AutonetSellCar/frontend/src/lib/exchangeRateStore.ts

/**
 * Exchange Rate Store
 * 한국수출입은행 API에서 가져온 환율 정보를 저장하고 관리
 */
import { create } from 'zustand';
import { exchangeRateApi, ExchangeRateSimple } from './api';

// 기본 환율 (API 실패 시 사용) - 2024년 12월 기준
const DEFAULT_RATES: ExchangeRateSimple = {
  USD: { rate: 1483, symbol: '$', name: '미국 달러' },
  MNT: { rate: 0.43, symbol: '₮', name: '몽골 투그릭' },
  RUB: { rate: 14.5, symbol: '₽', name: '러시아 루블' },
  CNY: { rate: 203, symbol: '¥', name: '중국 위안' },
  EUR: { rate: 1750, symbol: '€', name: '유로' },
  JPY: { rate: 9.5, symbol: '¥', name: '일본 엔' },
};

interface ExchangeRateState {
  rates: ExchangeRateSimple;
  isLoading: boolean;
  lastUpdated: Date | null;
  error: string | null;
  fetchRates: () => Promise<void>;
  getKrwToUsd: () => number;  // KRW를 USD로 변환하는 비율 (1 KRW = X USD)
  getUsdToMnt: () => number;  // USD를 MNT로 변환하는 비율 (1 USD = X MNT)
  getUsdToRub: () => number;  // USD를 RUB로 변환하는 비율 (1 USD = X RUB)
  convertKrwTo: (krwAmount: number, currency: string) => number;
}

export const useExchangeRateStore = create<ExchangeRateState>((set, get) => ({
  rates: DEFAULT_RATES,
  isLoading: false,
  lastUpdated: null,
  error: null,

  fetchRates: async () => {
    // 이미 로딩 중이면 스킵
    if (get().isLoading) return;

    // 30분 이내에 업데이트했으면 스킵
    const lastUpdated = get().lastUpdated;
    if (lastUpdated && Date.now() - lastUpdated.getTime() < 30 * 60 * 1000) {
      return;
    }

    set({ isLoading: true, error: null });

    try {
      const rates = await exchangeRateApi.getSimpleRates();
      set({
        rates: { ...DEFAULT_RATES, ...rates },
        isLoading: false,
        lastUpdated: new Date(),
      });
    } catch (error) {
      console.error('Failed to fetch exchange rates:', error);
      set({
        isLoading: false,
        error: 'Failed to fetch exchange rates',
      });
      // 실패해도 기본값 사용
    }
  },

  getKrwToUsd: () => {
    const { rates } = get();
    const usdRate = rates.USD?.rate || DEFAULT_RATES.USD.rate;
    return 1 / usdRate; // 1 KRW = 1/1450 USD
  },

  getUsdToMnt: () => {
    const { rates } = get();
    const usdRate = rates.USD?.rate || DEFAULT_RATES.USD.rate;
    const mntRate = rates.MNT?.rate || DEFAULT_RATES.MNT.rate;
    // MNT rate is already in KRW per MNT
    // So 1 USD = (USD_KRW / MNT_KRW) MNT
    return usdRate / mntRate;
  },

  getUsdToRub: () => {
    const { rates } = get();
    const usdRate = rates.USD?.rate || DEFAULT_RATES.USD.rate;
    const rubRate = rates.RUB?.rate || DEFAULT_RATES.RUB.rate;
    return usdRate / rubRate;
  },

  convertKrwTo: (krwAmount: number, currency: string) => {
    const { rates } = get();
    const rate = rates[currency]?.rate || DEFAULT_RATES[currency]?.rate;
    if (!rate) return 0;
    return krwAmount / rate;
  },
}));

// 환율 초기화 함수 (앱 시작 시 호출)
export async function initExchangeRates() {
  const store = useExchangeRateStore.getState();
  await store.fetchRates();
}

// 환율 변환 헬퍼 함수들
export function formatWithExchangeRate(
  krwAmount: number,
  currency: 'USD' | 'MNT' | 'RUB' | 'CNY' | 'EUR'
): string {
  const store = useExchangeRateStore.getState();
  const converted = store.convertKrwTo(krwAmount, currency);
  const symbol = store.rates[currency]?.symbol || DEFAULT_RATES[currency]?.symbol || '';

  return `${symbol}${converted.toLocaleString('en-US', {
    minimumFractionDigits: 0,
    maximumFractionDigits: currency === 'USD' ? 0 : 0,
  })}`;
}