move bitcoinunit to drongo

src/main/java/com/sparrowwallet/drongo/BitcoinUnit.java

@@ -0,0 +1,50 @@
+package com.sparrowwallet.drongo;
+
+import com.sparrowwallet.drongo.protocol.Transaction;
+
+public enum BitcoinUnit {
+    BTC("BTC") {
+        @Override
+        public long getSatsValue(double unitValue) {
+            return (long)(unitValue * Transaction.SATOSHIS_PER_BITCOIN);
+        }
+
+        public double getValue(long satsValue) {
+            return (double)satsValue / Transaction.SATOSHIS_PER_BITCOIN;
+        }
+    },
+    SATOSHIS("sats") {
+        @Override
+        public long getSatsValue(double unitValue) {
+            return (long)unitValue;
+        }
+
+        public double getValue(long satsValue) {
+            return (double)satsValue;
+        }
+    };
+
+    private final String label;
+
+    BitcoinUnit(String label) {
+        this.label = label;
+    }
+
+    public String getLabel() {
+        return label;
+    }
+
+    public abstract long getSatsValue(double unitValue);
+
+    public abstract double getValue(long satsValue);
+
+    public double convertFrom(double fromValue, BitcoinUnit fromUnit) {
+        long satsValue = fromUnit.getSatsValue(fromValue);
+        return getValue(satsValue);
+    }
+
+    @Override
+    public String toString() {
+        return label;
+    }
+}