From d1bdc6af5dba94b6baaef7a314ae9fb0e1e84f4f Mon Sep 17 00:00:00 2001
From: Adrian Gallagher <thrasher@addictionsoftware.com>
Date: Mon, 28 Aug 2017 09:06:53 +1000
Subject: [PATCH] Use fixer.io currency rates API instead of Yahoo due to Yahoo
 service issues

---
 currency/currency.go      | 97 +++++++++++++++++++++++++++++++++++----
 currency/currency_test.go | 29 +++++++++---
 2 files changed, 111 insertions(+), 15 deletions(-)

diff --git a/currency/currency.go b/currency/currency.go
index c6165c2f..32cfe22d 100644
--- a/currency/currency.go
+++ b/currency/currency.go
@@ -39,10 +39,19 @@ type YahooJSONResponse struct {
 	}
 }
 
+// FixerResponse contains the data fields for the Fixer API response
+type FixerResponse struct {
+	Base  string             `json:"base"`
+	Date  string             `json:"date"`
+	Rates map[string]float64 `json:"rates"`
+}
+
 const (
 	maxCurrencyPairsPerRequest = 350
 	yahooYQLURL                = "https://query.yahooapis.com/v1/public/yql?"
 	yahooDatabase              = "store://datatables.org/alltableswithkeys"
+	yahooEnabled               = false
+	fixerAPI                   = "http://api.fixer.io/latest"
 	// DefaultCurrencies has the default minimum of FIAT values
 	DefaultCurrencies = "USD,AUD,EUR,CNY"
 	// DefaultCryptoCurrencies has the default minimum of crytpocurrency values
@@ -53,6 +62,7 @@ const (
 // queries
 var (
 	CurrencyStore             map[string]Rate
+	CurrencyStoreFixer        map[string]float64
 	BaseCurrencies            string
 	CryptoCurrencies          string
 	ErrCurrencyDataNotFetched = errors.New("yahoo currency data has not been fetched yet")
@@ -170,11 +180,11 @@ func SeedCurrencyData(fiatCurrencies string) error {
 		fiatCurrencies = DefaultCurrencies
 	}
 
-	err := QueryYahooCurrencyValues(fiatCurrencies)
-	if err != nil {
-		return ErrQueryingYahoo
+	if yahooEnabled {
+		return QueryYahooCurrencyValues(fiatCurrencies)
 	}
-	return nil
+
+	return FetchFixerCurrencyData()
 }
 
 // MakecurrencyPairs takes all supported currency and turns them into pairs.
@@ -196,21 +206,90 @@ func MakecurrencyPairs(supportedCurrencies string) string {
 // ConvertCurrency for example converts $1 USD to the equivalent Japanese Yen
 // or vice versa.
 func ConvertCurrency(amount float64, from, to string) (float64, error) {
-	currency := common.StringToUpper(from + to)
+	from = common.StringToUpper(from)
+	to = common.StringToUpper(to)
 
-	_, ok := CurrencyStore[currency]
+	if from == to {
+		return amount, nil
+	}
+
+	if yahooEnabled {
+		currency := from + to
+		_, ok := CurrencyStore[currency]
+		if !ok {
+			err := SeedCurrencyData(currency[:len(from)] + "," + currency[len(to):])
+			if err != nil {
+				return 0, err
+			}
+		}
+
+		result, ok := CurrencyStore[currency]
+		if !ok {
+			return 0, ErrCurrencyNotFound
+		}
+		return amount * result.Rate, nil
+	}
+
+	_, ok := CurrencyStoreFixer[from]
 	if !ok {
-		err := SeedCurrencyData(currency[:len(from)] + "," + currency[len(to):])
+		err := FetchFixerCurrencyData()
 		if err != nil {
 			return 0, err
 		}
 	}
 
-	result, ok := CurrencyStore[currency]
+	var resultFrom float64
+	var resultTo float64
+
+	// First check if we're converting to USD, USD doesn't exist in the rates map
+	if to == "USD" {
+		resultFrom, ok = CurrencyStoreFixer[from]
+		if !ok {
+			return 0, ErrCurrencyNotFound
+		}
+		return amount / resultFrom, nil
+	}
+
+	// Check to see if we're converting from USD
+	if from == "USD" {
+		resultTo, ok = CurrencyStoreFixer[to]
+		if !ok {
+			return 0, ErrCurrencyNotFound
+		}
+		return resultTo * amount, nil
+	}
+
+	// Otherwise convert to USD, then to the target currency
+	resultFrom, ok = CurrencyStoreFixer[from]
 	if !ok {
 		return 0, ErrCurrencyNotFound
 	}
-	return amount * result.Rate, nil
+
+	converted := amount / resultFrom
+	resultTo, ok = CurrencyStoreFixer[to]
+	if !ok {
+		return 0, ErrCurrencyNotFound
+	}
+
+	return converted * resultTo, nil
+}
+
+// FetchFixerCurrencyData seeds the variable C
+func FetchFixerCurrencyData() error {
+	var result FixerResponse
+	values := url.Values{}
+	values.Set("base", "USD")
+	url := common.EncodeURLValues(fixerAPI, values)
+
+	CurrencyStoreFixer = make(map[string]float64)
+
+	err := common.SendHTTPGetRequest(url, true, &result)
+	if err != nil {
+		return err
+	}
+
+	CurrencyStoreFixer = result.Rates
+	return nil
 }
 
 // FetchYahooCurrencyData seeds the variable CurrencyStore; this is a
diff --git a/currency/currency_test.go b/currency/currency_test.go
index 2fa00516..17a081d1 100644
--- a/currency/currency_test.go
+++ b/currency/currency_test.go
@@ -274,12 +274,14 @@ func TestSeedCurrencyData(t *testing.T) {
 			err2, currencyRequestUSDAUD,
 		)
 	}
-	err3 := SeedCurrencyData(currencyRequestObtuse)
-	if err3 == nil {
-		t.Errorf(
-			"Test Failed. SeedCurrencyData: Error %s with currency as %s.",
-			err3, currencyRequestObtuse,
-		)
+	if yahooEnabled {
+		err3 := SeedCurrencyData(currencyRequestObtuse)
+		if err3 == nil {
+			t.Errorf(
+				"Test Failed. SeedCurrencyData: Error %s with currency as %s.",
+				err3, currencyRequestObtuse,
+			)
+		}
 	}
 }
 
@@ -323,7 +325,18 @@ func TestConvertCurrency(t *testing.T) {
 	}
 }
 
+func TestFetchFixerCurrencyData(t *testing.T) {
+	err := FetchFixerCurrencyData()
+	if err != nil {
+		t.Errorf("Test failed. FetchFixerCurrencyData returned %s", err)
+	}
+}
+
 func TestFetchYahooCurrencyData(t *testing.T) {
+	if !yahooEnabled {
+		return
+	}
+
 	t.Parallel()
 	var fetchData []string
 	fiatCurrencies := DefaultCurrencies
@@ -344,6 +357,10 @@ func TestFetchYahooCurrencyData(t *testing.T) {
 }
 
 func TestQueryYahooCurrencyValues(t *testing.T) {
+	if !yahooEnabled {
+		return
+	}
+
 	err := QueryYahooCurrencyValues(DefaultCurrencies)
 	if err != nil {
 		t.Errorf("Test Failed. QueryYahooCurrencyValues: Error, %s", err)