"""StereoYoloConfig 与 JSON 配置加载（需求说明 §4 配置项需求）。

全部配置外置、构造期一次加载并校验：缺项、未知字段、类型错误、非法取值
一律拒绝进入运行期（fail-fast）。几何参数（F/B/cx/cy/原分辨率）不在此
重复存储——输出框位于**输入图像自身的原生坐标系**，几何参数的唯一来源
是 utils/config/stereo_ranger.json（§4 配置一致性要求：同一配置源驱动，
杜绝两处漂移）。
"""

import json
from dataclasses import dataclass, fields
from typing import Any, Dict, Optional, Tuple

_CONCURRENCY_MODES = ("parallel", "sequential")
_INT_FIELDS = frozenset({"imgsz"})
_STR_FIELDS = frozenset({"model_path", "concurrency"})


@dataclass
class StereoYoloConfig:
    model_path: str = "models/yolo26n-drone.pt"
    imgsz: int = 640  # 左右共用（§2.2 第 2 条：同一缩放、同一填充）
    conf_threshold: float = 0.25  # ⚠占位：识别端自身过滤口径（§2.4）
    iou_threshold: float = 0.7  # ⚠占位：NMS IoU 门限
    class_whitelist: Optional[Tuple[int, ...]] = None  # None = 不过滤（§4 可选白名单）
    device: Optional[str] = None  # None = 自动选择（cpu / cuda:0 / …）
    concurrency: str = "parallel"  # parallel = 左右并发（§5 硬性要求，串行会吃掉全部预算）

    def __post_init__(self) -> None:
        _require(bool(self.model_path.strip()), "model_path", "不得为空")
        _require(
            self.imgsz >= 32 and self.imgsz % 32 == 0,
            "imgsz",
            "须为 32 的整数倍且 ≥ 32（YOLO 步长约束）",
        )
        _require(0.0 <= self.conf_threshold <= 1.0, "conf_threshold", "须落在 [0, 1]")
        _require(0.0 < self.iou_threshold <= 1.0, "iou_threshold", "须落在 (0, 1]")
        _require(self.concurrency in _CONCURRENCY_MODES, "concurrency", f"须为 {_CONCURRENCY_MODES} 之一")
        _require(self.device is None or bool(self.device.strip()), "device", "须为非空字符串或 null")
        if self.class_whitelist is not None:
            ids = tuple(self.class_whitelist)
            _require(
                len(ids) > 0 and all(isinstance(item, int) and not isinstance(item, bool) and item >= 0 for item in ids),
                "class_whitelist",
                "须为非空非负整数列表或 null",
            )
            self.class_whitelist = ids


def load_from_json(path: str) -> StereoYoloConfig:
    """从 JSON 文件构建配置；缺项/未知字段/类型错误/非法取值一律抛 ValueError。"""
    with open(path, encoding="utf-8") as handle:
        data: Dict[str, Any] = json.load(handle)
    if not isinstance(data, dict):
        raise ValueError("配置非法: 顶层须为 JSON 对象")
    known = {item.name for item in fields(StereoYoloConfig)}
    unknown = sorted(set(data) - known)
    if unknown:
        raise ValueError(f"未知配置字段: {unknown}")
    missing = sorted(known - set(data))
    if missing:
        raise ValueError(f"缺少配置字段: {missing}")
    for name, value in data.items():
        if name == "class_whitelist":
            if value is not None and not (
                isinstance(value, list)
                and all(isinstance(item, int) and not isinstance(item, bool) for item in value)
            ):
                raise ValueError("配置类型非法: class_whitelist 须为整数数组或 null")
        elif name == "device":
            if value is not None and not isinstance(value, str):
                raise ValueError("配置类型非法: device 须为字符串或 null")
        elif name in _STR_FIELDS:
            if not isinstance(value, str):
                raise ValueError(f"配置类型非法: {name} 须为字符串")
        elif name in _INT_FIELDS:
            if not isinstance(value, int) or isinstance(value, bool):
                raise ValueError(f"配置类型非法: {name} 须为整数")
        elif isinstance(value, bool) or not isinstance(value, (int, float)):
            raise ValueError(f"配置类型非法: {name} 须为数值")
    return StereoYoloConfig(**data)


def _require(condition: bool, field_name: str, message: str) -> None:
    if not condition:
        raise ValueError(f"配置非法: {field_name} {message}")