gocryptotrader/currency/currency.go

package currency

import (
	"fmt"
	"log"

	"github.com/thrasher-/gocryptotrader/common"
	"github.com/thrasher-/gocryptotrader/currency/forexprovider"
	"github.com/thrasher-/gocryptotrader/currency/pair"
)

const (
	// DefaultBaseCurrency is the base currency used for conversion
	DefaultBaseCurrency = "USD"
	// DefaultCurrencies has the default minimum of FIAT values
	DefaultCurrencies = "USD,AUD,EUR,CNY"
	// DefaultCryptoCurrencies has the default minimum of crytpocurrency values
	DefaultCryptoCurrencies = "BTC,LTC,ETH,DOGE,DASH,XRP,XMR"
)

// Manager is the overarching type across this package
var (
	FXRates map[string]float64

	FiatCurrencies   []string
	CryptoCurrencies []string

	BaseCurrency string
	FXProviders  *forexprovider.ForexProviders
)

// SetDefaults sets the default currency provider and settings for
// currency conversion used outside of the bot setting
func SetDefaults() {
	FXRates = make(map[string]float64)
	BaseCurrency = DefaultBaseCurrency

	FXProviders = forexprovider.NewDefaultFXProvider()
	err := SeedCurrencyData(DefaultCurrencies)
	if err != nil {
		log.Printf("Failed to seed currency data. Err: %s", err)
		return
	}
}

// SeedCurrencyData returns rates correlated with suported currencies
func SeedCurrencyData(currencies string) error {
	if FXRates == nil {
		FXRates = make(map[string]float64)
	}

	if FXProviders == nil {
		FXProviders = forexprovider.NewDefaultFXProvider()
	}

	newRates, err := FXProviders.GetCurrencyData(BaseCurrency, currencies)
	if err != nil {
		return err
	}

	for key, value := range newRates {
		FXRates[key] = value
	}

	return nil
}

// GetExchangeRates returns the currency exchange rates
func GetExchangeRates() map[string]float64 {
	return FXRates
}

// IsDefaultCurrency checks if the currency passed in matches the default fiat
// currency
func IsDefaultCurrency(currency string) bool {
	defaultCurrencies := common.SplitStrings(DefaultCurrencies, ",")
	return common.StringDataCompare(defaultCurrencies, common.StringToUpper(currency))
}

// IsDefaultCryptocurrency checks if the currency passed in matches the default
// cryptocurrency
func IsDefaultCryptocurrency(currency string) bool {
	cryptoCurrencies := common.SplitStrings(DefaultCryptoCurrencies, ",")
	return common.StringDataCompare(cryptoCurrencies, common.StringToUpper(currency))
}

// IsFiatCurrency checks if the currency passed is an enabled fiat currency
func IsFiatCurrency(currency string) bool {
	return common.StringDataCompare(FiatCurrencies, common.StringToUpper(currency))
}

// IsCryptocurrency checks if the currency passed is an enabled CRYPTO currency.
func IsCryptocurrency(currency string) bool {
	return common.StringDataCompare(CryptoCurrencies, common.StringToUpper(currency))
}

// IsCryptoPair checks to see if the pair is a crypto pair e.g. BTCLTC
func IsCryptoPair(p pair.CurrencyPair) bool {
	return IsCryptocurrency(p.FirstCurrency.String()) &&
		IsCryptocurrency(p.SecondCurrency.String())
}

// IsCryptoFiatPair checks to see if the pair is a crypto fiat pair e.g. BTCUSD
func IsCryptoFiatPair(p pair.CurrencyPair) bool {
	return IsCryptocurrency(p.FirstCurrency.String()) && !IsCryptocurrency(p.SecondCurrency.String()) ||
		!IsCryptocurrency(p.FirstCurrency.String()) && IsCryptocurrency(p.SecondCurrency.String())
}

// IsFiatPair checks to see if the pair is a fiat pair e.g. EURUSD
func IsFiatPair(p pair.CurrencyPair) bool {
	return IsFiatCurrency(p.FirstCurrency.String()) &&
		IsFiatCurrency(p.SecondCurrency.String())
}

// Update updates the local crypto currency or base currency store
func Update(input []string, cryptos bool) {
	for x := range input {
		if cryptos {
			if !common.StringDataCompare(CryptoCurrencies, input[x]) {
				CryptoCurrencies = append(CryptoCurrencies, common.StringToUpper(input[x]))
			}
		} else {
			if !common.StringDataCompare(FiatCurrencies, input[x]) {
				FiatCurrencies = append(FiatCurrencies, common.StringToUpper(input[x]))
			}
		}
	}
}

func extractBaseCurrency() string {
	for k := range FXRates {
		return k[0:3]
	}
	return ""
}

// ConvertCurrency for example converts $1 USD to the equivalent Japanese Yen
// or vice versa.
func ConvertCurrency(amount float64, from, to string) (float64, error) {
	if FXProviders == nil {
		SetDefaults()
	}

	from = common.StringToUpper(from)
	to = common.StringToUpper(to)

	if from == to {
		return amount, nil
	}

	if from == "RUR" {
		from = "RUB"
	}

	if to == "RUR" {
		to = "RUB"
	}

	if len(FXRates) == 0 {
		SeedCurrencyData(from + "," + to)
	}

	// Need to extract the base currency to see if we actually got it from the Forex API
	// Fixer free API sets the base currency to EUR
	baseCurr := extractBaseCurrency()

	var resultFrom float64
	var resultTo float64

	// check to see if we're converting from the base currency
	if to == baseCurr {
		resultFrom, ok := FXRates[baseCurr+from]
		if !ok {
			return 0, fmt.Errorf("Currency conversion failed. Unable to find %s in currency map [%s -> %s]", from, from, to)
		}
		return amount / resultFrom, nil
	}

	// Check to see if we're converting from the base currency
	if from == baseCurr {
		resultTo, ok := FXRates[baseCurr+to]
		if !ok {
			return 0, fmt.Errorf("Currency conversion failed. Unable to find %s in currency map [%s -> %s]", to, from, to)
		}
		return resultTo * amount, nil
	}

	// Otherwise convert to base currency, then to the target currency
	resultFrom, ok := FXRates[baseCurr+from]
	if !ok {
		return 0, fmt.Errorf("Currency conversion failed. Unable to find %s in currency map [%s -> %s]", from, from, to)
	}

	converted := amount / resultFrom
	resultTo, ok = FXRates[baseCurr+to]
	if !ok {
		return 0, fmt.Errorf("Currency conversion failed. Unable to find %s in currency map [%s -> %s]", to, from, to)
	}

	return converted * resultTo, nil
}