sb-backend/src/main/java/com/sb/web/account/controller/FxController.java

package com.sb.web.account.controller;

import com.sb.web.account.service.FxService;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.math.BigDecimal;
import java.time.Instant;
import java.util.HashMap;
import java.util.Map;

/**
 * 환율 조회 API. 외화 결제 입력 시 통화→원화 환율 자동 채움용.
 *   GET /api/fx/rate?from=USD&to=KRW  →  { from, to, rate }
 */
@RestController
@RequestMapping("/api/fx")
public class FxController {

    private final FxService fxService;

    public FxController(FxService fxService) {
        this.fxService = fxService;
    }

    @GetMapping("/rate")
    public Map<String, Object> rate(@RequestParam String from,
                                    @RequestParam(defaultValue = "KRW") String to) {
        BigDecimal rate = fxService.getRate(from, to);
        Instant updatedAt = fxService.getCachedAt(from);
        Map<String, Object> res = new HashMap<>();
        res.put("from", from == null ? null : from.toUpperCase());
        res.put("to", to == null ? null : to.toUpperCase());
        res.put("rate", rate); // 조회 실패 시 null
        res.put("updatedAt", updatedAt != null ? updatedAt.toString() : null);
        return res;
    }
}