support exchange rate

pkg/api/exchange_rates.go

@@ -0,0 +1,54 @@
+package api
+
+import (
+	"encoding/xml"
+	"io/ioutil"
+	"net/http"
+
+	"github.com/mayswind/lab/pkg/core"
+	"github.com/mayswind/lab/pkg/errs"
+	"github.com/mayswind/lab/pkg/log"
+	"github.com/mayswind/lab/pkg/models"
+)
+
+const EuroCentralBankExchangeRateUrl = "https://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml"
+
+type ExchangeRatesApi struct {}
+
+var (
+	ExchangeRates = &ExchangeRatesApi{}
+)
+
+func (a *ExchangeRatesApi) LatestExchangeRateHandler(c *core.Context) (interface{}, *errs.Error) {
+	uid := c.GetCurrentUid()
+	resp, err := http.Get(EuroCentralBankExchangeRateUrl)
+
+	if err != nil {
+		log.ErrorfWithRequestId(c, "[exchange_rates.LatestExchangeRateHandler] failed to request latest exchange rate data for user \"uid:%d\", because %s", uid, err.Error())
+		return nil, errs.ErrFailedToRequestRemoteApi
+	}
+
+	if resp.StatusCode != 200 {
+		log.ErrorfWithRequestId(c, "[exchange_rates.LatestExchangeRateHandler] failed to get latest exchange rate data response for user \"uid:%d\", because response code is not 200", uid)
+		return nil, errs.ErrFailedToRequestRemoteApi
+	}
+
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	euroCentralBankData := &models.EuroCentralBankExchangeRateData{}
+	err = xml.Unmarshal(body, euroCentralBankData)
+
+	if err != nil {
+		log.ErrorfWithRequestId(c, "[exchange_rates.LatestExchangeRateHandler] failed to parse xml data for user \"uid:%d\", response is %s, because %s", uid, string(body), err.Error())
+		return nil, errs.ErrFailedToRequestRemoteApi
+	}
+
+	latestExchangeRateResponse := euroCentralBankData.ToLatestExchangeRateResponse()
+
+	if latestExchangeRateResponse == nil {
+		log.ErrorfWithRequestId(c, "[exchange_rates.LatestExchangeRateHandler] failed to parse latest exchange rate data for user \"uid:%d\", response is %s,", uid, string(body))
+		return nil, errs.ErrFailedToRequestRemoteApi
+	}
+
+	return latestExchangeRateResponse, nil
+}

pkg/errs/global.go

@@ -11,6 +11,7 @@ var (
 	ErrRequestIdInvalid                = NewNormalError(NORMAL_SUBCATEGORY_GLOBAL, 2, http.StatusInternalServerError, "request id is invalid")
 	ErrCiphertextInvalid               = NewNormalError(NORMAL_SUBCATEGORY_GLOBAL, 3, http.StatusInternalServerError, "ciphertext is invalid")
 	ErrNothingWillBeUpdated            = NewNormalError(NORMAL_SUBCATEGORY_GLOBAL, 4, http.StatusBadRequest, "nothing will be updated")
+	ErrFailedToRequestRemoteApi        = NewNormalError(NORMAL_SUBCATEGORY_GLOBAL, 5, http.StatusBadRequest, "failed to request third party api")
 )
 
 func GetParameterInvalidMessage(field string) string {

pkg/models/exchange_rate.go

@@ -0,0 +1,67 @@
+package models
+
+import "encoding/xml"
+
+const EuroCentralBankDataSource = "European Central Bank"
+const EuroCentralBankBaseCurrency = "EUR"
+
+type LatestExchangeRateResponse struct {
+	DataSource    string                `json:"dataSource"`
+	Date          string                `json:"date"`
+	BaseCurrency  string                `json:"baseCurrency"`
+	ExchangeRates []*LatestExchangeRate `json:"exchangeRates"`
+}
+
+type LatestExchangeRate struct {
+	Currency string `json:"currency"`
+	Rate     string `json:"rate"`
+}
+
+type EuroCentralBankExchangeRateData struct {
+	XMLName          xml.Name                        `xml:"Envelope"`
+	AllExchangeRates []*EuroCentralBankExchangeRates `xml:"Cube>Cube"`
+}
+
+type EuroCentralBankExchangeRates struct {
+	Date          string                         `xml:"time,attr"`
+	ExchangeRates []*EuroCentralBankExchangeRate `xml:"Cube"`
+}
+
+type EuroCentralBankExchangeRate struct {
+	Currency string `xml:"currency,attr"`
+	Rate     string `xml:"rate,attr"`
+}
+
+func (e EuroCentralBankExchangeRateData) ToLatestExchangeRateResponse() *LatestExchangeRateResponse {
+	if len(e.AllExchangeRates) < 1 {
+		return nil
+	}
+
+	latestEuroCentralBankExchangeRate := e.AllExchangeRates[0]
+
+	if len(latestEuroCentralBankExchangeRate.ExchangeRates) < 1 {
+		return nil
+	}
+
+	exchangeRates := make([]*LatestExchangeRate, len(latestEuroCentralBankExchangeRate.ExchangeRates))
+
+	for i := 0; i < len(latestEuroCentralBankExchangeRate.ExchangeRates); i++ {
+		exchangeRates[i] = latestEuroCentralBankExchangeRate.ExchangeRates[i].ToLatestExchangeRate()
+	}
+
+	latestExchangeRateResp := &LatestExchangeRateResponse{
+		DataSource:    EuroCentralBankDataSource,
+		Date:          latestEuroCentralBankExchangeRate.Date,
+		BaseCurrency:  EuroCentralBankBaseCurrency,
+		ExchangeRates: exchangeRates,
+	}
+
+	return latestExchangeRateResp
+}
+
+func (e EuroCentralBankExchangeRate) ToLatestExchangeRate() *LatestExchangeRate {
+	return &LatestExchangeRate{
+		Currency: e.Currency,
+		Rate:     e.Rate,
+	}
+}