Move FiatMoney object to core-util module.

core-util/src/main/java/org/signal/core/util/money/FiatMoney.java

@@ -0,0 +1,59 @@
+package org.signal.core.util.money;
+
+import androidx.annotation.NonNull;
+
+import java.math.BigDecimal;
+import java.text.NumberFormat;
+import java.util.Currency;
+
+public class FiatMoney {
+  private final BigDecimal amount;
+  private final Currency   currency;
+  private final long       timestamp;
+
+  public FiatMoney(@NonNull BigDecimal amount, @NonNull Currency currency) {
+    this(amount, currency, 0);
+  }
+
+  public FiatMoney(@NonNull BigDecimal amount, @NonNull Currency currency, long timestamp) {
+    this.amount    = amount;
+    this.currency  = currency;
+    this.timestamp = timestamp;
+  }
+
+  public @NonNull BigDecimal getAmount() {
+    return amount;
+  }
+
+  public @NonNull Currency getCurrency() {
+    return currency;
+  }
+
+  public long getTimestamp() {
+    return timestamp;
+  }
+
+  /**
+   * @return amount, rounded to the default fractional amount.
+   */
+  public @NonNull String getDefaultPrecisionString() {
+    NumberFormat formatter = NumberFormat.getInstance();
+    formatter.setMinimumFractionDigits(currency.getDefaultFractionDigits());
+    formatter.setGroupingUsed(false);
+
+    return formatter.format(amount);
+  }
+
+  /**
+   * @return amount, in smallest possible units (cents, yen, etc.)
+   */
+  public @NonNull String getMinimumUnitPrecisionString() {
+    NumberFormat formatter = NumberFormat.getInstance();
+    formatter.setMaximumFractionDigits(0);
+    formatter.setGroupingUsed(false);
+    BigDecimal multiplicand = BigDecimal.TEN.pow(currency.getDefaultFractionDigits());
+
+
+    return formatter.format(amount.multiply(multiplicand));
+  }
+}