prefix="/api/cma/thresholds", tags=["阈值分析"],
    dependencies=[Depends(require_role("ceo", "finance", "business", "it"))],
)

KPI_TYPES = {
    "higher_better": ["SALES_TOTAL", "CUSTOMER_COUNT", "SALES_PROFIT_RATE", 
                      "CUSTOMER_SATISFACTION", "ORDER_DELIVERY_RATE", "TRAINING_COMPLETION",
                      "RECEIVABLE_TURNOVER", "TURNOVER_RATE"],
    "lower_better": ["COST_CONTROL_RATE"],
    "middle_best": ["TOP5_CUSTOMER_RATIO"],
}


def _r(v) -> float:
    """保留2位小数（避免浮点噪声写进表达式）"""
    return round(float(v), 2)


def _fmt(v) -> str:
    """数值 → 表达式文本。禁用科学计数法：`:g` 在 |v|>=1e6 时会输出 1.6e+06，
    解析器不认（会导致推荐值再次静默失效）。"""
    s = f"{float(v):.2f}".rstrip("0").rstrip(".")
    return s if s not in ("", "-") else "0"


def build_suggestion(kpi_type: str, target: float, tolerance: Optional[float] = None) -> dict:
    """按类型生成可解析的红黄绿阈值建议（仅生成表达式，不含 I/O）。

    口径（label = 该等级的触发条件，判定优先级 red→green→yellow）：
        higher_better：绿 `>=0.8T`、黄 `>=0.5T`（更宽的兜底带）、红 `<0.5T`
        lower_better ：绿 `<=1.2T`、黄 `<=2.0T`、红 `>2.0T`
        middle_best  ：绿 `T±tol` 闭区间、黄 `T±2tol` 外环带（green ⊂ yellow）、红 `<T-2tol|>T+2tol`
    """
    if kpi_type == "higher_better":
        green_min = _r(target * 0.8)
        yellow_min = _r(target * 0.5)
        red_max = yellow_min
        return {
            "type": "higher_better",
            "description": "越高越好型",
            "green": {"min": green_min, "max": None, "label": f">={_fmt(green_min)}"},
            "yellow": {"min": yellow_min, "max": green_min, "label": f">={_fmt(yellow_min)}"},
            "red": {"min": None, "max": red_max, "label": f"<{_fmt(red_max)}"},
        }
    if kpi_type == "lower_better":
        green_max = _r(target * 1.2)
        yellow_max = _r(target * 2.0)
        red_min = yellow_max
        return {
            "type": "lower_better",
            "description": "越低越好型",
            "green": {"min": None, "max": green_max, "label": f"<={_fmt(green_max)}"},
            "yellow": {"min": green_max, "max": yellow_max, "label": f"<={_fmt(yellow_max)}"},
            "red": {"min": red_min, "max": None, "label": f">{_fmt(red_min)}"},
        }
    # middle_best（适中最好型）：绿=内区间 T±tol，黄=外环带 T±2tol（green ⊂ yellow），红=环带之外
    tol = float(tolerance) if tolerance else abs(float(target)) * 0.2
    if tol <= 0:
        tol = 1.0
    a, b = _r(target - tol), _r(target + tol)
    c, d = _r(target - 2 * tol), _r(target + 2 * tol)
    return {
        "type": "middle_best",
        "description": "适中最好型",
        "green": {"min": a, "max": b, "label": f"{_fmt(a)}~{_fmt(b)}"},
        "yellow": {"min": c, "max": d, "label": f"{_fmt(c)}~{_fmt(d)}"},
        "red": {"min": None, "max": None, "label": f"<{_fmt(c)}|>{_fmt(d)}"},
    }


def suggest_by_type(kpi):
    """无历史数据时按类型推荐（同样输出可解析表达式，含 yellow/red 标签）"""
    target = kpi.target_value or 100
    kpi_type = _kpi_type(kpi)
    suggestion = build_suggestion(kpi_type, target)
    return {"kpi_id": kpi.id, "kpi_name": kpi.kpi_name, "message": "无历史数据",
            "format_hint": THRESHOLD_HELP, "suggestion": suggestion}


def _kpi_type(kpi) -> str:
    if kpi.kpi_code in KPI_TYPES["lower_better"]:
        return "lower_better"
    if kpi.kpi_code in KPI_TYPES["middle_best"]:
        return "middle_best"
    return "higher_better"


def _sanity_check(suggestion: dict) -> dict:
    """自检：推荐值必须过解析器（防再次生成不可解析格式），并挂 format 提示给前端。"""
    bad = []
    for level in ("green", "yellow", "red"):
        label = (suggestion.get(level) or {}).get("label")
        if label and not is_valid_threshold(label):
            bad.append({"level": level, "label": label})
    suggestion["parseable"] = not bad
    if bad:
        suggestion["unparseable"] = bad
    return suggestion


@router.get("/suggest/{kpi_id}")
def suggest_threshold(kpi_id: int, db: Session = Depends(get_db)):
    """根据历史数据自动推荐阈值（输出格式保证被 threshold_parser 解析生效）"""
    kpi = db.query(KPIDefinition).filter(KPIDefinition.id == kpi_id).first()
    if not kpi:
        return {"error": "KPI不存在"}
    
    values = db.query(KPIValue).filter(KPIValue.kpi_id == kpi_id).order_by(KPIValue.period.asc()).all()
    
    if not values:
        # 无历史数据，按行业标准推荐
        return suggest_by_type(kpi)
    
    nums = [v.actual_value for v in values if v.actual_value is not None]
    
    if len(nums) < 2:
        return suggest_by_type(kpi)
    
    # 注: SQLAlchemy 模型属性未做 Mapped 注解, Pyright 会推断为 Column;
    # 这里统一标注 Any 抑制静态噪音(运行期均为 float)。
    avg: Any = sum(nums) / len(nums)
    # 计算标准差
    variance: Any = sum((x - avg) ** 2 for x in nums) / len(nums)
    std: Any = variance ** 0.5
    
    target: Any = kpi.target_value or avg
    kpi_type = _kpi_type(kpi)

    if kpi_type == "middle_best":
        tolerance: Any = max(std * 1.5, target * 0.2)
        suggestion = build_suggestion(kpi_type, target, tolerance)
    else:
        suggestion = build_suggestion(kpi_type, target)
    suggestion = _sanity_check(suggestion)
    suggestion["current_avg"] = round(avg, 2)
    suggestion["target"] = target

    return {"kpi_id": kpi_id, "kpi_name": kpi.kpi_name,
            "format_hint": THRESHOLD_HELP, "suggestion": suggestion}