WIP message-delivery-method-web-push

services/message-delivery-method-web-push/src/serviceSeqTracker.ts

@@ -0,0 +1,38 @@
+import { serviceDb, type ServiceDoc } from "./dbs";
+
+const SERVICE_DOC_ID = "_local/service:message-delivery-method-web-push";
+
+export class ServiceSeqTracker {
+  private serviceDoc: ServiceDoc;
+
+  async getSince() {
+    this.serviceDoc = await serviceDb.get(SERVICE_DOC_ID).catch((error) => {
+      if (error.name === "not_found") {
+        return {
+          _id: SERVICE_DOC_ID,
+          lastSeq: "0",
+        };
+      }
+      throw error; // Re-throw other errors
+    });
+
+    this.serviceDoc.lastSeq = 0;
+
+    return this.serviceDoc.lastSeq;
+  }
+
+  checkNextSeq(seq: number | string) {
+    const next = parseInt(seq as string, 10);
+    const current = parseInt(this.serviceDoc.lastSeq as string, 10);
+    if (next < current) {
+      throw new Error(
+        `Sequence number is too old: ${seq} (${next} < ${current})`,
+      );
+    }
+  }
+
+  saveSeq(seq: number | string) {
+    this.serviceDoc.lastSeq = seq;
+    return serviceDb.put(this.serviceDoc);
+  }
+}