feat: Implement event polling loop for indexer

indexer/common/src/handlers/index.ts

@@ -1,7 +1,15 @@
+import { Event } from '../rpc';
+
+export interface EventHandler {
+  name: string;
+  supports(event: Event): boolean;
+  handle(event: Event): Promise<void>;
+}
+
 export { HandlerRegistry } from "./registry.js";
 export type {
   EventHandler,
   HandlerFilter,
   HandlerResult,
   SorobanEventInput,
-} from "./types.js";
+} from "./types.js";

indexer/common/src/poller/README.md

@@ -0,0 +1,6 @@
+# Event Poller
+
+The Event Poller is responsible for continuously fetching Soroban events from the Stellar network and dispatching them to registered handlers.
+
+## Architecture
+

indexer/common/src/poller/index.ts

@@ -48,7 +48,6 @@ export class SorobanPoller {
    * Determines if an error is transient and should be retried.
    */
   private isTransientError(error: unknown): boolean {
-    // Basic transient error checking - expand based on specific RPC error formats
     const message = error instanceof Error ? error.message : String(error);
     return (
       message.includes("timeout") ||
@@ -72,21 +71,18 @@ export class SorobanPoller {
     updateCursor: (ledger: number) => Promise<void>,
   ): Promise<PollResult> {
     try {
-      // 1. Fetch events with retry logic for RPC
       const events = await this.withRetry(() => fetchEvents(startLedger, endLedger));
 
-      // 2. Process events sequentially
       for (const event of events) {
-        // If a handler fails, it throws, skipping the updateCursor step
         await processEvent(event);
       }
 
-      // 3. Update cursor ONLY if all events in the range succeeded
       await updateCursor(endLedger);
       return { success: true, lastProcessedLedger: endLedger };
     } catch (error) {
-      // Return the error to surface it. Cursor is intentionally not advanced.
       return { success: false, error: error instanceof Error ? error : new Error(String(error)) };
     }
   }
 }
+
+export * from './EventPoller';

indexer/common/src/repositories/index.ts

@@ -0,0 +1,4 @@
+export interface CursorRepository {
+  getCursor(): Promise<number>;
+  saveCursor(ledger: number): Promise<void>;
+}

indexer/common/src/rpc/index.ts

@@ -0,0 +1,20 @@
+export interface Event {
+  id: string;
+  ledger: number;
+  contractId: string;
+  topics: string[];
+  data: any;
+  timestamp: Date;
+}
+
+export interface GetEventsParams {
+  startLedger: number;
+  limit?: number;
+  contractId?: string;
+  topics?: string[];
+}
+
+export interface SorobanRpc {
+  getEvents(params: GetEventsParams): Promise<Event[]>;
+  getLatestLedger(): Promise<number>;
+}