"""
DAT10: 오프라인 단말 간 1차 P2P/USB 재고 데이터 교환 및 베이스라인 탐지 모델
- P2P 재고 상태 교환 및 단순 LWW(Last-Write-Wins) 동기화
- 룰 기반 베이스라인 재고 급감/안전재고 미달 탐지
"""

from typing import Dict, List, Any
import datetime

class P2PInventoryBaselineSync:
    def __init__(self, node_id: str):
        self.node_id = node_id
        self.local_state: Dict[str, Dict[str, Any]] = {}
        # nsn_code -> {"stock": int, "lamport": int, "updated_at": str, "source_node": str}

    def update_local_inventory(self, nsn_code: str, stock: int, lamport: int) -> Dict[str, Any]:
        self.local_state[nsn_code] = {
            "stock": stock,
            "lamport": lamport,
            "updated_at": datetime.datetime.utcnow().isoformat() + "Z",
            "source_node": self.node_id
        }
        return self.local_state[nsn_code]

    def merge_p2p_payload(self, incoming_state: Dict[str, Dict[str, Any]]) -> Dict[str, Any]:
        """P2P/USB를 통해 수신된 피어 노드의 상태를 LWW 규칙으로 1차 병합"""
        merged_count = 0
        conflicts = []

        for nsn, remote_data in incoming_state.items():
            if nsn not in self.local_state:
                self.local_state[nsn] = remote_data
                merged_count += 1
            else:
                local_data = self.local_state[nsn]
                # Lamport Clock 비교
                if remote_data["lamport"] > local_data["lamport"]:
                    self.local_state[nsn] = remote_data
                    merged_count += 1
                elif remote_data["lamport"] == local_data["lamport"]:
                    # 타임스탬프 동률 시 노드 ID 사전식 순서
                    if remote_data["source_node"] > local_data["source_node"]:
                        self.local_state[nsn] = remote_data
                        merged_count += 1
                    elif remote_data["stock"] != local_data["stock"]:
                        conflicts.append({
                            "nsn_code": nsn,
                            "local_stock": local_data["stock"],
                            "remote_stock": remote_data["stock"],
                            "lamport": local_data["lamport"],
                            "peer_id": remote_data["source_node"]
                        })

        return {
            "merged_count": merged_count,
            "conflicts_count": len(conflicts),
            "conflicts": conflicts,
            "current_state": self.local_state
        }

class BaselineRuleDetector:
    def __init__(self, safety_threshold: int = 10, drop_ratio_threshold: float = 0.5):
        self.safety_threshold = safety_threshold
        self.drop_ratio_threshold = drop_ratio_threshold

    def evaluate_inventory_health(self, inventory_states: Dict[str, Dict[str, Any]]) -> List[Dict[str, Any]]:
        alerts = []
        for nsn, data in inventory_states.items():
            stock = data.get("stock", 0)
            if stock < self.safety_threshold:
                alerts.append({
                    "nsn_code": nsn,
                    "alert_type": "SAFETY_STOCK_VIOLATION",
                    "severity": "WARNING",
                    "current_stock": stock,
                    "threshold": self.safety_threshold,
                    "reason": f"잔여 재고({stock})가 안전 재고 기준({self.safety_threshold}) 미만입니다."
                })
        return alerts