Add Coal Cents economy

CoalGov/src/main/java/com/librewiki/coalgov/util/CoalMoney.java

@@ -0,0 +1,69 @@
+package com.librewiki.coalgov.util;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+
+public final class CoalMoney {
+    public static final long CENTS_PER_COAL = 100L;
+
+    private CoalMoney() {
+    }
+
+    public static long fromCoal(double coal) {
+        return Math.round(coal * CENTS_PER_COAL);
+    }
+
+    public static long fromCoalConfig(double coal) {
+        return Math.max(0L, fromCoal(coal));
+    }
+
+    public static String format(long cents) {
+        boolean negative = cents < 0L;
+        long absolute = Math.abs(cents);
+        long coal = absolute / CENTS_PER_COAL;
+        long coalCents = absolute % CENTS_PER_COAL;
+        String prefix = negative ? "-" : "";
+        if (coal > 0L && coalCents > 0L) {
+            return prefix + coal + " coal " + coalCents + "cc";
+        }
+        if (coal > 0L) {
+            return prefix + coal + " coal";
+        }
+        return prefix + coalCents + "cc";
+    }
+
+    public static long parsePositive(String raw) {
+        long amount = parse(raw);
+        return amount > 0L ? amount : -1L;
+    }
+
+    public static long parse(String raw) {
+        if (raw == null) {
+            return -1L;
+        }
+        String normalized = raw.trim().toLowerCase();
+        if (normalized.isEmpty() || normalized.startsWith("-")) {
+            return -1L;
+        }
+        try {
+            if (normalized.endsWith("cc")) {
+                return Long.parseLong(normalized.substring(0, normalized.length() - 2));
+            }
+            if (normalized.endsWith("c")) {
+                return parseDecimalCoal(normalized.substring(0, normalized.length() - 1));
+            }
+            if (normalized.endsWith("coal")) {
+                return parseDecimalCoal(normalized.substring(0, normalized.length() - 4));
+            }
+            return parseDecimalCoal(normalized);
+        } catch (ArithmeticException | NumberFormatException exception) {
+            return -1L;
+        }
+    }
+
+    private static long parseDecimalCoal(String raw) {
+        BigDecimal coal = new BigDecimal(raw.trim());
+        BigDecimal cents = coal.multiply(BigDecimal.valueOf(CENTS_PER_COAL));
+        return cents.setScale(0, RoundingMode.HALF_UP).longValueExact();
+    }
+}