1 files changed, 61 insertions, 0 deletions
diff --git a/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/billing/StatusHistory.java b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/billing/StatusHistory.java
new file mode 100644
index 00000000000..f0c7f806c8c
--- /dev/null
+++ b/controller-api/src/main/java/com/yahoo/vespa/hosted/controller/api/integration/billing/StatusHistory.java
@@ -0,0 +1,61 @@
+package com.yahoo.vespa.hosted.controller.api.integration.billing;
+
+import java.time.Clock;
+import java.time.ZoneOffset;
+import java.time.ZonedDateTime;
+import java.util.Map;
+import java.util.SortedMap;
+import java.util.TreeMap;
+
+/**
+ * @author ogronnesby
+ */
+public class StatusHistory {
+    SortedMap<ZonedDateTime, BillStatus> history;
+
+    public StatusHistory(SortedMap<ZonedDateTime, BillStatus> history) {
+        // Validate the given history
+        var iter = history.values().iterator();
+        BillStatus next  = iter.hasNext() ? iter.next() : null;
+        while (iter.hasNext()) {
+            var current = next;
+            next = iter.next();
+            if (! validateStatus(current, next)) {
+                throw new IllegalArgumentException("Invalid transition from " + current + " to " + next);
+            }
+        }
+
+        this.history = history;
+    }
+
+    public static StatusHistory open(Clock clock) {
+        var now = clock.instant().atZone(ZoneOffset.UTC);
+        return new StatusHistory(
+                new TreeMap<>(Map.of(now, BillStatus.OPEN))
+        );
+    }
+
+    public BillStatus current() {
+        return history.get(history.lastKey());
+    }
+
+    public SortedMap<ZonedDateTime, BillStatus> getHistory() {
+        return history;
+    }
+
+    public void checkValidTransition(BillStatus newStatus) {
+        if (! validateStatus(current(), newStatus)) {
+            throw new IllegalArgumentException("Invalid transition from " + current() + " to " + newStatus);
+        }
+    }
+
+    private static boolean validateStatus(BillStatus current, BillStatus newStatus) {
+        return switch(current) {
+            case OPEN -> true;
+            case FROZEN -> newStatus != BillStatus.OPEN; // This could be subject to change.
+            case CLOSED -> newStatus == BillStatus.CLOSED;
+            case VOID -> newStatus == BillStatus.VOID;
+        };
+    }
+
+}