feat: abstract OutboxModel into RequestRouter

packages/system/src/request-router.ts

@@ -0,0 +1,76 @@
+import { NostrEvent, ReqFilter } from "./nostr";
+import { FlatReqFilter } from "./query-optimizer";
+
+export interface RelayTaggedFilter {
+  relay: string;
+  filter: ReqFilter;
+}
+
+export interface RelayTaggedFlatFilters {
+  relay: string;
+  filters: Array<FlatReqFilter>;
+}
+
+export interface RelayTaggedFilters {
+  relay: string;
+  filters: Array<ReqFilter>;
+}
+
+/**
+ * Request router managed splitting of requests to one or more relays, and which relay to send events to.
+ */
+export interface RequestRouter {
+  /**
+   * Pick relays to send an event to
+   * @param ev The reply event to send
+   * @param system Nostr system interface
+   * @param pickN Number of relays to pick per recipient
+   * @returns
+   */
+  forReply(ev: NostrEvent, pickN?: number): Promise<Array<string>>;
+
+  /**
+   * Split a request filter to one or more relays.
+   * @param filter Filter to split
+   * @param pickN Number of relays to pick
+   * @returns
+   */
+  forRequest(filter: ReqFilter, pickN?: number): Array<RelayTaggedFilter>;
+
+  /**
+   * Split a request filter to one or more relays.
+   * @param filter Filters to split
+   * @param pickN Number of relays to pick
+   * @returns
+   */
+  forFlatRequest(filter: Array<FlatReqFilter>, pickN?: number): Array<RelayTaggedFlatFilters>;
+}
+
+export abstract class BaseRequestRouter implements RequestRouter {
+  abstract forReply(ev: NostrEvent, pickN?: number): Promise<Array<string>>;
+  abstract forRequest(filter: ReqFilter, pickN?: number): Array<RelayTaggedFilter>;
+  abstract forFlatRequest(filter: FlatReqFilter[], pickN?: number): Array<RelayTaggedFlatFilters>;
+
+  forAllRequest(filters: Array<ReqFilter>) {
+    const allSplit = filters
+      .map(a => this.forRequest(a))
+      .reduce((acc, v) => {
+        for (const vn of v) {
+          const existing = acc.get(vn.relay);
+          if (existing) {
+            existing.push(vn.filter);
+          } else {
+            acc.set(vn.relay, [vn.filter]);
+          }
+        }
+        return acc;
+      }, new Map<string, Array<ReqFilter>>());
+
+    return [...allSplit.entries()].map(([k, v]) => {
+      return {
+        relay: k,
+        filters: v,
+      } as RelayTaggedFilters;
+    });
+  }
+}