refactor exchange rates data backend, supports multi data source, supports timeout

pkg/exchangerates/euro_central_bank_datasource.go

@@ -0,0 +1,103 @@
+package exchangerates
+
+import (
+	"encoding/xml"
+
+	"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"
+const euroCentralBankDataSource = "European Central Bank"
+const euroCentralBankBaseCurrency = "EUR"
+
+// EuroCentralBankDataSource defines the structure of exchange rates data source of euro central bank
+type EuroCentralBankDataSource struct {
+	ExchangeRatesDataSource
+}
+
+// EuroCentralBankExchangeRateData represents the whole data from euro central bank
+type EuroCentralBankExchangeRateData struct {
+	XMLName          xml.Name                        `xml:"Envelope"`
+	AllExchangeRates []*EuroCentralBankExchangeRates `xml:"Cube>Cube"`
+}
+
+// EuroCentralBankExchangeRates represents the exchange rates data from euro central bank
+type EuroCentralBankExchangeRates struct {
+	Date          string                         `xml:"time,attr"`
+	ExchangeRates []*EuroCentralBankExchangeRate `xml:"Cube"`
+}
+
+// EuroCentralBankExchangeRate represents the exchange rate data from euro central bank
+type EuroCentralBankExchangeRate struct {
+	Currency string `xml:"currency,attr"`
+	Rate     string `xml:"rate,attr"`
+}
+
+// ToLatestExchangeRateResponse returns a view-object according to original data from euro central bank
+func (e *EuroCentralBankExchangeRateData) ToLatestExchangeRateResponse() *models.LatestExchangeRateResponse {
+	if len(e.AllExchangeRates) < 1 {
+		return nil
+	}
+
+	latestEuroCentralBankExchangeRate := e.AllExchangeRates[0]
+
+	if len(latestEuroCentralBankExchangeRate.ExchangeRates) < 1 {
+		return nil
+	}
+
+	exchangeRates := make([]*models.LatestExchangeRate, len(latestEuroCentralBankExchangeRate.ExchangeRates))
+
+	for i := 0; i < len(latestEuroCentralBankExchangeRate.ExchangeRates); i++ {
+		exchangeRates[i] = latestEuroCentralBankExchangeRate.ExchangeRates[i].ToLatestExchangeRate()
+	}
+
+	latestExchangeRateResp := &models.LatestExchangeRateResponse{
+		DataSource:    euroCentralBankDataSource,
+		Date:          latestEuroCentralBankExchangeRate.Date,
+		BaseCurrency:  euroCentralBankBaseCurrency,
+		ExchangeRates: exchangeRates,
+	}
+
+	return latestExchangeRateResp
+}
+
+// ToLatestExchangeRate returns a data pair according to original data from euro central bank
+func (e *EuroCentralBankExchangeRate) ToLatestExchangeRate() *models.LatestExchangeRate {
+	return &models.LatestExchangeRate{
+		Currency: e.Currency,
+		Rate:     e.Rate,
+	}
+}
+
+// GetRequestUrl returns the euro central bank data source url
+func (e *EuroCentralBankDataSource) GetRequestUrl() string {
+	return euroCentralBankExchangeRateUrl
+}
+
+// Parse returns the common response entity according to the euro central bank data source raw response
+func (e *EuroCentralBankDataSource) Parse(c *core.Context, content []byte) (*models.LatestExchangeRateResponse, error) {
+	euroCentralBankData := &EuroCentralBankExchangeRateData{}
+	err := xml.Unmarshal(content, euroCentralBankData)
+
+	if err != nil {
+		log.ErrorfWithRequestId(c, "[euro_central_bank_datasource.Parse] failed to parse xml data, content is %s, because %s", string(content), err.Error())
+		return nil, errs.ErrFailedToRequestRemoteApi
+	}
+
+	latestExchangeRateResponse := euroCentralBankData.ToLatestExchangeRateResponse()
+
+	if latestExchangeRateResponse == nil {
+		log.ErrorfWithRequestId(c, "[euro_central_bank_datasource.Parse] failed to parse latest exchange rate data, content is %s", string(content))
+		return nil, errs.ErrFailedToRequestRemoteApi
+	}
+
+	latestExchangeRateResponse.ExchangeRates = append(latestExchangeRateResponse.ExchangeRates, &models.LatestExchangeRate{
+		Currency: euroCentralBankBaseCurrency,
+		Rate:     "1",
+	})
+
+	return latestExchangeRateResponse, nil
+}

pkg/exchangerates/exchange_rates_datasource.go

@@ -0,0 +1,15 @@
+package exchangerates
+
+import (
+	"github.com/mayswind/lab/pkg/core"
+	"github.com/mayswind/lab/pkg/models"
+)
+
+// ExchangeRatesDataSource defines the structure of exchange rates data source
+type ExchangeRatesDataSource interface {
+	// GetRequestUrl returns the data source url
+	GetRequestUrl() string
+
+	// Parse returns the common response entity according to the data source raw response
+	Parse(c *core.Context, content []byte) (*models.LatestExchangeRateResponse, error)
+}

pkg/exchangerates/exchange_rates_datasource_container.go

@@ -0,0 +1,26 @@
+package exchangerates
+
+import (
+	"github.com/mayswind/lab/pkg/errs"
+	"github.com/mayswind/lab/pkg/settings"
+)
+
+// ExchangeRatesDataSourceContainer contains the current exchange rates data source
+type ExchangeRatesDataSourceContainer struct {
+	Current ExchangeRatesDataSource
+}
+
+// Initialize a exchange rates data source container singleton instance
+var (
+	Container = &ExchangeRatesDataSourceContainer{}
+)
+
+// InitializeExchangeRatesDataSource initializes the current exchange rates data source according to the config
+func InitializeExchangeRatesDataSource(config *settings.Config) error {
+	if config.ExchangeRatesDataSource == settings.EuroCentralBankDataSource {
+		Container.Current = &EuroCentralBankDataSource{}
+		return nil
+	}
+
+	return errs.ErrInvalidExchangeRatesDataSource
+}