add International Monetary Fund exchange rates data source

pkg/exchangerates/exchange_rates_datasource_container.go

@@ -32,6 +32,9 @@ func InitializeExchangeRatesDataSource(config *settings.Config) error {
 	} else if config.ExchangeRatesDataSource == settings.NationalBankOfPolandDataSource {
 		Container.Current = &NationalBankOfPolandDataSource{}
 		return nil
+	} else if config.ExchangeRatesDataSource == settings.InternationalMonetaryFundDataSource {
+		Container.Current = &InternationalMonetaryFundDataSource{}
+		return nil
 	}
 
 	return errs.ErrInvalidExchangeRatesDataSource

pkg/exchangerates/international_monetary_fund_datasource.go

@@ -0,0 +1,231 @@
+package exchangerates
+
+import (
+	"strings"
+	"time"
+
+	orderedmap "github.com/wk8/go-ordered-map/v2"
+
+	"github.com/mayswind/ezbookkeeping/pkg/core"
+	"github.com/mayswind/ezbookkeeping/pkg/errs"
+	"github.com/mayswind/ezbookkeeping/pkg/log"
+	"github.com/mayswind/ezbookkeeping/pkg/models"
+	"github.com/mayswind/ezbookkeeping/pkg/utils"
+	"github.com/mayswind/ezbookkeeping/pkg/validators"
+)
+
+const internationalMonetaryFundExchangeRateUrl = "https://www.imf.org/external/np/fin/data/rms_five.aspx?tsvflag=Y"
+const internationalMonetaryFundExchangeRateReferenceUrl = "https://www.imf.org/external/np/fin/data/param_rms_mth.aspx"
+const internationalMonetaryFundDataSource = "International Monetary Fund"
+const internationalMonetaryFundBaseCurrency = "USD"
+
+const internationalMonetaryFundDataUpdateDateFormat = "January 02, 2006 15:04"
+const internationalMonetaryFundDataUpdateDateTimezone = "America/New_York"
+
+var internationalMonetaryFundCurrencyNameCodeMap map[string]string
+
+// InternationalMonetaryFundDataSource defines the structure of exchange rates data source of international monetary fund
+type InternationalMonetaryFundDataSource struct {
+	ExchangeRatesDataSource
+}
+
+func init() {
+	internationalMonetaryFundCurrencyNameCodeMap = make(map[string]string, 38)
+	internationalMonetaryFundCurrencyNameCodeMap["Chinese yuan"] = "CNY"
+	internationalMonetaryFundCurrencyNameCodeMap["Euro"] = "EUR"
+	internationalMonetaryFundCurrencyNameCodeMap["Japanese yen"] = "JPY"
+	internationalMonetaryFundCurrencyNameCodeMap["U.K. pound"] = "GBP"
+	internationalMonetaryFundCurrencyNameCodeMap["U.S. dollar"] = "USD"
+	internationalMonetaryFundCurrencyNameCodeMap["Algerian dinar"] = "DZD"
+	internationalMonetaryFundCurrencyNameCodeMap["Australian dollar"] = "AUD"
+	internationalMonetaryFundCurrencyNameCodeMap["Botswana pula"] = "BWP"
+	internationalMonetaryFundCurrencyNameCodeMap["Brazilian real"] = "BRL"
+	internationalMonetaryFundCurrencyNameCodeMap["Brunei dollar"] = "BND"
+	internationalMonetaryFundCurrencyNameCodeMap["Canadian dollar"] = "CAD"
+	internationalMonetaryFundCurrencyNameCodeMap["Chilean peso"] = "CLP"
+	internationalMonetaryFundCurrencyNameCodeMap["Czech koruna"] = "CZK"
+	internationalMonetaryFundCurrencyNameCodeMap["Danish krone"] = "DKK"
+	internationalMonetaryFundCurrencyNameCodeMap["Indian rupee"] = "INR"
+	internationalMonetaryFundCurrencyNameCodeMap["Israeli New Shekel"] = "ILS"
+	internationalMonetaryFundCurrencyNameCodeMap["Korean won"] = "KRW"
+	internationalMonetaryFundCurrencyNameCodeMap["Kuwaiti dinar"] = "KWD"
+	internationalMonetaryFundCurrencyNameCodeMap["Malaysian ringgit"] = "MYR"
+	internationalMonetaryFundCurrencyNameCodeMap["Mauritian rupee"] = "MUR"
+	internationalMonetaryFundCurrencyNameCodeMap["Mexican peso"] = "MXN"
+	internationalMonetaryFundCurrencyNameCodeMap["New Zealand dollar"] = "NZD"
+	internationalMonetaryFundCurrencyNameCodeMap["Norwegian krone"] = "NOK"
+	internationalMonetaryFundCurrencyNameCodeMap["Omani rial"] = "OMR"
+	internationalMonetaryFundCurrencyNameCodeMap["Peruvian sol"] = "PEN"
+	internationalMonetaryFundCurrencyNameCodeMap["Philippine peso"] = "PHP"
+	internationalMonetaryFundCurrencyNameCodeMap["Polish zloty"] = "PLN"
+	internationalMonetaryFundCurrencyNameCodeMap["Qatari riyal"] = "QAR"
+	internationalMonetaryFundCurrencyNameCodeMap["Russian ruble"] = "RUB"
+	internationalMonetaryFundCurrencyNameCodeMap["Saudi Arabian riyal"] = "SAR"
+	internationalMonetaryFundCurrencyNameCodeMap["Singapore dollar"] = "SGD"
+	internationalMonetaryFundCurrencyNameCodeMap["South African rand"] = "ZAR"
+	internationalMonetaryFundCurrencyNameCodeMap["Swedish krona"] = "SEK"
+	internationalMonetaryFundCurrencyNameCodeMap["Swiss franc"] = "CHF"
+	internationalMonetaryFundCurrencyNameCodeMap["Thai baht"] = "THB"
+	internationalMonetaryFundCurrencyNameCodeMap["Trinidadian dollar"] = "TTD"
+	internationalMonetaryFundCurrencyNameCodeMap["U.A.E. dirham"] = "AED"
+	internationalMonetaryFundCurrencyNameCodeMap["Uruguayan peso"] = "UYU"
+}
+
+// GetRequestUrls returns the international monetary fund data source urls
+func (e *InternationalMonetaryFundDataSource) GetRequestUrls() []string {
+	return []string{internationalMonetaryFundExchangeRateUrl}
+}
+
+// Parse returns the common response entity according to the international monetary fund data source raw response
+func (e *InternationalMonetaryFundDataSource) Parse(c core.Context, content []byte) (*models.LatestExchangeRateResponse, error) {
+	lines := strings.Split(string(content), "\n")
+
+	if len(lines) < 1 {
+		log.Errorf(c, "[international_monetary_fund_datasource.Parse] content is invalid, content is %s", string(content))
+		return nil, errs.ErrFailedToRequestRemoteApi
+	}
+
+	exchangeRatesToSDR := orderedmap.New[string, float64]()
+	latestUpdateDate := ""
+
+	findSDRsPerCurrencyUnitLine := false
+	findExchangeRateDataHeader := false
+
+	for i := 0; i < len(lines); i++ {
+		line := lines[i]
+
+		if line == "" {
+			continue
+		}
+
+		line = strings.ReplaceAll(line, "\r", "")
+
+		if strings.Index(line, "Currency units per SDR") == 0 {
+			break
+		}
+
+		if strings.Index(line, "SDRs per Currency unit") == 0 {
+			findSDRsPerCurrencyUnitLine = true
+			continue
+		}
+
+		if findExchangeRateDataHeader {
+			items := strings.Split(line, "\t")
+
+			if len(items) != 6 {
+				continue
+			}
+
+			currencyCode, exchangeRate := e.parseExchangeRate(c, line, items)
+
+			if currencyCode != nil && exchangeRate != nil {
+				exchangeRatesToSDR.Set(*currencyCode, *exchangeRate)
+			}
+
+			continue
+		}
+
+		if findSDRsPerCurrencyUnitLine {
+			items := strings.Split(line, "\t")
+
+			if len(items) != 6 {
+				continue
+			}
+
+			if items[0] == "Currency" {
+				findExchangeRateDataHeader = true
+				latestUpdateDate = items[1]
+				continue
+			}
+		}
+	}
+
+	if latestUpdateDate == "" {
+		log.Errorf(c, "[international_monetary_fund_datasource.Parse] latest update date is empty")
+		return nil, errs.ErrFailedToRequestRemoteApi
+	}
+
+	if exchangeRatesToSDR.Len() < 1 {
+		log.Errorf(c, "[international_monetary_fund_datasource.Parse] exchange rates date is empty")
+		return nil, errs.ErrFailedToRequestRemoteApi
+	}
+
+	defaultCurrencyExchangeRateToSDR, exists := exchangeRatesToSDR.Get(internationalMonetaryFundBaseCurrency)
+
+	if !exists {
+		log.Errorf(c, "[international_monetary_fund_datasource.Parse] exchange rates date does not have default currency \"%s\"", internationalMonetaryFundBaseCurrency)
+		return nil, errs.ErrFailedToRequestRemoteApi
+	}
+
+	exchangeRates := make(models.LatestExchangeRateSlice, 0, exchangeRatesToSDR.Len())
+
+	for pair := exchangeRatesToSDR.Oldest(); pair != nil; pair = pair.Next() {
+		exchangeRates = append(exchangeRates, &models.LatestExchangeRate{
+			Currency: pair.Key,
+			Rate:     utils.Float64ToString(defaultCurrencyExchangeRateToSDR / pair.Value),
+		})
+	}
+
+	timezone, err := time.LoadLocation(internationalMonetaryFundDataUpdateDateTimezone)
+
+	if err != nil {
+		log.Errorf(c, "[international_monetary_fund_datasource.Parse] failed to get timezone, timezone name is %s", internationalMonetaryFundDataUpdateDateTimezone)
+		return nil, errs.ErrFailedToRequestRemoteApi
+	}
+
+	updateDateTime := latestUpdateDate + " 11:00" // The IMF posts Representative and SDR exchange rates every 20 minutes from 11:00 AM to 6:00 PM U.S. EST Monday to Friday except for these holidays
+	updateTime, err := time.ParseInLocation(internationalMonetaryFundDataUpdateDateFormat, updateDateTime, timezone)
+
+	if err != nil {
+		log.Errorf(c, "[international_monetary_fund_datasource.Parse] failed to parse update date, datetime is %s", updateDateTime)
+		return nil, errs.ErrFailedToRequestRemoteApi
+	}
+
+	latestExchangeRateResp := &models.LatestExchangeRateResponse{
+		DataSource:    internationalMonetaryFundDataSource,
+		ReferenceUrl:  internationalMonetaryFundExchangeRateReferenceUrl,
+		UpdateTime:    updateTime.Unix(),
+		BaseCurrency:  internationalMonetaryFundBaseCurrency,
+		ExchangeRates: exchangeRates,
+	}
+
+	return latestExchangeRateResp, nil
+}
+
+func (e *InternationalMonetaryFundDataSource) parseExchangeRate(c core.Context, line string, lineItems []string) (*string, *float64) {
+	currencyCode, exists := internationalMonetaryFundCurrencyNameCodeMap[lineItems[0]]
+
+	if !exists {
+		log.Warnf(c, "[international_monetary_fund_datasource.parseExchangeRate] unknown currency name %s, line is %s", lineItems[0], line)
+		return nil, nil
+	}
+
+	if _, exists := validators.AllCurrencyNames[currencyCode]; !exists {
+		return nil, nil
+	}
+
+	for i := 1; i < 6; i++ {
+		item := lineItems[i]
+
+		if item == "" {
+			continue
+		}
+
+		rate, err := utils.StringToFloat64(item)
+
+		if err != nil {
+			log.Warnf(c, "[international_monetary_fund_datasource.parseExchangeRate] failed to parse rate, line is %s", line)
+			return nil, nil
+		}
+
+		if rate <= 0 {
+			log.Warnf(c, "[international_monetary_fund_datasource.parseExchangeRate] rate is invalid, line is %s", line)
+			return nil, nil
+		}
+
+		return &currencyCode, &rate
+	}
+
+	log.Warnf(c, "[international_monetary_fund_datasource.parseExchangeRate] no exchange rate data exists for currency \"%s\", line is %s", currencyCode, line)
+	return nil, nil
+}

pkg/exchangerates/international_monetary_fund_datasource_test.go

@@ -0,0 +1 @@
+package exchangerates