Fix reversed ordering in altcoin market

desktop/src/main/java/bisq/desktop/main/market/offerbook/OfferBookChartViewModel.java

@@ -279,6 +279,14 @@ private void updateChartData() {
 
         // Offer price can be null (if price feed unavailable), thus a null-tolerant comparator is used.
         Comparator<Offer> offerPriceComparator = Comparator.comparing(Offer::getPrice, Comparator.nullsLast(Comparator.naturalOrder()));
+
+        // Trading btc-fiat is considered as buying/selling BTC, but trading btc-altcoin is
+        // considered as buying/selling Altcoin. Because of this, when viewing a btc-altcoin pair,
+        // the buy column is actually the sell column and vice versa. To maintain the expected
+        // ordering, we have to reverse the price comparator.
+        boolean isCrypto = CurrencyUtil.isCryptoCurrency(getCurrencyCode());
+        if (isCrypto) offerPriceComparator = offerPriceComparator.reversed();
+
         // Offer amounts are used for the secondary sort. They are sorted from high to low.
         Comparator<Offer> offerAmountComparator = Comparator.comparing(Offer::getAmount).reversed();