Feature/accquire order min (#138)

* Store the minimal order volume in kraken exchange adapter

* Read ordermin only if its available

* Added minOrderVolume to api and implemented kraken

* Fixed javadoc

* Fixed checkstyle and tests

bxbot-exchange-api/src/main/java/com/gazbert/bxbot/exchange/api/PairPrecisionConfig.java

@@ -23,19 +23,21 @@
 
 package com.gazbert.bxbot.exchange.api;
 
+import java.math.BigDecimal;
+
 /**
- * <p>Some Exchange Adapters will need custom precision configs when placing orders.</p>
+ * Some Exchange Adapters will need custom precision configs when placing orders.
  *
- * <p>This interface allows us to have a uniform way to fetch this precision for the
- * various Exchange houses.</p>
+ * <p>This interface allows us to have a uniform way to fetch this precision for the various
+ * Exchange houses.
  *
  * @author maiph
  * @since 1.2
  */
 public interface PairPrecisionConfig {
 
   /**
-   * Gets the number of decimal places for price precision. The default value id no pair is found
+   * Gets the number of decimal places for price precision. The default value if no pair is found
    * will be -1.
    *
    * @param pair the coin pair.
@@ -44,12 +46,20 @@ public interface PairPrecisionConfig {
   int getPricePrecision(String pair);
 
   /**
-   * Gets the number of decimal places for volume precision. The default value id no pair is found
+   * Gets the number of decimal places for volume precision. The default value if no pair is found
    * will be -1.
    *
    * @param pair the coin pair.
    * @return the number of decimal places for volume.
    */
   int getVolumePrecision(String pair);
 
+  /**
+   * Gets the minimal amount of order volume for this pair. The default value if no pair is found
+   * will be null.
+   *
+   * @param pair the coin pair.
+   * @return the minimum amount of order volume.
+   */
+  BigDecimal getMinimalOrderVolume(String pair);
 }

bxbot-exchanges/src/main/java/com/gazbert/bxbot/exchanges/KrakenExchangeAdapter.java

@@ -533,6 +533,11 @@ public BigDecimal getPercentageOfSellOrderTakenForExchangeFee(String marketId) {
     return sellFeePercentage;
   }
 
+  @Override
+  public BigDecimal getMinimumOrderVolume(String marketId) {
+    return pairPrecisionConfig.getMinimalOrderVolume(marketId);
+  }
+
   @Override
   public String getImplName() {
     return "Kraken API v1";
@@ -662,6 +667,7 @@ PairPrecisionConfig loadPrecisionConfig() {
       Gson gson = new Gson();
       Map<String, Integer> prices = new HashMap<>();
       Map<String, Integer> volumes = new HashMap<>();
+      Map<String, BigDecimal> orderMins = new HashMap<>();
 
       for (Entry<String, Object> entry : this.entrySet()) {
         JsonElement jsonElement = gson.toJsonTree(entry);
@@ -670,12 +676,17 @@ PairPrecisionConfig loadPrecisionConfig() {
         String name = jsonObject.get("altname").getAsString();
         int price = jsonObject.get("pair_decimals").getAsInt();
         int volume = jsonObject.get("lot_decimals").getAsInt();
+        if (jsonObject.has("ordermin")) {
+          BigDecimal orderMin = jsonObject.get("ordermin").getAsBigDecimal();
+          orderMins.put(name, orderMin);
+        }
+
 
         prices.put(name, price);
         volumes.put(name, volume);
       }
 
-      return new PairPrecisionConfigImpl(prices, volumes);
+      return new PairPrecisionConfigImpl(prices, volumes, orderMins);
     }
   }
 

bxbot-exchanges/src/main/java/com/gazbert/bxbot/exchanges/config/PairPrecisionConfigImpl.java

@@ -24,6 +24,7 @@
 package com.gazbert.bxbot.exchanges.config;
 
 import com.gazbert.bxbot.exchange.api.PairPrecisionConfig;
+import java.math.BigDecimal;
 import java.util.Map;
 
 /**
@@ -35,10 +36,18 @@ public class PairPrecisionConfigImpl implements PairPrecisionConfig {
 
   private final Map<String, Integer> prices;
   private final Map<String, Integer> volumes;
+  private final Map<String, BigDecimal> orderMins;
 
-  public PairPrecisionConfigImpl(Map<String, Integer> prices, Map<String, Integer> volumes) {
+  /**
+   * Default implementation of {@link PairPrecisionConfig} backed by {@link Map}s.
+   */
+  public PairPrecisionConfigImpl(
+      Map<String, Integer> prices,
+      Map<String, Integer> volumes,
+      Map<String, BigDecimal> orderMins) {
     this.prices = prices;
     this.volumes = volumes;
+    this.orderMins = orderMins;
   }
 
   @Override
@@ -50,4 +59,9 @@ public int getPricePrecision(String pair) {
   public int getVolumePrecision(String pair) {
     return volumes.getOrDefault(pair, -1);
   }
+
+  @Override
+  public BigDecimal getMinimalOrderVolume(String pair) {
+    return orderMins.getOrDefault(pair, null);
+  }
 }

bxbot-exchanges/src/test/java/com/gazbert/bxbot/exchanges/TestKrakenExchangeAdapter.java

@@ -1105,6 +1105,32 @@ public void testGettingExchangeBuyingFeeIsAsExpected() throws Exception {
     PowerMock.verifyAll();
   }
 
+  @Test
+  public void testGettingMinOrderVolumeIfAvailable() throws Exception {
+    PowerMock.replayAll();
+
+    final ExchangeAdapter exchangeAdapter = new KrakenExchangeAdapter();
+    exchangeAdapter.init(exchangeConfig);
+
+    final BigDecimal minimumOrderVolume = exchangeAdapter.getMinimumOrderVolume("XBTUSD");
+    assertEquals(0, minimumOrderVolume.compareTo(new BigDecimal("0.0001")));
+
+    PowerMock.verifyAll();
+  }
+
+  @Test
+  public void testGettingMinOrderVolumeIfNotAvailable() throws Exception {
+    PowerMock.replayAll();
+
+    final ExchangeAdapter exchangeAdapter = new KrakenExchangeAdapter();
+    exchangeAdapter.init(exchangeConfig);
+
+    final BigDecimal minimumOrderVolume = exchangeAdapter.getMinimumOrderVolume("XBTGBP.d");
+    assertNull(minimumOrderVolume);
+
+    PowerMock.verifyAll();
+  }
+
   // --------------------------------------------------------------------------
   //  Initialisation tests
   // --------------------------------------------------------------------------

bxbot-trading-api/src/main/java/com/gazbert/bxbot/trading/api/TradingApi.java

@@ -51,7 +51,7 @@ public interface TradingApi {
    * @since 1.0
    */
   default String getVersion() {
-    return "1.1";
+    return "1.2";
   }
 
   /**
@@ -215,6 +215,36 @@ BigDecimal getPercentageOfBuyOrderTakenForExchangeFee(String marketId)
   BigDecimal getPercentageOfSellOrderTakenForExchangeFee(String marketId)
       throws TradingApiException, ExchangeNetworkException;
 
+  /**
+   * Returns the minimum order volume for a given market id. The returned value is the order volume
+   * that a SELL or BUY order must at least have as amount of the base currency for the given
+   * currency pair.
+   *
+   * <p>Not all exchanges provide this information or not fully provide it (only for some
+   *  currency pairs)- you'll need to check the relevant Exchange Adapter code/Javadoc and online
+   *  Exchange API documentation.
+   *
+   * <p>If the exchange does not provide the information at all or for the current market id,
+   * a null value is returned.
+   *
+   * @param marketId the id of the market.
+   * @return the minimum order volume in base currency that is needed to place a Order as a {@link
+   *     BigDecimal}.
+   * @throws ExchangeNetworkException if a network error occurred trying to connect to the exchange.
+   *     This is implementation specific for each Exchange Adapter - see the documentation for the
+   *     adapter you are using. You could retry the API call, or exit from your Trading Strategy and
+   *     let the Trading Engine execute your Trading Strategy at the next trade cycle.
+   * @throws TradingApiException if the API call failed for any reason other than a network error.
+   *     This means something bad as happened; you would probably want to wrap this exception in a
+   *     StrategyException and let the Trading Engine shutdown the bot immediately to prevent
+   *     unexpected losses.
+   * @since 1.2
+   */
+  default BigDecimal getMinimumOrderVolume(String marketId)
+          throws TradingApiException, ExchangeNetworkException {
+    return null;
+  }
+
   /**
    * Returns the exchange Ticker a given market id.
    *

bxbot-trading-api/src/test/java/com/gazbert/bxbot/trading/api/TestTradingApi.java

@@ -41,7 +41,7 @@ class TestTradingApi {
   @Test
   void testGetVersion() {
     final MyApiImpl myApi = new MyApiImpl();
-    assertEquals("1.1", myApi.getVersion());
+    assertEquals("1.2", myApi.getVersion());
   }
 
   @Test
@@ -61,6 +61,13 @@ void testGetTicker() throws Exception {
     assertNull(ticker.getTimestamp());
   }
 
+  @Test
+  public void testGetMinOrder() throws Exception {
+    final MyApiImpl myApi = new MyApiImpl();
+    final BigDecimal minimumOrderVolume = myApi.getMinimumOrderVolume("market-123");
+    assertNull(minimumOrderVolume);
+  }
+
   /** Test class. */
   class MyApiImpl implements TradingApi {