Fix global chart always showing in USD, and add current currency to chart name (#209)

* Use exchange-rates to convert GlobalMarketGraphData
* Ask for global data in usd just in case it starts working again :)
* Include currency conversion in chart title #207
* Better error handling

cointop/marketbar.go

@@ -78,9 +78,10 @@ func (ct *Cointop) UpdateMarketbar() error {
 		chartInfo := ""
 		if !ct.State.hideChart {
 			chartInfo = fmt.Sprintf(
-				"[ Chart: %s %s ] ",
+				"[ Chart: %s %s %s ] ",
 				charttitle,
 				timeframe,
+				ct.State.currencyConversion,
 			)
 		}
 
@@ -141,9 +142,10 @@ func (ct *Cointop) UpdateMarketbar() error {
 		chartInfo := ""
 		if !ct.State.hideChart {
 			chartInfo = fmt.Sprintf(
-				"[ Chart: %s %s ] ",
+				"[ Chart: %s %s %s] ",
 				ct.colorscheme.MarketBarLabelActive(chartname),
 				timeframe,
+				ct.State.currencyConversion,
 			)
 		}
 

pkg/api/impl/coingecko/coingecko.go

@@ -154,18 +154,40 @@ func (s *Service) GetGlobalMarketGraphData(convert string, start int64, end int6
 	if convertTo == "" {
 		convertTo = "usd"
 	}
-	graphData, err := s.client.GlobalCharts(convertTo, days)
+	graphData, err := s.client.GlobalCharts("usd", days)
 	if err != nil {
 		return ret, err
 	}
 
+	// This API does not appear to support vs_currency and only returns USD, so use ExchangeRates to convert
+	rate := 1.0
+	if convertTo != "usd" {
+		rates, err := s.client.ExchangeRates()
+		if err != nil {
+			return ret, err
+		}
+		if rates == nil {
+			return ret, fmt.Errorf("expected rates, received nil")
+		}
+		// Combined rate is USD->BTC->other
+		btcRate, found := (*rates)[convertTo]
+		if !found {
+			return ret, fmt.Errorf("unsupported currency conversion: %s", convertTo)
+		}
+		usdRate, found := (*rates)["usd"]
+		if !found {
+			return ret, fmt.Errorf("unsupported currency conversion: usd")
+		}
+		rate = btcRate.Value / usdRate.Value
+	}
+
 	var marketCapUSD [][]float64
 	var marketVolumeUSD [][]float64
 	if graphData.Stats != nil {
 		for _, item := range *graphData.Stats {
 			marketCapUSD = append(marketCapUSD, []float64{
 				float64(item[0]),
-				float64(item[1]),
+				float64(item[1]) * rate,
 			})
 		}
 	}