ev-charging-backend/app/routers/payments.py

"""결제 API — 토스페이먼츠 연동

결제 흐름:
  1. POST /payments/prepare     → orderId 발급 + Redis에 임시 저장
  2. 프론트에서 토스 결제 UI 호출 → 사용자 카드 입력
  3. POST /payments/confirm      → 백엔드에서 토스 confirm API 호출
  4. 승인 성공 → 세션 상태 AUTHORIZED → 충전 시작 가능
"""

import uuid
import json
import logging
from datetime import datetime, timezone

from fastapi import APIRouter, Depends, HTTPException, Request
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.database import get_db
from app.models import ChargingSession, Payment, SessionStatus, PaymentStatus
from app.schemas import PaymentRequest, PaymentConfirm, PaymentOut
from app.services.payment import toss_service
from app.config import get_settings

logger = logging.getLogger(__name__)
settings = get_settings()
router = APIRouter(prefix="/payments", tags=["결제"])


@router.post("/prepare")
async def prepare_payment(
    data: PaymentRequest,
    db: AsyncSession = Depends(get_db),
):
    """결제 준비 — orderId 발급

    프론트에서 토스 결제 UI를 호출하기 전에 호출.
    orderId와 클라이언트 키를 반환.
    """
    # 세션 확인
    result = await db.execute(
        select(ChargingSession).where(
            ChargingSession.session_uid == data.session_uid
        )
    )
    session = result.scalar_one_or_none()
    if not session:
        raise HTTPException(404, "세션 없음")
    if session.status != SessionStatus.PENDING:
        raise HTTPException(400, f"결제 불가 상태: {session.status}")

    # 주문 ID 생성
    order_id = f"EV-{uuid.uuid4().hex[:16].upper()}"

    # Payment 레코드 생성
    payment = Payment(
        session_id=session.id,
        order_id=order_id,
        amount=data.amount,
        status=PaymentStatus.PENDING,
    )
    db.add(payment)
    await db.flush()

    return {
        "order_id": order_id,
        "amount": data.amount,
        "session_uid": data.session_uid,
        "client_key": settings.TOSS_CLIENT_KEY,
        "customer_name": "EV 충전",
        "order_name": f"전기차 충전 ({data.amount:,}원)",
    }


@router.post("/confirm", response_model=PaymentOut)
async def confirm_payment(
    data: PaymentConfirm,
    db: AsyncSession = Depends(get_db),
):
    """결제 최종 승인

    프론트에서 토스 결제 완료 후 paymentKey, orderId, amount 전달.
    백엔드에서 토스 confirm API 호출 → 실제 청구 확정.
    성공 시 세션 상태를 AUTHORIZED로 변경.
    """
    # Payment 조회
    result = await db.execute(
        select(Payment).where(Payment.order_id == data.order_id)
    )
    payment = result.scalar_one_or_none()
    if not payment:
        raise HTTPException(404, f"주문 없음: {data.order_id}")

    # 금액 검증
    if payment.amount != data.amount:
        raise HTTPException(400, "결제 금액 불일치")

    # 토스페이먼츠 최종 승인
    toss_result = await toss_service.confirm_payment(
        payment_key=data.payment_key,
        order_id=data.order_id,
        amount=data.amount,
    )

    if not toss_result["success"]:
        payment.status = PaymentStatus.FAILED
        raise HTTPException(400, toss_result.get("message", "결제 승인 실패"))

    # 결제 성공 처리
    toss_data = toss_result["data"]
    payment.payment_key = data.payment_key
    payment.status = PaymentStatus.CONFIRMED
    payment.method = toss_data.get("method", "")
    payment.card_company = (
        toss_data.get("card", {}).get("company", "") if toss_data.get("card") else ""
    )
    payment.confirmed_at = datetime.now(timezone.utc)

    # 세션 상태 → AUTHORIZED (충전 시작 가능)
    session = await db.get(ChargingSession, payment.session_id)
    session.status = SessionStatus.AUTHORIZED

    logger.info(
        f"결제 승인 완료: {data.order_id} / {data.amount}원 → "
        f"세션 {session.session_uid} AUTHORIZED"
    )

    await db.flush()
    await db.refresh(payment)
    return payment


@router.post("/{order_id}/cancel")
async def cancel_payment(
    order_id: str,
    cancel_reason: str = "사용자 취소",
    db: AsyncSession = Depends(get_db),
):
    """결제 취소"""
    result = await db.execute(
        select(Payment).where(Payment.order_id == order_id)
    )
    payment = result.scalar_one_or_none()
    if not payment:
        raise HTTPException(404, "주문 없음")
    if not payment.payment_key:
        raise HTTPException(400, "승인된 결제가 아닙니다")

    cancel_result = await toss_service.cancel_payment(
        payment_key=payment.payment_key,
        cancel_reason=cancel_reason,
    )

    if not cancel_result["success"]:
        raise HTTPException(400, cancel_result.get("message", "취소 실패"))

    payment.status = PaymentStatus.REFUNDED
    payment.refunded_at = datetime.now(timezone.utc)

    # 세션 취소
    session = await db.get(ChargingSession, payment.session_id)
    session.status = SessionStatus.CANCELLED

    return {"message": "결제 취소 완료", "order_id": order_id}


@router.get("/{order_id}", response_model=PaymentOut)
async def get_payment(
    order_id: str,
    db: AsyncSession = Depends(get_db),
):
    """결제 상세 조회"""
    result = await db.execute(
        select(Payment).where(Payment.order_id == order_id)
    )
    payment = result.scalar_one_or_none()
    if not payment:
        raise HTTPException(404, "주문 없음")
    return payment