curl --request GET \
  --url https://uat-api.clinkbill.com/api/coupon/{couponId} \
  --header 'X-API-KEY: <api-key>' \
  --header 'X-Timestamp: <api-key>'

{
  "code": 200,
  "msg": "success",
  "data": {
    "couponId": "<string>",
    "couponName": "<string>",
    "percentage": 123,
    "fixedAmounts": {},
    "durationMonths": 123,
    "maxRedemptionCount": 123,
    "redeemedCount": 123,
    "validPeriodEnd": 1754819711382,
    "mirroring": true,
    "terms": "<string>",
    "createTime": 1754819711382,
    "valid": true,
    "applicableProducts": [
      "<string>"
    ],
    "applicablePrices": {},
    "promotionCodeList": [
      {
        "couponId": "<string>",
        "promotionCodeId": "<string>",
        "code": "<string>",
        "status": "active",
        "firstOrderOnly": true,
        "redemptionCount": 123,
        "maxRedemptionLimit": 123,
        "validPeriodEnd": 1754819711382,
        "createTime": 1754819711382,
        "mirroring": true
      }
    ],
    "currency": "<string>",
    "amount": 123
  }
}