EV 충전 플랫폼 초기 백업

app/services/billing.py

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+"""전력량 기반 요금 정산 서비스
+
+OCPP MeterValues의 Energy.Active.Import.Register (Wh 단위)를
+세션 시작/종료 시점에 기록하여 실제 충전량 기반 요금 계산.
+"""
+
+from app.config import get_settings
+
+settings = get_settings()
+
+
+def calculate_bill(start_wh: int, end_wh: int) -> dict:
+    """충전 요금 계산
+
+    Args:
+        start_wh: 충전 시작 시 meter 값 (Wh)
+        end_wh:   충전 종료 시 meter 값 (Wh)
+
+    Returns:
+        dict: 정산 내역
+    """
+    charged_wh = max(0, end_wh - start_wh)
+    charged_kwh = charged_wh / 1000
+
+    electricity_cost = round(charged_kwh * settings.ELECTRICITY_RATE)
+    service_fee = round(charged_kwh * settings.SERVICE_MARGIN)
+    total_bill = round(charged_kwh * settings.total_rate)
+
+    # CPO 방식(350원/kWh) 대비 절감액
+    cpo_rate = 350
+    saved_vs_cpo = round(charged_kwh * (cpo_rate - settings.total_rate))
+
+    return {
+        "charged_wh": charged_wh,
+        "charged_kwh": round(charged_kwh, 3),
+        "electricity_cost": electricity_cost,
+        "service_fee": service_fee,
+        "total_bill": total_bill,
+        "saved_vs_cpo": saved_vs_cpo,
+    }
+
+
+def estimate_charge_cost(kwh: float) -> dict:
+    """예상 충전 요금 계산 (QR 결제 화면용)"""
+    return {
+        "estimated_kwh": kwh,
+        "rate_per_kwh": settings.total_rate,
+        "estimated_cost": round(kwh * settings.total_rate),
+        "cpo_comparison": round(kwh * 350),
+        "savings": round(kwh * (350 - settings.total_rate)),
+    }