from dataclasses import dataclass
from typing import Enum

class OccupantClass(Enum):
    EMPTY = 0
    CHILD = 1       # <36kg
    SMALL_ADULT = 2 # 36-60kg
    ADULT = 3       # 60-100kg
    LARGE_ADULT = 4  # >100kg

class PostureClass(Enum):
    NORMAL = 0
    FORWARD_LEAN = 1   # OOP前倾
    RECLINED = 2        # 后仰
    SIDE_LEAN = 3       # 侧倾
    OUT_OF_POSITION = 4 # 严重OOP

@dataclass
class OccupantState:
    classification: OccupantClass
    posture: PostureClass
    distance_to_wheel: float    # cm
    weight_estimate: float      # kg
    height_estimate: float      # cm
    seat_position: float        # 0-1 (0=最前, 1=最后)
    belt_fastened: bool

@dataclass
class RestraintStrategy:
    airbag_enabled: bool
    airbag_volume: float         # L (60-90)
    airbag_venting: str         # 'low', 'medium', 'high'
    belt_pretension_force: float # N
    belt_load_limiter: str      # 'low', 'medium', 'high'
    deploy_timing: str          # 'normal', 'delayed', 'early'

class RestraintController:
    """ZF LIFETEC风格约束控制决策"""
    
    def compute_strategy(self, state: OccupantState, 
                         crash_severity: float) -> RestraintStrategy:
        """根据乘员状态+碰撞严重度计算约束策略"""
        
        # 空座
        if state.classification == OccupantClass.EMPTY:
            return RestraintStrategy(
                airbag_enabled=False, airbag_volume=0,
                airbag_venting='low', belt_pretension_force=0,
                belt_load_limiter='low', deploy_timing='normal'
            )
        
        # 儿童座椅
        if state.classification == OccupantClass.CHILD:
            return RestraintStrategy(
                airbag_enabled=False, airbag_volume=0,
                airbag_venting='low', belt_pretension_force=200,
                belt_load_limiter='low', deploy_timing='normal'
            )
        
        # OOP检测
        if state.posture == PostureClass.FORWARD_LEAN:
            if state.distance_to_wheel < 25:  # <25cm严重OOP
                return RestraintStrategy(
                    airbag_enabled=True, airbag_volume=60,
                    airbag_venting='high',  # 快速排气
                    belt_pretension_force=400,  # 强力预紧拉回
                    belt_load_limiter='low',
                    deploy_timing='delayed'  # 延迟部署
                )
        
        # 根据体型调整
        if state.classification == OccupantClass.SMALL_ADULT:
            volume, limiter = 60, 'low'
        elif state.classification == OccupantClass.LARGE_ADULT:
            volume, limiter = 90, 'high'
        else:
            volume, limiter = 75, 'medium'
        
        # 后仰
        if state.posture == PostureClass.RECLINED:
            volume = min(volume + 10, 90)  # 增大体积
            limiter = 'low'
        
        return RestraintStrategy(
            airbag_enabled=True,
            airbag_volume=volume,
            airbag_venting='medium',
            belt_pretension_force=300 + crash_severity * 200,
            belt_load_limiter=limiter,
            deploy_timing='normal'
        )


# 测试
if __name__ == "__main__":
    controller = RestraintController()
    
    test_cases = [
        ("空座", OccupantClass.EMPTY, PostureClass.NORMAL, 50, 70),
        ("儿童", OccupantClass.CHILD, PostureClass.NORMAL, 30, 100),
        ("小身材成人", OccupantClass.SMALL_ADULT, PostureClass.NORMAL, 45, 50),
        ("大身材成人", OccupantClass.LARGE_ADULT, PostureClass.NORMAL, 60, 55),
        ("前倾OOP", OccupantClass.ADULT, PostureClass.FORWARD_LEAN, 20, 60),
        ("后仰休息", OccupantClass.ADULT, PostureClass.RECLINED, 55, 40),
    ]
    
    print("=== 乘员状态→约束策略映射 ===")
    print(f"{'场景':<15} {'气囊':>6} {'体积(L)':>8} {'排气':>8} {'预紧(N)':>8} {'限力':>8} {'时序'}")
    print("-" * 70)
    
    for name, occ_class, posture, dist, weight in test_cases:
        state = OccupantState(
            classification=occ_class,
            posture=posture,
            distance_to_wheel=dist,
            weight_estimate=weight,
            height_estimate=170,
            seat_position=0.5,
            belt_fastened=True
        )
        strategy = controller.compute_strategy(state, crash_severity=0.8)
        print(f"{name:<15} {'✅' if strategy.airbag_enabled else '❌':>6} "
              f"{strategy.airbag_volume:>8.0f} {strategy.airbag_venting:>8} "
              f"{strategy.belt_pretension_force:>8.0f} {strategy.belt_load_limiter:>8} "
              f"{strategy.deploy_timing}")